NASA's Stardust spacecraft is heading home with its one-of-a-kind cargo: The first-ever return of pristine samples of comet material. The mission collected the samples in January 2004 as it flew through the cloud of gas and dust surrounding comet Wild 2.

After traveling more than 4.6 billion kilometers (more than 2.8 billion miles), Stardust will release a return capsule from space in the pre-dawn hours of Jan. 14, 2006 , Mountain Standard Time ( Jan. 15, 12:57 a.m. EST ). The capsule, carrying cometary and interstellar particles, will land inside the U.S. Air Force's Utah Test and Training Range little more than four hours later.

If necessary, the Stardust team can stop the entry procedure and direct the spacecraft into a backup orbit around the sun. This maneuver would allow for another landing opportunity 3-and-a-half to 4 years later. .

About 15 minutes after letting go of the capsule, Stardust will fire its thrusters in a maneuver that will put it in orbit around the sun. The capsule will continue streaking toward Earth.

Four hours after separation, the capsule will enter Earth's atmosphere, moving at 46,440 kilometers per hour (28,860 miles per hour). This will be the fastest reentry of any human-made object on record. Weather permitting, radar and range cameras at the Utah Test and Training Range will see the incoming capsule within minutes of the capsule entering Earth's atmosphere.

Fifty-two seconds after entry, at an altitude of 61 kilometers (200,000 feet), the capsule will reach its highest temperature. The temperature on the exterior heat shield will spike to 2700 degrees Celsius (4900 Fahrenheit).

During the next 60 seconds, the capsule will rapidly decelerate from 38 times the force of gravity (38 G's) to 3 G's and a small parachute, called a drogue chute, will deploy. At this point, the capsule will be nearly over its landing zone.

About three minutes after atmosphere entry, the capsule will begin its vertical descent over its landing area. At an altitude of about 3 kilometers (10,000 feet), the capsule will cut one of the lines holding the drogue chute. This will allow the drogue to pull out a larger parachute. At the same time, the capsule will activate its UHF locator beacon. Batteries powering the UHF can operate the beacon for 10 hours.

The sample return capsule will touch down at about 3:12 a.m. MST,* traveling at about 4.5 meters (14.8 feet) per second. The landing zone is 44 by 76 kilometers (27 by 47 miles), ample space to allow for winds that might affect the direction the capsule travels.

*(5:12 a.m. EST/2:12 a.m. PST)

Minutes after the capsule touches down, a helicopter will arrive at the landing site. The capsule will be inspected, photographed and placed in a special handling fixture, then flown to a temporary cleanroom. The sample canister will be removed from the capsule and connected to a purge system that feeds it with a constant flow of ultra-pure gaseous nitrogen. The image to the left is a rehearsal.

A few days later, the capsule and canister will be transported to NASA's Johnson Space Center , Houston , where a special curation lab for Stardust samples has been built. The curation team will make an initial analysis of the samples and then distribute them to science teams around the world for further study.

Launch

Feb. 7, 1999. Stardust embarked on a nearly seven-year journey that will culminate with the landing of a return capsule at the Utah Test and Training Range on Jan. 15, 2006. The mission's main goal: To collect particles while flying through a comet's cloud of gas and dust, and return the samples to Earth.
http://www-pao.ksc.nasa.gov/kscpao/images/1999/feb/99pc0158.jpg

Passing by Home

Stardust's flight path took it around the sun three times. During its first pass by Earth, the spacecraft used Earth's gravity to set it on a path to rendezvous with comet Wild 2. At its closest approach to Earth, Stardust was about 6,000 kilometers (more than 3,700 miles) away and viewable from high-powered telescopes.

Image courtesy: Camarillo Observatory
http://stardust.jpl.nasa.gov/photo/ega1.jpg

Particle Collection

While traveling to Wild 2, Stardust deployed its collector grid over two time periods to catch interstellar particles flowing into our solar system. Scientists believe these particles contain heavy chemical elements that originated in stars.
http://www.jpl.nasa.gov/images/spacecraft/stardust_solo_browse.jpg

Asteroid Annefrank

As a rehearsal for its comet encounter, Stardust flew within 3,100 kilometers (1,927 miles) of asteroid Annefrank on Nov. 2, 2002. The asteroid was found to be about 8 kilometers (5 miles) in length, twice the size predicted from Earth-based observations.

