On Comet, On Cupid



Comet Tempel 1 will get a return visit from a NASA spacecraft on Valentine’s Day when the Stardust-NeXT probe whizzes by with its high speed camera and other instruments.  This encounter will occur about 180 million miles away from Earth with the space probe traveling at 24,000 mph.  The closest approach distance will be a scant 124 miles. Tempel 1 was struck, literally, by another NASA probe during the Deep Impact mission in 2005, and the deliberate crash created a crater in the comet.  Tomorrow’s encounter is a unique opportunity to observe the man-made damage from 6 years ago as well as to see how the comet has changed during that time.   

Comets are continuously changing objects that orbit the Sun.  They spew dust, ice, carbon dioxide, and who knows what other constituents as they travel through space, leaving signature trails behind.  They are thought to be remnants of the origin of the solar system so their study can hopefully offer clues as to how the solar system came to be. 

Tomorrow’s visit culminates a bonus mission for the Stardust probe.  In 2004, the probe flew by another comet (Wild 2), snapping pictures as well as gathering samples of the comet dust.  The “dust collector” was jettisoned from the spacecraft and successfully returned to Earth in 2006 – a complete mission success.  However, since Stardust still had sufficient fuel reserves, and was functioning properly, NASA decided to send it on another mission, the return to Tempel 1.  The additional cost for the new mission was only 10% of the original mission cost.  Recycling just makes sense.  This will be the last hurrah for Stardust though; it won’t have enough fuel for any more adventures, but it will be retired as a great success story. 

In this time of austerity, it is good to know that NASA is finding creative ways of accomplishing science objectives with less.  Last year’s visit to Comet Hartley 2 by the EPOXI spacecraft was another example of utilizing an asset beyond its primary mission.  EPOXI is a new name given to the Deep Impact “mother ship” that flew by and watched the collision with Tempel 1 in 2005.  Following that success, EPOXI was re-programmed to seek out Hartley 2 and the successful rendezvous occurred on November 3, 2010.

Learning more about the solar system provides incrementally more information in the quest to answer the “big question” about the universe’s Big Bang singularity.  See the entry two blogs ago for more.  It is truly exciting to witness ancient objects up close and personal and to gather valuable data.  As NASA Associate Administrator for Science Ed Weiler said at the press conference following the download of images from the Hartley 2 encounter, “This is real.  It is not a video game.  No human being has ever seen this comet before.”  Congratulations to two old, but capable spacecraft and to the teams that made these bonus missions possible.