NASA craft set for flyby of comet

LOS ANGELES – After a long-distance courtship, a NASA spacecraft is set to meet up with its celestial sweetheart – a comet half the size of Manhattan that had an encounter with another spacecraft not long ago.

The rendezvous between Stardust and comet Tempel 1 occurs on Valentine’s Day some 210 million miles from Earth. Hurtling at 24,000 mph, Stardust will fly within 125 miles of the potato-shaped comet, snapping pictures along the way.

If successful, it will be the first time that scientists will have before-and-after images of Tempel 1, allowing them to observe any changes on the uneven surface.

In 2005, Tempel 1 received a visit from another NASA probe named Deep Impact, which fired a copper bullet into the comet on the Fourth of July that sparked cosmic fireworks and excavated a crater. The high-speed crash hurled out so much dust and debris that Deep Impact failed to see the man-made hole even as it beamed back dazzling pictures of other surface features.

Scientists hope to get a second chance with Stardust, which is expected to pass near the 2005 bull’s-eye.

“I’m going to be sleepless on Valentine’s Day and sending a lot of love to this comet,” quipped mission co-investigator Pete Schultz of Brown University.

Comets, irregular bodies of ice and dust that orbit the sun, are frozen leftover building blocks of the solar system, which formed when a huge cloud of gas and dust collapsed about 4.5 billion years ago. Studying comets could yield clues to the birth of the solar system.

Tempel 1 is not the first comet Stardust will get cozy with. In 2004, it swooped past comet Wild 2 and captured a bounty of interstellar and comet dust. The probe jettisoned samples to Earth in a capsule that parachuted to the Utah desert – the first time that a spacecraft had fetched particles from a comet back to Earth.

Stardust has traveled 3  1/2 billion miles since launching from Cape Canaveral, Fla., in 1999.