Let's Hope Dawn Doesn't Break!

Clean-room technicians at NASA's Kennedy Space Center examine the Dawn spacecraft after extending one of its two solar-cell panels, each of which is 8.3 meters (27 feet) long.

Kelly Beatty

The rocketeers at the Kennedy Space Center in Florida are getting ready to hurl two spacecraft into interplanetary space within a month: asteroid-bound Dawn this Monday, July 9th; and Phoenix, the latest Mars probe, on August 3rd. Phoenix represents the reincarnation of NASA's Mars Polar Lander mission, tragically lost as it descended to the Red Planet in December 1999.

But the Dawn mission has a risen-from-the-dead story to tell as well. Little more than a year ago, the program was canceled outright by Mary Cleave, then NASA's associate administrator for science. The project was over budget and had a slew of unresolved technical issues, but the hardware was 98% complete. Cleave's decision angered the planetary-science community and its Congressional allies so much that the space agency soon rescinded the cancellation. Cleave has since retired from NASA.

Monday's liftoff is scheduled for 3:56 p.m. EDT. Project managers have avoided saying just how many more days remain in this particular launch "window," though if Dawn doesn't launch soon it'll need to vacate the pad until September to make way for Phoenix. (The launch, originally slated for June 30th, has already been delayed three times.)

If everything goes well, a souped-up Delta rocket will boost the craft to escape velocity. After that a high-performance xenon-ion engine will push it onward toward a rendezvous with the asteroid Vesta in 2011 and then with Ceres in 2015.

Catch Monday's launch live on NASA Television. And visit Dawn's website for details about this ambitious mission.