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Posted by: cIclops Jan 29 2005, 12:17 PM

An overlooked mission yet one that will be the focus of media attention in 155 days from now on July 4 2005, so there's time left to post a message before impact

cIc

Posted by: Decepticon Feb 1 2005, 01:03 AM

Does annyone know if DI has any plans after primary mission?

Waste of a probe if its not used for anything else.

Posted by: cIclops Feb 1 2005, 08:18 AM

Good question. After data playback DI will be a fully functioning spacecraft with nowhere to go. It has two telescopes (30cm and 12cms diameter) a multispectral camera and an infrared spectrometer. There should also be some of the original 86kg of fuel left after trajectory corrections.

There is an undefined period between EOM and EOP where something may happen such as navigation tests. Retargeting to another object followed by hibernation may be possible.

There is very little or no money as, according to http://www.diamondbackonline.com/vnews/display.v/ART/2005/01/26/41f71b8d3fd5d the project has overspent (from $279M to $313M) and been descoped (one year earth orbit test phase cancelled) so an extended mission will need more funding.

Impact: 4 July 2005
End of Mission: 3 August 2005
End of Project: April 2006

http://www.nasa.gov/deepimpact
http://deepimpact.umd.edu/
http://deepimpact.jpl.nasa.gov/

152 days to impact

Posted by: tedstryk Feb 1 2005, 10:47 AM

I have heard talk about trying to send it to at least one more comet. If funded and if it has enough fuel, maybe it will be able to somewhat make up for Contour.

Posted by: djellison Feb 1 2005, 02:06 PM

I'm sure it'll get that funding - a pre launch press conf mentioned that they have several follow-on candidate targets.

Of course - the spacecraft may get damanged during the flypast, who knows.

I think they're planning to use Genesis for training, and to measure some solar wind features as well - if nothing else, DI could be used for that.

DI will only be 6 months old when it's primary mission is over. For most spacecraft, they've barely finished checkout and have 8 years ahead of them at that stage

Doug

Posted by: tedstryk Feb 1 2005, 03:22 PM

Lets hope DI has 8 years to explore many comets!

Posted by: Decepticon Feb 5 2005, 03:24 AM

Looks like great news!

Thanks for the updates.

Posted by: djellison Feb 5 2005, 03:54 PM

I wonder if DI's done any Earht Observations as a calibration exercise as it was leaving
?

Doug

Posted by: tedstryk Feb 5 2005, 05:35 PM

I remember reading it would. But whether it will be Mariner 10 quality or Rosetta quality or somewhere inbetween is unkown.

Posted by: DEChengst Feb 5 2005, 05:54 PM

Posted by: djellison Feb 5 2005, 09:32 PM

They recovered from that safing very quickly - and I would have thought some calib.type stuff would have been maybe 5, 10 days out ( a couple of lunar distances ) and would have been unaffeected.

Doug

Posted by: cIclops Feb 7 2005, 02:34 PM

There is a neat DI simulator available at http://neo.jpl.nasa.gov/orbits/deepimpact.html
(requires Java) that will trace the trajectory all the way through to impact on July 4 2005.

The simulator will also run forward until 14 February 2008 and show close encounters between DI and both Mars and Earth. It's not clear if these encounters are based on the trajectory changes that will be made just before encountering Tempel 1. The simulator does warn that it uses 2 body methods and is not accurate over longer timescales.

Further to Decepticon's question about plans after encounter, in the second to last paragraph on that page it says:

"If the spacecraft is healthy and if NASA is able to grant the necessary permission and resources, the spacecraft could then be re-targeted for another cometary flyby by using the Earth encounter to re-shape the spacecraft's trajectory."

There is also a project outreach page about observing Tempel 1 and the impact here: http://deepimpact.umd.edu/amateur/index.shtml

146 days to impact

Posted by: cIclops Feb 12 2005, 09:42 AM

1st trajectory correction maneuver (TCM) performed successfully on 11 February 2005.

Coming up: scientific calibrations, an encounter demonstration test, ground operational readiness checks and a second TCM.

http://www.nasa.gov/mission_pages/deepimpact/main/index.html


141 days to impact

Posted by: BruceMoomaw Feb 14 2005, 10:28 AM

(1) The DI people have been considering a follow-up comet flyby almost from the start, and two possible targets have been identified. One is Comet Finlay, but I don't know what the other one is.

(2) DI did indeed take some calibration photos of the Moon shortly after leaving Earth, and one has been released. It looks -- unlike the fuzzy misted-up Stardust photos -- nice and clear.

Posted by: OWW Mar 6 2005, 09:53 AM

Posted by: cIclops Mar 6 2005, 12:46 PM

Thanks for the image ObsessedWithWorlds, it's good to see proof that the camera works

Deep Impact have the image on their site now with a caption that i'll paste here to save clicking.

"Four days after launch from Cape Canaveral on January 12, 2005, the Deep Impact spacecraft pointed at the Moon to test its telescopes, cameras and spectrometer. This image was taken on January 16, 2005, with the Medium Resolution Imager (MRI). It was a 9.5 sec exposure. The spacecraft was more than 1.65 million kilometers (1.02 million miles) from the Moon, and a little more than 1.27 million kilometers (789,000 miles) from Earth. The spacecraft is scheduled to impact comet Tempel 1 on July 4, 2005."

http://www.nasa.gov/mission_pages/deepimpact/multimedia/deepimpact-moon.html

Posted by: cIclops Mar 25 2005, 04:08 PM

Only 100 days to impact and still no update from the Deep Impact team, hopefully no news means good news.

Here is another site to browse while waiting for the encounter to begin: http://www.spacetoday.org/SolSys/Comets/DeepImpact.html

Posted by: Sunspot Mar 25 2005, 04:15 PM

Only 100 days to impact and still no update from the Deep Impact team, hopefully no news means good news.

Here is another site to browse while waiting for the encounter to begin:  http://www.spacetoday.org/SolSys/Comets/DeepImpact.html

Posted by: cIclops Mar 26 2005, 08:11 AM

From http://www.nasa.gov/mission_pages/deepimpact/media/deepimpact-032505.html

the good news:

"NASA's Deep Impact spacecraft has completed the commissioning phase of the mission and has moved into the cruise phase."

the not so good news:

"At completion of the bake-out procedure, test images were taken through the High Resolution Instrument. These images indicate the telescope has not reached perfect focus."

Posted by: dot.dk Mar 26 2005, 08:58 AM

"At completion of the bake-out procedure, test images were taken through the High Resolution Instrument. These images indicate the telescope has not reached perfect focus."

Posted by: DEChengst Mar 26 2005, 11:25 AM

QUOTE (cIclops @ Mar 26 2005, 08:11 AM)

"At completion of the bake-out procedure, test images were taken through the High Resolution Instrument. These images indicate the telescope has not reached perfect focus."

Oh dear, Hubble disease again

Hope it's not too bad...

Posted by: DEChengst Mar 26 2005, 11:27 AM

Oh dear, Hubble disease again 

Hope it's not too bad...

Posted by: Roby72 Mar 26 2005, 07:50 PM

The image of Jupiter taken with the HRI looked unsharp - I think it must be sometimes sharper and is described as "not reached focus" at the Deep Impact homepage.

Robert

Posted by: tedstryk Apr 5 2005, 02:07 AM

http://aviationnow.ecnext.com/free-scripts/comsite2.pl?page=aw_document&article=04045p04

Here is the latest. Looks bad.

Posted by: Marcel Apr 5 2005, 11:35 AM

http://aviationnow.ecnext.com/free-scripts/comsite2.pl?page=aw_document&article=04045p04

Here is the latest.  Looks bad.

Posted by: gpurcell Apr 5 2005, 06:47 PM

http://aviationnow.ecnext.com/free-scripts/comsite2.pl?page=aw_document&article=04045p04

Here is the latest.  Looks bad.

Posted by: BruceMoomaw Apr 5 2005, 07:02 PM

I'm looking into this matter myself -- I suspect that, given the cost problems with recent Discovery missions (including this one), they simply could not afford such a secondary focusing system. After all, they haven't had one on other cameras on planetary spacecraft, and were presumably gambling that it would not be necessary this time -- although this is by far the most powerful optical system ever put on a planetary spacecraft. As for how much ground-based deconvolution can compensate for the problem: I'm hearing conflicting accounts.

But at any rate this may be a further consequence of the crisis that the Discovery Program has now encountered, and which forced them to completely cancel their last mission selection -- namely, that the current cost cap for scientifically worthwhile Discovery missions has simply become too low and must be raised, at the expense of flying the missions less frequently than was previously the case. As was pointed out recently, given the cost rise in launch vehicles and the less general inflation rate, the Messenger mission -- which was initialy accepted beneath a $300 million cost cap -- would take $430 million to fly today. And the current cap is only $350 million, so obviously something has to give. The new Discovery mission selection round -- which will be initiated this month -- will have a raised cap.

We are now running out of Solar System missions that can be so cheap and yet make significant new scientific discoveries at this point. By insisting on flying one new Discovery mission per year, we have been flying them at a faster rate than the rate at which new technical innovations can cut their cost back down. And one conclusion of NASA's new Solar System Strategic Roadmap Committee is that, in another decade, the same thing will start happening to the the medium-cost New Frontiers missions as well.

Posted by: cIclops Apr 21 2005, 07:56 PM

edit: oops nothing to read here now, i see sunspot has already posted this story http://www.unmannedspaceflight.com/index.php?showtopic=896.

Posted by: Sunspot Apr 27 2005, 11:13 PM

http://www.planetary.org/news/2005/deep_impact_image_tempel1_0427.html

Deep Impact's First Glimpse of Its Destiny

Two months away from its rendezvous with a comet, Deep Impact has caught its first glimpse of its target. Comet Tempel 1 was 63.9 million kilometers (39.7 million miles) away from the spacecraft when it captured the snapshot at right.

Posted by: cIclops Apr 28 2005, 08:22 AM

http://www.nasa.gov/mission_pages/deepimpact/media/deepimpact-042705.html

now just 68 days to impact

Posted by: edstrick Apr 28 2005, 09:23 AM

"Too Cheap" can compromize you till you fail to achieve the primary mission goals. I'm afraid, despite the spectacular degree of the NEAR Eros orbiter mission's success, including it's "obviously impossible" landing on the asteroid, many scientists feel the mission failed to achieve it's primary mission objective: Proving that S Type Asteroids are or are-not the parent bodies of chondritic meteorites.

The camera was small, with frame dimensions since Mariner 4, with non-square pixels, and a good deal of perioduc and random noise clearly visible in 8-bit versions of the images. After the attutude upsed during the "anomaly" at the initial rendezvous burn at Eros, the camera also had some significant fogging due to vented hydrazine or combustion product contamination, that didn't help, either.

The infrared spectrometer failed relatively early in the orbital period and wasn't able to clearly separate fresh and non-fresh exposures of surface material, and the X-ray and Gamma ray instruments simply weren't sensative enough and didn't have enough dwell-time and spatial resolution to resolve fresh from non-fresh material from very low orbital passes. In fact, the only really good gamma data for some analysis from the mission was the data taken after landing.

The mission was a major success, but still, it just didn't really do the job it was supposed to be able to do for the mission to be fully justified.

Posted by: BruceMoomaw Apr 28 2005, 04:32 PM

Jeffrey Bell (the one at the U. of Hawaii) certainly thinks NEAR fizzled at that task. Indeed he thinks that nothing short of an asteroid sample return can setttle the issue; he takes a dim view of remote compositional observations in general.

As for Discovery: NASA has now announced that the cost cap for the next Discovery selection has been hiked all the way up to $450 million -- which also means that there are going to be fewer missions. The plan was to release the new Announcement of Opportunity this week -- but there has been a delay: apparently someone has now managed to persuade Congress to launch an investigation of the whole Discovery program, with as-yet uncertain ultimate consequences.

