This is semi-related to last couple of posts, specifically A Dusty Blog Post and Mercurial Monday. And a bit of a eulogy to a fantastic and amazing spacecraft that provided groundbreaking science for 12 years.
One of the mission's I learned a little bit more about the science behind was Stardust-NExT. A spacecraft that undertook a fascinating mission in comet exploration. The probe is now burning the last of its residual fuel and is being decommissioned about 312 million miles away from Earth.
NASA's Jet Propulsion Laboratory sent these last commands today at about 7 PM EST (March 24). [I found it a sobering moment amongst my birthday celebration.]
In the article on cosmic dust, I briefly mentioned the mission, it has been involved in the study of interplanetary dust from comets. But the actual story of the mission is fascinating and groundbreaking on several levels. A real workhorse for NASA, and something to be proud about. Not just for the scientists either, but for the entirety of the human race that a feat like this can be accomplished.
Although this spacecraft undertook two missions, this is the story of two spacecraft and four missions.
The first mission was called Stardust. It was an amazing mission in its own right. Launched in 1999, the Stardust probe's goal was to collect dust from Comet Wild 2 and return it to Earth. You may have heard of aerogel, the Stardust grid is pictured above. This material was refined and used specifically for this mission.
In the course of the original mission, the probe:
-Collected dust from Comet Wild 2 on a couple occasions,
-Set a distance record for solar powered spacecraft (going halfway into the asteroid belt),
-Rendezvoused with Asteroid Annefrank to test instruments for the main event and the only close images of the asteroid,
-Flew by Comet Wild 2 to catch samples and image the surface (providing the best comet images at the time),
-Returned to Earth to jettison the samples (which landed safely near Salt Lake City)
Mission completed 2006. Great success. So much has been learned about comets through this mission, including the basic building blocks of life being found in comets. The capsule that returned the particles is now on display in the Smithsonian. I've seen it, and it is one of the more humbling exhibits in the Air & Space Museum if you ever check it out.
The probe was still in space and still had fuel though. What to do next with it? Well, while Stardust was finishing up, Deep Impact had just launched in 2005. It's goal was to release an impactor in to Comet Temple 1 and study the debris and take pictures of the resulting crater. This mission took less then a year to complete.
Overall, the mission was a success. The impactor hit exactly where it was supposed to. Much has been learned as a result of the spectral analysis of the debris thrown up by the impact. However, the images of the impact crater were not satisfactory in any scientific sense. This is when, in 2007, NASA approved the New Exploration of Temple 1 (NExT) mission.
This mission would utilize the Stardust spacecraft to approach Temple 1 and study look for the crater created by Deep Impact. The crater was identified by NASA scientists on February 15th of this year. It also identified some other features, see the image below. The science from this will help determine comet density and composition. This marked the first time a comet has been visited twice by probes from Earth
The fuel that remains, although there is no fuel gauge on the spacecraft to tell precisely, is incapable of another mission. The Stardust probe will still provide valuable data with this firing still. It will let engineers know exactly how much fuel was used, and can be used in future mission.
Overall the probe has performed some 2 million rocket firings, executed 40 major flight path maneuvers, and traveled nearly 6 billion kilometers.
I mentioned that there were 4 missions between the probes, and I've covered three so far. The last involves an extension on the Deep Impact probe. The idea of recycling spacecraft is catching on with NASA, it is affordable and capable of producing great scientific exploits.
The last mission is called EPOXI, Extrasolar Planet Observation and Deep Impact Extended Investigation. Another mission I learned more about with my visit to the Applied Physics Lab. After it's initial mission was complete, it was decided to send the probe to Comet Boethin, a 25 month long trip in hibernation. Unfortunately, in 2008 astronomers were unable to locate the comet, which may have broken up into pieces to small to be observable.
A course correction was made, and the probe was set in motion to flyby Comet Hartley 2 in November 2010. The probe returned the "peanut" shaped comet seen above. The probe has also done observations of known extrasolar planets, two of the Earth's polar regions, and one of Mars. The EPOXI mission is on going.
tl;dr: This is the end of a comet hunter, who flew by an asteroid (Annefrank), two comets (Wild 2 and Temple 1) and returned the first ever pristine comet samples to Earth for the most advanced analysis available to scientists.