Two-timing spacecraft has date with another comet

The planned Valentine’s Day (Feb. 14, 2011) rendezvous between NASA’s Stardust-NExT mission and comet Tempel 1 inspired this chocolate-themed artist’s concept. Credit: NASA/JPL-Caltech

NASA’s Stardust spacecraft, equipped with the University of Chicago’s Dust Flux Monitor Instrument (DFMI), is hurtling at more than 24,000 miles an hour toward a Valentine’s Day encounter with comet Tempel 1.

Stardust will approach to within 124 miles of Tempel 1 at 10:56 p.m. CST Monday, Feb. 14. The spacecraft flew within 150 miles of comet Wild 2 in 2004, when it collected thousands of tiny dust particles streaming from the comet’s nucleus for laboratory analysis.

The spacecraft dropped off the samples in a canister that parachuted onto the desert salt flats of Utah in January 2006 following a journey of approximately 3.5 billion miles. But Stardust, still healthy and with fuel to spare, soon went back onto the interplanetary market, looking for a second mission.

The mission will be the first to allow Thanasis Economou, Senior Scientist at UChicago’s Enrico Fermi Institute, and his fellow members of the Stardust-NExT (New Exploration of Tempel) science team to look for changes on a comet’s surface that occurred following an orbit around the sun. They will compare Stardust’s data from Tempel 1 with findings from a previous probe that also studied that comet.

“We are very excited that we can visit a second comet—comet Tempel 1—with the same spacecraft after we visited the Wild 2 comet in 2004,” Economou said. “The Dust Flux Monitor Instrument is healthy and ready to take another look at this comet.”

Stardust had only one sample-return canister, so this time the spacecraft will be unable to capture cometary dust for analysis back on Earth. Few at the time thought that the spacecraft would be able to visit another comet, “but even so, we are looking forward to seeing what kind of results we will get,” Economou said.

Sizing up a new crater

Ice can be found in many places in space, including the surface of comets. This image of the comet Tempel 1 shows icy patches in blue.
Credit: NASA

They also are interested in obtaining photographs of the crater left on Tempe 1 by a probe launched from the Deep Impact spacecraft in July 2005. The 817-pound copper-aluminum probe generated so much dust that the spacecraft was unable to obtain images of the crater following impact. Such images would permit scientists to estimate the new crater’s depth and diameter.

The impact enabled scientists to study the composition of Tempel 1, a Jupiter-family comet whose orbit has been modified by close passages to the planet. Stardust now has the opportunity to collect additional data on how Jupiter-family comets formed and evolved.

The DFMI was developed by Economou and the late John Simpson, the Arthur Holly Compton Distinguished Service Professor Emeritus in Physics, and the late Anthony Tuzzolino, Senior Scientist in UChicago’s Fermi Institute.

The instrument detected as many as several hundred particles each second during Stardust’s flyby of comet Wild 2 in January 2004. Most of those particles measured no more than a few microns in diameter, too small to see with the naked eye. Just a few measured more than 10 microns, about one-fifth the diameter of a human hair.

Tempel 1 has displayed less surface activity than did Wild 2, “but we are going there with a higher velocity, so probably the flux will be equal to or a little more than we had during the Wild 2 encounter,” Economou said.

The Tempel 1 flyby likely will be the last assignment for Stardust, which is running low on fuel after logging almost 3.7 billion miles in space since its launch in 1999. Economou, meanwhile, will continue his collaborations on NASA’s Mars Exploration Rover mission and the Cassini mission to Saturn. He also is working to establish a new astronomical observatory near his childhood home in Ziakas, Greece.


Five Things About NASA’s Valentine’s Day Comet from NASA

Here are five facts you should know about NASA’s Stardust-NExT spacecraft as it prepares for a Valentine’s "date" with comet Tempel 1. Feel free to sing along!

Artist’s concept of NASA’s Stardust-NExT mission, which will fly by comet Tempel 1 on Feb. 14, 2011. Credit: NASA/JPL-Caltech/LMSS

1. "The Way You Look Tonight" – The spacecraft is on a course to fly by comet Tempel 1 on Feb. 14 at about 8:37 p.m. PST (11:37 p.m. EST) — Valentine’s Day. Time of closest approach to Tempel 1 is significant because of the comet’s rotation. We won’t know until images are returned which face the comet has shown to the camera.

2. "It’s All Coming Back To Me Now" – In 2004, Stardust became the first mission to collect particles directly from a comet, Wild 2, as well as samples of interstellar dust. The samples were returned in 2006 via a capsule that detached from the spacecraft and parachuted to the ground at a targeted area in Utah. Mission controllers then placed the still-viable Stardust spacecraft on a flight path that could reuse the flight system, if a target of opportunity presented itself. Tempel 1 became that target of opportunity.

3. "The First Time Ever I Saw Your Face" – The Stardust-NExT mission will allow scientists for the first time to look for changes on a comet’s surface that occurred after one orbit around the sun. Tempel 1 was observed in 2005 by NASA’s Deep Impact mission, which put an impactor on a collision course with the comet. Stardust-NExT might get a glimpse of the crater left behind, but if not, the comet would provide scientists with previously unseen areas for study. In addition, the Stardust-NExT encounter might reveal changes to Tempel 1 between Deep Impact and Stardust-Next, since the comet has completed an orbit around the sun.

4. "The Wind Beneath My Wings" – This Tempel 1 flyby will write the final chapter of the spacecraft’s success story. The aging spacecraft approached 12 years of space travel on Feb. 7, logging almost 6 billion kilometers (3.5 billion miles) since launch. The spacecraft is nearly out of fuel. The Tempel 1 flyby and return of images are expected to consume the remaining fuel.

5. "Love is Now the Stardust of Yesterday" – Although the spacecraft itself will no longer be active after the flyby, the data collected by the Stardust-NExT mission will provide comet scientists with years of data to study how comets formed and evolved.