Printable Version of Topic

Click here to view this topic in its original format

Unmanned Spaceflight.com _ Cometary and Asteroid Missions _ INCOMING!

Posted by: Paolo Oct 6 2008, 07:53 PM

no sone seems to have noticed http://cfa-www.harvard.edu/mpec/K08/K08T50.html yet

Posted by: climber Oct 6 2008, 07:57 PM

Too much info kill the info! Where do we have to look? I've seen something will hit the atmosphere tonigth over Sudan, correct?

Posted by: ugordan Oct 6 2008, 07:58 PM

Whoa! Any chance of organizing a crash observing campain from ground or even orbit?

Posted by: Holder of the Two Leashes Oct 6 2008, 07:58 PM

An asteroid... well, really a meteor, is now predicted to hit the atmosphere.

First time I know we have had advanced warning on a single natural object.

http://www.cfa.harvard.edu/mpec/K08/K08T50.html

Quote: "Steve Chesley (JPL) reports that atmospheric entry will occur on 2008
Oct 07 0246 UTC over northern Sudan."

Posted by: charborob Oct 6 2008, 08:00 PM

Any idea how big is this rock?

Posted by: Juramike Oct 6 2008, 08:03 PM

QUOTE
The absolute magnitude indicates that the
object will not survive passage through the atmosphere.

Steve Chesley (JPL) reports that atmospheric entry will occur on 2008
Oct 07 0246 UTC over northern Sudan.


Don't sell all your stocks yet, looks like we'll live to see another day....


Posted by: imipak Oct 6 2008, 08:05 PM

Is this the first time a fireball's been predicted in advance? I was very interested in meteor observing for a few years and read a lot of stuff (it seems so in retrospect, anyway) but I don't recall ever hearing of an event like this.

For those of us who can't interpret the MPEC data or ephemerides, what does the absolute magnitude mentioned tell us about the size of this object?

Posted by: TheChemist Oct 6 2008, 08:12 PM

Hey guys, don't just tear your swimming suits apart. laugh.gif

The link says that it will disintegrate in the atmosphere, as Juramike already pointed in the duplicate thread.

Why do you scare us with no reason ? huh.gif

THANKS FOR POINTING OUT THE DUPLICATE - BOTH TOPICS NOW MERGED -Admin

You 're welcome !

Posted by: Holder of the Two Leashes Oct 6 2008, 08:19 PM

There have been at least three revisions in the last hour, a lot of people are looking at this object.

Hard to say, but now it looks like it may be a near miss, by about a thousand miles. The latest Mpec
doesn't state whether an impact is still expected.

The absolute magnitude indicates a size of two to seven meters.

Gosh, I just mixed english and metric units in the same post.

Edit: Five meters big at most, more likely two to three. Absolute magnitude of 30.4

Posted by: climber Oct 6 2008, 08:45 PM

30.4!!! Gona be visible over the horizont!

Posted by: Holder of the Two Leashes Oct 6 2008, 08:46 PM

Space.com is now reporting the story, and says atmospheric entry is expected.

http://www.space.com/scienceastronomy/081006-asteroid-sudan.html

The report also emphatically states that it will be destroyed at altitude, and doesn't pose a significant danger.

True enough... if it's not a nickle-iron.

Posted by: SFJCody Oct 6 2008, 09:30 PM

I wonder if it can be imaged from orbit during entry a la Mars Phoenix? Probably too much uncertainty.

Posted by: Shaka Oct 6 2008, 09:31 PM

From TPS:

QUOTE
The meteor is expected to be visible from eastern Africa as an extremely bright fireball traveling rapidly across the sky from northeast to southwest. The object is expected to enter the atmosphere over northern Sudan at a shallow angle.

"We're eager for observations from astronomers near the asteroid's approach path. We really hope that someone will manage to photograph it," said Williams.


Shoot!
My SR71 is in maintenance, or I'd be over there like a shot.


Posted by: ngunn Oct 6 2008, 09:44 PM

It may be small and harmless, but for me knowing it is on the way represents a huge psychological milestone. It is a great achievement by those watchers of the skies who search for these objects that the fall of a meteorite need no longer take us by surprise. It feels as though in one more small way we have 'grown up' as a species. If it had been a bit larger and aimed at a suburb near you, you would already have heard when to head for the cellar (and felt quite safe out of doors until a few seconds beforehand).

Posted by: SFJCody Oct 6 2008, 09:44 PM

I guess once LSST and PanSTARRS come online we'll get these kind of alerts fairly regularly. I imagine it will change the public perception of 'asteroid impact predicted!' headlines a lot. People will go from thinking of the end of the world to thinking of photo ops + a mad scramble for very valuable rocks.

Posted by: Holder of the Two Leashes Oct 6 2008, 10:39 PM

Man, I've never seen anything quite like this. Twenty observatories have turned in collectively nearly 200 observations of this object, and the Minor Planet Center is issuing updates about every fifteen minutes. This little rock is definitely getting it's share of attention.

A fair number of professional observatories seem to be poised to follow this thing almost into the ground.

Posted by: Shaka Oct 6 2008, 10:53 PM

LINKS, man! Give us links, HTL!

Posted by: Holder of the Two Leashes Oct 6 2008, 10:59 PM

http://www.cfa.harvard.edu/mpec/RecentMPECs.html

Anything with 2008 TC3. Most recent on top.

BTW: "HTL"? Whazzat?

Posted by: Juramike Oct 6 2008, 11:31 PM

I guess they won't be seeing it from here (bad luck!): http://www.ireport.com/docs/DOC-104761

Posted by: dmuller Oct 6 2008, 11:38 PM

If this thing is coming in shallow from NE to SW then it should be visible in Alexandria, Cairo, Egyptian tourist destinations, maybe as far down as Khartoum ... so there is some chance to get it on film. If I get my timzones right, it will be night then. Anybody's got a groundtrack?

Posted by: volcanopele Oct 6 2008, 11:46 PM

hmm, I think my Celestia copy needs fixing. Using the most up-to-date orbital parameters, I get a miss distance of 5,850 km over North Africa.

Posted by: Fran Ontanaya Oct 6 2008, 11:55 PM

The NEO Program lists it as a close approach at 0.02 LD. That's under 8000 km.

http://neo.jpl.nasa.gov/ca/

It was briefly in the Recently Observed list of Impact Risk, with dates beyond 2080, but it isn't anymore.

Posted by: Holder of the Two Leashes Oct 6 2008, 11:59 PM

Used a reliable horizon calculator to come up with some figures. Provided you have a clear horizon.

When it is at 20 miles altitude (32 km), under perfect seeing, it should be visible for over 400 miles (640 km) in every direction. It will probably survive down to this far.

It should also be glowing brightly at 50 miles altitude (80 km), and at that point be seen for at least 650 miles (1000 km).

Posted by: dmuller Oct 7 2008, 12:47 AM

Emily pointed to a beautiful simulation of the event at http://orbit.psi.edu/?q=node/22

Posted by: elakdawalla Oct 7 2008, 12:56 AM

By the way, discussion on Minor Planets Mailing List (which is where I got the link to that simulation) indicates that the press release wasn't correct when it described the flight direction -- it's not coming in from northeast, it's coming in more from the west, basically over the Sahara.

--Emily

Posted by: volcanopele Oct 7 2008, 01:00 AM

I agree, that's the direction I got from my simulation in Celestia.

Posted by: Holder of the Two Leashes Oct 7 2008, 01:00 AM

QUOTE (Shaka @ Oct 6 2008, 06:48 PM) *
Er.. thanks, HTL. (If I wrote Holder of the Two Leashes every time, my posts would get trashed for wasting bandwidth.)
When you referred to loads of observatories, I sort of anticipated a CometCam live picture.
Ephemera are nice, but not very sexy. blink.gif


My bad. I'm one of the very few people who could even get a little excited over watching raw positional information pouring in.

Here is one real picture: http://www.skyandtelescope.com/

I'm pretty sure just about every other pic of 2008 TC3 looks like that at this point.

In a couple of hours, we may be getting some much more spectacular shots.

A lot of people will shorten my title to "Holder", and I'll answer to that. The dogs don't mind, either. Actually, they don't have a clue.

Posted by: nprev Oct 7 2008, 01:19 AM

"Major Bolide Forecast Tonight; No Damage Expected" (S&T from Holder's link.)


What a headline!!! What a time to be alive!!! Nigel is absolutely right; this is marvelous, this is an expansion of our general situational awareness. We've always grown thereby through such things.

Posted by: Hungry4info Oct 7 2008, 01:39 AM

If I did the math right, just a few more minutes until impact.

Two ways to look at it.

-> Small asteroid hits planet. No damage done.
-> Comparatively HUGE freaking Planet hits an asteroid, obliterating it. Owned.

Either way, the asteroid will be one with the planet. I look forward to pictures (I hope we get some).

Posted by: claurel Oct 7 2008, 01:44 AM

Here's a Celestia simulation of 2008 TC3's entry into Earth's atmopshere:

http://www.youtube.com/watch?v=4FW3oaZgCz0

The green circle indicates the region where the asteroid is visible over the horizon. The trajectory of 2008 TC3 was taken from HORIZONS (about an hour ago.)

--Chris

Posted by: dmuller Oct 7 2008, 01:58 AM

QUOTE (claurel @ Oct 7 2008, 11:44 AM) *
Here's a Celestia simulation of 2008 TC3's entry into Earth's atmopshere:
http://www.youtube.com/watch?v=4FW3oaZgCz0

Judging from that clip, 2008TC3 is gonna come down at / explode over the Nubian Desert, somewhere in the center of the triangle made up by the cities Wadi Halfa, Atbara & Port Sudan. Man, I flew over there some years ago!

EDIT: The Horizons system is very slow ... must have a lot of traffic!

Posted by: Hungry4info Oct 7 2008, 02:00 AM

Going to? Has it already? Or did I again get my math wrong with time conversions? Lol. sad.gif

Posted by: tedstryk Oct 7 2008, 02:23 AM

QUOTE (Hungry4info @ Oct 7 2008, 03:00 AM) *
Going to? Has it already? Or did I again get my math wrong with time conversions? Lol. sad.gif


The time given was 10:46 EDT (my time zone). It is now 10:19 EDT. I plan to go outside....we are far too far away, but I figure that just in case it has some smaller cousins, it couldn't hurt to go take a look.

Posted by: claurel Oct 7 2008, 02:31 AM

Here's a Celestia simulation of 2008 TC3's entry into Earth's atmopshere:

http://www.youtube.com/watch?v=4FW3oaZgCz0

The green circle indicates the region where the asteroid is visible over the horizon. The trajectory of 2008 TC3 was taken from HORIZONS (about an hour ago.)

This video gives the view from 2008 TC3:
http://www.youtube.com/watch?v=Cxa2PUluqVU
(Itokawa is standing in for 2008 TC3.)

The Celestia add-on used for both simulations is here: http://www.shatters.net/~claurel/celestia/asteroids/2008tc3.zip
It requires a very recent version of Celestia, however; I'll make a more widely usable available post-impact.

--Chris

Posted by: Holder of the Two Leashes Oct 7 2008, 02:32 AM

I will take the liberty of posting this quote from Emily's blog over at Planetary.org:

"Thanks to Ron Baalke for posting the following, from JPL asteroid scientist Paul Chodas, on the Minor Planets Mailing List:
Update - 6:45 PM PDT (1 hour prior to atmospheric entry)

Since its discovery barely a day ago, 2008 TC3 has been observed extensively by astronomers around the world, and as a result, our orbit predictions have become very precise. We estimate that this object will enter the Earth's atmosphere at around 2:45:28 UTC and reach maximum deceleration around 2:45:54 UTC at an altitude of about 14 km. These times are uncertain by +/- 15 seconds or so. The time at which any fragments might reach the ground depends a great deal on the physical properties of the object, but should be around 2:46:20 UTC +/- 40 seconds."


Well, the asteroid has passed into the earth's shadow, so telescope observations are at an end now.

Just waiting for the fireworks ...

Posted by: volcanopele Oct 7 2008, 02:40 AM

As 2008 TC3 passes over Niger, let's us have a moment of silence for this little asteroid that could. 2008 TC3 started life when it was freed from sub-surface of a larger asteroid. For millions of years it wondered. Unloved. Uncared for. Unnoticed. Now, as it's end approachs, in a fiery burst of light, people care for this little guy.

God speed little doodle. sad.gif

Now at 1,900 km above north africa.

Posted by: stevesliva Oct 7 2008, 02:50 AM

And the earth emits a contented belch. wink.gif

Posted by: deglr6328 Oct 7 2008, 02:50 AM

Well that was that....it would seem. Looks like we're all still here! smile.gif I doubt anyone caught it. It hit news outlets so late in the day and it's almost 3am there. Even with seemingly everybody these days having a cameraphone on them... still doubtful.

Posted by: volcanopele Oct 7 2008, 02:51 AM

At last check, Earth still here.

2008 TC3...not so much

Posted by: deglr6328 Oct 7 2008, 02:53 AM

my mistake, nearly 5am local time rather than 3 UTC.

Posted by: dmuller Oct 7 2008, 02:57 AM

I can confirm that Australia is still here as well at 1:55 PM Sydney summer time rolleyes.gif ... and I couldnt even put up a realtime simulation (I was 4 minutes late) [at least the decision whether to use Earth Received Time or Space Object Event Time would have been easy this time around]. Just imagine this had been a very dark 'biggie' - the stock markets wouldn't even had time to crash further

Posted by: Bobby Oct 7 2008, 03:48 AM

Any Videos or Photos of the event yet???

Posted by: deglr6328 Oct 7 2008, 03:57 AM

here you go!

