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spacedaily.com wrote:US probe 'Stardust' returns to Earth with samples, perhaps secrets
WASHINGTON, Jan 15 (AFP) Jan 15, 2006

The US space probe "Stardust" returned to Earth Sunday carrying precious samples of dust from stars and comets, which scientists believe could offer vital clues about the origins of our solar system, NASA television showed.

After a seven-year journey, a capsule weighing 46 kilograms (101 pounds) and carrying a teaspoonful of space dust landed in a Utah desert at 0957 GMT after flying 4.63 billion kilometers (2.88 billion miles) in space, or 10,000 times more than the distance separating Earth from the Moon.

"All stations, we have touchdown," a jubilant mission control announcer said as the capsule made its touchdown in Utah.

NASA described the capsule's entry speed -- at 46,444 kilometers per hour (28,860 miles per hour) -- as the fastest ever of any human-made object, topping the record set in May 1969 by the returning Apollo 10 command module.

The samples were collected during the first attempt to gather, beyond the Moon, space particles that date back to before our solar system was born, or about 4.5 billion years ago.

A helicopter crew found the capsule at about 1054 GMT, NASA said. Two more choppers then headed to the recovery scene to package it up before flying it to the US Army Dugway Proving Ground, Utah, for initial processing.

That painstaking analysis could take scientists as long as 10 years. The work, according to one scientist, could be compared to finding 45 ants on a football field, or studying five square centimeters of earth at a time.

To help the researchers, the University of California, Berkeley, has launched a drive to recruit 30,000 volunteer students, who will have access to a powerful microscope via the Internet.

The Stardust probe, weighing 385 kilograms (849 pounds), was launched in 1999, circled the Sun twice and then flew by comet Wild 2 in January 2004, which at the time was located next to Jupiter.

During its hazardous traverse, the spacecraft first deployed a shield to protect itself from gases and space dust contained in the halo of the comet.

It then flew within 240 kilometers (149 miles) of Wild 2, catching samples of comet particles and taking detailed pictures of Wild 2's pockmarked surface.

The 72 pictures of Wild 2 taken by the probe show its rugged surface, including craters as well as about 20 "geysers" spewing gas and dust.

During 195 days of the flight, NASA engineers used a collector to gather interstellar dust that will also allow scientists to study the make-up of stars.

The special collector contains aerogel, a unique substance that can trap the particles and store the precious cargo safely for the trip back to Earth.

About four hours after releasing its return capsule Stardust entered Earth's atmosphere at about 410,000 feet (125 kilometers). The capsule then released a drogue parachute at approximately 105,000 feet (32 kilometers).

Once the capsule had descended to about 10,000 feet (three kilometers), its main parachute deployed, leading to a very swift deceleration.

"It's like (being) the parent at the graduation of a cum laude student," glowed former Stardust project manager Ken Atkins. "We had a great navigation and engineering team."

Find the Stardust
based on an UC Berkeley release

Spectacular gas remnants from exploding star.
Image Credit: Hubble

Astronomy buffs who jumped at the chance to use their home computers in the SETI@home search for intelligent life in the universe will soon be able to join an Internet-based search for dust grains originating from stars millions of light years away.

In a new project called Stardust@home, University of California, Berkeley, researchers will invite Internet users to help them search for a few dozen submicroscopic grains of interstellar dust captured by NASA's Stardust spacecraft and due to return to Earth in January 2006.

Though Stardust's main mission was to capture dust from the tail of comet Wild 2 - dust dating from the origins of the solar system some 4.5 billion years ago - it also captured a sprinkling of dust from distant stars, perhaps created in supernova explosions less than 10 million years ago.

"These will be the very first contemporary interstellar dust grains ever brought back to Earth for study," said Andrew Westphal, a UC Berkeley senior fellow and associate director of the campus's Space Sciences Laboratory who developed the technique NASA will use to digitally scan the aerogel in which the interstellar dust grains are embedded. "Stardust is not only the first mission to return samples from a comet, it is the first sample return mission from the galaxy."

"Like SETI@home, which is the world's largest computer, we hope Stardust@home will also be a large computer, though more of a neural network, using brains together to find these grains," said Bryan Mendez of the Center for Science Education at the Space Sciences Laboratory. Mendez and Nahide Craig, assistant research astronomer at the laboratory, plan to create K-12 curricula around the Stardust@home project and to reach out to local astronomy groups to boost participation.

Mendez and Craig will describe their educational outreach program in a poster session on Jan. 10 at the national meeting of the American Astronomical Society in Washington, D.C.

Based on previous measurements of interstellar dust by both the Ulysses and Galileo spacecrafts, Westphal expects to find approximately 45 grains of submicroscopic dust in the collector, a mosaic of tiles of lightweight aerogel forming a disk about 16 inches in diameter - nearly a square foot in area - and half an inch thick. Though those searching for pieces of Wild 2's tail will easily be able to pick out the thousands of cometary dust grains embedded in the front of the detector, finding the 45 or so grains of interstellar dust stuck in the back of the detector won't be so easy.

This aerogel array, which was mounted atop the Stardust spacecraft, was used to collect interstellar dust particles as well as dust from the tail of comet Wild 2.
Credit: Berkeley

Thanks to a grant from NASA and assistance from the Planetary Society, however, Westphal and his colleagues at the Space Sciences Laboratory have created a "virtual microscope" that will allow anyone with an Internet connection to scan some of the 1.5 million pictures of the aerogel for tracks left by speeding dust. Each picture will cover an area smaller than a grain of salt.

