At about 1 a.m. ET, Stardust will release its return capsule. Four hours later the capsule will blaze into Earth's atmosphere over the Pacific Ocean traveling at 28,860 miles (44,446 kilometers) an hour.
"As we come in over the western United States, this thing will light up the night sky for a brief period of time," said NASA's Tom Duxbury at a December 21 press briefing. Duxbury is the Stardust project manager at the Jet Propulsion Laboratory in Pasadena, California.
The capsule's speed is expected to be the fastest ever obtained by a human-made object, surpassing the record set in 1969 by the returning Apollo 10 command module, which reached a comparatively poky 24,791 miles (39,897 kilometers) an hour.
When Stardust's capsule drops to approximately 105,000 feet (32,000 meters), it will deploy a small parachute to slow the speeding craft.
At about 10,000 feet (3,048 meters) the main parachute will open, allowing for a soft landing at the U.S. Air Force's Utah Test and Training Range southwest of Salt Lake Cityor so NASA hopes.
Project scientists want to avoid a repeat of the hard landing of NASA's Genesis spacecraft, whose parachutes failed to open upon its return to Earth on September 8, 2004. Genesis crashed into the Utah desert.
"Parachutes are parachutes. No matter how well you do it, they will occasionally not work," said Brownlee, the mission's principal investigator, when asked if the same could happen to Stardust.
"The probability of that happening is small, but it's not zero."
Even if the capsule crash-lands, however, scientists should be able to recover some of the particles, which are encased in an "extremely hard frame," Brownlee said.
The particles Stardust collected will be the first unaltered bits of this primordial matter ever studied.
In fact, comet Wild 2 only began orbiting close enough to the sun for the material to boil off the comet's surface in 1974. Then, a gravitational tug by the planet Jupiter pulled the comet's orbit from beyond Uranus to just past Mars.
As such, there hasn't been sufficient time for heat to destroy the comet's particles, which have remained since the solar system formed 4.6 billion years ago.
After the capsule lands, a canister containing the aerogel will be transported to the Johnson Space Center in Houston, Texas. There, the samples will be cataloged and sent to scientists around the world for analysis.
Scientists are particularly interested in bits of particles that are composed differently from those found in our solar system. Some such grains are believed to be older than the sun.
"We expect to find those things," Brownlee said.
"We've found things like that in meteors and interplanetary dust. The only surprise we would have is if we don't find 'stardust,'" Brownlee said, referring to particles from outside our solar system.
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