------------------*

is breathtaking, no? laugh.gif

Posted by: jumpjack Oct 7 2008, 07:49 AM

QUOTE (volcanopele @ Oct 7 2008, 04:40 AM) *
As 2008 TC3 passes over Niger, let's us have a moment of silence for this little asteroid that could. 2008 TC3 started life when it was freed from sub-surface of a larger asteroid.

mmmh....
hope mother-asteroid is not chasing her daughter.... laugh.gif

Posted by: ugordan Oct 7 2008, 08:33 AM

http://spaceweather.com/ has news about a possibly positive sighting (from a plane at roughly 750 nm away) of a flash at around the expected time of impact.

Posted by: deglr6328 Oct 7 2008, 08:48 AM

Well we can at least say that it wasn't CATASTROPHICALLY larger than predicted! smile.gif Also the nearest ISS pass over the area is way off at the time of expected entry so there was no chance of observation from there...

http://www.heavens-above.com/gtrack.asp?lat=21.28937&lng=28.125&alt=0&loc=Unspecified&TZ=CET&Date=39728.3487230956&satid=25544

http://earthquake.usgs.gov/eqcenter/recenteqsww/Maps/region/Africa.php

Posted by: volcanopele Oct 7 2008, 09:20 AM

Surprised I haven't seen any word of this from Aswan or Abu Simbel in southern Egypt. These would seem like the likeliest places where word/images/movies would have been returned and posted on the net.

Posted by: Fran Ontanaya Oct 7 2008, 09:49 AM

A small piece of info about spectra: http://tech.groups.yahoo.com/group/mpml/message/21169

Posted by: djellison Oct 7 2008, 09:57 AM

That series of 10s exposures showing the thing 'speeding up' as it were - that's one of those rare astronomical observations that puts the Earth, the solar system, and the things flying around it into sharp '3d' context.

Doug

Posted by: Tman Oct 7 2008, 10:27 AM

Maybe an indirect sighting of a webcam at El Grouna (middle east in Egypt): http://home.pages.at/thie/Asteroid/

In a German meteorite http://www.jgr-apolda.eu/index.php?topic=2960.0 had someone contact to people in Egypt and they say it was great (more will be come I guess - the guy in the forum is sleeping now). Sadly Sadly their camera went off in waiting of the event and it was too late to start it again sad.gif

Posted by: PhilCo126 Oct 7 2008, 05:06 PM

Based on 26 optical observations, the probability of impact is between 99.8 percent and 100 percent,... so this thing dropped in the sea?

Posted by: centsworth_II Oct 7 2008, 05:25 PM

QUOTE (PhilCo126 @ Oct 7 2008, 01:06 PM) *
Based on 26 optical observations, the probability of impact is between 99.8 percent and 100 percent,...

"Impact" could just mean impact with the atmosphere. Is there any indication that the original estimation that no impactor would reach the ground (or sea) was wrong?

Posted by: PhilCo126 Oct 7 2008, 05:31 PM

O.K. impact with Earth's atmosphere was for sure, but I guess there was some chance this meteorite ended up somewhere in the desert?
As the meteor appeared at nighttime it was spotted by an airliner... so maybe something made it through the atmosphere???
huh.gif

Posted by: tedstryk Oct 7 2008, 06:29 PM

QUOTE (PhilCo126 @ Oct 7 2008, 06:31 PM) *
As the meteor appeared at nighttime it was spotted by an airliner... so maybe something made it through the atmosphere???
huh.gif


What in the world does being spotted from an airliner have to do with reaching the ground?

Posted by: ElkGroveDan Oct 7 2008, 08:20 PM

QUOTE (tedstryk @ Oct 7 2008, 11:29 AM) *
What in the world does being spotted from an airliner have to do with reaching the ground?


Maybe the airliner spotted it streaking by BELOW tongue.gif

Posted by: ngunn Oct 7 2008, 09:45 PM

Spaceweather.com now has an update on an infrasound recording of the event.

Posted by: dmuller Oct 8 2008, 02:36 AM

well it did get some coverage in Australia: headline at http://www.abc.net.au/news



unsure.gif

Posted by: jumpjack Oct 8 2008, 06:38 AM

No images/video after more than 24 hours. I guess it means none took any shot of the event? mad.gif

Posted by: PhilCo126 Oct 8 2008, 10:36 AM

Other than the webcam images in the German forum and this press article, nothing special I'm afraid...
http://www.abc.net.au/news/stories/2008/10/08/2385111.htm
huh.gif

Posted by: jumpjack Oct 8 2008, 02:09 PM

I found some guys who actually have SEEN the object!
http://www.chileastro.com/?p=329

RAW data (???): http://www.christen-eagle.com/slooh/2008_tc3/index.htm

Slooh forum: http://forum.slooh.com/

Slooh blog post on 2008 TC£ with links: http://www.slooh.com/blog/2008-tc3-a-serendipitous-event/

2 hours before atmosphere entry:


Slooh forum thread about raw data: http://forum.slooh.com/viewtopic.php?t=5936&start=0&postdays=0&postorder=asc&highlight=

Slooh forum thread with images: http://forum.slooh.com/viewtopic.php?t=5935&start=0&postdays=0&postorder=asc&highlight=

00:40 animation:

Posted by: jumpjack Oct 8 2008, 02:43 PM

Standalone Windows .fit viewer:
http://www.nrao.edu/software/fitsview/fvwin.html

But I can't find .fit data around impact time! They end at 02.15!!

And I can't understand how to register to those forums...???

Posted by: Fran Ontanaya Oct 8 2008, 06:26 PM

Meteosat 8 catched it! (see SpaceWeather.com)


Posted by: ugordan Oct 8 2008, 06:33 PM

Nice! I was hoping some satellite would catch it or at least the infrared afterglow.

Posted by: Tman Oct 9 2008, 10:37 AM

Another processed image of Meteosat http://www.eumetsat.int/groups/public/documents/image/img_homepage_asteroid_2008.jpg

Posted by: jumpjack Oct 9 2008, 01:04 PM

Another incoming?!?
http://remanzacco.blogspot.com/2008/10/fly-by-of-apollo-type-asteroid-2008.html

Posted by: jumpjack Oct 9 2008, 01:06 PM

2008 TC3 just 1 hour before reentry, while entering Earth shadow:
http://www.minorplanets.org/OLS/2008_TC3/


Another picture before impact, from Canaries islands:
http://www.inaf.it/news_cartella/asteroide-2008-tc3-tng

Posted by: djellison Oct 9 2008, 01:06 PM

QUOTE (jumpjack @ Oct 9 2008, 02:04 PM) *
Another incoming?!?



Errr, NO. Very no.

"008 QS11 (classified as an Apollo-type NEO) will reach on 02 October 2008 the minimum distance from Earth (0.02767 A.U.) "

That's about 4 million km, or 10 times the earth-moon distance.

Posted by: jumpjack Oct 9 2008, 01:21 PM

Full inline quote removed - Admin

according to an italian forum, MAYBE a page appeared on NASA site predicting a 1:79 chance to hit Earth (or enter atmosphere??), but page would be no more visible...

But actually I think somebody thaught that "REMOVED" from risk list means "HIDDEN", although it means "NO MORE RISKFUL"...

Posted by: PhilCo126 Oct 9 2008, 06:09 PM

True video of 2008 TC3 ??? ??? ??? huh.gif

http://www.youtube.com/watch?v=WPWqB5Zo53M&feature=related


Posted by: ugordan Oct 9 2008, 06:12 PM

QUOTE (PhilCo126 @ Oct 9 2008, 08:09 PM) *
True video of 2008 TC3 ??? ??? ??? huh.gif

I don't buy it.

Posted by: djellison Oct 9 2008, 06:14 PM

Nor do I - that's just your average meteor streak.

Posted by: deglr6328 Oct 9 2008, 07:53 PM

on the NIGHT OF entry I was looking at random youtube videos of meteorites and this was on there as another video name then. So, def fake.

Posted by: Tman Oct 10 2008, 07:13 AM

Some analyses of the Meteosat images http://www.eumetsat.int/Home/Main/Media/Features/707785?l=en

Posted by: ugordan Oct 10 2008, 07:35 AM

I haven't seen their ideas on whether the Meteosat images captured the streaking bolide or the fading fireball after disintegration. The fact IR and visible channel hotspot locations don't match, it's plausible the IR frame was captured a couple of seconds earlier with the "RGB" channels capturing the static fireball.
Thoughts?

Posted by: PhilCo126 Oct 10 2008, 06:56 PM

Looks like our doubts on the 2008 TC3 video were correct:

http://www.astronomy.com/asy/default.aspx?c=a&id=7468

Posted by: jumpjack Oct 11 2008, 08:49 AM

QUOTE (PhilCo126 @ Oct 10 2008, 08:56 PM) *
Looks like our doubts on the 2008 TC3 video were correct:

http://www.astronomy.com/asy/default.aspx?c=a&id=7468

what?!?

Posted by: Tman Oct 11 2008, 09:15 AM

Nice GIF of the fast gyrating http://www.skyandtelescope.com/community/skyblog/newsblog/30686199.html

QUOTE
...telescopic observations show that 2008 TC3 was gyrating wildly before it hit. According to Czech asteroid specialist Petr Pravec, it was "definitely a tumbler." His analysis reveals two distinct periods of 49 and 98 seconds long. One is probably due to rotation and the other to spin-axis precession, but he can't tell yet which is which. But he notes that this ranks (or ranked!) as one of the three fastest-spinning asteroids known.


Another one here http://news.astronomie.info/ai.php/headlines/200810020

Posted by: Tman Oct 11 2008, 04:11 PM

That's by far a better one to trick with it - wow!

Today's APOD of a huge bolide http://antwrp.gsfc.nasa.gov/apod/ap081011.html

QUOTE
Astronomy enthusiast Howard Edin reports that he was looking in the opposite direction at the time, but saw the whole observing field light up and at first thought someone had turned on their car headlights.

Posted by: dilo Oct 11 2008, 05:49 PM

Really impressive and beatiful lucky picture! ohmy.gif

Posted by: jumpjack Oct 11 2008, 06:02 PM

QUOTE (Tman @ Oct 11 2008, 06:11 PM) *
That's by far a better one to trick with it - wow!

Today's APOD of a huge bolide http://antwrp.gsfc.nasa.gov/apod/ap081011.html

it's NOT 2008 TC3, so what?!? huh.gif

Posted by: claurel Oct 11 2008, 06:46 PM

While hoping and waiting for some images of the bolide, I created another visualization of the trajectory and ground track of 2008 TC3 right before atmospheric entry. The trajectory comes from a HORIZONS integration on Oct. 6 (I don't think there have been any subsequent refinements since then.) The trajectory is marked off in minutes.


Posted by: Spin0 Oct 11 2008, 07:59 PM

QUOTE (ugordan @ Oct 10 2008, 10:35 AM) *
I haven't seen their ideas on whether the Meteosat images captured the streaking bolide or the fading fireball after disintegration. The fact IR and visible channel hotspot locations don't match, it's plausible the IR frame was captured a couple of seconds earlier with the "RGB" channels capturing the static fireball.
Thoughts?

Could it be possible that the explosion had a highspeed directional jet of hot gas and dust? The explosion would be visible in visible channels and the hot jet-burst in infrared. And as the burst is very high-speed maybe it explains the 23 km distance between the two hotspots.

Last year Sandia Labs made new computer models and simulations regarding Tunguska explosion. Their simulations showed a higly directional high-speed jet of hot gas and dust emanating from an exploding asteroid when it explodes in the atmosphere. Here's a link to their news (with cool animations!): http://www.sandia.gov/news/resources/releases/2007/asteroid.html

QUOTE
Simulations show that the material of an incoming asteroid is compressed by the increasing resistance of Earth’s atmosphere. As it penetrates deeper, the more and more resistant atmospheric wall causes it to explode as an airburst that precipitates the downward flow of heated gas.




Posted by: ugordan Oct 11 2008, 08:02 PM

QUOTE (Spin0 @ Oct 11 2008, 09:59 PM) *
Could it be possible that the explosion had a highspeed directional jet of hot gas and dust? The explosion would be visible in visible channels and the hot jet-burst in infrared.

Why wouldn't the explosion be visible in the infrared as well?

Posted by: DDAVIS Oct 11 2008, 09:58 PM

I created another visualization of the trajectory and ground track of 2008 TC3 right before atmospheric entry.

What would the entry angle have been?

Don

Posted by: claurel Oct 12 2008, 04:51 AM

QUOTE (DDAVIS @ Oct 11 2008, 02:58 PM) *
What would the entry angle have been?


Using the HORIZONS trajectory, I calculated it to be just over 19 degrees above the horizon plane within about a minute of impact.

--Chris


Posted by: Spin0 Oct 12 2008, 11:24 AM

QUOTE (ugordan @ Oct 11 2008, 11:02 PM) *
Why wouldn't the explosion be visible in the infrared as well?

Well... um.. a good question!
You are right - the two different hot spots couldn't have been simultaneous. It looks like the 23 km difference in distance could have been actually a difference in time. Here's how I think it happened. And I really tried to be short but bear with me.

I found a Eumetsat pdf describing the imaging system of Meteosat 8 (SEVIRI): http://www.eumetsat.int/groups/ops/documents/document/pdf_ten_05105_msg_img_data.pdf (pp.12-13)

Meteosat 8 spins 100 rpm in its geostationary orbit. For imaging it has 12 spectral channels and each channel has 3 detectors, except HRV has 9. The detectors are arranged into two 'rows' in the focal point: the 'warm row' has visual channels (HRV and VIS aka VNIR) and the 'cold row' has IR channels. A mirror reflects light into each detector line by line as the satellite spins and scans the image. During image scanning all 12 channels are recording the image simultaneously, but there will be a small timing difference between each channel. Within the same row the maximum timing difference is only 432 microseconds. But between warm and cold rows it's 3.6 seconds because of the time it takes for the mirror to turn it's angle to reflect the same spot of Earth to different rows. Timing differences are compensated by readdressing the images' lines and columns accordingly. As Earth and clouds move relatively slowly this difference in timing is not a big deal.

