Lockheed Martin’s control room during the final fuel burn, with program manager Allan Cheuvront and engineer Sandy Freund monitoring telemetry and engineer Kevin Gilliland and JPL Stardust project manager Tim Larson in the background. (Lockheed Martin)
Let me add a bit to what Heather has already blogged about the end of the Stardust-NExT mission on Thursday night.
The 560 lb. spacecraft, launched in 1999, flew past an asteroid named for Anne Frank and then traveled half-way to Jupiter to collect particle samples from the comet Wild 2. It then headed back toward Earth to drop off a capsule containing samples collected from Wild 2 before heading on for a rendezvous with the Comet Temple 1. In all, it traveled 3.54 billion miles.
I covered the sample return part of the mission from Wild 2 and remember it as filled with some high drama.
The Jan. 15, 2006 descent was filmed by a DC-8 chase plane and ended with a successful splash-down in the mud at the Utah Test and Training Range Center southeast of the Nevada-Utah border. It had a high angle of descent, giving it a re-entry speed of 12.8-km-per-second, which is as fast as a meteor’s and the reason the DC-8’s science crew was so interested.
Besides the element of speed, capsule returns are always a bit problematical. For one thing, the parachutes used to slow the touchdown of return capsules sometimes don’t open. Two years before, NASA’s Genesis mission’s solar samples were wrecked when its chutes didn’t deploy and it came in for a hard landing.
And, there was a snowstorm at the time, which only added to the anxiety for the Stardust science crew that a chute might get entangled.
But for the Stardust sample return mission there was a happy ending. Its Jan. 2, 2004 ride across the face of Wild 2 lasted 12 minutes and peppered aerogel suspended in sample return trays with bits of Wild 2’s frozen out gassing. Scientists were delighted by how well preserved everything was.
Among the mission’s science returns was the discovery of glycine in the comet dust. Glycine is an amino acid used by living organisms to make proteins, so its unexpected discovery in a comet’s frozen vapor supports the idea that the fundamental building blocks of life are prevalent in space.
Besides being a safe containment vessel for comet dust, the 32-in. diameter Stardust capsule had other uses. Its heat shield, which achieved a 3,100K glow, was made of ablative material being studied for the Orion Crew Exploration Vehicle.
Meanwhile, Stardust, which measures 5.5 ft. high, 2.2 ft. wide and 2.2 ft deep and has solar arrays stretching 16 ft. across, was re-tasked as Stardust-NExT for a bonus mission to fly past the comet Temple 1. Temple 1 had been struck by NASA’s Deep Impact mission in 2005 and Stardust’s assignment was to collect some post-impact images for comparison with what Deep Impact got.
But in the end, every thing runs out of gas. For Stardust, it came after 12 years. Unsure just how much fuel it had left, mission control commanded it to burn up what was left so it could close out the mission. The motors burned for 146 seconds, according to Lockheed Martin’s Stardust program manager, Allan Cheuvront.
Mission control can never be quite sure how much fuel is aboard a spacecraft – gas gauges don’t work in microgravity – so they make their calculations based on the history of its burns. Now that they know how long the burn lasted they can do some number crunching to see how realistic their calculations are.
“That will be a great data set to have in our back pocket when we plan for future missions,” says Cheuvront.
Stardust transmitted its last signal to Denver at 7:33 p.m. EDT and is now in an eternal orbit around the sun on the other side of Mars in the planetary plane.
To meet NASA’s rules, the mission ops team has projected its orbit beyond the next 100 years to assure the space agency that it will not hit any body. The closest candidate for that would be Mars, whose thin atmosphere would probably mean that at least some of Stardust would survive an entry to become Earthly space junk on its barren surface.
The other reason for wanting to know where it is so that it will not pose a risk to other missions.
By the way, the closest Stardust will come to Earth is 1.7 million miles.
Aeroget from the Wild 2 capsule return. (NASA)
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