Posted by: Sunspot May 30 2005, 10:59 PM

http://www.eso.org/outreach/press-rel/pr-2005/pr-15-05.html

Preparing for the Impact
ESO Telescopes Take Snapshot of Comet 9P/Tempel 1 in Readiness for Major Observation Campaign

Posted by: Sunspot May 31 2005, 10:19 AM

http://www.floridatoday.com/apps/pbcs.dll/article?AID=/20050531/NEWS01/505310327/1006

CAPE CANAVERAL - Deep Impact is on track to smash its impactor into a comet July 4, but its high-resolution camera's focus is still imperfect.

Posted by: Sunspot Jun 3 2005, 11:09 PM

Jun. 9 -- Deep Impact Briefing - NASA TV

10 a.m. PDT

Posted by: maycm Jun 10 2005, 12:49 PM

New report on the HRI

http://www.space.com/missionlaunches/050609_impact_camera.html

Posted by: Bob Shaw Jun 11 2005, 04:16 PM

It appears that Deep Impact is suffering from a re-run of the old Hubble optical problem. Ball Aerospace used an optical surface during the camera manufacturing process which changed shape slightly with different temperatures, and the flyby images will need to be deconvoluted to recover detail. The impact vehicle appears to be OK, however.

I think the only response possible is 'D'oh!'.

Posted by: dilo Jun 15 2005, 11:52 PM

Tempel-1 pictured with Medium Resolution Imager (MRI) camera:
http://deepimpact.umd.edu/gallery/DI_T1_doy164.html
(quite strange linear artifacts near the comet... ).

A sad question/consideration. The impactor uses a high-precision star tracker, which imply some kind of optical instrument... why they didn't planned to use it (or add a dedicated small camera) to take a "movie" of nucleus approach?
Even using a low resolution and limiting bit rate (let's say, one picture/min) last images should easily reach sub-meter resolution of pre-impact area, a result impossible even with perfectly focused HRI...

Posted by: jamescanvin Jun 16 2005, 12:21 AM

A sad question/consideration. The impactor uses a high-precision star tracker, which imply some kind of optical instrument... why they didn't planned to use it (or add a dedicated small camera) to take a "movie" of nucleus approach?
Even using a low resolution and limiting bit rate (let's say, one picture/min) last images should easily reach sub-meter resolution of pre-impact area, a result impossible even with perfectly focused HRI...

Posted by: dilo Jun 16 2005, 01:47 AM

Thanks James, I completely missed it (hope this will not happens to impactor camera! ).

Posted by: Comga Jun 21 2005, 06:33 AM

To be precise, the neucleus and coma images will be taken with the Impactor Target Sensor, which peers out forward through a port in the Impactor's copper mass. The star tracker points at right angles to this camera. It has a wider field of view with fewer pixels so that it can determine the orientation of the spacecraft relative to the stars.

The number and size of the images returned to the Fly-by spacecraft is constrained by the limited power available for the S-band communications link and the distance between the spacecraft, which grows to >8000 km at impact. Pictures of the surface would be great, but the science is in the impact, which takes priority.

Impact minus 12 days!

Posted by: dilo Jun 21 2005, 09:36 PM

Tank you very much, comga!
I understand that impact is the main objective, but can you kindly give a little bit infos about the Impactor Target Sensor (optics/sensor)...?

Posted by: Decepticon Jun 21 2005, 11:48 PM

When will science observation start?

Posted by: alan Jun 22 2005, 03:39 AM

Deep impact detects comet nucleus
http://www.newsdesk.umd.edu/scitech/release.cfm?ArticleID=1087

Posted by: Comga Jun 22 2005, 06:34 AM

I understand that impact is the main objective, but can you kindly give a little bit infos about the Impactor Target Sensor (optics/sensor)...?

Posted by: Comga Jun 22 2005, 06:51 AM

You can also look at the JPL site

http://deepimpact.jpl.nasa.gov/tech/instruments.html

There is a wealth of information on the instruments, and lots of links.

You can see that with a pixel projection of 10 microradians, (10 meters at 1,000,000 meters distance) if it snaps a picture ten seconds out, at a distance of 100 km, the resolution would be one meter. If it gets one five seconds out, its half a meter. The 20 cm resolution mentioned as a limit would require taking the picture at 2 seconds out, from 20km, and sending it to the fly-by spececraft before being vaporized. That assumes that the impactor doesn't get hit with a dust particle, which could cause it to lose stability. The crater would be uneffected, but any images would be smeared.

Posted by: edstrick Jun 22 2005, 07:36 AM

The Ranger 7-9 moon probes were each transmitting images when they went ZIP-CRUNCH. In each case, a variable portion of a full-frame image <either A or B frame> and one of the 200 line partial scan <P1 through P4> images was "in transmission" at impact. Since the data was analog slow-scan raster, there was no problem making an image of the fragment up to the last millisecond of image.

Are the impactor's data compressed, so that partial frame data will be partially corrupted, or are they raw bit stream, so that every last pixel up to the one "in transmission" at the moment of impact will be recoverable?

Posted by: djellison Jun 22 2005, 09:19 AM

It's going to be a bit like NEAR in a way isnt it - image image image wow - didnt expect them this low - image image - crunch

I would imagine there isnt enough grunt or time to compress, it's not like they can re-transmit to get back some lost bits - and compressed data suffers a lot with a single lost bit, so they'll wizz straight back to the fly-by uncompressed I'd imagine - and thus, the last image will almost certainly be partial
Doug

Posted by: dilo Jun 22 2005, 04:45 PM

Thanks again, Comga!
About compression, I made a little small calculation: based on Impactor Technology description (http://deepimpact.jpl.nasa.gov/tech/impactor.html), it will transmit at nominal data rate of 64 Kbps, so this translates into a mere 16 KBytes every 2 seconds... a full res image from ITS, however, should be 1 MB uncompressed (assuming 8bit/pixel), so they should strongly compress it before transmission (more than 60:1 ratio!); this would require heavy/fast number crunching but, probably, board computer is not so sophisticated and, in addition, Doug is right about compression side effects.
I tend also to exclude pixel re-bin (subsampling) because this would compromise nominal resolution which is declared to be 20cm @ 20 Km distance. The only possible conclusion is that, at least for very last pictures, only a (central) small portion of image will be transmitted, probably something like 256x256 or even less, considering that shortly before impact the pace of imaging will increase until it reaches a maximum of one picture every 0.7 second...
So, under the best conditions, let's prepare to see only a small portion (50m?) of the comet nucleus with maximum resolution...

Posted by: Bob Shaw Jun 22 2005, 07:58 PM

Judging from the Giotto dust impact experience (it *really* needed the Whipple bumpers!) I'd expect the smart bullet to get some pretty hefty whacks, so there's every chance it's tumbling whern it hits. Assuming that the transmitter antenna geometry isn't critical then that could actually give us an interesting spread of images - or none at all!

Posted by: BruceMoomaw Jun 22 2005, 10:40 PM

Keep in mind also that that camera is going to get seriously sandblasted as it plows through the central regions of the coma -- I wouldn't count on its photos being much better than those from the main spacecraft's HRI.

Posted by: Comga Jun 23 2005, 07:22 AM

The images will be sub-frame towards the end.

Note that Tempel 1 is a much less active comet than 1P/Halley, and seems to be less active this orbit than on its last orbit. Deep Space 1 flew by Borelley without ever recording an impact that registered on the attitude control system. However, 20 km is a lot closer than either Giotto or DS1 got.

If memory serves, Giotto got hit on the camera steering mirror that was sticking out around the edge of the Whipple shield. A probe can either be safe and blind, or stick its "neck" out, get the data, and take the risk. The same goes for the fly-by.

Posted by: abalone Jun 23 2005, 08:10 AM

If memory serves, Giotto got hit on the camera steering mirror that was sticking out around the edge of the Whipple shield.  A probe can either be safe and blind, or stick its "neck" out, get the data, and take the risk.  The same goes for the fly-by.

Posted by: edstrick Jun 23 2005, 08:19 AM

Giotto *LOST* the periscope during the flyby.
During post-encounter testing, the camera saw approximately no illumination, though the CCD and detector system were working, Also, the spacecraft <spin stabilized> balance behaved abnormally while they attempted to point the periscope. Inference was that most of the periscope and mirror were destroyed and debris blocked the light path between CCD and inboard optics and the mirror.

(this is from memory, I can't be more precise)

I'd ***LOVE*** some millennium to see what Giotto ended up looking like after the encounter.

Posted by: Bob Shaw Jun 23 2005, 02:17 PM

There is also a very big difference in encounter velocity. Stardust was 6.1km/s, Deep Impact 11km/s vs Giotto 70?km/s That equates to an almost 50X kinetic energy content of similar sized dust particle that struck Giotto compared to DI.

Posted by: edstrick Jun 23 2005, 06:28 PM

Comet dust seems to be made of stuff that's cigarette smoke sized. Look at the SUBSTRUCTURE of the dust-bunny clumps of cosmic dust we collect from the stratosphere. But this stuff does clump into clods, and even if a clod of comet dust has a density of 0.1 or maybe even 0.05 <like aerogel>... at 70 something km/sec, a 1 centimeter clod packs a whallop. Like the foam at 300 miles/hr and a shuttle wing, but with far far more bounce-per-ounce kinetic energy.

Posted by: djellison Jun 23 2005, 07:18 PM

a 1 gramme clod at 11000 m/s is like a car hitting something at 30 mph or a Mach 1.5 golf ball

Doug

Posted by: helvick Jun 23 2005, 08:20 PM

Just to put the problem of "cometary dust" in perspective.

0.05 grammes @ 70km/sec == kinetic energy of 1Kg at 1800kph.

Or about 60% of the KE of 1 round from the GAU-8, the gattling gun that the A-10 was basically built around (360 grammes @ 988m/sec). 6 of those is reckoned to be enough to take out a main battle tank, more or less.

50milligrams sounds small but it's about the mass of small piece of gravel, 5-6mm or so in diameter. Hopefully there's none of those.

The online material seems to indicate that nanometer to fractions of a micron in diameter particles are the order of the day at densities lower than the best vacuums on earth. I'd guess that it will be very nasty but much more like running into the top of a planetary atmosphere than hitting a shower of shotgun pellets.

Posted by: helvick Jun 23 2005, 08:42 PM

Don't know why I was rabbitting on about 70km/sec. 10.2km/sec is what's up on the info page.

Yep ~30mph car it is, the idea of a Mach 1.5 golfball is too much to handle.

JoeM

Posted by: Bob Shaw Jun 23 2005, 09:58 PM

Don't know why I was rabbitting on about 70km/sec. 10.2km/sec is what's up on the info page.

Yep ~30mph car it is, the idea of a Mach 1.5 golfball is too much to handle.

JoeM

Posted by: BruceMoomaw Jun 23 2005, 11:54 PM

Both Giotto and Stardust got clouted by several particles a sizable fraction of the mass of bullets, but travelling MUCH faster -- two such impacts knocked Giotto into a wobble that caused it to temporarily lose contact with Earth during its flyby, and Stardust got hit by four or five big enough to pierce the outer layer of its Whipple shields. (Its attitude-control system had been switched to an emergency high-thrust mode, so that even getting periodically shot -- there's no other word for it -- failed to shake its attitude stability.)

Presumably these are indeed fragile, easily crumbling clods, or they would have done a lot more damage. In fact, the local, high-density cloud of small particles that Stardust unexpectedly plowed through at one point when it was hundreds of km from Wild 2 seems to have been the result of a jet of such larger particles ejected from one of the comet nucleus' geysers -- which then evaporated their ice and exploded into puffs of their tinier component grains after they had traveled some distance from the comet, exactly like a fireworks display. (This model of explosively ejected fragile clods which then fragment further also seems to best explain the behavior of comets when they break up.) But, fragile or not, they are a real hazard for comet exploration spacecraft, and must be taken very seriously.

Posted by: edstrick Jun 24 2005, 12:17 AM

The 70 km/sec bit was the very rough figure for Giotto relative to Halley.

