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Another sample return capsule landing in the Utah desert:

Stardust Brought Home Comet Dust

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First photo of Wild 2 by Stardust
Stardust saw lots of features, some as small 65 feet across, on Comet Wild 2 from a distance of 147 miles on January 2, 2004.
click to enlarge the NASA JPL photo

Animated sequence of Stardust flyby images »

Stardust completed its 2.88 billion mile round-trip journey to a comet and back, bringing comet and interstellar dust particles back to Earth on January 15, 2006.

It was the first time an interplanetary probe from Earth had flown deep into space and brought back tiny bits of a comet.

Landing on Earth. As it flew by our planet on January 15: Meanwhile, at 0618 UTC, the Stardust spacecraft fired its thrusters to send itself away from Earth into orbit around the Sun.
About the Genesis crash  »        What is UTC or universal time?  »

From Utah to Texas. The sample return canister will be opened at the planetary material curatorial facility at NASA's Johnson Space Center, Houston, Texas. The samples will be carefully stored and examined there. Scientists will remove the particles and analyze their composition for chemicals, minerals, and clues about how life began on Earth.

Some of the most powerful science instruments on Earth will be used to study the comet dust. The instruments themselves are more than 100 times larger and heavier than the Stardust spacecraft.

NASA artist concept of Stardust spacecraft
Stardust approaching Comet Wild 2
click to enlarge NASA artist concept
Events at Wild 2:

January 16, 2004: Scientists on Earth were surprised at what they saw in the photos sent back by Stardust. They had expected Wild 2 would match their idea of a typical comet – lumpy cores with uninteresting terrain. Such comets would have been warmed by the Sun for thousands of years, which would have melted away any sharp features. Surprise! Wild 2 doesn't look like that. It's surface is rich with highly complex features. It has 300-ft.-high high cliffs and boulders big as barns and impact craters almost a mile across.
The Stardust Story »

January 6, 2004: Having survived a sandblasting by comet particles hurtling toward it at six times the speed of a rifle bullet as it flew by Wild 2, Stardust now is continuing along its 708 million mile trek home to Earth. Scientists on Earth receiving data by radio discovered Stardust had flown through sheets of comet particles that jostled the spacecraft and, on at least ten occasions, breeched the first layer of its shielding. The scientists had thought Stardust would encounter a uniform increase in the number of particles the closer it came to the comet nucleus and then a reduction as it flew away from the nucleus. It turned out that was not the case. Data radioed back to Earth revealed that the spacecraft flew first through a swarm of particles, then through an area with almost no particles, and then through another swarm. Comet particles struck the spacecraft at 3.8 miles per second. Stardust scooped up a bunch of the particles for analysis by its instruments. It also stored many particles for in-depth analysis back on Earth.
NASA flyby video »

January 3, 2004: Stardust was headed home with its precious cargo of collected particles stowed in a sample return capsule. That dramatic homecoming will occur in just over one million minutes on January 15, 2006, when the capsule parachutes to a soft landing on the U.S. Air Force Utah Test and Training Range. The first comet samples in the history of space exploration will be analyzed at the planetary material curatorial facility at NASA's Johnson Space Center, Houston, Texas.
Aerogel dust trap »

January 2, 2004: NASA's Stardust spacecraft passed safely within 149 miles of Comet Wild 2, collected particles, and began its return trip to Earth. Six hours after the encounter, the particle collector grid was retracted, securing the captured particles for the flight home. Mission controllers at NASA's Jet Propulsion Laboratory in Pasadena, California, are analyzing downloads of data and images from the spacecraft. The photos were called the "best pictures ever taken of a comet."
latest from JPL »
The comet flyby. On January 2, 2004, Stardust flew within 147 miles of Comet Wild 2, snapping photos and capturing tiny dust specks from the glistening halo of debris surrounding the dirty ball of ice and rock.

Stardust encountered the comet's tiny nucleus – probably just 3.4 miles wide – at a distance of 242 million miles from Earth. The name Wild is pronounced vilt.

Stardust was expected to grab a minimum of 1,000 particles from the gases boiled off of Wild 2's surface by the Sun's heat. More likely, about a million tiny samples of comet and interstellar dust have been returned. Scientists were eager to examine them as pristine examples of the ancient building blocks of our Solar System.

Hidden heart. From Earth, a comet appears obscured by a bright veil of dust and gas. From close up, Stardust saw through the veil to record numerous images of the comet. Stardust was the third spacecraft from Earth to snap close-up photos of a comet's core.

The probe was protected during the close encounter by something called a Whipple Shield, a a stack of five sheets of carbon filament and ceramic cloths each spaced 2 in. apart. Stardust bulldozed through the shimmering cloud of gas and dust around the comet at 13,650 mph. That's more than six times faster than a speeding rifle bullet.