According to Eumetsat the meteor's entry velocity was 12.8 km/s.

The Eumetsat's http://www.eumetsat.int/Home/Main/Media/Features/707785?l=en has three images of the fireball: two visual HRV and NCOL, and one infrared. Their channels are accordingly HRV, VIS and IR3.9. In the visual channels the images of the fireball seem to overlap and there's no mention of a noticeable difference in distance. The difference is noticeable in the IR-image and can be measured as a distance of approx. 23 km between the IR and visual channel image.

In the satellite the detectors for HRV and VIS channels are in the 'warm row' and IR3.9 is in the 'cold row'. So one would expect for the images from the same row to have a tiny timing difference of a few hundred microseconds, and the images from different rows to have a timing difference of 3.6 seconds plus some microseconds. And it looks like this is what we see - HRV and VIS channels' images don't show a noticeable difference in distance. But the timing difference becomes notable when compared to the IR3.9 channel image from the cold row. I think that's why there's two separate fireballs and not three.

The maximum timing difference between the 'warm row' channels is 432 microseconds, at 12.8 km/s velocity it translates to 0.55 km distance. This is well within the satellite's interchannel Residual Misregistration Requirement of 1.5 km and would not be noticeable in the visual channel images. But the 3.6 s timing difference between visual and IR channels would be noticeable at the meteor's velocity.

But 3.6 seconds at 12.8 km/s would translate to 46 km distance - not 23 km as measured in the images. Could this be due to meteor's deceleration?

Posted by: ugordan Oct 12 2008, 11:38 AM

Great analysis, Spin0. I think you've nailed the reason for the discrepancy. I had a hunch it had something to do with different timings in the satellite, but I didn't expect the thing to be rotating so fast and with mirrors and all!

I agree that the smaller 23 km distance likely comes from deceleration - the time is near expected impact, well into peak heating and deceleration.

Posted by: dilo Oct 12 2008, 05:36 PM

Excellent work, Spin! I think too that halved distance could be easily explained by atmospheric deceleration, obviously definitive confirm would need a more accurate simulation to match data.

Posted by: Spin0 Oct 16 2008, 02:34 PM

US Gov fireball data release regarding 2008 TC3:

QUOTE
Fireball Detection

Sensors aboard US satellites detected the impact of a bolide over Africa on 7 October 2008 at 02:45:40 UT. The initial observation put the object at 65.4 km altitude at 20.9 degrees North Latitude, 31.4 degrees East Longitude. The object detonated at an altitude of approximately 37 km at 20.8 degrees North Latitude, 32.2 degrees East Longitude. The total radiated energy was approximately 4.0X10^11 joules. This is equivalent to approximately 0.1 KT of radiated energy (assumes a 6000 Kelvin black body).

http://aquarid.physics.uwo.ca/~pbrown/usaf.html

Posted by: ugordan Oct 16 2008, 02:56 PM

QUOTE (Spin0 @ Oct 16 2008, 04:34 PM) *
US Gov fireball data release regarding 2008 TC3

Interestingly, the radiative energy of 0.1 kT is an order of magnitude lower than the infrasound estimate of the blast wave (between 1.1 and 2.1 kT). I find that a bit surprising, for example nuclear detonations (a bad analogue, but similar high energy density in a low volume after the initial high energy fireball expands a bit) produce roughly a 60:40 thermal:blast energy distribution, shifting even more in favor of thermal effect at higher altitudes.

What's more, the detonation altitude of 37 kilometers is seriously high which puzzles me even more - how can a small fast moving object couple most of its energy to a very rarified atmosphere? I'd expect vaporization of the body, plasma around it and radiative cooling as primary energy deposition mechanism.

Posted by: Mongo Oct 16 2008, 05:14 PM

I guess that this shows that we still have a lot to learn about upper-atmosphere meteoric explosions -- were any hard data on radiative vs blast energy collected from previous similarly-sized events?

I would guess that military observation sats have recorded similar explosions in the past, but their detailed results would presumably not have been made publicly available.

I would love to see a plot of total energy vs blast/radiation ratio vs detonation altitude for as many events as the information has been obtained for.

Posted by: ugordan Oct 16 2008, 05:22 PM

QUOTE (Mongo @ Oct 16 2008, 07:14 PM) *
I would guess that military observation sats have recorded similar explosions in the past, but their detailed results would presumably not have been made publicly available.


http://aquarid.physics.uwo.ca/~pbrown/usaf.html

Posted by: nprev Oct 16 2008, 09:58 PM

Neat link, Gordan; thanks!

Re the detonation stats: I suspect what we're seeing is a lot more compositional variation in these objects than is generally assumed. Recovered meteorites are overwhelmingly fairly robust rocks (iron/nickel, stony); falls like that extremely volatile-rich one up in Canada a few years ago are exceedingly rare since the material is so fragile; has to be a true big 'un to survive the trip.

So, this might be affecting our assumptions about the entire meteoritic/asteroidal population in general. Sure wish that some of these staring sats were obtaining detailed broad-band spectra of the events, esp. the residual trails. (Hey, there's a mission proposal in there for somebody! Maybe ride-along sensors on GOES or other geosynchronous satellites?)

Posted by: jumpjack Oct 17 2008, 07:25 AM

QUOTE (ugordan @ Oct 16 2008, 07:22 PM) *
http://aquarid.physics.uwo.ca/~pbrown/usaf.html

So we have a military high-atmosphere monitoring system? huh.gif Relic from ancient "Star Wars project"?

Do those acronyms in that page mean that there are so MANY USAF satellites up there? Or do they refer to observation times?

Posted by: djellison Oct 17 2008, 07:37 AM

QUOTE (jumpjack @ Oct 17 2008, 08:25 AM) *
So we have a military high-atmosphere monitoring system?


Loads. It doesn't take much imagination to figure out what they're actually for.


Doug

Posted by: volcanopele Oct 17 2008, 08:59 AM

Spying for Major League Baseball? (sorry, old Simpsons joke)

Seriously, the military routinely monitors meteoric airbursts as part of their campaign to monitor nuclear weapons testing and as an early warning system. I seem to recall hearing that there are usually a few events per year that are big enough to set off alerts at NORAD (but that could just be an urban legend).

Posted by: ugordan Oct 17 2008, 09:16 AM

QUOTE (volcanopele @ Oct 17 2008, 10:59 AM) *
I seem to recall hearing that there are usually a few events per year that are big enough to set off alerts at NORAD (but that could just be an urban legend).

I don't think those are rumors. There's a relatively recent story of a large asteroid detonating over the Mediterranean right at the time India and Pakistan were engaged in a military standoff. The asteroid released a yield of 26 kilotons which, had it detonated above India or Pakistan, could have caused some hairy consequences.

More at wikipedia: http://en.wikipedia.org/wiki/Eastern_Mediterranean_Event

Posted by: jumpjack Oct 17 2008, 09:16 AM

full inline quote removed. Admins are VERY scary. - Admin

Scary. blink.gif

Posted by: ugordan Oct 17 2008, 09:18 AM

QUOTE (jumpjack @ Oct 17 2008, 11:16 AM) *
Scary. blink.gif

Welcome to the real world...

Posted by: stevesliva Oct 18 2008, 01:04 PM

QUOTE (volcanopele @ Oct 17 2008, 04:59 AM) *
Seriously, the military routinely monitors meteoric airbursts as part of their campaign to monitor nuclear weapons testing and as an early warning system.

Launch-detect, too. They're monitoring ballistic missile and orbital rocket launches.

The first gamma-ray detectors in orbit were, of course, looking down.

For nuclear weapons test monitoring, I believe the USAF has planes setup for atmospheric sampling, or did. It would be neat if http://en.wikipedia.org/wiki/WC-135_Constant_Phoenix happened to be near enough to sniff around after a bolide. And of course, the satellites have also led to a regime of pre-announcing missile tests, so there are the http://en.wikipedia.org/wiki/Boeing_RC-135 that are configured to watch things fall into the atmosphere. The planes are 40-some-years old! (And will likely be flying when they're 60...)

Posted by: tty Oct 18 2008, 05:52 PM

It's the same in Sweden. We use 45 year old J 32B Lansen aircraft for the air sampling mission. In addition they are also part of the Air Force Historical Flight......

Posted by: nprev Oct 18 2008, 06:23 PM

QUOTE (ugordan @ Oct 17 2008, 02:18 AM) *
Welcome to the real world...


I do seem to remember seeing a report on the Montana local news a few days after the http://en.wikipedia.org/wiki/The_Great_Daylight_1972_Fireball happened that NORAD was rapidly ramping up to a full alert, since it at first glance looked like a possible sub-launched missile heading in the general direction of Malmstrom AFB...scary indeed.

Posted by: PhilCo126 Oct 19 2008, 09:51 AM

Pitty the list doesn't give info on the satellite-recorded impact of 1s February 1994 above Papua New Guinea.
The event was witnessed by fishermen near the island of Kusaie, the explosion occurred at 35 km altitude.
According to the observed flash, scientists estimated that the original object was about 15 m in diameter and the blast energy was in the range of about 100 KiloTons ( comparison: Atombombs: Hiroshima = 10 KiloTon , Nagasaki = 20 KiloTon ).

So far statistics point out that a 1 KiloTon event takes place every WEEK, and a 1 MegaTon event once every MONTH...
Although 35000 tons of material per year fall into Earth's atmosphere, and 70% of our planet consists of oceans, the 1 MegaTon rate seems alarming huh.gif

Posted by: nprev Oct 19 2008, 10:34 AM

No worries:

"The Earth gains mass each day, as a result of incoming debris from space. This occurs in the forms of "falling stars", or meteors, on a dark night. The actual amount of added material depends on each study, though it is estimated that 10 to the 8th power kilograms of in-falling matter accumulates every day. The seemingly large amount, however, is insignificant to the Earth's total mass. The Earth adds an estimated one quadrillionth of one percent to its weight each day."

--from http://hypertextbook.com/facts/2002/SamanthaDong2.shtml.

Posted by: PhilCo126 Oct 19 2008, 10:50 AM

Indeed no worries, but being a meteorite collector, the subject fascinates me cool.gif

Posted by: nprev Oct 19 2008, 11:04 AM

I hear ya; I have a couple myself (a Silkhote-Alin & a small Allende piece.)

Posted by: ugordan Oct 19 2008, 03:58 PM

QUOTE (PhilCo126 @ Oct 19 2008, 11:51 AM) *
... a 1 MegaTon event once every MONTH...

Um, are you sure about this? Can you give some references?

That doesn't jibe with estimates I've found on the web, I could buy a kiloton event every month or a few months, but a megaton event is a major fraction of a Tunguska-type event - those are said to happen once every few decades at most.

Posted by: Fran Ontanaya Oct 19 2008, 09:57 PM

In a 2002 interview for the BBC, a retired member of the US Department of Defense recalled a 100 kT explosion detected over Greenland in 1996. That seems to imply that 1 MT bolids aren't very common.

Posted by: mchan Oct 20 2008, 02:48 AM

Agree with ugordan on the dubious megaton class events. I recall the Sky and Telescope article (c. late 1980's) which discussed the stats when data on atmospheric detonation detections from the US Defense Support Program (early warning satellites) were sanitized and released. The largest events going back decades were in the ten to low tens of kiloton range. A megaton class event would likely make the television news even if it happened over in the middle of the Pacific Ocean.

The sensor that detects these detonations are intended to detect nuclear explosions --

http://en.wikipedia.org/wiki/Bhangmeters

The etymology of the word is an interesting bit of trivia.

In the Cold War days of long nuclear war scenarios, the US had some pretty Strangelovian plans for capabilities that were at least partially implemented. This was the Integrated Operational NUDET Detection System (IONDS) which put bhangmeters on GPS satellites so the location of detonations can be plotted to tens of meters. One use would be for nuclear attack damage assessment, i.e., did the target get blown up or are additional attacks needed?

Atmospheric detonations of meteors would similarly be well pinpointed.

Posted by: deglr6328 Oct 20 2008, 04:01 AM

I was the one who initially created the Bhangmeter article a few years ago. smile.gif

Posted by: PhilCo126 Oct 20 2008, 10:34 AM

It looks like nobody noticed the question mark in blue circle at top left of my reply smile.gif
Indeed the 1 MegaTon event rate seemed over-estimated, I'll check this evening in which book/article I've found that number. I have been using it in lectures during the last few years unsure.gif so for IYA 2009 a recheck might be necessary...

BTW superb reply on the etymology of the word "Bhangmeter" cool.gif

US Department of Defense and Department of Energy satellites scanning the Earth for evidence of nuclear explosions over the last eight years detected nearly 300 optical flashes caused by small asteroids (one to 10 metres in size) exploding in the upper atmosphere. This provided research teams with a new estimate of the flux of near-Earth objects colliding with the Earth. The revised estimate suggests Earth's upper atmosphere is hit about once a year by asteroids that release energy equivalent to five kilotons of TNT. The object that exploded above Tunguska, Siberia in 1908 was considered 'small' (30 to 50 metres across), yet its energy was big enough to flatten 2,000 square kilometres of forest. It would have completely destroyed a city the size of New York.
Prior estimates suggested that Tunguska-like events (10-15 MegaTon) happened every 1,000 years or so. New estimates put that closer to the 250-300 year range. Although estimates are based on a lot of uncertainty, every couple of centuries there could be a significant event…

So I guess that brings numbers down to a 10 KiloTon event every year huh.gif


Posted by: PhilCo126 Oct 20 2008, 05:53 PM

http://www.astroguard.com/

and a few good books on the subject:

Posted by: PhilCo126 Oct 20 2008, 07:25 PM

Back on topic; 2008TC3 meteor of 7th October 2008:
http://www.observatorij.org/News/News.html
ohmy.gif

Posted by: Tman Nov 6 2008, 10:28 AM

Summary of the fall on http://neo.jpl.nasa.gov/news/2008tc3.html

It also mentions the Egyptian webcam as a possible capture of the flash http://home.pages.at/thie/asteroid_2008_tc3/

Btw. the search for fragments in Sudan seems to be under way.