Posted by: Marcel Jun 24 2005, 11:50 AM

Something else: I wil try to take a look what happens with my C8. Could someone tell me what will be the exact time (corrected for one way light-time) of the impact ?

Posted by: odave Jun 24 2005, 01:37 PM

Take a look at the http://www.griffithobs.org/comettempel.html page:

"The collision between the Deep Impact impactor and the nucleus of Tempel 1 is to be within a few minutes of 10:52 p.m. PDT on July 3 (allowing for the seven-minute light time delay between the actual collision and when its effects are seen here)."

Tempel 1 may be difficult in a C8. I had a gander in it a couple of weeks ago in my 12.5" dob and it took some some work to see. It's fairly diffuse and my skies are only so-so as far as light pollution goes. You'll probably need some really dark skies.

Good luck!

Posted by: Toma B Jun 24 2005, 02:37 PM

Can someone tell me why all images taken so far are taken with Medium res camera?
They said that HRI is fixed...
HRI has 10x resolution of MRI...so why not HRI???

Posted by: abalone Jun 24 2005, 03:23 PM

The 70 km/sec bit was the very rough figure for Giotto relative to Halley.

Posted by: dvandorn Jun 24 2005, 04:09 PM

Can someone tell me why all images taken so far are taken with Medium res camera?
They said that HRI is fixed...
HRI has 10x resolution of MRI...so why not HRI???

Posted by: 4th rock from the sun Jun 25 2005, 01:24 AM

Hi,

Image contrast will suffer from the deconvolution.
Spatial resolution will be recovered, and I think that the images of the comet nucleous will be fine, but to image the coma, jets, and other large tenuous features around it you need contrast.

So my guess is that the MRI, even with lower resolution, might record this structures much better.
Also, there isn't much detail in the latest images, so in my opinion the HRI wouldn't give better results at the present time.

Posted by: lyford Jun 26 2005, 05:16 PM

Hope this isn't a repost (I skimmed the topic but couldn't find it):

Dan Maas, of the awesome MER animations fame, has turned his rendering attentions towards Deep Impact.



http://www.nasa.gov/mission_pages/deepimpact/multimedia/di-animation.html

(Requires QuickTime)

Posted by: Gsnorgathon Jun 26 2005, 10:09 PM

Using optical measurements, the impactor's AutoNav software will steer itself to the brightest object in its line of sight, the Sun-facing side of Tempel 1's nucleus.

Posted by: Comga Jun 27 2005, 02:57 AM

Image contrast will suffer from the deconvolution.
Spatial resolution will be recovered, and I think that the images of the comet nucleous will be fine, but to image the coma, jets, and other large tenuous features around it you need contrast.

So my guess is that the MRI, even with lower resolution, might record this structures much better.
Also, there isn't much detail in the latest images, so in my opinion the HRI wouldn't give better results at the present time.

Posted by: Marcel Jun 27 2005, 07:19 AM

Take a look at the http://www.griffithobs.org/comettempel.html page:

"The collision between the Deep Impact impactor and the nucleus of Tempel 1 is to be within a few minutes of 10:52 p.m. PDT on July 3 (allowing for the seven-minute light time delay between the actual collision and when its effects are seen here)."

Tempel 1 may be difficult in a C8.  I had a gander in it a couple of weeks ago in my 12.5" dob and it took some some work to see.  It's fairly diffuse and my skies are only so-so as far as light pollution goes.  You'll probably need some really dark skies.

Good luck!

Posted by: odave Jun 27 2005, 01:44 PM

I'm shut out too, Tempel 1 will be below my horizon at impact time

From what I've read, the change in brightness from the impact is expected to be
too faint to be observed visually, but it could show up in CCD images.

Let's hope our more westerly friends have their cameras rolling!

Posted by: alan Jun 27 2005, 04:21 PM

Gas jets shoot from Deep Impact’s target

Plumes of dust and gas shooting from Comet Tempel 1, captured in a Hubble Space Telescope image, have given a preview of what may be seen on 4 July when NASA's Deep Impact spacecraft smashes into the comet.

Hubble captured the brief spurt of activity on the icy body while performing a practice run for its observations on 4 July. The jet of gas and dust was seen in several images snapped over the course of eight hours on 14 June

http://www.newscientistspace.com/article/dn7585-gas-jets-shoot-from-deep-impacts-target.html

Posted by: volcanopele Jun 27 2005, 06:19 PM

I sure hope there aren't any bright jets positioned so that the impactor ends up aiming off into empty space...

Posted by: BruceMoomaw Jun 27 2005, 09:11 PM

Yeah, it is a worry -- they had a lot of trouble, even without the jet factor, in designing the Impactor's targeting software, since it must aim the Impactor not just for the center of the illuminated part of the nucleus, but for an area which isn't in any local shadow caused by terrain features. (Which helps explain why they couldn't just release the Impactor when the main craft was far away from the nucleus and let it fly -- although the distance at which the Impactor must be released is so far from the nucleus that it would be impossible to aim a passive Impactor for an impact with the tiny nucleus at that range anyway.)

This thing is a real gamble and always has been, even without the HRI problem. Its selection as a Discovery mission was something of a surprise, and I suspect that that choice was yet another of Dan Goldin's harebrained PR brainstorms -- big fireworks display on the 4th of July and all that.

Posted by: edstrick Jun 28 2005, 02:44 AM

What is the phase angle on the approach to the comet. The simulatoins show a "gibbous" phase, maybe 70 degrees phase angle.

The dust plumes, as Giotto saw, (compared with the soviet VEGA images of Halley, and compared with Borelly and Stardust data at Wildt), are much brighter at high phase when backlit.

Some late afternoon, when the sun is maybe 20 degrees above the horizon, take a handfull of dusty dirt and throw it in the air between you and the sun. The dust is pretty bright. Now turn so the sun is behind you and repeat the experiment. Contrast between dust and the ground will be much lower.

Charcoal-black rough surfaces like a comet's nucleus show very strong phase angle effects. Looking upsun, you see mostly black shadows and surfaces that are on the average tilted away from the sun and not well illuminated. And since the surface is black, both macroscopic shadows, and the non-illuminated side of even microscropic dust grains will be nearly black, without bounce light adding much indirect illumination.

Having the impactor aim for a dust jet is possible, but it's probably less likely than some really unanticipated software or hardware glitch.

Posted by: BruceMoomaw Jun 29 2005, 06:16 PM

It now seems that fdeep Impact's second destination is likely to be Comet Boethin:
http://www.space.com/businesstechnology/050629_deep_impact_beyond.html

This is a change from what I was told by A'Hearn two years ago, which was
that the leading second destination was Comet Finlay.

Also note the latest conveniently vague comment on how well deconvolution
may correct the HRI problem: "[Ball Aerospace official] Henderson said
through this process, Deep Impact's picture taking can be 'massaged and
tweake' on the ground to greatly overcome the out-of-focus problem."

"Greatly overcome" it? Still nothing said lately on what kind of resolution
they're actually hoping for.

Posted by: dilo Jul 3 2005, 07:13 AM

MRI gallery of last week images:
http://img300.imageshack.us/my.php?image=mriapproachseq3lb.jpg
And a false color version to enhance both nucleus and faint coma (based on images I suspect a spacecraft orientation change after Jun,29):
http://img300.imageshack.us/my.php?image=mriapproachseqc6qk.jpg

Posted by: SFJCody Jul 3 2005, 08:01 AM

It now seems that fdeep Impact's second destination is likely to be Comet Boethin:
http://www.space.com/businesstechnology/050629_deep_impact_beyond.html

This is a change from what I was told by A'Hearn two years ago, which was
that the leading second destination was Comet Finlay.

Posted by: BruceMoomaw Jul 3 2005, 08:33 AM

Unfortunately, I was told a couple of years ago by Don Brownlee that there is no chance of an extended mission for Stardust, because it simply won't have enough attitude-control and maneuvering fuel to make it worthwhile.

Posted by: SFJCody Jul 3 2005, 08:44 AM

Unfortunately, I was told a couple of years ago by Don Brownlee that there is no chance of an extended mission for Stardust, because it simply won't have enough attitude-control and maneuvering fuel to make it worthwhile.

Posted by: Sunspot Jul 3 2005, 08:47 AM

JPL and the Deep Impact site have a link for viewing "near realtime mages" They're only thumbnails though

Posted by: edstrick Jul 3 2005, 08:57 AM

I continue to be somewhat astonished by Stardust not having enough "consumables" for an extended mission.

I keep wondering if they used propellants at a higher than expected rate during the mission, or during design cut the supply margin too close for real comfort...?

Posted by: djellison Jul 3 2005, 09:47 AM

Well - the difference between having a sensible margin, and having enough for an extended mission - is not inconsiderable

Doug

Posted by: edstrick Jul 3 2005, 10:12 AM

We've lost missions, recent example being DART, which had a "reasonable" excess of propellant, and used it all up and failed.

Deep Impact's going to have <I think> do it all on it's own to retarget to an extended mission target.

Stardust releases the return capsule and then can do a deflection maneuver to do a range of earth swingby's, rather like Contour was going to do, giving a gravity assist magnified delta-V capability to retarget for an extended mission.

I'd like details I don't have on Stardust's performance.

Posted by: BruceMoomaw Jul 3 2005, 10:39 AM

Brownlee told me they had taken into account the possibilities of an Earth gravity-assist flyby to retarget Stardust -- there was simply no way, even then, to maintain its maneuvering and attitude fuel supply long enough for another target.

Posted by: edstrick Jul 3 2005, 11:09 AM

I'm wondering what the magnitude of the burn to deflect from the earth-impacting capsule release trajectory to a flyby trajectory is. While atmosphere entry doesn't have the same G limits Apollo astronauts had, it's not a vertical descent. But it could still be a very considerable deflection maneuver that would use almost the entire remaining propellant supply. Potentially considerably larger than Deep Impact's deflection burn.

Not every mission can get extended. Mariner 2 fried and died some 10 days or 2 weeks after Venus flyby.

Mariner 4 made it once around and got back into radio contact for some months of interplanetary weather study before attitude control gas ran out. Mariner 5 was flying at the same time, but when it came around and back into antenna range, it wasn't there. They FINALLY found it, way off frequency and wandering in frequency, carrier wave only, varying in amplitude with a slow spacecraft roll. They got it eventually to lock on to an uplink, but it was a "mindless reflex". Signal strength and behavior provided no indication it ever responded to any uplinked command. Nowdays, I'd call it a Persistant Vegetative State. They wanted simultaneous deep space solar wind observations with Mariner 4 but never got it.

Mariner 6 and 7 had brief extended missions as they flew out into the inner fringe of the asteroid belt. They'd been launched on fast-trajectory Mars flybys and had extra encounter speed and got a mild gravity assist from Mars during the flyby. The did engineering tests, post encounter and fired the midcourse engines a second time and watched the exhaust cloud's spectra with the short wave channel on the infrared spectrometers. No interplanetary science instruments onboard, so they couldn't do much else.

Posted by: abalone Jul 3 2005, 01:28 PM

I'm wondering what the magnitude of the burn to deflect from the earth-impacting capsule release trajectory to a flyby trajectory is.

Posted by: djellison Jul 3 2005, 01:44 PM

And you dont want to do it too early - because you have no control of the entry capsule after you deploy it, so you want to be attached to the thing that can adjust your trajectory essentially until the last possible moment

PS - I dont think it's worth making a deep impact forum on its own - but i'll start a new threads after the 1800UT press conf (3:15 from now)

Doug

Posted by: Myran Jul 4 2005, 03:27 PM

It impacted! Hurray hurray! And happy july 4 for the USA guys in this forum.

