And they're off! Well, one of them is anyway. As far as getting the new Mars
Exploration Rovers (MERs) up through the atmosphere and out past the thermosphere
is concerned, NASA has hit its half-way mark.
Grounded in Florida by a poor weather forecast Sunday and Monday, the MER-A rover, now known as "Spirit," in its metal-shielded seat atop a Boeing Delta II rocket, launched this afternoon at 1:58 pm EDT. Spirit will spend the next seven months making its way to Mars. If all goes well it will hopefully provide (to forgivably alter Neal Armstrong's famous first words of space exploration), "one giant leap for planetary geology."
They say a little rain never hurt anyone, but it's easy to imagine why NASA and JPL, after spending countless man-hours and about 800 million dollars combined on the two rovers, wouldn't want to compromise Spirit's mission. Caution seems to have been the name of the game this time around. The last two days' delays were just the most recent in a line of multiple delays that held the rovers back.
The Spirit was originally slated to launch on May 30. Mid-April, NASA announced that the rover would not launch any sooner than June 6, due to a potentially mission-fatal problem present in both MER spacecrafts. According to NASA, the problem involved faulty circuit boards that might have caused the spacecrafts to misinterpret signals as cables were severed during the landers' disconnection from their cruise stages and then the rovers' disconnection from their landers. The cables connect the main computer inside each rover to peripherals in its lander, cruise stage and small deep space transponder.
Failure to fix this problem could have resulted in two less-than-responsive MERs when it came time to land. On April 15, Peter Theisinger, MER project manager at JPL, told the New York Times there was a "substantial risk" that without a fix they would lose the mission. "We would not be able to tell where the ground was and how fast we were coming down," Theisinger said.
Spirit and MER-B (now known as "Opportunity") were both disassembled and repaired at the Kennedy Space Center in Cape Canaveral, Fla. Two extra electronic parts and about 20 wires were added to each circuit board to the fix the problem.
On May 27, NASA pushed the launch date back an extra couple days, no earlier than June 8, to make time for engineering reviews.
Even as he gave Spirit and Opportunity a clean bill of health in a June 4 JPL press release, Ed Weiler, associate administrator for space science at NASA Headquarters in Washington expressed the attitude of cautious optimism behind the extra measures. "Historically, two out of three missions, from all countries who have tried to land on Mars, ended in failure," Weiler said. "We have done everything we can to ensure our rovers have the best chance of success, and today I gave the order to proceed to launch."
As has become typical of these robotic missions, there are still a few small software quirks to iron out during flight. But what remains is simply to see, once January 4, 2004 rolls around, whether the Spirit after bouncing around the surface of Mars in its airbag pyramid emerges on the red soil of Gusev Crater fully functional.
Geotimes contributing writer
Landing the Mars Exploration Rovers, May 2003
Robotic Field Geologists Take to Mars, May 2003
May 2003 Geotimes special issue on geology on Mars
Athena science team site
JPL Mars rover site
Download footage of today's launch. You'll need RealPlayer software.