After a seven-year, 2.9 billion-mile round trip, NASA's Stardust space capsule floated down to a landing in the Utah desert early Sunday, bringing back interstellar dust and comet samples that scientists hope will yield clues to the origins of the solar system.
"All stations, we have touchdown," declared Stardust project manager Tom Duxbury, dressed in a navy blue NASA pilot's jumpsuit for the occasion. That sparked a roomful of smiles and a round of applause from mission controllers at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
The Stardust mission came to a climax in the middle of the night, starting with the sample return capsule's release from its mothership when it was 69,000 miles (110,000 kilometers) away from Earth. The shuttlecock-shaped capsule streaked through the atmosphere at about 29,000 mph (46,000 kilometers per hour), representing the fastest re-entry of any human-made probe.
NASA said the falling capsule could be seen as an orange fireball by observers in Nevada and Utah. Parachutes eased the final phase of the descent, and the capsule hit the ground at just 10 mph (16 kilometers per hour) at about 3:10 a.m. MT (5:10 a.m. ET). The recovery team said the capsule bounced three times before coming to rest on its side.
“It’s an absolutely fantastic end to the mission,” said Carlton Allen of NASA’s Johnson Space Center.
Stardust's principal investigator, Donald Brownlee of the University of Washington, said he sneaked out from his post on the Dugway Proving Ground to watch the capsule and its fiery trail. “It's ironic that we have a comet mission that ends producing a ‘comet,’” he told reporters at a post-landing news briefing.
The $212 million mission marked the first time a spacecraft flew into deep space and brought back tiny fragments of a comet. Most of the granules are so small that a microscope will be required to study them.
The Stardust mothership will remain in orbit around the sun, and Duxbury said NASA is considering sending it to another comet or asteroid.
Comets are frozen bodies of ice and dust that formed soon after a gaseous disk collapsed to create the sun and planets 4.6 billion years ago. Comets formed from what was left over, and studying them could shed light on the solar system’s birth.
The cosmic samples were gathered in 2004 from Comet Wild 2, a frozen body of ice and dust believed to have been formed billions of years ago. The Stardust spacecraft used a tennis racket-sized collector mitt to snag the particles in a porous material and stored them in the capsule.
Dust from birth of solar system
Scientists say Stardust's collectors should contain about a million samples of comet and interstellar dust — most tinier than the width of a human hair. The dust grains, believed to be pristine leftovers from the birth of the solar system, contain many of the organic molecules necessary for life.
A helicopter recovery team located the capsule within an hour after landing, then brought it to Michael Army Air Field in Dugway for processing in a clean room. From there, the capsule will be flown to the Johnson Space Center in Houston on Tuesday, where experts will open an inner canister, cut the aerogel collectors into thin slices and start analyzing the grains themselves.
Brownlee said researchers around the world would be studying the grains for years to come. "Much of the science in this mission hasn’t been done yet," he told reporters. Eventually, the findings from the Stardust mission will wind up in textbooks that address the origins of the solar system, Brownlee said.
Sunday's landing came as a relief for scientists after the 2004 Genesis mission, when the returning craft carrying solar wind particles slammed into the Utah desert and cracked open, exposing the solar atoms to contamination.
Scientists had to spend days picking through the wreckage to salvage the fragile wafers containing the samples.
The crash was caused by the faulty installation of gravity switches designed to trigger the parachute release on Genesis. Engineers reviewed Stardust’s blueprints and rechecked its systems to make sure it wouldn’t happen again.
Genesis and Stardust were the first robotic retrievals of extraterrestrial material since 1976, when the unmanned Soviet Luna 24 mission brought back lunar rocks and soil.
Seven years, almost 3 billion miles
Launched in 1999, the Stardust spacecraft traveled nearly 3 billion miles (4.6 billion kilometers), looping around the sun three times.
In 2004, it flew through the comet’s coma, a fuzzy halo of gas and dust. Outfitted with armored bumpers, the spacecraft survived a hail of debris to trap comet dust with a collector mitt packed with aerogel, a porous material made up of mostly air. The cosmic particles were then tucked inside the capsule for the trip home.
Along with the comet dust, the spacecraft also captured interstellar dust — tiny particles that stream through the solar system thought to be from ancient stars that exploded and died.
The spacecraft also beamed back 72 black-and-white pictures showing broad mesas, craters, pinnacles and canyons with flat floors on the surface of Wild 2, a craggy comet about 500 million miles (800 million kilometers) from Earth at Stardust’s launch.
Stardust’s sample return is the latest mission designed to study comets up close.
Six months earlier, NASA sent a probe called Deep Impact into the path of an onrushing comet. The high-speed collision with Comet Tempel 1 set off a celestial fireworks display in space and exposed the comet’s primordial interior. Scientists have been analyzing the voluminous debris hurled from the comet’s belly and are trying to figure out the size of the crater caused by the impact.
NASA's , due for launch on Tuesday, is aimed at studying Pluto and other "icy dirtballs" on the solar system's fringe — and Brownlee noted that Pluto may not be all that different from Comet Wild 2.
"It’s the same class of body as the planet Pluto, except that it's small," Brownlee said.