Posted by: Bob Shaw Jul 4 2005, 04:19 PM

Mariner 6 and 7 had brief extended missions as they flew out into the inner fringe of the asteroid belt.  They'd been launched on fast-trajectory Mars flybys and had extra encounter speed and got a mild gravity assist from Mars during the flyby.  The did engineering tests, post encounter and fired the midcourse engines a second time and watched the exhaust cloud's spectra with the short wave channel on the infrared spectrometers.  No interplanetary science instruments onboard, so they couldn't do much else.

Posted by: edstrick Jul 4 2005, 08:31 PM

There's orbit info in the JPL TR series final mission technical report on Mariner 69, but I don't have those volumes. They got more or less out to the inner edge of the asteroid belt. They were the furthest from the sun on solar power till <maybe/probably> Near or certainly Stardust.

The spacecraft were too heavy for Atlas Agena and too light (in effect) for Atlas Centaur. Some, I think 900 lb vs 450 or so lb for Mariner 4 and nearly 1 ton for Mariner 9, which was almost the same spacecraft, but with fuel tanks and an orbit-insertion engine added.

Posted by: jaredGalen Jul 4 2005, 09:07 PM

Just threw this together to give myself a bit of a context shot of where the impactor most likely hit.
Hope we get some good shots of the crater from underneath that bright ejecta cone.


http://img107.echo.cx/my.php?image=dpcollage2nb.jpg

Posted by: jaredGalen Jul 4 2005, 09:31 PM

Teased some more detail from on the great image of the comet.
ImageShack isn't cooperating so have to upload it here

Posted by: um3k Jul 4 2005, 09:52 PM

An animation made from an impactor image and a deconvolved hi resolution camera image:

Posted by: 4th rock from the sun Jul 4 2005, 10:00 PM

A mosaic of several impactor images.
It's a little big but this way you can see the context of the impact area.

Posted by: edstrick Jul 5 2005, 06:52 AM

This evening, I grabbed "tif" versions of press release images from the Planetary Photojournal site and did bandpass filtering enhancements on the images. I've spotted things that haven't been commented on and am posting 3 sets of images with some comments.

Note: A lot of the so-called TIF images on the photojournal apparently were initially generated as jpg's and were then turned into tifs, complete with jpg artifacts. Enhancing those tends to result in a mess with the jpg artifacts being strongly enhanced with other small low contrast details.

Pia02127 is a whole-comet image from the impactor, and is the best single-frame view of the nucleus I've seen. The nucleus is divided into at least 3 "regions" with well divided curving borders separating them. Region 1 is the top half of the visible nucleus, Region 3 is the bottom, lower left and lower right edges. Region 2 is sandwiched between 1 and 3, but the borders between 2 and 3 curves up and 2 pinches out in a triangular "cusp" between the borders of 1 and 3. 1 and 3 both give the impression of overlapping 2, with features and texture patterns in 2 stopping abruptly at the borders. In both the region 1 border and the lower right border of region 3 against 2 and against 1, there are features sub-parallel to the border behind the border, giving both borders a very substantial width of a couple hundred meters.

The whole impression is of plastically deformed bodies that were gently "smushed" <very technical geological term, there> together to form one body, which is now being "etched" as ices ablate and crust disintegrates and blows away into space, shownig internal traces of how it was assembled. This is not a "rubble pile", but I get the impression of an assembled object, put together with ultra-low-speed collissions.

The top half of region 1 is very irregular, above the "pitted plains" that are nearly at the center of this view of the nucleus. The large depression with strong shadows on its wall to the right seems floored with very irregular material, and the sharp edges on the right and bottom sides disappear on the upper left. Above it is a smooth plains unit with little texture above the noise and artifacts in the image, and to the depression's upper left is another depression, shallower, but also vaguely circular, filled or floored with extremely irregular material which may have a raised edge compared with the irregular textured material on the uppermost part of the nucleus. Some possible lobes of the smooth plains seem to extend up to a very obliquely viewed facet or depression at the top edge of the nucleus. The plains seem superimposed on the rough terrain with in places locally sharp boundaries.

Another plains unit is present on Region 2, with well defined escarpments as edges. There's faint textures within this feature, but it's surface is remarkably uniform and smooth in all images I've seen.

The different regions have distinctly different populations of surface features. The bottom half of region 1, above the thick border with regions 2 and 3, has multiple rimless crater-like pits, resembling those on Comet Wildt as seen by Stardust. In contrast, Region 2, other than the superimposed smooth plains, seems to have an abundance of dark rimmed features with light spots or patches in the centers. The most prominent is the thing everybody's seeing and saying "impact crater", and I think it probably is... but ... there are many other smaller dark spots with light centers you can see in the next pair of images I'll post. The dark "rims" indeed appear to be raised, both on the "crater" and the smaller spots, as though they're erosion resistant relative to the lighter material outside the spots. Perhaps these are indeed impact craters, with altered, maybe compressed or heated and sintered crater walls and near-wall material resisting erosion. Why these are so different from the flat floored rimless craters in region 1... go figure!

Posted by: edstrick Jul 5 2005, 07:02 AM

These images are press-released and enhanced versions of image PIA02135, from the impactor, showing most of region 2, it's border with region 3, and the smooth plains superimposed on region 2.

The smooth plains have weak textures converging into it's center from the upper right and lower right edges, but is remarkably smooth and flat. The escarpment at it's edge seems pretty uniform in height over much of it's length. Scattered bright spots are visible for a ways to the right and below the edge of the smooth plains. Some of these appear to be real albedo features, rather than sunward facing slopes.

Further to the right, region 2 seems smoother, but has the scattered dark spots, many/most with light centers, as described in the previous posting. Light patches seem decidedly less common.

The border of Region 3 and 2 forms a well defined topographic break on the surface of region 3, but seems to descend into a hummocky "badlands" as it transitions into region 2. Much of the border below and to the lower right of the topographic break is fairly smooth, but the rest of region 3 all the way down to the the limb is extremely rough and "hackly" Some vaguely elliptical features give the impression of obliquely viewed crater-form depressions in the rough terrain, but resolution is not good enough to clearly tell if this is so.

Posted by: edstrick Jul 5 2005, 07:24 AM

Pia02130 is a cleaned up but not deconvolved hirez camera image of the impact. The enhanced version clearly shows the defocused blur pattern of the high contrast sun-facing wall of the sharp depression at the terminator. The picture is badly out of focus, but at least this file does not have JPG artifacts introduced before it was turned into the TIF I downloaded.

The images is labled "Moment of Impact". The caption says, in part:

"When NASA's Deep Impact probe collided with Tempel 1, a bright, small flash was created, which rapidly expanded above the surface of the comet. This flash lasted for more than a second. Its overall brightness is close to that predicted by several models. After the initial flash, there was a pause before a bright plume quickly extended above the comet surface. The debris from the impact eventually cast a long shadow across the surface, indicating a narrow plume of ejected material, rather than a wide cone."

In the enhancement, the bright part of the flash is *NOT* saturated in the press release image, and has a very well defined sharp edge, beyond which there is diffuse glow which progressively gets fainter beyond the edge. I cannot tell if the edge is real, or an artifact of the imaging system or data processing, but if it's real, it's clearly an important feature of the expanding plasma and vapor cloud.

Low contrast mottled features are visible within the edge of the bright spot, in particular, there is a dark smudge at the bottom of the ejecta plume's shadow, apparently shadow visible through the bright "blob". The ejecta plume is not itself at all clearly visible or recognizable. Of particular interest, not otherwise noted yet that I've seen.. the shadow is *DOUBLE*.. with a darker portion on the right, and parallel to it a fainter portion on the left. This *might* suggest an irregular, maybe keyhole shaped hole punched in the surface layer of the comet with the high angle early ejecta emerging in a double plume.

I've tried enhancing later post-impact images. In the versions on the planetary photojournal, the brighter portions of the eject plume are saturated and contain no detail. Elswhere, there are strong vertical stripe and some horizontal stripe artifacts that have not been cleaned up from the totally raw data before the images were deconvolved, and they really degrade the enhancement. Image Pia02123 is the best of the 4 (2 of the 4 are the same data). The ejecta streamers are not perfectly radial to one point, but they do converge on a not-saturated part of the image just above a main saturated area and to the left of a smaller saturated bright spot. Texture is faintly visible in this area behind the strong vertical and several horizontal stripes from the camera artifacts, but no feature I'm inclined to interpret as a crater is evident above the noise and artifact level.

Posted by: Sunspot Jul 5 2005, 08:27 AM

WOW.........the HRI images look almost useless.......

Posted by: jaredGalen Jul 5 2005, 08:35 AM

WOW.........the HRI images look almost useless.......

Posted by: Sunspot Jul 5 2005, 08:47 AM

Did they plan on taking colour images with the MRI too?... I'm sure I read that somewhere.

Posted by: jaredGalen Jul 5 2005, 08:48 AM

In looking at the MRI's I noticed these two frames.
I think you can see a radial shock wave extending around the impact site.

Or maybe it's just the beginning og the plume and it's really low.
Not sure.
It's cool though

Posted by: edstrick Jul 5 2005, 09:21 AM

The HRI image of the flash has been pretty well cleaned up.. very few streaks, etc. Just the blur of the de-focus. The DECONVOLVED HRI image shows much sharper details, but it hasn't been cleaned up, so the artifacts and streaks are horribly exaggerated. The focus problem is a real shame, but they're gonna be able to produce deconvolved clean images that are several times sharper than the MRI images, with some grain from bosting fine details during deconvolution, much the way my bandpass filtering boosted grain from single pixel random noise.

Posted by: Phil Stooke Jul 5 2005, 12:25 PM

Here's another slightly modified version of a press release image...

Posted by: BruceMoomaw Jul 5 2005, 04:08 PM

At the last press conference, it was specified by Peter Schultz that the impact movies show three different waves of ejected material. First, you see an extremely brief hemispherical wave of vaporized material from the initial impact; then a bright region that extends upwards into a tall column of ejecta blown almost straight up from the impact; then a separate cone-curtain of ejecta sprayed outwards at an angle. According to him, this is precisely what they expected from an impact into a very loose powdery surface -- the impactor drills down a short distance through that surface before exploding, at which point a column of ejecta is sprayed upwards through the entrance hole, and only then is a slanting curtain of ejecta thrown outwards for some time from the edge regions of the outwardly growing crater. The two separate shadows that Ed reports are apparently from the initial vertical column of ejecta and the later slanting conical curtain of it. They hope to be able to judge the precise angle of that slanting curtain from both stereo views of it and its shadow's orientation

Posted by: BruceMoomaw Jul 5 2005, 04:10 PM

As for those circular, flat-bottomed but steep-edged "craters" seen on both Wld 2 and Tempel 1, I really don't think these are all that puzzling. They can be explained very well (as I said in my short piece on "Stardust "in the April 2004
"Astronomy") by the assumption that we have an initial small pit -- probably
a small impact crater -- which then grows as follows:

The combination of sublimating freshly exposed water ice and plain old
gravity explains it all. When the ice sublimates away from the shallowly
sloping floor parts of a bowl-shaped initial small impact crater, their lag
deposit of dust is going to just sit there without shifting (or fall back
onto the same places from which the sublimating water vapor blows it) -- and
in the process gradually build up a shield layer to inhibit further ice
sublimation from the floor. When ice sublimates away from the more steeply
sloping parts of the crater's walls, on the other hand, the dust that's left
behind IS going to slide downslope -- or get blown downslope by the water
vapor -- onto the crater's floor. And so the vertical slope of such walls
will remain high (and they'll recede horizontally away from the center of
the crater as more and more new ice is exposed by landslips of the
lag-deposit dust), while the depth of the crater floor, after its dust lag
deposit builds up to a certain thickness, will sink further downwards only
very slowly. Voila: growth of an initial small bowl-shaped impact crater
into a big, pancake-shaped depression which continues to grow steadily
sideways without increasing much in depth -- until such spreading
flat-floored depressions finally merge into each other and eat away the
comet's outer surface layer almost completely, leaving behind only a few
remaining "mesas" like those on the evolved surface of Borrelly. Then,
after that's finished, the process doesn't resume until some new small
impact craters are produced on the comet's new flat surface that are deep
enough to punch through its surface dust layer and expose some ice again.