Posted by: Tman Nov 8 2008, 10:43 AM

Wow, eventually someone managed to capture the persistent train after the impact http://asima.seti.org/

http://antwrp.gsfc.nasa.gov/apod/ap081108.html

Posted by: PhilCo126 Nov 22 2008, 09:21 AM

Another Fireball this month: Canada 20th November 2008

YouTube video:
http://www.youtube.com/watch?v=e_2aX-784sw

More info:
http://www.ctvbc.ctv.ca/servlet/an/local/CTVNews/20081120/alta_fireball_081121/20081121/?hub=BritishColumbiaHome


Posted by: PhilCo126 Nov 28 2008, 11:06 AM

The search continues: http://www.sciencedaily.com/releases/2008/11/081125141602.htm
cool.gif

Posted by: marsbug Nov 28 2008, 11:48 AM

QUOTE (PhilCo126 @ Nov 22 2008, 09:21 AM) *
Another Fireball this month: Canada 20th November 2008

YouTube video:
http://www.youtube.com/watch?v=e_2aX-784sw



!

Thats beautifull, but quite scary...

Posted by: Tman Nov 29 2008, 05:19 PM

First piece has been located (looks nice... the meteorite) http://www.youtube.com/watch?v=UjU8boyXwqc

Posted by: PhilCo126 Nov 29 2008, 09:36 PM

Indeed a very nice piece:
http://www.foxnews.com/story/0,2933,458984,00.html
cool.gif

http://skyriver.ca/astro/bruce/meteorite.htm

Posted by: PhilCo126 Dec 5 2008, 05:59 PM

Beauties indeed:
http://blogs.discovery.com/whats_up_astronomy/2008/11/saskatchewan-me.html

http://skyriver.ca/astro/bruce/meteorite.htm

Posted by: Mongo Dec 23 2008, 08:55 PM

Information is starting to come out about the composition and possible origins of the Buzzard Coulee meteorite fall (that's the name that is being recommended for official designation of the fall).

First I suggest taking a look at this http://www.stumbleupon.com/toolbar/#topic=Science/Tech&url=http%253A%252F%252Fskyriver.ca%252Fastro%252Fbruce%252Fmeteorite.htm of the initial recovery efforts, followed by lab photos, including several cross-polarized thin sections.

Here is the text of a http://www.ucalgary.ca/news/december2008/meteoriterecord about what is being found out:

A University of Calgary-organized team recovered more than one hundred meteorites from the November 20 meteorite fall southwest of Lloydminster, Saskatchewan/Alberta, which is expected to set a new Canadian record for the largest recorded meteorite fall.

“Finding all we could before the snow came on December 6 was a real challenge and tough on searchers with wind chills routinely colder than –20 degrees,” said Dr. Alan Hildebrand, holder of the Canada Research Chair in Planetary Science. “We did as well as we did by collaborating with experienced researchers from The University of Western Ontario including Dr. Phil McCausland and Dr. Peter Brown.” Both Hildebrand and Brown are veterans of the Tagish Lake (2000) and St-Robert (1994) meteorite recovery efforts and McCausland is a veteran of the Tagish Lake recovery.

Volunteer searchers numbered up to twenty people per day including local residents, U of C staff and graduate & undergraduate students, professors from the University of Saskatchewan and the University of Regina, amateur astronomers from the Saskatoon, Calgary and Edmonton Centres of the Royal Astronomical Society of Canada, and geoscientists from ConocoPhillips Canada. Most searchers found at least one meteorite despite having a thin layer of snow down the last five days.

“The last day that the search teams were out, it snowed all day and we still found five meteorites which is ridiculous. It shows just how many are out there,” Hildebrand said.

Using the abundance of meteorites on the pond where U of C grad student Ellen Milley found the first fragments on November 27, Hildebrand calculated that about 2,000 meteorites of more than 10 grams in size occur per square kilometer in the northern part of the strewn field, and probably more than 10,000 meteorites of this size are on the ground altogether. Many local residents and landowners also found meteorites, as well as persons from across the prairies and meteorite dealers who traveled to Saskatchewan to try their luck.

“We have had great cooperation from landowners, who are having a once-in-a-lifetime experience of a meteorite harvest,” Hildebrand said. “Approximately 130 well-substantiated meteorites have been found totaling about 40 kg, but probably double that number, weighing more than 50 kg, have been recovered.”

Hildebrand encourages everyone who has collected specimens to please send him the masses (in grams) and locations (GPS coordinates, NAD27 datum) of their finds to help map the strewn field.

Milley and Hildebrand have formally proposed the name Buzzard Coulee to describe the fall to the International Meteoritical Society. The name comes from the picturesque valley near the hamlet of Lone Rock, Sask. where the first meteorites were discovered.

Typing of the meteorite has been completed with the collaboration of Dr. Alex Ruzicka and Dr. Melinda Hutson, a husband and wife team at the Cascadia Meteorite Laboratory at Portland State University, Portland, Oregon.

“The meteorite is at the low end of the H4 type and may be transitional with type 3. It will take some more work to sort out everything, but we have good prospects to learn a lot about the rock’s history,” Ruzicka said.

A lower number in the classification indicates that a meteorite experienced less heating on its parent asteroid, making it of more interest to researchers and potentially to collectors as well. Lower metamorphic grades are relatively unusual in meteorites of the H, or “high iron” type, such as the Buzzard Coulee rocks.

Dr. Hutson observed: “The meteorite also appears to show that different types of material are mixed together in a subtle way, but we will have to study more thin sections to better understand this. The meteorite is slightly shocked, so the material was possibly stirred by an impact on its parent asteroid.”


Hand specimens of the meteorite show only rare fragmental texture, but with the prospect of hundreds of meteorites to study, including some large ones (the largest recovered to date is approximately 13 kg), more will be learned about the history of the asteroid fragment that fell at Buzzard Coulee than for most falls.

"It was a great experience to visit the Cascadia Meteorite Lab to see how they do things, and it has been fun to apply the things that we learned in class to a new meteorite fall,” said Milley, who is pursuing her MSc with Hildebrand in the U of C’s Department of Geoscience. “It feels good to be making a real research contribution. When we determine the orbit we will also know from where in the asteroid belt this rock originated."

The recovered meteorites are being stored in an inert nitrogen atmosphere in a clean room in the meteorite lab at the University of Calgary to prevent weathering by the Earth’s atmosphere.

“Since these meteorites are a fresh fall collected early and nearly dry, they are unweathered for the most part and deserve the best care anywhere,” Milley said.

The U of C researchers and their collaborators will now turn their attention back to determining the orbit for the space rock. The H4 classification matches the history of meteorite falls of this type that usually occur during the afternoon or evening. About 8 million years ago a large impact occurred on an asteroid of H composition and further studies will be done to see if Buzzard Coulee is another fragment from that impact. Although orbit evolution is chaotic, determining this rock’s orbit may help locate that impact. Knowing the fireball’s exact trajectory will also allow better planning for the spring searching.

“I think that the number of individual meteorites that will be recovered for Buzzard Coulee will easily set the Canadian record for the largest fall recovery, but we still don’t know how big the biggest meteorite out there is, so we don’t know how much mass we can expect to be recovered of the approximately 1 tonne that fell,” Hildebrand said. The largest Canadian meteorite fall currently on record dates to 1960 when hundreds of meteorites fell near Bruderheim, Alberta.

“During the spring before cultivating and seeding, we will try to organize the biggest meteorite search effort that Canada has ever seen,” Hildebrand said. “One of our ambitions at the Prairie Meteorite Search project is to train everyone in the country to recognize meteorites so more new ones will be discovered, and this is a great opportunity to introduce hundreds of people to rocks from space.”

Posted by: ups Dec 25 2008, 04:02 PM

QUOTE (Mongo @ Dec 23 2008, 09:55 PM) *
Information is starting to come out about the composition and possible origins of the Buzzard Coulee meteorite fall (that's the name that is being recommended for official designation of the fall).

First I suggest taking a look at this http://www.stumbleupon.com/toolbar/#topic=Science/Tech&url=http%253A%252F%252Fskyriver.ca%252Fastro%252Fbruce%252Fmeteorite.htm of the initial recovery efforts, followed by lab photos, including several cross-polarized thin sections.



Thanks for the update -- looks like there is quite a bit of new information.


---ups

Posted by: nprev Dec 31 2008, 07:28 AM

Hopefully not OT, but I stumbled upon a http://curator.jsc.nasa.gov/antmet/us_clctn.cfm about the US Antarctic meteorite collection, including an Excel file listing the entire thing.

I had no idea that there were already several identified classes of lunar meteorites. Shows the value of the ground truth obtained by Apollo & the Luna sample returns.

Posted by: PhilCo126 Feb 10 2009, 04:38 PM

And another one, this time observed above Belgium, the Netherlands and Sweden... must have been a nice one!
http://www.expressen.se/1.1435795?articlePopup=true&img=1

Dutch website with map:
http://www.hemelwacht.net/20090117.htm

ohmy.gif

Posted by: nprev Feb 12 2009, 03:02 AM

Very cool; anybody looking for fragments? Lotsa water about, though.

Posted by: PhilCo126 Feb 20 2009, 10:24 AM

Pieces of the Texas meteor, seen Sunday 15th February 09, were found:
http://www.dallasnews.com/sharedcontent/dws/dn/latestnews/stories/021909dntexmeteor.3c40815.html
and
http://www.sciam.com/blog/60-second-science/post.cfm?id=texas-meteorite-hunters-turn-up-pos-2009-02-19
smile.gif

Posted by: PhilCo126 Feb 23 2009, 04:23 PM

Remember the October 2008 meteor above Sudan?
It looks like fragments were found:
http://www.newscientist.com/article/dn16635-first-tracked-space-rock-recovered-after-impact.html

Posted by: Mongo Mar 2 2009, 11:02 PM

http://www.newscientist.com/article/dn16697-tunguskasized-space-rock-buzzes-earth.html

QUOTE
An asteroid about the size of the one that levelled the forest in Tunguska, Siberia, a century ago flew past Earth on Monday - well within the Moon's orbit. The risk of a future impact with the object is not yet known.

The asteroid, dubbed 2008 DD45, whizzed just 72,000 kilometres above the Earth's surface. That is less than a fifth of the distance to the Moon and just twice the distance to geosynchronous satellites.


QUOTE
Based on its brightness, the asteroid seems to be between 20 and 50 metres across, says Timothy Spahr of the International Astronomical Union's Minor Planet Center.




Posted by: Floyd Mar 3 2009, 02:45 AM

The surveys are just getting better and better at finding these rocks before the pass by or hit earth.

Posted by: jumpjack Mar 3 2009, 10:06 AM

[edit]
Really close this time! ohmy.gif

Posted by: nprev Mar 3 2009, 10:44 AM

Close indeed! blink.gif

I dunno if I buy the Tunguska comparison, though. AFAIK, nobody has any real idea of the T. object's composition other than it must have been some pretty soft stuff (no recovered debris), so how can any meaningful size estimates be derived?

Just to give some benefit of the doubt, perhaps the author meant to compare kinetic energy releases if DD45 had actually hit?

Posted by: Ken90000 Mar 3 2009, 01:15 PM

I'm sure it is just an order of magnitude estimate. Anyway, is there any information about how bright the object became at closest approach? Naked eye, perhaps? Was there enough time for amatures to observe it?

Posted by: PhilCo126 Mar 3 2009, 01:36 PM

Indeed Asteroid 2009 D45 was observed by some amateur astronomer as it buzzed by Earth at a distance of 75000 Kilometers.
Question remains how Earth's gravity changed the orbit of this space rock...

http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2009%20DD45;orb=1
http://www.universetoday.com/2009/03/02/asteroid-2009-dd45-just-buzzed-by-earth/



Posted by: PhilCo126 Mar 19 2009, 12:33 PM

And another one = 2009FH
http://www.universetoday.com/2009/03/17/newly-discovered-asteroid-2009-fh-to-buzz-past-the-earth-tonight/
http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2009%20FH;orb=1

huh.gif

Posted by: Holder of the Two Leashes Mar 25 2009, 07:13 PM

Article on the recovered pieces of 2008 TC3 found in Sudan's Nubian desert.
http://www.space.com/scienceastronomy/090325-asteroid-meteorites.html

Edit 26 March. Two more articles:
http://www.spacedaily.com/reports/Scientists_Track_Asteroid_That_Hurtles_To_Earth_And_Recover_Pieces_999.html
http://www.spacedaily.com/reports/Surprise_Recovery_Of_Meteorites_Following_Asteroid_Impact_999.html

Another Edit: 'Nother one.
http://www.spacedaily.com/reports/UK_Astronomers_Observe_Asteroid_Before_It_Crashes_Into_Earth_999.html
This last article clarifies that although the fragments belong to a known rare class of meteorites, they were "... dark ureilite achondrite meteorites with a texture and composition unlike any other ureilite meteorites found on Earth before."

Posted by: Holder of the Two Leashes Mar 28 2009, 03:49 AM

http://www.planetary.org/blog/article/00001896/ has a good story on the recovery of the TC3 meteorites, plus a neat picture of the field team (all pointing to a discovery). It includes additional information on the tracking efforts plus a link to a more detailed description of the recovery (also on the planetary society website).

Posted by: Paolo Mar 28 2009, 07:25 AM

Main article is published in http://www.nature.com/nature/journal/v458/n7237/full/nature07920.html, for those who have a subscription, plus a http://www.nature.com/news/2009/090325/pdf/458401a.pdf

Posted by: ilbasso Mar 30 2009, 10:06 PM

Sorry I missed this last night...