It took several hours for Stardust to fly through the coma – the cloud of dust and gas blowing off of the comet's nucleus. The spacecraft survived the hail of debris as it passed through some 149 miles ahead of the comet nucleus. Stardust trapped comet dust in its Aerogel collector.

Dust trapping Aerogel. A canister, like a tennis racket strung with a material called Aerogel, snagged the comet dust particles during the flyby. A porous material made up mostly of air, Aerogel is foamed glass so lightweight that it is barely visible and almost floats in air.

It is 99.8 percent air. That is, 99.8 percent of the volume is empty space. Aerogel is the world's lightest solid. In fact, it is so light and airy that it looks like solid smoke. Aerogel is fragile and can break if dropped. On the other hand, it was strong enough to withstand the pressures of space launch.

Aerogel is a silicon solid with a porous, sponge-like structure. It is 1,000 times less dense than glass, which also is a silicon solid. However, Aerogel provides 39 times more insulating than the best fiberglass insulation. Aerogel has been recognized by Guinness World Records as the solid with the lowest density.

Most particles from a comet are smaller than the diameter of a human hair. They make carrot-shaped tunnels in the Aerogel as they are stopped. At the pointed tip of each tunnel a tiny particle will be found.

During Stardust's travel across the Solar System from launch in 1999 to arrival at Comet Wild 2 in 2004, the canister swept up microscopic bits of interstellar dust. After arrival at the comet, the Aerogel collector was retracted into the Sample Return Capsule for return to Earth.

Stardust's Aerogel was prepared by NASA's Jet Propulsion Laboratory (JPL) at Pasadena, California. Aerogel also was used on the Mars Pathfinder rover in 1997. And Aerogel capture experiments were flown on shuttle flights, Spacelab II and Eureca.
Photos of aerogel

NASA artist concept of Stardust sample return capsule landed in Utah with dust captured at Comet Wild 2
NASA artist concept of the Stardust sample return capsule down on the Utah desert.
The Stardust Landing Site

On January 15, 2006, Stardust dropped its precious cargo of particles in a sample return capsule by parachute to a soft landing on the U.S. Air Force Utah Test and Training Range.

UTTR has 2,624 square miles of airspace over the Great Salt Lake Desert in northwestern Utah and eastern Nevada. The desert has undulating sand dunes, mountains rising abruptly from the desert floor, and rolling hills building up to mountain ranges.

The range is 70 miles west of Salt Lake City. A small town nearby is Callao, Utah, west of Fish Springs and north of Trout Creek, on the old Overland and Pony Express route south of a gold mining area. In 1860, the Pony Express established a station there when gold was discovered in Gold Hill. Today, there are 27 residents and Callao is the last town in Utah to use a one-room schoolhouse.
Dust Collection. A total of less than one-thousandth of an ounce of comet dust was collected. Even so, 1,000 of the particles collected were expected be large enough for complete scientific analysis. In addition, millions of smaller particles will be analyzed as groups.

The Stardust project includes international participation. For instance, as they were gathered, a German instrument analyzed volatile ice grains and organic materials in comet particles.

As an added bonus, scientists hoped to collect more than 100 particles from a newly discovered beam of particles streaming into our Solar System from other stars beyond our Solar System.

Surprising pictures. Scientists on Earth were surprised at what they saw in the 72 black-and-white photos sent back by Stardust. They had expected Wild 2 would match their idea of a typical comet – lumpy cores with uninteresting terrain. Such comets would have been warmed by the Sun for thousands of years, which would have melted away any sharp features.

Surprise! Wild 2 doesn't look like that. It's surface is rich with highly complex features. It has 300-ft.-high high cliffs and boulders big as barns and impact craters almost a mile across.

The craggy comet has broad mesas, high pinnacles and canyons with flat floors. The high cliffs suggest the crust of Wild 2 is firm. It may be a mixture of fine-grained rocky material held together by frozen water, carbon monoxide and methanol.

The comet has gaseous jets, probably from fissures or vents in the comet's surface where ice could be vaporizing and rushing off of the tiny body into space. That vapor leaving the nucleus would become part of the comet's tail.

Answers sought. The samples of comet dust and interstellar dust returned by Stardust should help scientists find answers to fundamental questions about the origins of the Solar System. Could comet dust contain any organic compounds necessary for life? Could comets have delivered those molecules to Earth billions of years ago?

Wild 2 is the comet that almost collided with planet Jupiter in 1974.

NASA artist concept of Stardust encounter with Comet Wild 2
NASA artist concept of Stardust chasing the comet
Flyby of Asteroid Annefrank. Hurtling across the Solar System at 77,200 miles per hour, Stardust flew within 1,864 miles of Asteroid 5535 Annefrank on November 2, 2002. Controllers at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, used the asteroid flyby as a rehearsal testing systems the spacecraft would use at Wild 2. Some 70 photos of Annefrank showed a dark, irregularly-shaped, cratered asteroid nearly four miles across.