The one possible problem with this -- as set forth by the Stardust team in
the "Science" article -- is that initial calculations suggest that Wild 2's
current foray into the inner Solar System, which had run only 25 years
before Stardust arrived, would not be enough to sublimate away more than
about a meter of its surface ice, and of course its depressions are much
deeper than that. However, they also point out that Wild 2 has been tossed
around by the giant planets enough that it may very well have undergone
earlier, longer-period forays into the inner System, each one ending when a
Jupiter flyby happened to redivert it back out into the outer System for a
while -- and those could have allowed the necessary deeper
sublimation-erosion to occur on its surface. Moreover, if there's one thing
Deep Impact proved beyond doubt, it's that exposed cometary ice sublimates
like hell -- maybe either because of lower-temperature ices mixed into the
water ice, or because we're seeing the conversion of some amorphous water
ice into crystalline ice by heat, which in turn releases some additional
heat to sustain and extend the process.

Posted by: BruceMoomaw Jul 5 2005, 04:15 PM

And as for the possibility that Tempel 1 consists of several different KBOs that squished loosely together: this has long been thought to be the likely explanation for the strange "bowling pin" shape of Borrelly. We seem to be seeing what the planetesimals looked like in the earliest Solar System.

Posted by: dilo Jul 5 2005, 06:17 PM

It's the lookback image with the area 'behind' the nucleus brightened a bit to show the full outline a bit better.

Posted by: um3k Jul 5 2005, 06:46 PM

Finally, cannot resist to make personal approach sequence (last magnification region is not sure, however):
http://img236.imageshack.us/my.php?image=pia02127e0ua.jpg

Posted by: alan Jul 5 2005, 06:58 PM

They are in trouble now

-----------------------------------)
The People of Ziquikcikty )
(also known as Comet Tempel-1); )
A class, seeking )
certification as such; )
Plaintiffs )
)
v. )
)
Michael A'Hearn, )
Rick Grammier, )
Alphonso Diaz, )
Michael Griffin, )
Karl Rove, )
Andrew Card, )
Richard Cheney, )
George W. Bush, )
Does 1-100, )
and Does 101-600,000, )
1 et Prcpui 50 n 1 abrat 05135, )
Government of Bars and Stripes; )
Defendants ) FILED:
-----------------------------------) Minxktaquicky 43, Year Nipathatep
(July 3, 2005)


STATEMENT OF FACTS

1. The matter before the court regards loss of life and limb, injuries, mental anguish, and property damage suffered on the early morning of Minxktaquicky 43, Year Nipathatep (July 3, 2005) at or around Mong 54 (10:52 PM PST).

2. At or around that time, inhabitants of Ziquikcikty (Comet Tempel-1) were awoken by a large explosion. They awoke to find that a large segment of the surface of Ziquikcity had been destroyed by an unknown agent, leaving a large crater in the surface. Ejected debris caused serious damage to approximately half the surface of Ziquikcity, and minor damage to all remaining areas of the comet......

http://www.transterrestrial.com/archives/005451.html#005451

Posted by: Bob Shaw Jul 6 2005, 12:25 AM

The combination of sublimating freshly exposed water ice and plain old
gravity explains it all.

Posted by: Bob Shaw Jul 6 2005, 12:29 AM

I blame Bob Geldoff!

Posted by: Phil Stooke Jul 6 2005, 12:38 AM

Bob... Miranda?

Phil

Posted by: Bob Shaw Jul 6 2005, 12:40 AM

Bob... Miranda?

Phil

Posted by: BruceMoomaw Jul 6 2005, 01:17 AM

"The People of Ziquikcikty )
(also known as Comet Tempel-1); )
A class, seeking )
certification as such; )
Plaintiffs )"

Would they be willing to take Tom Cruise as recompense, or would that be regarded as an act of war?

Posted by: Bob Shaw Jul 6 2005, 01:21 AM

"The People of Ziquikcikty )
(also known as Comet Tempel-1); )
A class, seeking )
certification as such; )
Plaintiffs )"

Would they be willing to take Tom Cruise as recompense, or would that be regarded as an act of war?

Posted by: BruceMoomaw Jul 6 2005, 01:33 AM

Regarding the peculiarly discontinuous nature of both Borrelly and Tempel 1, Peter Thomas' very useful paper from the new "Space Science Reviews" ( http://www.beltonspace.com/bsei_web_page_g000000.pdf ) suggests that there are three possible causes for it:

(1) Separate cometesimals that collided gently.

(2) A nucleus that was fragmented but whose pieces then recollided.

(3) A nucleus affected by the "comet splitting" phenomenon, which as they say is still poorly understood.

And, regarding my theory of what causes the steep-walled but flat-bottomed depressions on Wild and Tempel, one additional detail: the phenomenon which initiates the formation of steep walls suddenly meeting a flat floor may well be the angle of repose of the surface lag deposit of loose cometary dust -- which could be quite steep, on such a low-gravity world, if the grains of dust are even slightly sticky. Once you get the lag layer of dust sliding off the very steep upper slopes of a crater, but remaining where it is on the slopes that are shallower han the dust's angle of repose in that gravity, the two phenomena are going to become self-amplifying as dust sliding off the steeper slopes accumulates on the shallower floor slopes below and serves as a pressure seal against more ice sublimating from off that floor -- while the steep slopes will continue to sublimate and thus retreat away from the crater's center, dumping their residual dust on the depression's floor below them as they retreat.

By the way, after reading the DI team's official scientific justification for their mission ( http://www.beltonspace.com/bsei_web_page_g000002.pdf ), I remain puzzled as to why it was selected. Apparently the only things that can only be done by this type of mission is the analysis (to some degree) of the chemical composition and hardness of very deeply buried cometary ice.

Posted by: BruceMoomaw Jul 6 2005, 01:35 AM

Christ. If Keith Cowing is to be believed, NASA is now cranking up to throw away another perfectly good spacecraft:

http://www.spaceref.com/news/viewnews.html?id=1041

This, really, is quite insane if true.

Posted by: djellison Jul 6 2005, 07:19 AM

Well - there was never any mention of an extension at any of the press confs. and when pressed my a reporter, the reponse was that indeed, they would simply prepare for a sun-safe hybernation state after playback was complete.

Doug

Posted by: Decepticon Jul 6 2005, 01:00 PM

Wow! new image up.

http://deepimpact.umd.edu/gallery/HRI_937_1.html

Posted by: Bob Shaw Jul 6 2005, 01:26 PM

Christ.  If Keith Cowing is to be believed, NASA is now cranking up to throw away another perfectly good spacecraft:

http://www.spaceref.com/news/viewnews.html?id=1041

This, really, is quite insane if true.

Posted by: Sunspot Jul 6 2005, 01:41 PM

Well - there was never any mention of an extension at any of the press confs. and when pressed my a reporter, the reponse was that indeed, they would simply prepare for a sun-safe hybernation state after playback was complete.

Doug

Posted by: MiniTES Jul 6 2005, 09:17 PM

The word "mothballed" came up at the press conference when talking about a possible mission extension.

Posted by: Sunspot Jul 6 2005, 11:18 PM

I dont see anything about the mission being extended....

edit: nevermind, I found it, had problems loading the site.

Posted by: edstrick Jul 7 2005, 01:38 AM

I've run a couple bandpass filter enhancements on the newly released "Tempel alive with light" captioned imagel.

The e2 enhancement used statistics of a box on the bulk of the nucleus to run the enhancement in an attempt to maximize geologic detail in this hi rez cam image. Certainly, the deconvolved image's resolution is greatly improved above that of the raw data... compare the sunlit wall of the caldera-like depression at the terminator with the defocused pattern in the image I enhanced of the initial plasma-ball from the impact. But, as usual with deconvolution, there are a lot of secondary artifacts from the deconvolution next to high contrast edges in the image, imperfectly decalibrated image artifacts make nasty fringes, and the random noise level of the data is enhanced and turned into a characteristic texture. Also, deconvolution, at least at this stage, is impossible in a fringe surrounding the saturated data in the core of the impact plume.

I do expect, however, that the deconvolved images of the nucleus from near closest approach, will have resolution comparable or better than the best whole-nucleus impages from the impactor. At least I hope so!

The e3 enhancement used statistics from a box on the plume, mostly beyond the limb of the nucleus, and dramatically brings out texture in the ejecta plume structures. "Plumelets" <new word.. got a better one?> seem to change shape and brightness with distance from the impact. A plumelet at 10:00 clock angle appears curved or one segment grows fainter and another grows brighter with distance from the nucleus. A plumelet at 8:30 to 9:00 seems non-radial to the impact, with a "head" that is detached from the source. When deconvolved tif images of the entire sequence of these images become available, the changes in these structures over time should be both spectacular and informative.

Posted by: alan Jul 8 2005, 01:18 AM

Rocky material seen by Gemini
http://www.universetoday.com/am/publish/deep_impact_gemini.html?772005

Posted by: dilo Jul 8 2005, 02:19 AM

Rocky material seen by Gemini

Posted by: djellison Jul 8 2005, 08:51 AM

Anaglyph = cool

Doug

Posted by: Bob Shaw Jul 8 2005, 02:06 PM

Is it possible that some of the plume structures are caused by diffraction effects, rather than being physically there?

Posted by: Bill Harris Jul 8 2005, 04:15 PM

The plume is really there. It has the appearance of a bright overexposed flash because the image exposure is made to capture the dark comet surface. Remember, the comet is very very black in color. The plume is faint, but much less so than the comet body.

--Bill

Posted by: Bob Shaw Jul 8 2005, 05:41 PM

Bill:

I don't doubt that the plume is there! It's the structures within it I'm thinking of - S&T (I think) ran an article four or five years ago about 'Moonbows' and other atmospheric phenomena and how they'd work in different atmospheres and with different crystals in the upper reagions of such atmospheres, and I was wondering if we're seeing what we think we are!

Bob Shaw

Posted by: dvandorn Jul 8 2005, 07:23 PM

Very true -- I was expecting to see more obvious interaction between the ejecta plume(s) and the coma, some type of concentric shock pattern that would occur when the ejected particles and gasses plowed through the relatively motionless haze of gas and dust that surrounds the nucleus. But what we seem to be seeing is pure ballistic motion with radial structuring (probably controlled by topography at the impact point).

You know, Bruce asked the question earlier in this thread (or a related one) as to why this mission got approved in the first place, since its scientific harvest would be rather thin. I think one of the more interesting benefits, maybe one of the more important ones, is the observation of impact dynamics. Impact has apparently shaped every rocky/icy body in the Universe -- it's nice to finally get a first-hand look at an impact of *any* size and observe the real-world dynamics. As I've stated before, models are only good for certain things, and unless a model is as complex as the phenomenon it attempts to predict, it will never be completely accurate. Seeing and measuring an actual impact, on *any* body and of *any* size, helps us refine our models and understand the actual processes in far greater detail. I just wish we could now land at the crater we made and examine *it* in detail...

-the other Doug

Posted by: Decepticon Jul 8 2005, 08:12 PM

Could DI revisit the same comet in the future?

Posted by: BruceMoomaw Jul 9 2005, 02:15 AM

Looks like I have a siazable amount of crow to eat today on this mission -- but the same thing may be true of the mission's scientific advocates.

(1) Contrary to all my confident statements, it starts to look as though the impact actually vaporized very little ice from the comet's interior -- virtually all that huge ejecta cloud was simply dry, very fine surface dust kicked into space by the impact itself. At any rate, that seems to be the case from both the craft's own observations and those of the SWAS satellite (which was roused from long-term hibernation for this particular mission):
http://www.jpl.nasa.gov/news/news.cfm?release=2005-113a
http://www.cfa.harvard.edu/press/pr0523.html

Jeffrey Bell will be delighted -- he was cackling to me right after the impact that the entire huge ejecta cloud could be explained by this alone. I didn't believe him. But, as he said at the time, this also calls the science rationale for the mission into still further question: it seems to make it even more certain that any impact which produced a crater big enough to be seen would also produce a cloud of ejecta big enough to completely blot it out from the main craft's cameras. About all we've really learned from this impact is that Tempel 1 has a very thick but very loose surface dust layer, as opposed to a thinner and/or cemented one -- and couldn't we have learned that just as well (and more besides) just from equipping the main craft with a radar sounder?