Streaking Lights in Night Sky Likely Were Falling Space Debris

By Ashley Halsey III
Washington Post Staff Writer
Monday, March 30, 2009; 3:43 PM

The "great ball of fire" that lighted the Sunday night sky -- and then lighted up police switchboards across several mid-Atlantic states -- almost certainly was a big chunk of space junk falling from orbit.

Everyone seemed to think it was falling near them. Callers to 911 said it was "a rocket or comet" or maybe "a plane or helicopter on fire" that was of a "greenish color" that came "down from the sky near the tree line."

After flooding 911 lines, anxious people turned next to the weather services, hopeful that they could explain the scary flash the lighted up the sky just after 9:40 p.m., but nothing about the night's weather patterns could account for this one.

Geoff Chester, at the U.S. Naval Observatory in Washington, had the answer. He's fairly certain that it was the second-stage booster from a Russian Soyuz rocket that took off on Thursday from the Baikonur Cosmodrome in Kazakhstan.

The Soyuz went on to deliver its Russian commander, a NASA flight engineer and a billionaire tourist to the space station.

The booster went into a lazy orbit, and after its batteries went dead the best experts could do was pick a 12-hour window when it was likely to reenter the earth's atmosphere. That window, between 6 p.m. Sunday and 6 a.m. today, carried the more than 20-foot-long booster over the East Coast during that period.

"When I saw the ground tracking right over Tidewater at the time of the reports, I was pretty well convinced it was the Soyez," Chester said.

If anything remained of the booster it probably landed in the water more than a hundred miles off of Cape Hatteras. Without anything to put an astronomical event like last night's into scale, it's challenging for observers to calculate just how close they are.

"I once saw a fireball and thought it was going to land on my house," Chester said. "It's not uncommon to think it's a lot closer than it is."

Posted by: stevesliva Mar 30 2009, 11:16 PM

Spaceweather.com seems to think the Soyuz stage went into the Pacific ocean, not the Atlantic.

Posted by: centsworth_II May 30 2009, 01:39 AM

The asteroid watchers over at space.com have been talking about a http://www.space.com/common/forums/viewtopic.php?f=12&t=17957&start=20#p356377 that looks like it's coming very close in 2022.
We might need to redirect that Apophis mission!

Posted by: Holder of the Two Leashes May 30 2009, 06:00 PM

The impact probabilities for Apophis were far, far higher in its early days of tracking. The orbit for 2009 KK is still extremely preliminary at this point. No need to get excited yet.

BTW, this thread was set up specifically for 2008 TC3. You will notice that from the subtitle. Originally there were two threads about 2008 TC3 started almost simultaneously, which were merged into this one. Paolo gets credit for posting first, but the titles for this topic came from the one I started, so I can assure you this was the case.

Now this thread has become the repository for every fireball and every remotely possible impact threat, which for my part it was never intended to be. May I suggest someone please start another topic or two, appropriately titled, for everything not directly pertaining to 2008 TC3?

Posted by: ElkGroveDan May 30 2009, 06:33 PM

Well since 2008 TC3 is more or less settled, it's probably best to keep this discussion and change the title to a more general topic.

Posted by: Holder of the Two Leashes May 30 2009, 07:00 PM

That'll work too.

Posted by: Shaka May 30 2009, 07:22 PM

Let's rename it: INCOMING!, Detection and observation of Earth-approaching asteroids.
cool.gif

Posted by: ElkGroveDan May 30 2009, 08:30 PM

Good idea Shaka. You think like a seasoned Admin.

Posted by: ugordan Jun 10 2009, 09:45 PM

Via NSF.com : http://www.space.com/news/090610-military-fireballs.html

Posted by: Holder of the Two Leashes Jun 10 2009, 10:08 PM

Oh, boy. This one is just ripe for out-of-bounds political discussion. I'll do my best here. All through the recent troubled times, the release of this information has never been considered a problem. There is no good reason to classify it now. Perhaps the data needs to be "watered down" to prevent the full capabilities of the satellites from being revealed, but that still doesn't preclude the release of data of the quality that everyone already knows these satellites are capable of.

Posted by: Floyd Jun 10 2009, 11:01 PM

The information from military satalites was very helpful in the 2008 TC3 analysis--Which made the cover of Nature. What to do about this problem is definitely political--and I'm hopeful can be succesfully addressed--but not here at UMSF. Normally I would contact Emily--to find out what actions would be helpful, but she is out on maternity leave. Rather than make political comments or suggestions here, maybe people could suggest appropriate forums or people to visit or contact. I'm trying really hard here--would appreciate guidance form Doug or other Amdins.

Posted by: Fran Ontanaya Jun 11 2009, 01:26 AM

After the Easter Mediterranean Event, Gen. Simon Worden made a good case for sharing that information:

http://www.spaceref.com/news/viewpr.html?pid=8834

Posted by: Astro0 Jun 11 2009, 02:11 AM

Floyd got it right..."but not here at UMSF"

Can I suggest the http://www.bautforum.com/ or one called 'http://www.bearpit.net/index.php?act=idx' which has a section dedicated to discussion of science and technology and its politics.

BTW - these are personal recommendations - just to be political laugh.gif

Astro0

Posted by: Holder of the Two Leashes Jun 11 2009, 05:15 PM

One last word on this, having read some of what's being posted on some other sites, and expecting better from our blog here. Let's be cautious about assuming this all started with the military. The reconnaissance people seemed quite happy to share all this information in the past. I'm not saying it wasn't the military. I'm saying it's a strange situation.

My own idea about where to pursue this matter would involve the Planetary Society, for starters. Maybe contact some people at the NEO office at JPL, too.

Posted by: PhilCo126 Sep 15 2009, 09:40 PM

Just read an article by Brian Harvey in which Russian astronomers (E. Drobyshevski & T. Galushina) calculated the orbit of the June 1908 Tunguska event and came out at object 2005NB56, which will revisit Earth in July 2045 and June 2064 ohmy.gif

Posted by: peter59 Oct 1 2009, 06:27 AM

Spacecraft unnecessary, we have excellent radar. Boulders on asteroids' surface are clearly visible. http://spacefellowship.com/wp-content/uploads/2009/09/figure-2.jpg

Arecibo Observatory ‘uniquely powerful’ for detecting near-Earth objects
http://spacefellowship.com/2009/09/30/arecibo-observatory-uniquely-powerful-for-detecting-near-earth-objects/

Posted by: Hungry4info Oct 1 2009, 01:00 PM

I can't seem to see the full image mad.gif sad.gif
Your link doesn't work for me, and neither does the one on their site. Blah!

Posted by: peter59 Oct 1 2009, 01:34 PM

QUOTE (Hungry4info @ Oct 1 2009, 02:00 PM) *
I can't seem to see the full image
Your link doesn't work for me, and neither does the one on their site. Blah!




Posted by: Hungry4info Oct 1 2009, 11:53 PM

Thanks. =)
I appreciate it.

Posted by: tedstryk Oct 5 2009, 03:43 PM

The link didn't work, http://spacefellowship.com/2009/09/30/arecibo-observatory-uniquely-powerful-for-detecting-near-earth-objects/

Posted by: Paolo Oct 7 2009, 08:05 PM

At least Apophis seems set to become less of a menace
http://www.jpl.nasa.gov/asteroidwatch/newsfeatures.cfm?release=2332

Posted by: climber Oct 8 2009, 06:07 AM

I guess the people living on the Moon got the same topic as this one bloging about the INCOMING object due to hit Cabaeus tomorrow rolleyes.gif

Posted by: climber Oct 16 2009, 08:23 PM

Nice videos there: http://www.space.com/common/media/video/player.php?videoRef=SP_091008_AsteroidTrack

Posted by: Tman Oct 16 2009, 10:19 PM

And what a lucky guy http://planetary.org/blog/article/00002166/ to have the camera ready to fire in the right moment. Thanks for the great summary, Emily!

The possibility is unfortunately rather high that potential pieces fell into North Sea.

Posted by: nprev Oct 17 2009, 02:21 AM

Ironically enough, I saw a nice bright brief meteor (caught my eye while driving!) almost exactly at daybreak this morning over the Pacific. Would have been spectacular in a dark sky; left a brief trail against a blue sky!

(Sigh)...Just think of all the countless meteorites that go splash all the time instead of ending up in labs or on my mantle where they belong!

Posted by: Shaka Oct 18 2009, 10:04 PM

It all boils down to surface area, Nick.
The mantle is too far from the surface, and your mantel has too small an area!
You're an engineer! Just build a bigger mantel!

Posted by: nprev Oct 18 2009, 10:24 PM

I'll get right on it, Shak...gonna upgrade my internal spell-checker, too! rolleyes.gif tongue.gif

Posted by: Greg Hullender Oct 19 2009, 12:02 AM

Nah, "fireplace mantle" is an acceptable alternate spelling for "fireplace mantel. He's just pulling your chain.

Have you tried the experiment of using a magnet to pull metal fragments from ordinary dirt and then checking them under a microscope to see if they appear to have melted? I tried this as a kid and easily convinced myself I had found meteoritic material. Collect enough and perhaps you could make something suitable for display on your mantel. (In which case, you have to send us pics.) :-)

--Greg

Posted by: nprev Oct 19 2009, 12:27 AM

Hey, I strive for complete anality in spelling so that I can feed my innate sense of overwhelming superiority...I accept Shaka's rebuke! laugh.gif

Re magnet-dust meteors: I've heard that much of that stuff actually IS meteoritic material, which makes sense since literally tons of crap hits the atmosphere every day world-wide. Dunno if that's an urban legend or not; will try to dig up a reputable reference.

EDIT: Wow, that didn't take long. Here's a teacher's http://www.pbs.org/wgbh/nova/teachers/activities/3111_origins.html from PBS' Nova on how to collect & identify micrometeors! Near the end there's also mention of an ongoing project by one of the US government research agencies (forget which one...USGS?) to characterize the stuff.

Posted by: ilbasso Oct 26 2009, 01:56 PM

Report of a "meteorite like object" creating a crater in Latvia on http://www.cnn.com/2009/WORLD/europe/10/26/latvia.meteorite/index.html this morning.

Posted by: Tman Oct 26 2009, 02:24 PM

blink.gif http://www.youtube.com/watch?v=Z5C-Lh3UfQ8&feature=player_embedded

Was most likely a man made object. Maybe even faked http://foto.delfi.lv/album/41818/?page=1 of the burnt thing looks odd. Why should right there be a single burning thing after such a massive explosion?


...or a flammable meteorite/object outside of any norm ? huh.gif smile.gif

Posted by: centsworth_II Oct 26 2009, 04:15 PM

http://www.nytimes.com/aponline/2009/10/26/world/AP-EU-Latvia-Meteorite.html

Posted by: Vultur Oct 26 2009, 06:04 PM

If you see a meteor, is there any way to tell whether it probably survived to reach the ground? I remember reading somewhere, years ago, that if you can hear noises it probably reached the ground... is there any truth to that?

Just wondering because I saw a really bright meteor last night, but no actual 'fireball' or sound.

Posted by: ElkGroveDan Oct 26 2009, 06:59 PM

QUOTE (Vultur @ Oct 26 2009, 10:04 AM) *
If you see a meteor, is there any way to tell whether it probably survived to reach the ground?

A http://science.discovery.com/top-ten/2009/meteors/images/meteorite08-peekskill.jpg would be a good indication that it reached the ground. rolleyes.gif

Posted by: Phil Stooke Oct 26 2009, 08:38 PM

We had a big fireball up here in Ontario too, a few weeks ago. I heard an eyewitness report on Friday, and my buddies in Meteor Physics are collecting pieces of it. One fragment smashed a van window. Where's my can of repellant?

Phil

Posted by: imipak Oct 26 2009, 08:40 PM

I haven't heard of a correlation between sounds and meteorites being found on the ground. "sound effects" accompanying meteors has been a somewhat controversial (in the good, scientific sense) for a while...

http://www.google.co.uk/search?hl=en&q=meteorite+sounds++meteorobs&btnG=Search&meta=&aq=f&oq=

http://www.pibburns.com/catastro/metsound.htm

Posted by: nprev Oct 27 2009, 12:06 AM

I heard one make a sound...10 Aug 72.

Posted by: Greg Hullender Oct 27 2009, 03:13 AM

If it doesn't make a sound, then it definitely didn't hit the ground.

I'll go out on a limb and claim that applies to trees too. :-)

--Greg

Posted by: nprev Oct 27 2009, 03:43 AM

Greg, that was truly rancid... rolleyes.gif

Posted by: PFK Oct 27 2009, 07:01 PM

QUOTE (nprev @ Oct 27 2009, 12:06 AM) *
I heard one make a sound...10 Aug 72.

That made me check up on the date of one my old mum remembers seeing heading over the Irish sea (and it made such an impression on her she still recalls it with wonder today); I remembered her saying it was some time late 60s - turns out, after a bit of searching about, to have been what is now known as the Bovedy meteortite in 1969.
And its sound was in fact recorded - fortuantely someone was recording birdsong at the time:
http://fernlea.tripod.com/bovedy.wav

Posted by: Spin0 Oct 27 2009, 09:40 PM

50 kiloton explosion over Indonesia!

http://neo.jpl.nasa.gov/news/news165.html

QUOTE
On October 8, 2009 about 03:00 Greenwich time, an atmospheric fireball blast was observed and recorded over an island region of Indonesia. The blast is thought to be due to the atmospheric entry of a small asteroid about 10 meters in diameter that, due to atmospheric pressure, detonated in the atmosphere with an energy of about 50 kilotons (the equivalent of 100,000 pounds of TNT explosives).


