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

Scary.

Welcome to the real world...

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 these 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 sister aircraft 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...)

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......

I do seem to remember seeing a report on the Montana local news a few days after the 1972 Daylight 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.

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

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 this source.

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

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

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.

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.

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 --

Bhangmeter

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.

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

It looks like nobody noticed the question mark in blue circle at top left of my reply
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 so for IYA 2009 a recheck might be necessary...

BTW superb reply on the etymology of the word "Bhangmeter"

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

http://www.astroguard.com/

and a few good books on the subject:

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

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.

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

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

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/C...ishColumbiaHome

The search continues: http://www.sciencedaily.com/releases/2008/...81125141602.htm

!

Thats beautifull, but quite scary...

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

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


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

Beauties indeed:
http://blogs.discovery.com/whats_up_astron...tchewan-me.html

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

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 photo essay of the initial recovery efforts, followed by lab photos, including several cross-polarized thin sections.

Here is the text of a recent news story 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.”

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


---ups

Hopefully not OT, but I stumbled upon a rather cool site 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.

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

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

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

Pieces of the Texas meteor, seen Sunday 15th February 09, were found:
http://www.dallasnews.com/sharedcontent/dw...or.3c40815.html
and
http://www.sciam.com/blog/60-second-scienc...-pos-2009-02-19

Remember the October 2008 meteor above Sudan?
It looks like fragments were found:
http://www.newscientist.com/article/dn1663...ter-impact.html

Tunguska-sized space rock buzzes Earth

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

[edit]
Really close this time!

Close indeed!

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?

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?

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/as...uzzed-by-earth/

And another one = 2009FH
http://www.universetoday.com/2009/03/17/ne...-earth-tonight/
http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2009%20FH;orb=1

Article on the recovered pieces of 2008 TC3 found in Sudan's Nubian desert.
Rosetta Stone

Edit 26 March. Two more articles:
Tracking the asteroid
Recovery

Another Edit: 'Nother one.
UK observations
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."

Emily's blog 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).

Main article is published in Nature, for those who have a subscription, plus a free review article

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."

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

The asteroid watchers over at space.com have been talking about a newly spotted asteroid that looks like it's coming very close in 2022.
We might need to redirect that Apophis mission!

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?

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.

That'll work too.

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

Good idea Shaka. You think like a seasoned Admin.

Via NSF.com : Military Hush-Up: Incoming Space Rocks Now Classified