By the way, NASA TV didn't bother to cover today's DI press conference at all -- they were too busy covering really exciting stuff like the Shuttle...and...the ISS...ZZZZZZZZZZ

Where was I? Oh, yes:

(2) Ed Strick and Decepticon were right about the Impactor and I was wrong: during the final seconds of its descent, it did get clouted by two different particles big enough to throw it briefly off attitude. However, it also hit the surface at 25 degrees from the local vertical -- so, if its camera wasn't pointing directly down the line of approach, this would also have somewhat blurred its final photos as I suggested.

Posted by: Bob Shaw Jul 9 2005, 07:37 PM

Bill:

I don't doubt that the plume is there!  It's the structures within it I'm thinking of - S&T (I think) ran an article four or five years ago about 'Moonbows' and other atmospheric phenomena and how they'd work in different atmospheres and with different crystals in the upper reagions of such atmospheres, and I was wondering if we're seeing what we think we are!

Bob Shaw

Posted by: Bob Shaw Jul 9 2005, 07:45 PM

Could DI revisit the same comet in the future?

Posted by: Bob Shaw Jul 10 2005, 12:27 AM

Here's some diagrams of the Hayabusa orbital path:

http://www.isas.jaxa.jp/e/enterp/missions/hayabusa/scenario.shtml

Posted by: BruceMoomaw Jul 10 2005, 08:00 AM

No one has come up with any workable scheme to allow Deep Impact to reexamine Tempel 1 -- although it remains a real possibility that ANOTHER spacecraft might do so, and in fact there might be considerable scientific benefit in doing so. I think it likely that some kind of attempt to repeat CONTOUR's planned flybys of multiple comets is among the front-runners for the next selected Discovery mission, and it's very easy to visualize a repeat visit to Tempel 1 (or Wild 2, Borrelly or Churyumov-Gerasimenko) as being part of its itinerary.

Posted by: Bob Shaw Jul 15 2005, 12:08 PM

See Bruce's earlier comments regarding the lack of primordial material - looks like not only was the plume all surface dust, but it didn't have much of a, well, deep impact...

http://www.spaceflightnow.com/deepimpact/050714eso.html

Posted by: ljk4-1 Jul 15 2005, 02:09 PM

See Bruce's earlier comments regarding the lack of primordial material - looks like not only was the plume all surface dust, but it didn't have much of a, well, deep impact...

http://www.spaceflightnow.com/deepimpact/050714eso.html

Posted by: chris Jul 15 2005, 02:29 PM

So what does this mean for the Rosetta lander?  I know getting anything back from a comet's surface will be an achievement, but will it not sample nearly as much as scientists hope?

Posted by: djellison Jul 15 2005, 03:14 PM

Once they get samples back from Rosetta they'll learn a lot of things like..

How in hells name Rosetta brought a sample home when it's not a sample return mission

Doug

Posted by: Bob Shaw Jul 15 2005, 03:33 PM

Once they get samples back from Rosetta they'll learn a lot of things like..

How in hells name Rosetta brought a sample home when it's not a sample return mission

Doug

Posted by: BruceMoomaw Jul 16 2005, 01:29 AM

I think LJK was just talking about "getting back" DATA from a comet's surface, not actual material. Certainly the extreme dustiness of Tempel shows that they will have to be careful about selecting the absolute best landing site for the Rosetta Lander. (By the way, why didn't they stick with its nice original name of RoLand instead of renaming it "Philae"?)

Posted by: djellison Jul 16 2005, 08:16 AM

I HATE Philae - Roland was much better

Doug

Posted by: Comga Jul 18 2005, 04:37 AM

No one has come up with any workable scheme to allow Deep Impact to reexamine Tempel 1 -- although it remains a real possibility that ANOTHER spacecraft might do so, and in fact there might be considerable scientific benefit in doing so.  I think it likely that some kind of attempt to repeat CONTOUR's planned flybys of multiple comets is among the front-runners for the next selected Discovery mission, and it's very easy to visualize a repeat visit to Tempel 1 (or Wild 2, Borrelly or Churyumov-Gerasimenko) as being part of its itinerary.

Posted by: BruceMoomaw Jul 19 2005, 01:09 AM

It now turns out that they will probably never be able to see the impact crater at all -- due to a combination of the thick dust cloud and the HRI
deconvolution problem. Had it not been for the combination of both, they
could probably have seen it:

http://www.newscientistspace.com/article/dn7688--deep-impact-may-never-glimpse-comet-crater.html

And determining the overall size of the impact crater, at least, was an absolute primary mission goal. So, for the third time in a row, we have a Discovery mission very seriously screwed up due to a design or assembly error. One can still hope that Stardust will succeed; but at the moment, the last totally successful one we've had was Lunar Prospector. (Which makes it even more interesting that
the Senate just voted to keep the Discovery cost cap at an artificially low $350 million, in order to continue funding Shuttle/Station -- although I don't know whether that provision will hold in the final House/Senate
compromise.)

Posted by: tedstryk Jul 19 2005, 03:14 AM

Bruce, the jury is still out on this one. It often takes years for the really good science from a mission to be processed and digested. Perhaps they will find the crater, perhaps not. Is it dissapointing, yes, but there is still a lot of valuable science to be gleaned from this mission, despite its possible failure on one goal. I think you are starting to sound too much like Jeff Bell.

Posted by: Phil Stooke Jul 19 2005, 03:30 AM

Seeing the crater would have been nice, and layering in the walls very nice, but I imagine the most important results come from the remote sensing of the ejecta composition.

In fact if there was relatively little volatile ejecta and lots of dust, as suggested so far, there may not have been a lot to see in the crater anyway. I think (admittedly on little evidence) that any difficulties may be as much caused by the comet itself as by the focus problem.

I'm an image guy so the focus thing does concern me, but if spectroscopy answers the composition questions that's probably going to be a great result. I'm not as concerned as Bruce about this. So far.

I am concerned about that cost cap decision, though.

Phil

Posted by: tedstryk Jul 19 2005, 03:43 AM

I am concerned about that cost cap decision, though.

Phil

Posted by: edstrick Jul 19 2005, 09:07 AM

Phil: From what I can see, deconvolving the images increases single-pixel to few-pixel noise and artifacts "several times", about what you'd expect. If the crater would have been visible in images just before shield-mode at say 5% contrast through the plume, cutting contrast several times could eat your lunch.

And unfortunately, I don't expect diddly-squat from color imaging of the nucleus now. Typically, there is very little color contrast on "small bodies" in Galileo and NEAR and Giotto images and you need to squeese out maximum signal-to-noise from the data to have anything useful. NEAR, for example, had a nasty noisy little camera and could barely see color variations in different albedo materials on Eros. Blow your signal-to-noise level on deconvolution of images of a small body, and you've lost not just single-pixel color information but lost integrating color voer enough pixels on a given feature for useful color information at all. I hope I'm, wrong, but I expect to be frustrated.

Posted by: DDAVIS Sep 14 2005, 08:34 PM

[quote=edstrick,Jul 19 2005, 09:07 AM]
Phil: From what I can see, deconvolving the images increases single-pixel to few-pixel noise and artifacts "several times", about what you'd expect. If the crater would have been visible in images just before shield-mode at say 5% contrast through the plume, cutting contrast several times could eat your lunch.

This would be a good kind of mission to repeat on a series of small bodies for comparison, with good cameras. There is no reason to think we missed a once in a lifetime opportunity.

Don

Posted by: antoniseb Sep 14 2005, 10:31 PM

This would be a good kind of mission to repeat on a series of small bodies for comparison, with good cameras. There is no reason to think we missed a once in a lifetime opportunity.

Posted by: elakdawalla Dec 29 2005, 04:05 PM

I'm having trouble with the Quicktime plugin in Adobe Imageready (stupid Quicktime 7). Can anybody convert the two Deep Impact .movs to animated GIFs for me so I can play with them?
http://photojournal.jpl.nasa.gov/catalog/PIA02125
http://photojournal.jpl.nasa.gov/catalog/PIA02130

--Emily

Posted by: um3k Dec 29 2005, 04:34 PM

I've converted the files, Emily, but they are rather large, so I'll need your email address in order to send them to you.

Posted by: tedstryk Dec 29 2005, 11:35 PM

Ed: Yes, but I wonder what MRI got...while its resolution is poorer, it might have the S/N ration to identify broad variations.

Posted by: elakdawalla Jan 3 2006, 04:28 PM

I've converted the files, Emily, but they are rather large, so I'll need your email address in order to send them to you.

Posted by: um3k Jan 3 2006, 05:12 PM

Very nice, Emily!

Posted by: Bob Shaw Jan 3 2006, 06:24 PM

I thought the development of the ejecta plume was fascinating!

Bob Shaw

Posted by: RGClark Jan 5 2006, 06:56 AM

Is it definitively known that the secondary plume did not have significantly more water than the conditions before the impact?


- Bob Clark

Posted by: ljk4-1 Jan 5 2006, 02:17 PM

Is it definitively known that the secondary plume did not have significantly more water than the conditions before the impact?
  - Bob Clark

Posted by: ugordan Jan 5 2006, 02:29 PM

Posted by: ljk4-1 Jan 5 2006, 02:46 PM

It's possible a small amount of material in the immediate vicinity of the impact got chemically altered due to very high temperatures, but I suspect the majority of the plume material was simply "dislodged" and ejected, followed by sublimation of volatiles underneath.
Any lander on Europa is likely to only do melting of the ice, blowing up and excavating is pretty much out of the question - you'd need to carry explosives and the ice is virtually rock at those temperatures. Also, an Europa lander that melts its way through will benefit from the surface gravity to drag it downwards, the latter is practically nonexistent on a small comet. Their respective compositions are radically different, too, comets being icy dirtballs (as opposed to dirty iceballs, which was thought until recently).

I just don't see a point in proof testing a Europa lander on a comet.
They probably assumed the comet would have a much higher percentage of ice vs dust. You can't model the behaviour of something you don't know what it's made of. That's one of the reasons this mission was flown in the first place.

Posted by: Chmee Jan 5 2006, 04:55 PM

With the deep impact mission what they could have done was release the probe much sooner so that it would have impacted the comet several hours/days ahead of the main probe coming past it.

In that way we could have seen the impact crater after the "dust cleared". Problem with this of course would be targeting the impact probe precisely to the comet if it were released that far in advance of impact. Also, some of the science of the debris plume might be have benn degrade.

Posted by: djellison Jan 5 2006, 05:00 PM

And of course, that means packing a bigger battery into the impactor, and a more powerfull transmitter. Which makes it heavier and bigger and so on and so forth....

Doug

Posted by: tty Jan 5 2006, 06:57 PM

And it would have meant that the trajectories would have diverged more, so observations would have been from further away, unless you tweak the flyby craft's orbit, which requires additional fuel.....

tty

Posted by: abalone Jan 5 2006, 10:52 PM

And it would have meant that the trajectories would have diverged more, so observations would have been from further away, unless you tweak the flyby craft's orbit, which requires additional fuel.....

tty

Posted by: elakdawalla Jan 5 2006, 11:16 PM

And of course what they really wanted to do with the flyby craft was watch the crater develop, which they couldn't have done from a much greater distance. Basically, they had predicted a length of time it would take for the "dust to clear," and multiplied that by some number to make their guess "conservative," and then they planned their sequencing. Tempel 1 sure fooled them. Too bad they couldn't see the crater develop with the camera, but they seem to have gotten lots of interesting data from the ejecta with the spectrometer.