Fireball's dust trail was captured on video: http://www.youtube.com/watch?v=yeQBzTkJNhs&videos=jkRJgbXY-90

The article makes me wish we had more info and possibly more images on this (local cameras? satellites?).

Posted by: Tman Oct 29 2009, 10:23 AM

Fortunately, the small asteroid didn't make it deeper before it exploded. It would have been catastrophic.


There was also a noise/sound recorded from the Netherlands fireball:
http://www.hemelwacht.net/geluiden/geluid.htm
onversterkt/versterkt=normal/boosted
straaljager=jet plane

Posted by: Juramike Nov 11 2009, 09:02 PM

Swing and a miss!

http://www.universetoday.com/2009/11/09/surprise-unknown-asteroid-buzzed-earth/

Posted by: maschnitz Nov 11 2009, 09:38 PM

We will apparently be seeing 2009 VA again http://neo.jpl.nasa.gov/risk/2009va.html. Also, here's the http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2009+VA;orb=1.

Posted by: Holder of the Two Leashes Nov 12 2009, 01:27 AM

Sorry, but we will probably never be seeing it again, ever. It was poorly observed near closest approach. Unless someone has observations they have not yet turned in (a possiblility), then we're stuck with an orbit with large error margins. It is too close now to the sun to be observed, and will be too faint to see (25th magnitude) when it is back in view. And its sky location is already uncertain by a degree.

There is a 4% chance it will come within 0.2 AU of earth in 2026, and 3% in 2030. It will have to get a lot closer than that, and in the right part of the sky, to be bright enough for a survey to stumble on it again. That's even if PanSTARRS is up and running. 2009 VA is a tiny object.

Posted by: mcgyver Nov 18 2009, 06:39 PM

I googled around and looked for info in NASA NEO site, but couldn't find any statistical data, so I'm asking it here:
how much part of the sky, and for how long in a day is monitored for approaching NEOs? I was quite surprised by the asteroid passed half the GEO orbit near Earth some days ago, being spotted only a few hours before it reached minimum distance, as I thought the sky was constantly monitored for such events.
Is it not? huh.gif

Posted by: elakdawalla Nov 18 2009, 08:10 PM

Although there are constantly people looking at some part of the sky, the entire sky is not photographed continuously, and faint objects can (and, most often, do) slip by unobserved, or are only seen within hours of their closest approach. And don't forget that we basically have no hope of spotting previously undiscovered things that are coming at us from the dayside of Earth! But these faintest objects that are only discovered within hours of their closest approach are also the smallest and, if they were to hit us, would explode in the atmosphere on their way down; any damage on the ground is caused by direct hits from flying debris, rather than from impact effects. Larger objects are brighter and therefore discovered earlier. Only one asteroid has ever been discovered before it became an impactor -- 2008 TC3.

Posted by: Greg Hullender Nov 18 2009, 11:21 PM

QUOTE (mcgyver @ Nov 18 2009, 10:39 AM) *
how much part of the sky, and for how long in a day is monitored for approaching NEOs? . . . Is it not? huh.gif

Far as I know, it is not.

Although Pan-STARRS would do it, if it actually gets built.

http://pan-starrs.ifa.hawaii.edu/public/asteroid-threat/asteroid_threat.html

WISE, which should launch next month, ought to give us a MUCH better picture of what we're up against, at least.

http://wise.ssl.berkeley.edu/mission.html

--Greg

Posted by: alan Nov 19 2009, 03:57 AM

http://scully.cfa.harvard.edu/~cgi/SkyCoverage.html from the IAU Minor Planet Center

Posted by: PhilCo126 Nov 19 2009, 09:15 AM

Another nice meteor trail:
http://www.ksl.com/?nid=148&sid=8714738
and
http://www.heliotown.com/FB20091118_0707utAshcraft.mp4


Posted by: ElkGroveDan Nov 19 2009, 02:51 PM

QUOTE
Folks at the Clark Planetarium say this rock was big--between the size of a microwave and washer-dryer unit.


I see we have a couple of new units of measure.

Posted by: djellison Nov 19 2009, 03:51 PM

Microwave (Sojourner) and Washing Machine (Deep Imapct Impactor) are already on the official (but non existent) NASA scale of size objects list smile.gif

Others I know of...
Golf Cart ( MER )
Mini Cooper ( MSL )
School Bus ( Cassini )
Squash Court ( Eagle Crater )
Utah ( Hematite & Meridiani )

Thrust should be expressed in the weight of a piece of paper, or multiples of Jumbo Jets.

All rocks, described in terms of the closest representing piece of fruit.

Posted by: ElkGroveDan Nov 19 2009, 09:15 PM

Also any extremely elongated asteroid is described in multiples of "Manhattan" with Eros being the most commonly mentioned body as "twice the size of Manhattan".

Posted by: Fran Ontanaya Nov 19 2009, 09:58 PM

The amount of propane in the atmosphere of Titan is measured in Labor Day Barbecues. ohmy.gif

I wonder how many Labor Day Barbecues of fuel are needed to provide enough Jumbo Jets of thrust to propel a Washing Machine to Ludicrous speed.

Posted by: climber Nov 19 2009, 10:14 PM

QUOTE (djellison @ Nov 19 2009, 04:51 PM) *
Microwave (Sojourner) and Washing Machine (Deep Imapct Impactor) are already on the official (but non existent) NASA scale of size objects list smile.gif

Others I know of...

As soon as Spirit is making progress extracting herself from Troy, I don't mind new references been invented.
In France a very little distance is said as been "1/4th of a fly ass hair" (sorry for the rude reference)

Posted by: elakdawalla Nov 19 2009, 11:14 PM

That's OK, we're used to http://www.youtube.com/watch?v=9V7zbWNznbs. smile.gif

Posted by: ngunn Nov 19 2009, 11:25 PM

Excuse me, but on the ships I sailed the proper term for a small quantity was 'half a gnat's cock'.

Posted by: stevesliva Nov 20 2009, 01:25 AM

QUOTE (djellison @ Nov 19 2009, 10:51 AM) *
Utah ( Hematite & Meridiani )


Guess I haven't been paying attention. Usually Utah's used as a measuring stick for "redness."

Round where I came from, "a little bit" is commonly "a gnat's ass" with both the 'a' sounds properly nasally. We've got all the bases covered.

Posted by: mcgyver Nov 20 2009, 07:49 AM

QUOTE (mcgyver @ Nov 18 2009, 07:39 PM) *
I googled around and looked for info in NASA NEO site, but couldn't find any statistical data, so I'm asking it here:
how much part of the sky, and for how long in a day is monitored for approaching NEOs? I was quite surprised by the asteroid passed half the GEO orbit near Earth some days ago, being spotted only a few hours before it reached minimum distance, as I thought the sky was constantly monitored for such events.
Is it not? huh.gif

thanks to all for cool links.

This image is really frightening! blink.gif
http://pan-starrs.ifa.hawaii.edu/public/asteroid-threat/asteroid_orbits.htm
(DOn't know if I can show it directly in the post, it's really large)

Posted by: PhilCo126 Nov 20 2009, 10:22 AM

An overview of some NEO surveys:

1973 Palomar Asteroid & Comet Survey
1990 Anglo-Australian NEA Survey
1994 SpaceWatch Kitt Peak ( 1.80 + 0.90 refractors – short focal Sky Survey )
1998 Lincoln NEA Research LINEAR
2008 Panoramic Survey Telescope Rapid Response System ( 4 X 1.80 m Refractors Hawaii )
2015 Large Synoptic Survey Telescope ( 8.40 m Chile )

LSST will detect all objects larger than 150 meter within a decade of survey...

Posted by: Pertinax Nov 20 2009, 01:59 PM

QUOTE (Fran Ontanaya @ Nov 19 2009, 06:58 PM) *
I wonder how many Labor Day Barbecues of fuel are needed to provide enough Jumbo Jets of thrust to propel a Washing Machine to Ludicrous speed.


I don't know, but converting to units of gnat ass hairs, then I'd estimate at least a few bazzillion butt loads! laugh.gif rolleyes.gif


Sorry, I couldn't resist. I'll go and be quiet again now! laugh.gif



-- Pertinax

Posted by: mcgyver Nov 20 2009, 02:27 PM

QUOTE (PhilCo126 @ Nov 20 2009, 11:22 AM) *
An overview of some NEO surveys:

1973 Palomar Asteroid & Comet Survey
1990 Anglo-Australian NEA Survey
1994 SpaceWatch Kitt Peak ( 1.80 + 0.90 refractors – short focal Sky Survey )
1998 Lincoln NEA Research LINEAR
2008 Panoramic Survey Telescope Rapid Response System ( 4 X 1.80 m Refractors Hawaii )
2015 Large Synoptic Survey Telescope ( 8.40 m Chile )

LSST will detect all objects larger than 150 meter within a decade of survey...

This is the best one!
http://pan-starrs.ifa.hawaii.edu/public/design-features/cameras.html
billions of pixel per image! smile.gif

Posted by: Phil Stooke Nov 20 2009, 04:56 PM

We should note that these are being used for asteroid discovery and orbit determination, not monitoring for incoming objects in a real-time sense (as implied by the question that started this).

Phil

Posted by: Greg Hullender Nov 20 2009, 05:18 PM

I was going to point that out too. I think Pan-STARRS will be the first, as it'll scan the night sky every 4 days indefinitely, and its primary purpose is to look for incoming objects.

--Greg


Posted by: Paolo Nov 21 2009, 09:42 AM

In the latest issue of Astronomy & Astrophysics (and currently accessible for free): http://www.aanda.org/articles/aa/abs/2009/44/aa12639-09/aa12639-09.html

Posted by: Fran Ontanaya Nov 27 2009, 11:27 PM

A new Torino 1 asteroid:
http://neo.jpl.nasa.gov/risk/2009wm1.html

Posted by: nprev Dec 3 2009, 04:28 AM

And it's back to Torino 0. Didn't take long.

http://neo.jpl.nasa.gov/risk/2009wm1.html

Posted by: ngunn Dec 17 2009, 01:09 PM

This is from Spaceweather:

EVENTS IN NEBRASKA: "At 9 p.m. Central Time on Dec. 16th, a very bright meteor lit up the completely overcast sky like lightning in southeast Nebraska," reports Trooper Jerry Chab of the Nebraska State Patrol. "It flashed for approximately 2 seconds and was followed by ground shaking, which prompted many calls by the public to law enforcement in a three county wide area." The USGS says there was a magnitude 3.5 earthquake near Auburn, Nebraska, at 8:53 pm Wednesday night, about the same time and place as the fireball. Coincidence? Readers in Nebraska with photos or eyewitness accounts are encouraged to submit a report.

Anybody know more?

Posted by: PhilCo126 Jan 13 2010, 05:37 PM

The 15-meter sized 2010 AL30 came close: http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2010%20AL30;orb=1

Posted by: charborob Jan 13 2010, 06:37 PM

Passing so close to Earth, I suppose its orbit will be altered by Earth's gravitational boost?

Posted by: ugordan Jan 13 2010, 06:43 PM

Undoubtedly.

Posted by: ngunn Jan 13 2010, 08:55 PM

Emily has good posts on this, most recently this one:
http://www.planetary.org/blog/article/00002305/

Posted by: ugordan Jan 13 2010, 09:06 PM

Michael Khan's analysis certainly is compelling. For me personally it would be even more exciting if it turned out to be this (relatively) smallish Fregat stage instead of Yet Another Random Rock. What a little albedo difference can do...


Posted by: PDP8E Jan 14 2010, 01:11 AM

The (unmanned) Apollo 10 ascent stage is also in a earth centered heliocentric orbit. It was zoomed off from lunar orbit and has not been seen since (?) This makes it the only remaining true Apollo ascent stage in existence (all others were crashed into the moon, and Apollo 13's burned up in Erah's atmosphere after serving as a lifeboat). This angular aluminum structure would return very strong radar signals and it is almost 5 meters across.

Posted by: ElkGroveDan Jan 14 2010, 02:51 AM

Let's not forget http://www.spaceref.com/news/viewpr.html?pid=9497 which has its own asteroid designation - J002E3

Posted by: ugordan Jan 14 2010, 08:36 AM

QUOTE (PDP8E @ Jan 14 2010, 02:11 AM) *
This angular aluminum structure would return very strong radar signals and it is almost 5 meters across.

Though it's not very likely it would wind up in an orbit like this one after escaping Earth vicinity.

Posted by: PDP8E Jan 14 2010, 08:00 PM

Hi Gordan,

The current orbit that any heliocentric space flotsam is flying around in, has been influenced by a chaotic local environment. (Earth Moon, Sun...). After gravitational reactions and a slingshot or two, today's orbit may be completely counter-intuitive from the original trajectory.

I briefly 'collaborated' (read that: grunt work for 2 days) with Steve Ostro of JPL in the mid 90's about the identification of a transient object that was just outside the moon's orbit at that time. One of the possibilities he raised was the Apollo 10 ascent stage. I plowed through the archives at Rice for any supporting data (I didn't find anything that he didn't already know). The radar data (the work for which Steve was so famous for) was the appropriate size.

What we really need is a small fleet of little classifier spacecraft to track|radar|visit|image these close objects (1 million miles from Earth). It should be called the Ostro fleet for man who pioneered NEO and radar imaging of far far away objects. (Steve passed away a few years ago). Cheers

Posted by: hendric Jan 14 2010, 10:17 PM

This sounds like a great use for a solar sail. Perhaps if the Planetary Society has better luck with their next spacecraft, they can add to their Sun monitoring spacecraft a fleet for NEA encounters.

Posted by: ngunn Jan 14 2010, 11:02 PM

Great suggestion. They say they are not a space agency, yet they(we) may be about to cross that threshold. Once the snowball starts rolling there's no saying how big it could get.

