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The comet Wild 2, operation Stardust, and Deep Impact 
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Joined: Fri Mar 13, 2009 4:18 pm
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The comet Wild 2 is a 5 km ball of ice and dust that goes around the sun every six years at an average distance 1.59 astronomical units (going from 1.6 to 5.3 AU).

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image by Chesnok (source)

Wild 2 wasn't discovered until 1978, but it is thought that in 1974 it would have come within 1 million km of Jupiter, which then pulled it in from an original, much larger ~43 year solar orbit.

Wild 2 is particularly noteworthy as being just one of five bodies in our solar system of which we have recovered actual physical matter, the others being Earth, the Moon, Mars, and the dwarf planet candidate asteroid Vesta.

This was accomplished by the Stardust probe, which was launched in 1999, flew past Wild 2 in 2004, collecting cometary and interstellar dust in aerogel collectors, and returned the collection back to Earth in a capsule in 2006. After launch, Stardust looped back round to Earth to get slingshot off into a more distant orbit that would intersect the comet:

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image by NASA (source)

A pretty smooth operation! The craft traveled 3 billion miles, managing to land the capsule back on Earth right on target, just a few miles off from exact center due to wind. The capsule came down at 12.9 km/s, the fastest re-entry ever by a man-made object; it made a big fireball and sonic boom over Utah/Nevada! Here it is after landing at the USAF range in Utah:

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image by NASA (source)

The probe didn't have super cameras, but here's a pretty good image of the nucleus of the Wild 2 comet:

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image by NASA (source)

and the plumes jetting out of it

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image by NASA (source)

Stardust's aerogel collector looked like this

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image by NASA (source)

and was deployed like this

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image by NASA (source)

The capsule landed successfully and the ship was put into hibernation mode and placed into a three-year heliocentric orbit. But Stardust is really only just beginning!

Stardust@home (Wikipedia) is a massively distributed search by which ordinary people passing some sort of entrance test can spend their time sorting through microscopic photos of the side of the recovered Stardust aerogel that was used to capture space dust (the other side was used to recover dust from Wild 2): the gels have been divided into 700,000 "fields" consisting of 40 photos each; examining the photos for tracks of microscopic particles is the way to find the recovered space particles. So far they've found 28 particles, a few microns wide, most of which are only solar system micro meteoroids; however, a few appear to be the interstellar particles they were really hoping to capture. If you find one of these nanometer particles, it will be named after you! :D

Also, the Stardust craft is still going. In 2007 a mission was approved to take it by the Tempel 1 comet in 2011 for photographs. This is important because while Tempel 1 was successfully hit with the copper Deep Impact impactor in 2005, the Deep Impact probe didn't get a good photo of the resulting crater.

Deep Impact got some pretty spectacular shots and good data from the hit of its impactor on the comet, though:

Image
image by NASA (source)

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image by NASA (source)

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image by NASA (source)

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image by NASA (source)

Tempel 1 is about 6 km across and orbits the Sun every 5.5 years at an average of 3 AU. From the impact, they found it contained a surprising amount of dust vs water, the dust was very fine--powdery rather than sandy--and had a lot of empty space. The 370 kg impactor (made of copper, because copper wasn't expected to be in the comet, so the debris would be easy to distinguish) blew 5 million kg of water and 10-25 million kg of dust off the comet, and left a 100 meter wide, 30 meter deep crater.

So Stardust will go check out the crater left on Tempel 1. Meanwhile, the Deep Impact probe has been considered for intercept of a few other comets. They were going to send it to check out Comet Boethin in 2008, but the comet couldn't be found! They figure it probably broke up into pieces since it last went by in the 70's. So instead, they used an Earth slingshot to send it toward comet Hartley 2, which it will pass at a distance of 700 km on November 4th of this year, which is just after the comet will have come to its nearest 0.12 AU distance from Earth on October 20th, at which point the comet may be visible to the naked eye from Earth.

So look for Deep Impact and Stardust to be making the news with even more cometary exploration over the next few years!


Fri Mar 12, 2010 5:04 pm
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Joined: Wed Mar 18, 2009 1:59 pm
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As opposed to that other Operation Stardust.


Fri Mar 12, 2010 7:13 pm
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Whaaa? Hmm... Doesn't sound like there were enough comets involved. =P


Fri Mar 12, 2010 7:29 pm
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Joined: Fri Nov 04, 2016 1:12 am
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BrC wrote:
Whaaa? Hmm... Doesn't sounds like the breast actives works were enough comets involved. =P


Great story, seems almost unbelievable that they could get a man made object to travel 3 billion miles without malfunctioning. I wonder what the results were after checking the contents of the probe.


Last edited by Liber on Fri May 12, 2017 8:11 am, edited 2 times in total.



Sat Nov 05, 2016 12:47 am
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Liber wrote:
Great story, seems almost unbelievable that they could get a man made object to travel 3 billion miles without malfunctioning. I wonder what the results were after checking the contents of the probe.

Apparently PBS intends to include some stories of the crowd-sourced analysis of the gels in a documentary next year!

I didn't find a whole lot on a brief search about specific results of the examination of the particles captured in the aerosols, but the process of scanning and analyzing them is still very much underway; you can see interactive charts of the progress at NASA's Johnson Space Center site. Stardust@Home is still examining new movies of the gels and so forth.

The Stardust spacecraft did encounter comet Tempel 1 in 2011, getting 72 photos, including of Deep Impact's impact site, although "it was barely visible due to material settling back into the crater." Not long after that its fuel was exhausted, and its transmitter was switched off, since it could no longer maneuver to aim it back at Earth; its last transmission came from ~3.12 billion miles away.


Sat Nov 05, 2016 2:19 pm
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