--Emily

Posted by: tty Jan 6 2006, 05:35 PM

Not necessarily diverted more, the probe would have simply reduced delta V in the direction of travel. Targeting, communication and battery life would certainly have been an issue but one huge problem would have been that the probe would have to fly through the ejecta from the impact and probably not survive

Posted by: ljk4-1 Feb 10 2006, 03:01 PM

How porous/light would the comet have to have been for Deep Impact to have caused it to break apart?

Posted by: Comga Feb 10 2006, 09:43 PM

Contact has been made with the Deep Impact fly-by spacecraft hibernating in solar orbit. No anomalies were reported. It is in good shape to do more science.
It will do a fly-by of Earth in about 23 months, which could be used to control its trajectory. Where it goes from there is yet to be decided.

Posted by: BruceMoomaw Feb 11 2006, 05:41 AM

How porous/light would the comet have to have been for Deep Impact to have caused it to break apart?

Posted by: The Messenger Feb 15 2006, 10:26 PM

QUOTE (BruceMoomaw @ Feb 10 2006, 10:41 PM)

Posted by: BruceMoomaw Feb 15 2006, 11:59 PM

An new LPSC abstract on the subject by the Deep Impact science team ( http://www.lpi.usra.edu/meetings/lpsc2006/pdf/2192.pdf ) says that the impact flash was a lot DIMMER than expected: "The overall luminous efficiency of the flash was far lower than predicted, most likely due to the high porosity and volatile content of the Tempel 1 surface." Extensive details are provided.

As for Deep Impact being "a tremendous engineering and scientific success": no quarrel about the former, but I have PLENTY of quarrels about the latter. When I look at the LPSC abstracts on the mission, I get the distinct impression that:

(1) Where science return is concerned, this thing delivered a lot less than they had hoped for, in regard to both the comet's physical structure and its chemical makeup;

(2) Most of the really useful stuff they got was from its images of the comet before the impact; and

(3) A simple CONTOUR-type mission -- perhaps with a subsurface radar sounder added -- would have produced a lot more.

From the moment this mission was picked (which apparently came as a major surprise to planetary scientists), I've always thought the selection had Captain Crazy written all over it, although admittedly I have no direct evidence of this. The resemblance to his abortive 2003 Mars Airplane just to commemorate the Wright Brothers centennial -- and to his cancellation of the Pluto mission because "Nobody gives a damn about Pluto" and astrobiology was SO much more spectacular -- is unmistakable. He was the Cecil B. DeMille of NASA, and this thing would have struck him as just the sort of Big Spectacle capable of attracting the rubes... er, voters.

Posted by: ljk4-1 Feb 18 2006, 03:48 AM

DEEP NEWS

Newsletter for the Deep Impact mission

Issue #30, January/February 2005

--------------------------------------------------------------------------------

It's amazing that in the world of space exploration, in which spacecraft
sometimes take years to reach a destination, the Deep Impact mission journeyed
through funding, design, building, launch, encounter, and this month - the
release of findings from the science team. With more study still to come, Deep
Impact was proven to be a tightly scheduled mission with spectacular results.
You joined us somewhere along the way getting our monthly updates and we hope
you enjoyed the ride. This issue is the last of our monthly updates and in the
future, we will contact you with shorter news about Deep Impact's science and
technology. If for some reason you are just joining us take a look at what you
have missed on our web sites:

http://deepimpact.jpl.nasa.gov

http://deepimpact.umd.edu


PICTURE THIS - WATER, WATER EVERYWHERE!

Well, perhaps not everywhere - but results from the IR spectrometer aboard the
Deep Impact flyby spacecraft show that water ice exists on only about 0.5% of
the comet's surface. Take a look and see where the team found the water ice.

http://deepimpact.jpl.nasa.gov/gallery/SurfaceIceLocations.html


MISSION UPDATE: NEW RESULTS FROM THE SCIENCE TEAM

Results from the flyby spacecraft's IR spectrometer are shared in a summary from
a paper by Co-Investigator Dr. Jessica Sunshine and the science team. Also, read
Ray Brown's outline of Deep Impact findings based on a summary of telescope
observations from Co-Investigator, Dr. Karen Meech and collaborators.

Summary from the Ground Observation:

http://deepimpact.jpl.nasa.gov/mission/update-200602.html#rbrown

Summary from the IR Spectrometer:

http://deepimpact.jpl.nasa.gov/mission/update-200602.html#lmcfadden


TECHNICAL UPDATE FROM THE PI - DR. MIKE A'HEARN AT THE UNIVERSITY OF MARYLAND

Principal Investigator Dr. Mike A'Hearn gives his science team a technical
update on the Deep Impact flyby spacecraft after the engineering group at Jet
Propulsion Laboratory communicated with it on February 10th.

http://deepimpact.jpl.nasa.gov/mission/update-200602.html#mahearn


UP CLOSE AND PERSONAL: MEET DR. KAREN MEECH, DEEP IMPACT CO-INVESTIGATOR

Karen knew since she was very young that she would end up working in astronomy
someday and there were lots of Star Trek episodes and evenings with her father
watching the sky to help confirm that decision. Meet Karen Meech.

http://deepimpact.jpl.nasa.gov/mission/bio-kmeech.html


FOR EDUCATORS: WHAT DOES THE MOON HAVE TO DO WITH THE DEEP IMPACT MISSION?

Well, quite a lot actually. Shortly after takeoff, the science team used the
spacecraft images of the moon to check the calibrations for their instruments.
Here is a Mission Challenge based on their calculations and set to national math
standards. Have your students do real mission math!

Question: What was the distance from the Deep Impact spacecraft to the moon on
January 16, 2005?

On January 16, 2005, the Deep Impact spacecraft turned its cameras back toward
Earth and captured some beautiful images of our Moon. To aid in calibrating the
spacecraft instruments, astronomers would like to know precisely how far Deep
Impact was from the moon when this picture was taken.

http://deepimpact.jpl.nasa.gov/disczone/challenge_Moon_Distance.html


WAY TO GO, STARDUST! - RETURN TO SENDER

Congratulations to the Stardust Mission for the safe and successful return of
their capsule containing actual particles from comet Wild 2 on January 15, 2006.
There was great excitement as their science team viewed the grid in which
squares of aerogel safely cradled the first samples of cometary and interstellar
dust to be returned to Earth for study. As a sister to Deep Impact, findings
from both missions will bring scientists closer to answering questions about the
formation of the solar system.

http://stardust.jpl.nasa.gov/news/status/060125.html


PLANETARY SOCIETY ANNOUNCES THE WINNERS OF THE CRATER CONTEST

Although the precise dimensions of the crater made by the Deep Impact mission in
Tempel 1 were hidden by ejecta from its nucleus, the Planetary Society was able
to pick 3 winners from those whose predictions fell within the range determined
by the science team. Take a look.

http://www.planetary.org/about/press/releases/2006/0125_Comet_Dust_Clouds_Planetary_Society.html


DID YOU SEE OUR PAST DEEP NEWS ISSUES?

Visit http://deepimpact.jpl.nasa.gov/newsletter/archive.html to catch up on
exciting past news from the Deep Impact mission.

Deep Impact is a Discovery mission. For more information on the Discovery
Program, visit:

http://discovery.nasa.gov/

The Deep Impact mission is a partnership among the University of Maryland (UMD),
the California Institute of Technology's Jet Propulsion Laboratory (JPL) and
Ball Aerospace and Technology Corp (BATC). Deep Impact is a NASA Discovery
mission, eighth in a series of low-cost, highly focused space science
investigations. See http://deepimpact.jpl.nasa.gov or our mirror site at
http://deepimpact.umd.edu.


SUBSCRIPTION INFORMATION:
Send this email along to your friends. If you received this newsletter from a
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site for our high web traffic time and will be returned in the future. Thanks
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Posted by: The Messenger Feb 18 2006, 05:56 PM

QUOTE (BruceMoomaw @ Feb 15 2006, 04:59 PM)

Posted by: ljk4-1 Feb 22 2006, 09:15 PM

Article on Deep Impact in the latest The Planetary Society The Planetary Report:

Deep Impact: Understanding Comet Tempel 1

On July 4, 2005, the Deep Impact spacecraft sent a 370-kilogram (820-pound) copper ball on a collision course with comet Tempel 1 to give us our first look inside a comet. Within minutes of the impact, the spacecraft returned to Earth spectacular images of the explosive event. Exactly what these images and other data revealed, however, took much longer to analyze. Now, 6 months later, Deep Impact coinvestigator Lucy McFadden and coauthor Ray Brown detail what scientists are discovering about comet Tempel 1 and what Deep Impact has taught us about the oldest components of our solar system.

http://www.planetary.org/programs/planetary_report.html

Posted by: The Messenger Feb 23 2006, 06:22 AM

QUOTE (ljk4-1 @ Feb 22 2006, 02:15 PM)

Posted by: ljk4-1 Mar 14 2006, 03:52 PM

Astrophysics, abstract
astro-ph/0603306

From: Damien Hutsemekers [view email]

Date: Mon, 13 Mar 2006 13:46:17 GMT (26kb)

Deep Impact : High Resolution Optical Spectroscopy with the ESO VLT and the Keck 1 telescope

Authors: E. Jehin, J. Manfroid, D. Hutsemekers, A.L. Cochran, C. Arpigny, W. M. Jackson, H. Rauer, R. Schulz, J.-M. Zucconi

Comments: Accepted for publication in ApJ Letters

We report on observations of comet 9P/Tempel 1 carried out before, during, and after the NASA DEEP IMPACT event (UT July 4), with the optical spectrometers UVES and HIRES mounted on the telescopes Kueyen of the ESO VLT (Chile) and Keck 1 on Mauna Kea (Hawaii), respectively. A total observing time of about 60 hours, distributed over 15 nights around the impact date, allowed us (i) to find a periodic variation of 1.709 +/- 0.009 day in the CN and NH flux, explained by the presence of two major active regions; (ii) to derive a lifetime > ~ 5 x 10^4 s for the parent of the CN radical from a simple modeling of the CN light curve after the impact; (iii) to follow the gas and dust spatial profiles evolution during the 4 hours following the impact and derive the projected velocities (400 m/s and 150 m/s respectively); (iv) to show that the material released by the impact has the same carbon and nitrogen isotopic composition as the surface material (12C/13C = 95 +/- 15 and 14N/15N = 145 +/- 20).

http://fr.arxiv.org/abs/astro-ph/0603306

Posted by: The Messenger Mar 14 2006, 04:34 PM

QUOTE (ljk4-1 @ Mar 14 2006, 08:52 AM)

Posted by: The Messenger Mar 19 2006, 05:18 PM

Posted by: BruceMoomaw Mar 19 2006, 09:32 PM

Except that the reason Housen thinks this ( http://www.lpi.usra.edu/meetings/lpsc2006/pdf/1068.pdf ) is precisely that the plume particles shot away from the nucleus at several times the speed they would have travelled had they just been dry, loose dust particles ejected by the force of the impact -- which means that "comet-like acceleration mechanisms [by which he means a powerful blast of released gas from thawed-out volatiles inside the comet] are required to move the ejected mass to 100 km ranges in a few-hour time frame. But if there were such mechanisms, then up to all of the ejected mass could be transported to large ranges over an hour or two and observed. Then, to within the large uncertainties in particle sizes, albedo, ejecta scaling and so forth, any of the above strength cases, from 0 to 12 kPa, could furnish the amounts of total mass estimated. So, either gravity or strength craters can be consistent with the observations. Thus, the observations to date do not discern between the relative importance of strength and gravity in the DI event." That is, not only did the impact lead to a massive outburst of thawed-out ices from inside the comet -- that outburst was so powerful that it has ruined our ability to estimate the actual hardness of the outer dirt layer on the comet, except that it must be somewhere below 12 kilopascals (which is about 120 grams per square cm, or 1.8 lb. per square inch).