Posted by: ilbasso Jan 23 2010, 01:17 AM

Close call with a meteorite about 15 miles from my house...a half-pounder hit a doctor's office on Monday. See http://www.washingtonpost.com/wp-dyn/content/article/2010/01/20/AR2010012004767.html?hpid=moreheadlines in the Washington Post.

Interesting (and totally meaningless) coincidence: I was less than 100 meters from the location of this impact when I saw a daytime bolide one afternoon in 2001.

Posted by: Juramike Jan 23 2010, 05:23 AM

QUOTE (ilbasso @ Jan 22 2010, 08:17 PM) *
Close call with a meteorite about 15 miles from my house...a half-pounder hit a doctor's office on Monday. See http://www.washingtonpost.com/wp-dyn/content/article/2010/01/20/AR2010012004767.html?hpid=moreheadlines in the Washington Post.


Two of my friends say they saw a fireball on Monday evening from parking lot of the RBC center in Raleigh while they were at the Hurricanes game.
Likely it was this coming in.


Posted by: ilbasso Jan 29 2010, 03:37 AM

Another update to this story. The doctors whose office was hit donated the meteorite to the Smithsonian, who in turn gave them a $5,000 appreciation award for the donation.

Not so fast, say the landlords who owned the building - according to Virginia law, the property owners have ownership of any natural object that falls into the property. They are demanding "their" meteorite.

http://www.washingtonpost.com/wp-dyn/content/article/2010/01/28/AR2010012804235.html?hpid=artslot

Posted by: nprev Jan 29 2010, 03:46 AM

I've been waiting for a dispute like this to happen. It'll be interesting to see the outcome.

Posted by: stevesliva Jan 29 2010, 05:45 AM

I'd imagine that if the insurance company covers damages, they'd want proceeds, too. blink.gif

Posted by: nprev Jan 29 2010, 08:22 AM

All I know is that if by chance a couple of kg of meteoritic material ever falls into my apartment, the property management company's gonna be amazed at the amount of damage a dime-sized chunk of space rock did to their roof... tongue.gif

Posted by: PhilCo126 Feb 5 2010, 02:13 PM

does anyone has details on the Ireland meteor of 3rd Feb 2010?
Astronomy Ireland said a space rock collided with the earth's atmosphere at around 6pm, and is now showering debris in many parts of the country.


Posted by: helvick Feb 5 2010, 07:47 PM

I haven't heard of any convincing reports of anyone identifying any debris so far. It was a fairly significant fireball, it was seen over an area that covers about 200km north to south and (as is normal) everyone along the path seems to have been convinced that it fell nearby or "just over the horizon". It was visible for about 2 seconds according to Astronomy Ireland and there is a very strong chance that it actually landed in the sea (if indeed anything landed at all).

One problem they have narrowing down precisely where it might be is that we're notoriously hopeless with compass directions here in Ireland. Most people don't have even the vaguest notion of whether they are looking North, South or somewhere in between so the error bars on all of the eye witness reports are fairly large.

I'm personally disgusted that I missed it. It was a fairly clear sky, just after dusk and I was actually outside walking at the time but I didn't notice anything. Oh well, maybe next time. smile.gif

Posted by: stevesliva Mar 12 2010, 04:11 PM

http://www.technologyreview.com/blog/arxiv/24917/

QUOTE
In 2007, however, the Hipparcos data was revised and other measurements of star velocities have since become available. How do these numbers change the figures?
...
What the new data has allowed Bobylev to do is calculate the probability of Gliese 710 smashing into the Solar System. What he's found is a shock.

He says there is 86 percent chance that GL 710 will plough through the Oort Cloud of frozen stuff that extends some 0.5 parsecs into space. [In 1.5 million years]


Incoming Orange Dwarf!

Posted by: ups Apr 15 2010, 12:47 PM

http://www.youtube.com/watch?v=TR2uNajroOM

Big fireball over the US last night.

Posted by: galileo Apr 15 2010, 01:25 PM

Long time reader, first post. This was a bright meteor or fireball caught on dash cam of patrol car in Eastern Iowa.
Link below:


http://www.kcci.com/video/23158154/

Posted by: Explorer1 Apr 16 2010, 05:45 PM

They found a piece:
http://www.duluthnewstribune.com/event/article/id/165999/group/homepage/

Posted by: Paolo Oct 10 2010, 09:30 AM

There is some buzz on the internet today about object RT9B991, not yet issued a preliminary asteroid designation, that may come very close to Earth in the next days. It appears to have some significant parallax (i.e. to be close to us) but slow motion, as if it was seen "head on".
More observations will be needed to know when and how close it will get.

Posted by: dilo Oct 10 2010, 05:49 PM

Thanks Paolo for highlight!
Based on Harvard ephemeris, minimum distance will be reached on Oct,12 around 11:14 UT, when proper motion will reach maximum value of 3900 arcsec/min (see plot below, with days on abscissa) blink.gif Assuming a tipical speed of 15 Km/s, this means a geocentric distance slightly below 48000Km!

 

Posted by: scalbers Oct 10 2010, 06:48 PM

Good call, this discussion has it at 52000km.

http://tech.groups.yahoo.com/group/mpml/message/24302

Posted by: Paolo Oct 10 2010, 09:20 PM

meanwhile, our small rocky friend has got a preliminary designation: 2010 TD54 http://www.minorplanetcenter.org/mpec/K10/K10T65.html
according to the same circular, closest approach will be 0.00043 AU around noon UTC tuesday. That's about 64,000 km

Posted by: ngunn Oct 10 2010, 09:54 PM

Anybody know how big it is?

Posted by: nprev Oct 10 2010, 10:52 PM

Not very, it seems; I'd bet that it's a lot less than 50m across, and probably less than 10. Peak visual magnitude is around 14 real near perapsis, otherwise hovers around 20. Phase angle changes dramatically as well; looks like it's coming straight out of the solar glare.

Posted by: djellison Oct 10 2010, 11:49 PM

2008 TC3 was about 4m across iirc - that might be a point of reference.

Posted by: nprev Oct 11 2010, 12:07 AM

Yeah, it's just a pebble in the sky. Should be some pretty cool flyby movies from the amateur astronomy community, though.

Posted by: volcanopele Oct 11 2010, 12:14 AM

sad.gif So that's a stand down on the bull's eye sign for my roof? laugh.gif

2008 TC3 has spoiled me. Am I the only one who WANTS another to hit? (though obviously below a size limit where damage might occur)

Posted by: nprev Oct 11 2010, 12:48 AM

Not at all! smile.gif I'd love to see a nice, bright bolide & grab a hot chunk of virgin meteorite for my very own!

2008TC3 was basically a free sample-return mission; it'd be great to have these happen more often, and it looks like the whole NEO search/observation program is going to make major fall prediction much, much easier.

Posted by: dilo Oct 11 2010, 05:16 AM

QUOTE (Paolo @ Oct 10 2010, 09:20 PM) *
according to the same circular, closest approach will be 0.00043 AU around noon UTC tuesday. That's about 64,000 km

Data interpolation suggest a minimum distance slightly above 0.00040 AU (exactly 60000 km) on Oct 12.483 (slighty later than previously stated):

Based on magnitude in the approach phase (with phase angle close to 0 and assuming a standard albedo), diameter should be only 5m!

Posted by: ugordan Oct 11 2010, 07:37 AM

QUOTE (volcanopele @ Oct 11 2010, 02:14 AM) *
Am I the only one who WANTS another to hit? (though obviously below a size limit where damage might occur)

Guilty here...

Posted by: SFJCody Oct 11 2010, 07:53 AM

Same. If it's under 20m in diameter bring it on! smile.gif

Posted by: SolarSystemRubble Oct 12 2010, 03:31 AM

As seems to happen with the tiny close approach asteroids, the observation count for 2010 TD54 is skyrocketing. Already 62 obs in 2 days with a late evening update. (Sentry data, NEODyS has not updated)

The close approach time has advanced 2 minutes to 10:49 UTC tomorrow, Oct 12 (A bit less than 8 hours from now)

The distance is reduced a bit, to (nominal distance) 51,789 km (32,180 miles) from the earth's center, or about 45,420 km from the surface. Minimum distance (1 sigma) is about 75 km less. 0% chance of impact.

Number of listed close approaches to other objects have increased. Passes about 1 LD from the moon 2 hours after earth CA. Venus in November this year and 2016, Vesta in 2029, Earth in 2055,2057,2068, and 2126, Mars in 2071 and 2127, and Venus in 2129 and 2135. Obviously, they are manually running the projection past the normal Sentry automatic 2110 cutoff.

Posted by: dilo Oct 12 2010, 05:32 AM

Thanks for this update, SolarSystemRubble!
Any new information on object physical characteristics? (size, rotation, etc)?

Posted by: SolarSystemRubble Oct 12 2010, 09:30 AM

Size (estimated from H=28.8) would be expected to be 4-10 meters, but that's a guess based on assumed albedo. Any rotation data would take a bit of time to be analyzed, and since was only discovered 48 hours ago, obs are coming in hot and heavy. About 80 minutes to close approach (will pass over southeast Asia, from what I've read)

Posted by: SolarSystemRubble Oct 12 2010, 10:07 AM

2010 TD54 including 76 observations through 01:50 UT.

No change to timing (10:49 UTC, about 40 minutes from now) or nominal distance (51,789 km from earth center). Uncertainty in CA distance reduced to 51 km.

Future close appoaches trimmed.

Moon, 2 hours after earth CA, 317,000 km

Venus Nov 9 (Sentry only) 0.09 AU
Venus 2016 (Sentry only) 0.07 AU
4 Vesta 2029 (Sentry and NEODyS) 0.02/0.03 AU
Mars 2030 (NEODyS only) 0.02 AU
Earth 2033 (NEODyS only) 0.11 AU
Earth 2044 (Sentry and NEODyS) 0.10 AU
Earth 2046 (Sentry only) 0.41 AU
Earth 2068 (NEODyS only) 0.07 AU

Posted by: SolarSystemRubble Oct 12 2010, 04:37 PM

In response to the earlier question about rotation; if you look at the second video, you can see there is a periodic light curve, so with a little time some shape and rotation estimates will be possible.

http://www.universetoday.com/75564/video-asteroid-2010-td54-whizzes-close-to-earth/

Just a rough estimate, I'd say about a 30 second peak to peak light curve.

Posted by: hendric Oct 12 2010, 08:46 PM

Any comments that this might be a spent rocket stage of some sort?
I love the fact that soon we'll be able to detect these early enough and figure out where to fly for one HELL of an awesome fireball.

Posted by: Paolo Oct 12 2010, 08:53 PM

QUOTE (hendric @ Oct 12 2010, 10:46 PM) *
Any comments that this might be a spent rocket stage of some sort?


from the latest orbital elements the perihelion is at 0.68 AU and aphelion is at 2.89 AU. artificial objects tend to have one of the two close to Earth's orbit because that is the less "expensive" way to place something in orbit around the Sun.
I am quite sure that this is a natural rock

Posted by: brellis Oct 13 2010, 12:47 AM

QUOTE
soon we'll be able to detect these early enough and figure out where to fly for one HELL of an awesome fireball.


Amusing to think of a bunch of folks waiting for an incoming meteor like SF Giants baseball fans in McCovey Cove in their kayaks, waiting for a home run! laugh.gif

Posted by: stevesliva Oct 13 2010, 03:18 AM

QUOTE (Paolo @ Oct 12 2010, 04:53 PM) *
from the latest orbital elements the perihelion is at 0.68 AU and aphelion is at 2.89 AU. artificial objects tend to have one of the two close to Earth's orbit because that is the less "expensive" way to place something in orbit around the Sun.
I am quite sure that this is a natural rock


Would all the early space-age probes that flew by Venus still have a 1 AU aphelion?

Posted by: dmuller Oct 13 2010, 03:41 AM

QUOTE (stevesliva @ Oct 13 2010, 01:18 PM) *
Would all the early space-age probes that flew by Venus still have a 1 AU aphelion?

Probably not, but ... I'm speculating here ... raising aphelion from 1AU to 2.8AU (half-way to Jupiter) with accidental (i.e. non-targeted, non-planned) gravity assists at Venus seems a stretch. Galileo needed a well-planned Venus AND Earth flyby to raise its aphelion to 2.8AU-ish. IIRC early Soviet probes to Venus had a strongly type 1 (or 2 ... always mix them up) trajectory, trying to get there faster than a Hohman transfer, but I don't think their aphelions were far beyond Earth.

Posted by: jasedm Oct 27 2010, 02:22 PM

QUOTE (SFJCody @ Oct 11 2010, 08:53 AM) *
Same. If it's under 20m in diameter bring it on! smile.gif


It would be great to have a ringside seat for a nearside moon impact of something of this size (or bigger), a bit scary being underneath something headed for earth though. ohmy.gif

Incidentally, an interesting calculator of local and global effects of impactors can be found http://www.lpl.arizona.edu/impacteffects

It's a program whereby you can enter different parameters for the incoming body (size, density, velocity etc) and the program generates information on the impact effects.

Ghoulish, but fun..


Posted by: Holder of the Two Leashes Feb 5 2011, 06:08 AM

A small rock (about four feet across, or a meter to a meter and a half) just skimmed by the earth. It was spotted and tracked several hours before closest approach.

http://neo.jpl.nasa.gov/news/news170.html

Posted by: tasp Feb 5 2011, 03:56 PM

Interesting.

A ring side seat watching an object shift from an Apollo asteroid orbit to an Aten class.

60 degree deflection upon encountering earth's gravity!

Posted by: jasedm Feb 5 2011, 10:51 PM

It never ceases to amaze me that despite 4.6 billion years of accretion, there are still a prodigious number of pieces of junk out there. Inevitable I suppose that the on-going sky surveys will pick up a frighteningly large rock heading our way - just a question of when..

blink.gif

Posted by: ngunn Feb 9 2011, 10:23 AM

QUOTE (tasp @ Feb 5 2011, 03:56 PM) *
A ring side seat watching an object shift from an Apollo asteroid orbit to an Aten class.


