Deep Impact aftermath - science results

ToSeek · #1 (**permalink**) 05-July-2005, 03:13 PM

I think it would be nice to have a thread dedicated reports on the science findings from the Deep Impact collision. I'll start it off with XMM-Newton detects water in comet, as initially mentioned by the BA.

ToSeek · #2 (**permalink**) 05-July-2005, 05:37 PM

Crash Course in Comet Construction

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Comet Tempel 1 was hit hard by a NASA spacecraft earlier today. Deep Impact scientists provided more details about what the impact has taught us about the comet's structure.

Swift · #3 (**permalink**) 05-July-2005, 07:23 PM

Quote:

Originally Posted by ToSeek

Crash Course in Comet Construction

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A'Hearn says that Tempel 1 looks different from comets Wild 2 and Borrelly, and they're scratching their heads, trying to figure out why.

"When Wild 2 looked different from comet Borrelly, we thought it might be due to the different orbital histories of the two comets," says A'Hearn. "But this comet's had an orbital history that we think is pretty much similar to Borrelly, and yet it looks totally different. So there's something more going on here that we haven't understood yet."

I take the difference in orbital histories to mean what happened to the various comets since their formation (how close or far they are from the sun and how much they have been heated). I wonder if the remaining differences can be explained by differences in the formation phase? Do current models of solar system formation predict that all the cometary material would be relatively identical, or would you expect a certain amount of variation? My un-educated guess would be the latter.

Christopher Ferro · #4 (**permalink**) 05-July-2005, 07:28 PM

Quote:

A'Hearn says that Tempel 1 looks different from comets Wild 2 and Borrelly, and they're scratching their heads, trying to figure out why.

"When Wild 2 looked different from comet Borrelly, we thought it might be due to the different orbital histories of the two comets," says A'Hearn. "But this comet's had an orbital history that we think is pretty much similar to Borrelly, and yet it looks totally different. So there's something more going on here that we haven't understood yet."

I don't know. While there are clearly differences, I was thinking about how Tempel 1 looked like a cross between Borrelly and Wild 2. I didn't see anything so different among the three that made me think they weren't the same class of objects.

CJSF

John Kierein · #5 (**permalink**) 05-July-2005, 08:07 PM

From the Boulder Daily Camera. You may have to register? Or not.

http://tinyurl.com/a5qv4

Has unusual white areas on the surface.

Paladin · #6 (**permalink**) 05-July-2005, 08:33 PM

disregard

ToSeek · #7 (**permalink**) 05-July-2005, 09:52 PM

I would prefer that this thread remain focused on genuine scientific findings. There are plenty of other Deep Impact threads for discussing other issues. This one is probably the best for discussing, um, unconventional theories.

publiusr · #8 (**permalink**) 06-July-2005, 10:21 PM

Not along that line--but could the probe have put a minor amount of back spin on the body due to a hit on the edge(if not changing its course in the slightest)?

Superluminal · #9 (**permalink**) 07-July-2005, 03:02 AM

The change in velocity was expected to be so slight, something like .0014 meters per second, (IIRC) I doubt very seriously it put any back spin on it.

I just finished looking at old Astronomy articles about the SL9 impact on Jupiter. The leading model was that the comet fragments tunneled through the outer atmosphere before exploding, and the fireball traveled back out the tunnel before expanding. From looking at the impact movie from the flyby craft something similar happened on Temple. Except that instead of atmosphere the probe traveled some distance through a soft surface before impacting a solid surface.

The XMM-Newton team claimed a solid surface impact based on the amount of ultraviolet light observed at impact. But the thin shadow seen in the movie just after impact and before the plume began to spread out seem, to me anyway, to support the soft then solid surface impact.

Could that indicate that the upper surface wasn't just soft but was very fluffy? What would the investigators look for in the spectra to confirm that it was soft?

Kullat Nunu · #10 (**permalink**) 07-July-2005, 08:19 PM

Universe Today: Gemini Sees Rocky Material on Tempel 1

publiusr · #11 (**permalink**) 07-July-2005, 08:28 PM

I hear about two layers--a soft layer and a harder layer IIRC.

ToSeek · #12 (**permalink**) 08-July-2005, 05:23 PM

Odin's first post-hit water measurements of Tempel 1

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The first measurements by Odin of water vapour from the comet Tempel 1 after the Deep Impact hit are now available. The figure (click for full picture) shows four measurements at different occasions, 7 hours before impact and 5, 17, and 32 hours after. The scientist are now busy trying to interpret these measurements to understand what happened to the outgassing of water from the comet.

ToSeek · #13 (**permalink**) 08-July-2005, 07:41 PM

Scientists Measure How Deep "Deep Impact" Was, With X-rays

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Here come the X-rays, on cue. Scientists studying the Deep Impact collision using NASA's Swift satellite report that comet Tempel 1 is getting brighter and brighter in X-ray light with each passing day.

The X-rays provide a direct measurement of how much material was kicked up in the impact. This is because the X-rays are created by the newly liberated material lifted into the comet's thin atmosphere and illuminated by the high-energy solar wind from the Sun. The more material liberated, the more X-rays are produced.

Swift data of the water evaporation on comet Tempel 1 also may provide new insights into how solar wind can strip water from planets such as Mars.

"Prior to its rendezvous with the Deep Impact probe, the comet was a rather dim X-ray source," said Dr. Paul O'Brien of the Swift team at the University of Leicester. "How things change when you ram a comet with a copper probe traveling over 20,000 miles per hour. Most of the X-ray light we detect now is generated by debris created by the collision. We can get a solid measurement of the amount of material released."