In other words, the very fact that D.I.'s measurement of the comet's surface hardness is so inexact (according to Housen) is because the impact DID punch through the outer layer of dry crust to a large reservoir of ices beneath -- just as the D.I. team has insisted, and The Messenger has denied. Jessica Sunshine noted that not only was a fair amount of finely powdered ice and water vapor released by the impact (as detected by the craft's mapping near-IR spectrometer), but that jet of water wasn't spread out in a very wide cone of ejecta like the dust splattered by the impact -- it was "very collimated"; that is, it shot up in a relatively narrow jet from the bottom of the crater, proving that it was material that had been vaporized underneath the crater and had broken up through the thinnest part of the crater's dirt-layer floor. She also notes that the three patches of water ice located before the impact on the nucleus' surface by the near-IR spectrometer were all very dilute -- only about 3-6% of the material in them was ice, with the rest being dust -- and therefore sublimation from them couldn't even account for the natural jets of water vapor seen coming from the comet before the impact; those jets must have come from ice being vaporized underneath and breaking open ventholes in the outer dry layer. ( http://www.planetary.org/blog/article/00000499/ ; http://www.lpi.usra.edu/meetings/lpsc2006/pdf/1890.pdf )

And the impact also released much lower-temperature ices than mere water ice. The team noted from the start that the jet of gas coming out from the impact contained a much higher ratio of CO2 to water vapor than the pre-impact natural jets coming from the comet ( http://www.lpi.usra.edu/meetings/lpsc2006/pdf/1978.pdf . According to A'Hearn's "Science" article, the CO2-to-water ratio increased fivefold.) D.I. also detected a large amount of organic gases squirting out of the impact site, but didn't have the spectral resolution to identify any of them -- but Michael Mumma, using the Keck Telescope, WAS able to measure the pre- to post-impact ratios of three of them. Sure enough, ethane -- which has a very low freezing point -- shot up dramatically after the impact relative to the amount of water vapor released by the comet; while HCN and methanol -- which, unlike ethane and CO2, have much higher freezing points comparable to water -- did not increase in their released amounts relative to water vapor (although they did increase to about the same degree as the water vapor did after the impact). See his article in the Oct. 14 "Science".

So The Messenger is simply totally wrong on that particular point of his: the impact unquestionably did break all the way through the comet's dry outer crust to release a very violent jet of material from the ices underneath -- and it also broke through the layer of higher-temperature ices just beneath that dry layer (including water, HCN and methanol) to release some of the still lower-temperature frozen materials underneath that (including CO2 and ethane).

As for Housen's statement that the D.I. impact did not, after all, prove that the comet's surface was made of totally loose powdery dust but that it may have been caked instead: it meshes well both with the tendency of gas jets from comets to suddenly break through the outer layer and then erupt violently, and with the fact (indicated by some Earth-based spectral observations, and apparently confirmed by the sudden burst of particles Stardust ran into when it was very far from Wild 2's nucleus) that a lot of the debris blown off comets acts like "fireworks" -- that is, relatively large bits of caked dust and ice get blown off the comet, and then later explode into a burst of finer dust particles when the ice inside them is in turn vaporized by the Sun and produces gas pressure inside them.

Posted by: Bob Shaw Mar 19 2006, 09:51 PM

Bruce:

And comets, historically, have broken apart and formed new tails and so forth, often when warmed - which tends to suggest a 'pressure cooker' that's burst rather than a fluffy pile of dust.

However, I think it's also true that the trend over recent years *has* been away from the primeval rocky iceberg model, and towards a class of objects with rather more of a history - and a constitution closer to many asteroids.

Bob Shaw

Posted by: BruceMoomaw Mar 19 2006, 10:13 PM

Yeah; one would think, if the dust layer was entirely loose and fluffy, gases produced underneath would tend to diffuse upwards between the grains fairly gently and steadily -- and that this would be pretty evenly distributed all over the nucleus' surface. (Also, it's kind of hard to conceive how, underneath such circumstances, the quite sharp cliffs that we've seen all over the surface of all three of the nuclei we've gotten a really good look at could be sustained, even in such extremely weak gravity. I'll be having more to say about those shortly.)

Posted by: Bob Shaw Mar 19 2006, 10:33 PM

Anyone interested, or indeed perturbed, by references on UMSF to the Elder Gods (who may or may not like having innocent comets whacked by the engines of an upstart mankind) may care to visit the following website:

http://www.cthulhulives.org/cocmovie/index.html

Aiiii!

Bob Shaw

Posted by: BruceMoomaw Mar 20 2006, 01:16 AM

Ahem. Getting back to Deep Impact, I continue to be struck by how apparently little we actually learned from running into that comet as opposed to just flying past it a la CONTOUR. Spectral studies of the ejecta cloud have apparently told us very little about the composition of comets that we didn't already know (or wouldn't have learned from CONTOUR and Stardust); we never did see the crater; and if Kevin Housen is right, the impact didn't even give us much useful information about the hardness of the surface layer. The impact was a spectacular light show, but not very cost-effective scientifically -- which further bolsters my suspicions that Captain Crazy was behind its original selection as a Discovery mission.

Actually, to my mind, the most interesting DI-connected LPSC papers do indeed concern the craft's photos of the comet nucleus before impact. Joe Veverka has a very nice one on the peculiar structures seen on Tempel's surface ( http://www.lpi.usra.edu/meetings/lpsc2006/pdf/1364.pdf ) -- Emily, alas, apparently missed his talk during all her frantic running around to try to drop in on separate LPSC sessions simultaneously. Once again, we are seeing the layered structures, scarps and mesas that we saw earlier on Borrelly and Wild 2 (Giotto's photos of Halley were too fuzzy to be useful here). I've always believed that what we are seeing is evidence that comet nuclei literally "peel from sunburn". That is, when you get an quite small impact crater or vent pit in an initial nucleus surface that has a lot of ice in it, solar warmth sublimates the ice away and leaves a lag deposit of dry dirt. On a flat surface like an impact crater's floor, this lag deposit simply grows to a certain thickness and then serves as insulation to keep the ices underneath from boiling away further. But on a crater's or pit's side slope, provided it's steeper than the angle of repose of dry dust on that comet, the loosened rock dirt slides down the slope, exposing more fresh ice-dust mixture to be eroded away by the Sun -- so that such craters don't increase much in depth, but instead grow sideways into wider and wider flat-bottomed depressions (like those on Wild 2) that can ultimately wrap clean around the comet and leave only isolated mesas like those seen on Borrelly. Then, when new small impact or venting pits appear in that newly exposed layer that are deep enough to expose more ice, the whole process starts all over again -- and it's even possible then for ice to sublimate out from underneath the layer of dry caked dirt on top, producing actual overhangs such as have apparently been seen in a few places on Wild 2.

Nice theory, and Veverka seems to agree with it -- but Mike Belton proposes a startling alternative ( http://www.lpi.usra.edu/meetings/lpsc2006/pdf/1232.pdf ). Namely: we may be seeing evidence that comets (or at least Jupiter-family comets, which is all we've gotten a good look at yet), may have been originally formed not by smaller blobs of ice/dirt that bumped into each other and stuck together lightly while retaining most of their original shape (making the accumulated comet nucleus a "lumpy" conglomerate), but by such blobs hitting the accumulating nucleus hard enough to smear themselves flatly over its surface like a snowball hitting a wall. In that case, the nucleus is made up of an onion-like patchwork of multiple flattened layers from different cometesimals, almost none of which stretches all the way around the nucleus -- and "Mesas are formed, following the suggestion by Britt et al., as a result of erosional sublimation at the boundaries of the outermost layers during passages near the sun. Cometary splitting and tidal disruption is seen as the result of detachment of entire layers or, possibly, disassembly of essentially the entire, presumably weakly bonded, layer structure." Belton calls this the "talps" model (it took me a while to realize that this is "splat" spelled backwards). I'm inclined to agree with Veverka that, while Belton's theory is interesting, as yet we simply do not have the data yet to decide which of these two models is true (or whether both of them are). As Belton says, this makes the data from the CONSERT radar-sounding experiment on Rosetta even more important.

There are, however, two other very interesting kinds of surface structures seen on Tempel by DI and mentioned by Veverka. First: "Two areas of extensive smooth terrain are evident. They are completely uncratered, suggesting a young relative age, and very smooth at meter scales. Both occur in gravitational lows." The bigger one shows marks suggesting that it flowed downhill into this gravitational low, and "A potential source area (only a few hundred meters wide) can be identified. The extremely smooth surface of this feature suggests that this putative flow consisted of materials which are extremely fine and uniform in texture." We are, I imagine, looking at an analogy of the "ponds" of fine regolith seen in the gravitational lows of Eros and Itokawa -- some of the dust squirted off the comet's surface by gas jets and impacts does not escape completely, but tends to sift and slide back to form a deep, loose "pool" filling low spots on the nucleus (and later hardening a bit so that the erosive solar processes I mentioned earlier can nibble at its edge to produce a steep edge scarp, such as has also been seen for this big smooth area on Tempel).

Second, there are other spots on Tempel that "appear to preserve evidence of past cratering, suggesting that the nucleus spent significant amounts of time in environments in which sublimation erosion rates were very low compared to cratering rates. At least 60 craters ranging in diameter from 50 to 2500 meters can be identified. The resulting population has a slope of about -2 on a cumulative plot, consistent with a highly eroded crater population. The crater density is about one tenth that found on asteroid Gaspra. This value, low by asteroid standards, nevertheless suggests a remarkably old age for portions of the surface of 9P/Tempel 1." I had assumed that these craters -- one of which the Impactor just missed -- were steadily growing sublimation pits of the sort I've mentioned, like those seen by Stardust on Wild 2; but the DI team says that they have the same gradual bowl-shaped cross-sections seen on standard impact craters, unlike the Wild 2 "cookie-cutter" pits with their very flat floors suddenly bordering onto very deep and steep side slopes. It may still be that these really are also sublimation pits, which take on a different shape on Tempel due to a somewhat different surface consistency -- or it may be that these are patches of the nucleus which, very early in the comet's history, became hard enough (from the removal of their volatiles) and thick enough that no more gas vents can break through them from underneath, leaving them free to be gradually covered by regular impact craters like any standard non-active asteroid surface. Again, viewing the subsurface layering of comets seems to be crucial -- and doing this with radar sounding seems to be much better than trying to do it with expensive and localized artificial impacts.

In that connection, one more brief note: P.H. Schultz ( http://www.lpi.usra.edu/meetings/lpsc2006/pdf/2294.pdf ) confirms that the nature of the ejecta plume rising off the surface of Tempel after the impact suddenly changed in nature about 50 seconds after impact, suggesting again that at that point a jet of sublimating ice underneath started blowing more dust and ice particles into space (after the initial dust ejecta had simply been tossed out by the impact shock).

Posted by: The Messenger Mar 20 2006, 01:37 AM

QUOTE (BruceMoomaw @ Mar 19 2006, 03:13 PM)

Posted by: RGClark Mar 20 2006, 01:38 AM

QUOTE (BruceMoomaw @ Mar 20 2006, 01:16 AM)

Posted by: BruceMoomaw Mar 20 2006, 01:50 AM

It will certainly be very interesting to see if these are confirmed in the Stardust samples.

Posted by: dvandorn Mar 20 2006, 03:33 PM

Considering that the Tagish Lake meteor seems to have been composed mainly of clays, and considering that the Tagish Lake meteor behaved like a volatile-rich body when it entered Earth's atmosphere (acquiring some odd vectors as pockets of volatiles were released, and finally exploding well above the surface), we have some fairly decent proof that cometary bodies *can* contain clays. And that such bodies also have a good admixture of volatiles.

It's more a matter, I think, of trying to come up with a set of mechanisms that accounts for such differentiation and clay formation in cometary bodies...

-the other Doug

Posted by: The Messenger Mar 20 2006, 04:39 PM

http://www.spaceref.com/news/viewnews.nl.html?id=1103