Given that it will now have a lower perihelion I wonder if it will develop a tail?

Posted by: Holder of the Two Leashes Jun 24 2011, 05:00 AM

Another small rock to pay a close visit in a few days.

http://neo.jpl.nasa.gov/news/news172.html

Posted by: claurel Jun 27 2011, 04:56 PM

QUOTE (Holder of the Two Leashes @ Jun 23 2011, 10:00 PM) *
Another small rock to pay a close visit in a few days.

http://neo.jpl.nasa.gov/news/news172.html


Close approach in about 5 minutes!

Here's an animation I made that shows the encounter from the asteroid's point of view:
http://www.youtube.com/watch?v=AkBFNOah4q0

Itokawa standing in for 2011 MD, and a WAG for the rotation state.

--Chris

Posted by: ElkGroveDan Jun 27 2011, 05:01 PM

Nice work. Thanks for creating that.

Posted by: jasedm Jun 27 2011, 05:08 PM

Outstanding! Thanks for that Claurel.

Posted by: Bunker9603 Jun 28 2011, 02:57 AM

That is a great animation! I looked at your other videos and they are all very nice...I am also your newest subscriber!

Posted by: walfy Jun 28 2011, 03:04 AM

Excellent animation!

Posted by: SolarSystemRubble Sep 26 2011, 10:38 PM

NASA To Host News Conference On Asteroid Search Findings WASHINGTON -- NASA will hold a news conference at 1 p.m. EDT on Thurs., Sept. 29, to reveal near-Earth asteroid findings and implications for future research. The briefing will take place in the NASA Headquarters James E. Webb Auditorium, located at 300 E St. SW in Washington.

NASA's Wide-field Infrared Survey Explorer (WISE) mission, launched in December 2009, captured millions of images of galaxies and objects in space. During the news conference, panelists will discuss results from an enhancement of WISE called Near-Earth Object WISE (NEOWISE) that hunted for asteroids.

The panelists are:
-- Lindley Johnson, NEO program executive, NASA Headquarters, Washington
-- Amy Mainzer, NEOWISE principal investigator, NASA's Jet Propulsion Laboratory, Pasadena, Calif.
-- Tim Spahr, director, Minor Planet Center, Smithsonian Astrophysical Observatory, Cambridge, Mass.
-- Lucy McFadden, scientist, NASA's Goddard Space Flight Center, Greenbelt, Md.

The event will air live on NASA Television and the agency's website. For NASA TV streaming video, downlink and scheduling information, visit:

http://www.nasa.gov/ntv

The briefing also will be streamed live, with a chat available, at:

http://www.ustream.tv/nasajpl2

For more information about the mission, visit:

http://www.nasa.gov/wise



Posted by: Paolo Sep 30 2011, 05:30 AM

arXiv paper on NEOWISE results, presented at yesterday's press conf
http://arxiv.org/abs/1109.6400

Posted by: Paolo Oct 14 2011, 05:34 PM

a near miss in 1883?
http://arxiv.org/abs/1110.2798
I tend to be skeptical of this kind of old visual obs, but well, who knows...

Posted by: PDP8E Oct 14 2011, 07:20 PM

QUOTE (Paolo @ Oct 14 2011, 01:34 PM) *
a near miss in 1883? .... I tend to be skeptical of this kind of old visual obs, but well, who knows...


Seriously? Why would any scientist publish an article in ComicSans?
Especially one on very tenuous ground to begin with...


Posted by: centsworth_II Oct 14 2011, 10:13 PM

QUOTE (PDP8E @ Oct 14 2011, 03:20 PM) *
Seriously? Why would any scientist publish an article in ComicSans?

So that someone could incorporate an actual screen capture of their text into a cartoon. laugh.gif


Posted by: PDP8E Oct 15 2011, 12:10 AM

I see your logic centsworth the 2nd! wink.gif

Posted by: Paolo Oct 15 2011, 10:17 AM

the paper is making some buzz on the internet: http://www.universetoday.com/89911/was-the-first-photographed-ufo-a-comet/

Posted by: ilbasso Feb 5 2012, 09:44 PM

Fireball reported over the Washington DC area Friday night per http://wtop.com/?nid=46&sid=2735553. Also an interesting video linked on that page - a bolide over Texas/Oklahoma http://www.youtube.com/watch?feature=player_embedded&v=cHKElGrTo80 during a traffic stop.

Posted by: CosmicRocker Feb 9 2012, 06:42 AM

Both my wife and I saw that Texas-Oklahoma bolide from our place near Marble Falls, Texas. It was amazingly bright and appeared to move surprisingly slowly across the sky. I caught it out of the corner of my eye as I walked between two buildings. At first I thought, "That's the moon," but then I realized that the moon couldn't be north of me. I turned around and walked back to the view between my house and the garage for a second look to see the fireball die out on the horizon.

My wife jumped up from her seat in our living room when she saw it through the window. She ran out onto the back deck, initially thinking it was an airplane in flames. She watched it disappear as it descended toward the horizon. Her recollection was that its color was distinctly green. We both thought that it fell within a few miles of our house, but apparently it fell near Dallas, about 200 miles north of here.

I hope someone is able to collect some fragments from this one. smile.gif

Posted by: tty Feb 11 2012, 06:51 PM

Sci-Fi enthusiasts will note that if those observations in Zacatecas were really a fragmented comet it means that the scenario in S. M. Stirling's "The Peshawar Lancers" very, very nearly came true.

Posted by: ngunn Mar 4 2012, 09:43 PM

A British meteor: http://www.meteorwatch.org/2012/03/04/fireball-witnessed-over-uk-3rd-march-2012/

Did anybody here see it? (No such luck in my case, though I have enjoyed best-ever views of Mercury these last two evenings.)

Posted by: Rob Pinnegar Mar 5 2012, 01:58 AM

Apparently a good sized bolide (~100 kg) came down over Saskatchewan several days back as well. Oddly enough it landed in the same part of the province that experienced a good sized fall about three or four years ago.

This latest one was visible from Calgary. I'd have liked to have seen it, but unfortunately I wasn't outside at the time. Pity.

Posted by: jasedm Mar 5 2012, 07:52 PM

I've never seen a decent long-lived meteor despite living in an area with little light-pollution. I've seen meteors many times whilst on holiday in Wales in the 70's with my parents but they were always a few seconds duration, and by the time I zeroed in on them they'd gone. Disappointing.

Posted by: nprev Mar 6 2012, 11:13 PM

In addition to the 10 Aug 72 daylight fireball over the western US, I saw a terrific Perseid in the 70s. Around mag -6, and it exploded right in the bowl of the Big Dipper...orange glow remained for at least 2 min. Unforgettable.

Posted by: ngunn Mar 6 2012, 11:32 PM

I've seen one. It was sometime in the 1980s and I was on a city street whilst on holiday in Ireland. I reported the observation with a sketch of the trajectory relative to the buildings.

It's a shame that we spend so little time in sight of the sky the way we live now. On the other hand the lucky few are increasingly likely to carry recording devices, so it's not all bad.

Posted by: tedstryk Nov 8 2012, 03:17 AM

Looks like we got a nifty visitor! http://www.mnn.com/earth-matters/space/stories/nasas-radar-images-reveal-mile-wide-asteroid-in-deep-space

Posted by: Phil Stooke Nov 8 2012, 04:29 AM

This is a composite of the three images giving a rough idea of the overall shape - the caption says it's a roughly pole-on view.

Phil


Posted by: Paolo Feb 11 2013, 06:12 PM

info on "two independent but mutually supporting" asteroid deflection missions, one by the APL, the other by ESA
http://www.esa.int/Our_Activities/Technology/NEO/AIDA_Call_For_Experiment_Ideas

Posted by: Astro0 Feb 15 2013, 01:03 AM

I found this asteroid infographic both useful and amusing.


Posted by: Phil Stooke Feb 15 2013, 01:15 AM

Fun! But the Canadian crater is Charlevoix. Still, it's not an L of a difference, is it?

Phil

PS - darn, I've slipped onto the next page. That weakens my impact factor.

Posted by: Astro0 Feb 18 2013, 05:56 AM

ADMIN: Posts on the Chelyabinsk meteor event have been split into their own thread http://www.unmannedspaceflight.com/index.php?showtopic=7603.
Please continue the discussion there.

For all other "the sky is falling" events, please continue as per normal wink.gif

Posted by: Paolo Feb 19 2013, 07:05 AM

radar images of 2012DA14
http://www.oosa.unvienna.org/pdf/pres/stsc2013/2013neo-05E.pdf

Posted by: Paolo Feb 19 2013, 08:42 PM

and a video: http://www.youtube.com/watch?v=Zy0p0D3h9iA

Posted by: dvandorn Feb 19 2013, 08:56 PM

At least over the period observed, I only see rotation along a single axis. That would be somewhat rare, wouldn't it?

-the other Doug

Posted by: Phil Stooke Feb 19 2013, 09:16 PM

No, it's what we would expect from a fairly rapid rotator like this. But radar images are notoriously difficult to interpret so I would want to see more results of shape and rotation modelling before drawing any conclusions.

Phil

Posted by: Paolo Feb 24 2013, 04:32 PM

the Canadian NEOSSat, the first satellite dedicated to the detection of near Earth asteroids is due for launch tomorrow in India
http://www.asc-csa.gc.ca/eng/satellites/neossat/

Posted by: Hungry4info Feb 25 2013, 02:25 PM

Launch was successful.

Posted by: Floyd Feb 26 2013, 12:51 AM

http://www.csmonitor.com/Science/2013/0225/Little-telescope-to-hunt-big-game-hard-to-see-near-Earth-asteroids

Posted by: stevesliva May 30 2013, 10:41 PM

Goldstone finds a satellite for 1998 QE2, "Ocean Liner" size comparison results:
http://cosmiclog.nbcnews.com/_news/2013/05/30/18632613-thats-no-space-station-asteroid-1998-qe2-has-a-moon-radar-shows

Posted by: TheAnt May 31 2013, 10:53 AM

QUOTE (stevesliva @ May 31 2013, 12:41 AM) *
Goldstone finds a satellite for 1998 QE2, "Ocean Liner" size comparison results:


With the satellite about 1/4 the size of the main body, it might qualify 1998 QE2 as a binary asteroid.

Posted by: nprev May 31 2013, 11:04 AM

Hopefully not too OT, but I'm wondering just exactly how asteroids even have moons.

The only mechanism I can think of to create them is a very low relative speed impact, which would seem to be a rare event. However, asteroid moons seem to be fairly common, esp. for low-mass objects. (Note that Vesta apparently has none; jury's still out for Ceres. Gravitational capture would be a more likely mechanism for moons around a high-mass body, but thus far we haven't seen much of that.)

Might be something else happening here. Calving, perhaps, off of the main body over time due to heating/cooling cycles?

Posted by: elakdawalla May 31 2013, 02:21 PM

From "FORMING THE OBSERVED BINARY ASTEROID POPULATION. S. A. Jacobson1 and D. J. Scheeres2, 1Dept. Astrophysical and Planetary Sciences, Univ. of Colorado, Boulder, USA (seth.jacobson@colorado.edu), 2Dept. Aerospace Engineering Sciences, Univ. of Colorado, Boulder."

QUOTE
Rotational fission results in the
formation of all classes of observed near-Earth asteroid
(NEA) binaries. The NEA population is constantly
evolving due to the incredible influence of electromagnetic
radiation. The YORP effect, torque from the incident
solar irradiation and thermal radiation of an
asymmetric body, can rotationally accelerate individual
asteroids until centrifugal accelerations match gravitational
accelerations, releasing part of the body into
orbit and creating a binary asteroid system–i.e. rotational
fission. This process has been theoretically predicted
and modeled in detail [1, 2], as well as observationally
confirmed [3]. The figure below shows the
evolutionary pathways from rotational fission to each
of the observed binary classes indicated by an underline.
q is the mass ratio of the binary (secondary / primary
mass). Primary defined to be more massive.


http://www.lpi.usra.edu/meetings/acm2012/pdf/6092.pdf Or google for binary asteroid formation.

Posted by: Phil Stooke May 31 2013, 03:27 PM

Another explanation - forget where it came from - a large asteroid is blown apart in a big impact. Two chunks are ejected on almost parallel trajectories, and as they move outwards they stay together and become a binary. I think this dated from about the time Dactyl was discovered orbiting Ida.

Phil


Posted by: Paolo Oct 12 2013, 04:01 PM

I was looking for updates on the Canadian NEOSSat, but I could not find any. anybody knows whether the satellite is alive and producing data?

Posted by: dilo Oct 19 2013, 05:30 PM

2013 TV135, discovered one week ago, is now rated level #1 in the "Torino scale", with an impact probability 1:48000 for August 2032 approach:
http://neo.jpl.nasa.gov/risk/
Curiously, probability slightly increased from yesterday's value (http://www.jpl.nasa.gov/asteroidwatch/index.cfm).

Posted by: nprev Oct 20 2013, 09:02 AM

Doubtless the odds will drop to zero after further observations, as usual. Still, it is extremely prudent to maintain the watch for these things.

Posted by: dilo Oct 20 2013, 09:37 PM

QUOTE (nprev @ Oct 20 2013, 10:02 AM) *
Doubtless the odds will drop to zero after further observations, as usual.

Well, curiously impact probability keep increasing!
For http://neo.jpl.nasa.gov/risk/2013tv135.html odds rised to 1:14000, while http://newton.dm.unipi.it/neodys/index.php?pc=1.1.2&n=2013%20TV135 gives even higher value of 1:7500...
For sure, it will be very close to us in 2032!

Powered by Invision Power Board (http://www.invisionboard.com)
© Invision Power Services (http://www.invisionpower.com)