Endurance Missions

It's an interesting time to be studying Mars. In addition to the orbital looks of the ESA's Mars Express and NASA's Mars Reconnaissance Orbiter and 2001 Mars Odyssey (I'll have a writeup on these three in the future), we're still reaping the benefits from two other missions, both of which have lasted well past their "expiration dates."

(Update! The entry into Victoria Crater (see below) has been delayed due to a dust storm!)

On the ground, the mars rovers, MER-A and MER-B (more popularly known as Spirit and Opportunity) continue to operate in Gusev Crater (for Spirit) and at the edge of Victoria Crater (for Opportunity). Originally designed to last for ninety days on Mars, the rovers have had their missions extended again...and again...and again to the point where both rovers have been operating on the martian surface for nearly four years.

Mission managers have found ways of keeping the rovers operating (such as "wintering over" to keep batteries charged), have had the fortune of recovering from glitches (computer problems such as software resets and memory) and even have been helped by the environment (with an occasional "windshield wipe" from the winds to clean off the rovers solar panels).

Spirit has traveled from its landing site to the region known as Columbia Hills. There it most recently has found evidence of ancient volcanic explosions in the form of layered basalt. Spirit is somewhat worse of than Opportunity, with workarounds for a stuck wheel, a "stiff" arm (that restricts movement to a certain region) and a rock abrasion tool that has gotten stuck on occasion.

Opportunity is about to set forth on what might be it's final mission. It is poised to enter half-mile wide Victoria Crater. Victoria Crater could allow scientists to "peek" into the martian past, revealing layers upon layers of deposits that show the wet environment that was Mars of long ago. There's a chance that Opportunity might damage itself either on entry or trying to exit, trapping the rover inside the crater.

Why take the risk in damaging the rover and limiting its future explorations? "While we take seriously the uncertainty about whether Opportunity will climb back out, the potential value of investigations that appear possible inside the crater convinced me to authorize the team to move forward into Victoria Crater," says Alan Stern. "It is a calculated risk worth taking, particularly because this mission has far exceeded its original goals."

The other mission of note is the Mars Global Surveyor (MGS). It was launched in 1996 and sent back images from martian orbit until November 2006. During its long orbital career it sent back hundreds of thousands of images. Observing over several martian years allowed us to track changes on Mars. Some of the more significant things discovered by the MGS are the retreat of the southern polar cap, signs of fresh cratering and signs of something (dare we say...water?) causing fresh gullies to appear on the surface of the planet. The MGS even managed to capture images of Viking 1, Viking 2, Spirit, Opportunity and the Mars Pathfinder landers! Let's hope the current orbital missions last as long!

Mars, the dead planet? Not at all!

Addendum: I should have pointed out that July 4 marks ten years since the Mars Pathfinder mission (with the MER's "mother" rover, Sojourner!)

Posted by Fred Kiesche at July 3, 2007 08:40 AM