"Twenty or 30 years ago, we would have hired a small army of microscopists who would be hunched over microscopes focusing up and down through the aerogel looking for the tracks of these dust grains," said Westphal. "Instead, we developed an automated microscope to scan the aerogel and hope to use volunteers we have trained and tested to search for these tracks."

The Web-based virtual microscope will be made available to the public in mid-March, even before all the scans have been completed in a cleanroom at Houston's Johnson Space Center. In all, Westphal expects to need some 30,000 person hours to look through the scanned images at least four times. Searching each picture should take just a few seconds, but the close attention required as the viewer repeatedly focuses up and down through image after image will probably limit the number a person can scan in one sitting.

To insure that the volunteer scanners know what they're doing, each must pass a test where he or she is asked to find the track in a few test samples. To judge the reliability of each volunteer - and to provide some reward in what for most will be a fruitless search - the team also plans to throw in some ringers with and without tracks.

"We will throw in some calibration images that allow us to measure the volunteers' efficiency," Westphal said.

If at least two of the four volunteers viewing each image report a track, that image will be fed to 100 more volunteers for verification. If at least 20 of these report a track, UC Berkeley undergraduates who are expert at spotting dust grain tracks will confirm the identification. Eventually, the grain will be extracted for analysis. Discoverers will get to name their dust grains.

The dust grains were collected in two phases during the Stardust spacecraft's seven-year journey to and from Wild 2 as the spacecraft turned its Stardust Interstellar Dust Collector (SIDC) into the interstellar dust stream, which courses through the solar system at a speed of about 20 kilometers (12 miles) per second. The dust grains will have made carrot-shaped trails in the aerogel, which is a novel, silicon-based sponge 100 times lighter than water.

In the early morning hours of Jan. 15, 2006, the Stardust payload will parachute into Utah's Salt Lake Desert and be airlifted to Houston, where teams will open it so as to minimize contamination from other dust. When launched in 1999, NASA was unsure how to remove from the aerogel the micron-sized cometary grains and the nearly invisible interstellar dust grains.

"It's amazing that Stardust flew without anyone having a clue as to how to get particles out of the aerogel after it came back," Westphal said. "You have to give NASA credit for taking a risk."

In an experiment using a special air gun, particles shot into aerogel at high velocities leave carrot-shaped trails in the substance.
Credit: Berkeley

During Stardust's quiet journey to a rendezvous with a comet, however, Westphal led a team that created tools for extracting both comet grains and interstellar dust grains. Working with Chris Keller, formerly at the Berkeley Sensor and Actuator Center and now at MEMS Precision Instruments, he developed microtweezers and what he calls micro-pickle forks to pull comet grains from the aerogel for detailed analysis of their elemental and isotopic composition. The abundances and composition within comet grains will tell scientists about the conditions in the early solar system.

These same techniques will be used to extract interstellar dust grains, but first they have to be found. Based on earlier work with glass cosmic-ray detectors on the Mir space station, Westphal developed an automated microscope to digitally photograph the entire area of the aerogel in patches - the size of a salt grain - that can be viewed later in search of dust particles. The lengthy but exciting search for dust grains will be conducted by Internet volunteers.

Once the grains are identified and analyzed, Westphal hopes the information will tell about the internal processes of distant stars such as supernovas, flaring red giants or neutron stars that produce interstellar dust and also generate the heavy elements like carbon, nitrogen and oxygen necessary for life.

The virtual microscope was developed by computer scientist David Anderson, director of the SETI@home project, along with physics graduate student Joshua Von Korff. Craig and Mendez are now creating a teacher's lesson guide that uses the Stardust@home Virtual Microscope to teach students about the origins of the solar system. A section of the Stardust@home Web site also will be aimed at the general public.

Westphal expects to find approximately 45 grains of submicroscopic dust in the collector

Spaceflightnow.com wrote:Cosmic paydirt with Stardust
UNIVERSITY OF WASHINGTON NEWS RELEASE
Posted: January 18, 2006

Scientists at the Johnson Space Center in Houston were excited and awed Tuesday by what they saw when the sample-return canister from the Stardust spacecraft was opened.

"It exceeds all expectations," said Donald Brownlee, a University of Washington astronomy professor who is principal investigator, or lead scientist, for Stardust. "It's a huge success. We can see lots of impacts. There are big ones, there are small ones."

Stardust returned to Earth in a spectacular re-entry early Sunday after a 7-year mission to collect particles from comet Wild 2 and samples of interstellar dust streaming into our solar system from other parts of the galaxy. The comet dates from the formation of the solar system 4.6 billion years ago.

Brownlee calculated there might be more than a million microscopic specks of dust embedded in Stardust's aerogel collector. Aerogel, a remarkable material that is as much as 99.9 percent empty space, greatly reduced the stress of impact on the particles, he said. The carrot-shaped tracks of much larger particles are visible in the aerogel from several feet away, Brownlee said, and in some of the tracks the black comet dust is visible at the end of the track. One track, he said, "is almost large enough to put your little finger into it."

Scientists will search the aerogel grid for dust samples, and more than 65,000 people have signed up to help in a project called Stardust@home, in which their home computers will examine images of tiny sections of the aerogel grid looking for dust particles.

The Johnson Space Center will be the curator of the Stardust samples, and as many as 150 scientists worldwide are waiting to study them.

"Stardust is a phenomenal success," Brownlee said.