An artist’s impression showing NASA’s Stardust-NeXT spacecraft
Credit: NASA/JPL

NASA's Stardust-NExT spacecraft is heading to a close encounter with Comet Tempel 1, on 14 February 2011. The mission will provide scientists for the first time views of changes on a comet's surface that occurred following an orbit around the Sun.

Comets are small icy objects, orbiting the Sun mostly in markedly elongated orbits. They consist of various ices, such as water ice and carbon monoxide ice, rock and cosmic dust. They are believed to be primitive material, leftover from of the formation of the Solar System.
Stardust-NExT (NExT stands for New Exploration of Tempel) will take high-resolution images during the encounter, and attempt to measure the composition, distribution, and flux of dust emitted into the coma, the comet's gaseous envelope. Data from the mission would yield new information on a category of comets, known as the Jupiter-family, comets whose orbits are markedly influenced by the strong gravity of Jupiter, the largest planet.

Stardust-NExT will expand the investigation of the Comet Tempel 1, initiated by NASA's Deep Impact spacecraft. In July 2005, Deep Impact fired an impactor, a small space probe, to the surface of Tempel 1, to study its composition. The impactor successfully collided with the comet, giving rise to a large cloud of comet dust.

"Every day we are getting closer and closer and more and more excited about answering some fundamental questions about comets," said Joe Veverka, Stardust-NExT principal investigator at Cornell University. "Going back for another look at Tempel 1 will provide new insights on how comets work and how they were put together four-and-a-half billion years ago."

At approximately 336 million km from Earth, Stardust-NExT will be almost on the opposite side of the Solar System, at the time of the encounter. During the flyby, the spacecraft will take 72 images, and store them, in an onboard computer.

Initial raw images from the flyby will be relayed to Earth, for processing on the day next. Currently, the spacecraft is approximately 24.6 million km from Comet Tempel 1. Since 2007, Stardust-NExT performed eight trajectory correction maneuvers, and completed four circuits around the Sun.

Tempel 1's distance from the Sun ranges between approximately 225 million km and 680 million km. The spacecraft is expected to fly past the nearly 6-km-wide comet, at a distance of approximately 200 km.
In 2004, the Stardust mission became the first to collect particles directly from Comet Wild 2. Samples were returned in 2006, for study, via a capsule that detached from Stardust, when it flew by Earth, and parachuted to the ground southwest of Salt Lake City. Mission controllers placed the still reusable Stardust on a trajectory that allows it to fly to possible targets of opportunity.

Stardust-NExT was originally known as Stardust, but in January 2007, NASA changed the mission name to Stardust-NExT, beginning a four-and-a-half year cruse to Comet Tempel 1. The mission team expects this flyby will mark the conclusion of Stardust-NExT’s highly successful interplanetary voyage. The spacecraft is nearly out of fuel as it approaches 12 years of spaceflight, having traveled almost 6 billion km, since launch in 1999. This flyby and planned post-encounter imaging are expected to consume Stardust-NExT’s remaining fuel.

References

Jet Propulsion Laboratory
www.jpl.nasa.gov/

NASA
www.nasa.gov/

Wikipedia
Further Reading
Stardust Mission
http://stardustnext.jpl.nasa.gov/

Deep Impact
http://www.nasa.gov/mission_pages/deepimpact/main/index.html

Aymen Mohamed Ibrahem
Senior Astronomy Specialist