The false-color view (right) emphasizes the variations in surface brightness, which result from different angles of illumination from the sun, as well as from variations in the surface.
http://www.nasa.gov/mission_pages/stardust/multimedia/pia02885.html
http://photojournal.jpl.nasa.gov/catalog/PIA02886

Aerogel

Stardust used a substance called aerogel to capture and store the interstellar and cometary particles it collected.

Aerogel is a silicon-based solid with a porous sponge-like structure in which 99 percent of the volume is empty space. It is the lightest-weight, lowest-mass solid, and has been found to be ideal for capturing tiny particles in space.
http://www.nasa.gov/mission_pages/stardust/multimedia/pia03186.html

Dust Collectors

The aerogel was placed inside a grid of dust collectors that resemble a metal ice cube tray set in an oversize tennis racket.
http://www.nasa.gov/mission_pages/stardust/multimedia/pia03188.html

Collection

The collector grid was extended into the dust stream, exposing the blocks of aerogel to the particles. When Stardust flew through comet Wild 2's coma, the impact velocity of particles as they were captured was up to six times the speed of a bullet fired from a high-powered rifle. After collecting samples, the collector grid folded back down into the spacecraft.

Other Instruments

Stardust carries two other dedicated science instruments. The comet and interstellar dust analyzer studied the chemical composition of particle in the comet's coma. The dust flux monitor measured the size and frequency of dust particles in the coma.
Top image: comet and interstellar dust analyzer
http://www.nasa.gov/images/content/137833main_dustanalyzer-browse.jpg
Bottom image:dust flux monitor
http://stardust.jpl.nasa.gov/mission/dfm.html

Close Look

This close-up view of comet Wild 2, taken on Jan. 2, 2004, shows a rigid surface, craters, cliffs and jets. At its closest approach, Stardust was 240 kilometers (149 miles) from the comet. This image is Stardust's closest short exposure of Wild 2.
http://www.nasa.gov/mission_pages/stardust/multimedia/pia06285.html

Spewing Jets

This composite image was taken by Stardust's navigation camera during the close approach to comet Wild 2 on Jan 2, 2004. Several large depressed regions can be seen. Comet Wild 2 is about five kilometers (3.1 miles) in diameter.

To create this image, a short exposure image was overlain on a long exposure image taken just 10 seconds later.
http://www.nasa.gov/mission_pages/stardust/multimedia/pia05578.html

One Dozen Views

This sequence, showing some of the closest images of comet Wild 2, starts at the upper left and continues left to right on the first three rows. The overexposed and out-of-sequence images at the bottom are long exposures taken to help the spacecraft navigate during its encounter. They also capture the best images of the comet's jets.
http://stardust.jpl.nasa.gov/highres/1097899fig1.jpg

If You Were There

This is an artist's concept depicting a view of Wild 2 as seen from Stardust during its flyby of the comet on Jan. 2, 2004.
http://www.nasa.gov/mission_pages/stardust/multimedia/pia06283.html

Close-Up on Tempel 1

Scientists are interested in studying comets because they are believed to be like time capsules from the early formation of the solar system. The materials that make up a comet provide a record of conditions when the planets were forming 4.6 billion years ago.

Several NASA missions have already made close observations of comets. This image shows the view from Deep Impact's probe 90 seconds before its planned collision with comet Tempel 1 in July 2005.
http://www.nasa.gov/mission_pages/deepimpact/multimedia/PIA02128.html

Tempel Alive With Light

This view of comet Tempel 1 was taken 67 seconds after the planned impact with Deep Impact's probe. The image, taken by the mission's flyby spacecraft, reveals topographic features including ridges, scalloped edges and possibly impact craters formed long ago.
http://www.nasa.gov/mission_pages/deepimpact/multimedia/HRI-937.html

Comet Borrelly Close-Up

This is the highest resolution view of the icy, rocky nucleus of comet Borrelly, taken just before NASA's Deep Space 1 made its closest approach to the comet in September 2001. A variety of terrains, surface textures, mountains and fault structures are visible. The image shows the 8-kilometer-long (5-mile) nucleus from about 3417 kilometers (more than 2,000 miles) away.
http://photojournal.jpl.nasa.gov/catalog/PIA03500

Comet Borrelly

A false-color composite of images from Deep Space 1 shows features of comet Borrelly's nucleus, dust jets escaping the nucleus, and the cloud-like coma of dust and gases surrounding the nucleus. Deep Space 1 took these images on Sept. 22, 2001, from about 4,800 kilometers (3,000 miles) away from the comet.
http://photojournal.jpl.nasa.gov/catalog/PIA03865

Why Bring a Comet Home?

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How Do We Bring a Comet Home?

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Why Send the Science Home?

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