Manchurian Taikonaut · #14 (**permalink**) 08-July-2005, 11:21 PM

great pictures from the mission & very good data

ToSeek · #15 (**permalink**) 09-July-2005, 02:24 AM

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News Release: 2005-113 July 8, 2005

NASA’s Deep Impact Tells a Tale of the Comet

Data from Deep Impact's instruments indicate an immense cloud of fine powdery material was released when the probe slammed into the nucleus of comet Tempel 1 at about 10 kilometers per second (6.3 miles per second or 23,000 miles per hour). The cloud indicated the comet is covered in the powdery stuff. The Deep Impact science team continues to wade through gigabytes of data collected during the July 4 encounter with the comet measuring 5-kilometers-wide by 11-kilometers-long (about 3-miles-wide by 7-miles-long).

"The major surprise was the opacity of the plume the impactor created and the light it gave off," said Deep Impact Principal Investigator Dr. Michael A'Hearn of the University of Maryland, College Park. "That suggests the dust excavated from the comet's surface was extremely fine, more like talcum powder than beach sand. And the surface is definitely not what most people think of when they think of comets -- an ice cube."

How can a comet hurtling through our solar system be made of a substance with less strength than snow or even talcum powder?

"You have to think of it in the context of its environment," said Dr. Pete Schultz, Deep Impact scientist from Brown University, Providence, R.I. "This city-sized object is floating around in a vacuum. The only time it gets bothered is when the Sun cooks it a little or someone slams an 820-pound wakeup call at it at 23,000 miles per hour."

The data review process is not overlooking a single frame of approximately 4,500 images from the spacecraft's three imaging cameras taken during the encounter.

"We are looking at everything from the last moments of the impactor to the final look-back images taken hours later, and everything in between," added A'Hearn. "Watching the last moments of the impactor's life is remarkable. We can pick up such fine surface detail that objects that are only four meters in diameter can be made out. That is nearly a factor of 10 better than any previous comet mission."

The final moments of the impactor's life were important, because they set the stage for all subsequent scientific findings. Knowing the location and angle the impactor slammed into the comet's surface is the best place to start. Engineers have established the impactor took two not unexpected coma particle hits prior to impact. The impacts slewed the spacecraft's camera for a few moments before the attitude control system could get it back on track. The penetrator hit at an approximately 25 degree oblique angle relative to the comet's surface. That's when the fireworks began.

The fireball of vaporized impactor and comet material shot skyward. It expanded rapidly above the impact site at approximately 5 kilometers per second (3.1 miles per second). The crater was just beginning to form. Scientists are still analyzing the data to determine the exact size of the crater. Scientists say the crater was at the large end of original expectations, which was from 50 to 250 meters (165 to 820 feet) wide.

Expectations for Deep Impact's flyby spacecraft were exceeded during its close brush with the comet. The craft is more than 3.5 million kilometers (2.2 million miles) from Tempel 1 and opening the distance at approximately 37,000 kilometers per hour (23,000 miles per hour). The flyby spacecraft is undergoing a thorough checkout, and all systems appear to be in excellent operating condition.

The Deep Impact mission was implemented to provide a glimpse beneath the surface of a comet, where material from the solar system's formation remains relatively unchanged. Mission scientists hoped the project would answer basic questions about the formation of the solar system by providing an in-depth picture of the nature and composition of comets.

The University of Maryland is responsible for overall Deep Impact mission science, and project management is handled by JPL. The spacecraft was built for NASA by Ball Aerospace & Technologies Corporation, Boulder, Colo. JPL is a division of the California Institute of Technology, Pasadena, Calif.

For information about Deep Impact on the Internet, visit:

<http://www.kintera.org/TR.asp?ID=M69842575956263916425265>www.nasa.gov/deepimpact

Saluki · #16 (**permalink**) 09-July-2005, 02:57 AM

Is there any further science the flyby craft can do when it is out of range of the comet?

01101001 · #17 (**permalink**) 09-July-2005, 03:06 AM

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Originally Posted by Saluki

Is there any further science the flyby craft can do when it is out of range of the comet?

Yes, if they send it to examine another comet.

01101001 · #18 (**permalink**) 09-July-2005, 04:00 AM

Comet Tempel's Silhouette

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The colors represent brightness, with white indicating the brightest materials and black showing the faintest materials. This brightness is a measure of reflected sunlight. [...] The large plume of dust that was kicked up upon impact can be seen as the colorful, drop-shaped object. This plume was very bright, indicating that the comet's surface material must be very fine, like talcum powder.

01101001 · #19 (**permalink**) 09-July-2005, 10:49 AM

Harvard-Smithsonian Center for Astrophysics, Press Release: Deep Impact Was a Dust-up, Not a Gusher

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Results are still coming in, but so far the scientists report seeing only weak emission from water vapor and a host of other gases that were expected to erupt from the impact site. The most conspicuous feature of the blast was brightening due to sunlight scattered by the ejected dust. [...] SMA measurements corroborate the SWAS findings. Although the SMA wasn't tuned to frequencies of water emission, which are difficult to observe from the ground due to atmospheric water vapor, it watched for other chemicals such as hydrogen cyanide. SMA astronomers saw little increase in production of gases following the impact. Gas production rates remained so low that they could set only an upper limit on the total. [...] Qi added that the comet might become more active over the following days and weeks. "We're still hoping for a big outgassing from the new active area created by Deep Impact. If we see any signs of that, we'll make more observations."