Great distances. In terms of distance from the Sun, Stardust traveled well beyond Mars and over half the distance to Jupiter. While Wild 2 is 242 million miles from Earth, the spacecraft had to travel two billion miles to meet Comet Wild 2 – and then another one billion miles to get back home.

During its seven years in space, Stardust raced along at an average speed of 48,000 mph.

Gravity Slingshot. Along the way out to Wild 2, Stardust circled back to swing by Earth on January 15, 2001, to get a gravitational slingshot boost out to the comet. The gravity slingshot method of navigation allowed Stardust designers to use a smaller, less powerful, less expensive launch rocket, saving more than $8 million.

Phoning Home. During the Comet Wild 2 flyby, NASA's 20-story-tall radio receiving antennas on Earth – the Deep Space Network – picked up Stardust's transmissions of pictures and scientific data.

Stardust photograph of Asteroid 5535 Annefrank
Stardust photograph of Asteroid 5535 Annefrank
First samples beyond the Moon. As it was launched in 1999 on a Delta 2 rocket from Cape Canaveral Air Station, Florida, the spacecraft Stardust was: A Discovery mission. The Stardust concept was selected back in 1995 to be the fourth of NASA's so-called Discovery missions – planned to be inexpensive and bring quick results. Earlier NASA Discovery missions had been Lunar Prospector, Mars Pathfinder, and Near Earth Asteroid Rendezvous (NEAR).

The Stardust spacecraft was built on a standardized deep space probe "bus" developed by Lockheed Martin Astronautics. At five feet long, Stardust was about the size of an office desk. It weighed 838 lbs. including the deep space maneuvering fuel it started out with.

Could You Walk on the Comet?
Apparently, yes. The surface of Comet Wild 2 looks rigid enough for a lander to touch down and an astronaut to walk across the surface without worrying about the ground collapsing.

An astronaut standing on the comet would see a fantastic landscape of deep craters surrounded by high cliffs, according to those studying Stardust images of Wild 2. Spires of ice sticking up out of the floor of a crater might be as tall as the astronaut.

Getting out of the crater would not be hard, they say. The comet's gravity is only one ten-thousandth of Earth's gravity. If she weren't careful, an astronaut could leap all the way up into orbit.

An astronaut could walk all the way around the comet – a distance of about three miles – in just a few hours.

As she leaps and hops along the way, an astronaut would have to avoid those jets of vaporized ice. While a jet of ice gas probably would be transparent, the astronaut surely would notice a train of dust caught in the gas. Glinting sunlight would make the upward bound dust grains look like tracer bullets being fired into space.
For electrical power, the interplanetary probe used silicon solar cell arrays that converted sunlight into electricity. At the farthest distance from the Sun, the solar arrays had to generate enough electricity to operate the entire spacecraft with only 15 percent the sunlight intensity it has at Earth.

Comets Are Ancient. Since ancient times, myths about the origin of comets and their effect on Earth have made humans very curious. Today, astronomers think comets probably are the oldest, most primitive bodies in the Solar System. In fact, they may hold of some of the basic building blocks of life itself if they contain the organic molecules necessary for life.

Astronomers say comets are frozen bodies of ice and dust that probably formed soon after the huge disk of gas and dust collapsed to create the Sun and planets of the Solar System some 4.6 billion years ago. If comets were formed from what was left over after the collapse, studying them should shed light on the origin of the Solar System.

Astronomers say comets are composed of materials leftover after the planets formed around the Sun. In fact, comets probably contain the remains of materials used in the earlier formation of the stars themselves so some of the particles returned by Stardust might even be older than the Sun itself.

Comets are thought to contain many of the organic materials that scientists think are essential for the origin of life. They may hold volatile carbon-rich elements that could provide clues to the nature of the basic elements of our Solar System.

Studying comets today may provide evidence that these so-called dirty snowballs brought water to the Earth, making life possible.

In the early ages of the Solar System, comets frequently bombarded the then-new planets. For instance, it has been suggested that a large space object – maybe a comet – struck Earth 65 million years ago causing dinosaurs to become extinct.

Because the Stardust spacecraft not only returned samples of material from a comet, but also provided real time in-flight data about what it encountered, the scientific findings from its mission are likely to change the way we Earthlings view our origins.

The Stardust spacecraft was built by Lockheed Martin Space Systems, Denver, Colorado, and was managed by JPL for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology in Pasadena.


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Stardust Surprise   [nasa msfc]
Stardust Mission Description   [nasa jpl]
Photos of Aerogel   [nasa jpl]
Stardust Acronyms   [nasa jpl]
Stardust Flyby Images of Comet Wild 2   [nasa jpl]

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Comets: Comets   [sto]
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