It’s been a worrying month for the health of Mars Expedition Rover Spirit. Two weeks ago, the embattled robot failed to wake up after three successive communication sessions, and then over the Easter weekend (April 12th and 13th), mission HQ noticed the rover had rebooted its systems at least twice during use of the high-gain antenna. The same thing happened on April 18th. In addition to this, Spirit has been suffering bouts of what seems to be an ‘electronic amnesia’, where the onboard computers have failed to record data onto their flash memory.
Today however, it would appear Spirit is still operational after over two weeks of remaining planted in the same position. It managed to enact commands sent from NASA to start driving once more, trundling 1.7 metres over the Martian regolith. She hasn’t given up the good fight quite yet…
Since when have electronics on Earth ever lasted more than five years? I always seem to hit a two-year wall with my laptops when something nasty happens to the hardrive and/or motherboard (usually a day or two after the warranty runs out). But when we talk about the computers on board the Mars Expedition Rovers (MER), these electronics aren’t in the snug safety of my office; they are on the surface of an alien planet, dealing with extremes in temperature, high energy particles and copious amounts of dust. What’s more, the rovers were only designed to operate for a few months and yet they are still going strong, five years later. It’s the NASA mission that just keeps on giving.
I think this is what makes the MER mission so impressive for me. Not only are Spirit and Opportunity still operational, they are operating 20 times longer than their designated lifetime and they are notching up a very healthy odometer count. Their cumulative distance travelled is not measured in metres, or kilometres; it’s measured in tens of kilometres. They are giving us an unprecedented insight to the Martian surface, information that will shape our understanding of planetary science for generations to come.
But like any planetary mission, times can be tough, and both rovers have been tested to their engineered limits. Unfortunately, Spirit has been hit by a few more setbacks than Opportunity, but NASA has been able to find workarounds for each problem. The Mars Science Laboratory has a lot to live up to, I wonder if the MER mission will still be operational when the MSL finally touches down? Perhaps the next generation rover will have a robotic welcoming party!
The most recent issue for Spirit has been the flash memory problem. Flash memory helps the rovers store data even when they are powered down, but when the little rover forgets to actually store the data on the flash memory, something is obviously awry. In an attempt to make sure the rover can still take commands and to see if the computer problems persist, NASA ordered Spirit to travel 1.7 metres toward a target 150 metres away. All seems to be going well so far.
“We expect we will see more of the amnesia events, and we want to learn more about them when we do,” said JPL’s Sharon Laubach, chief of the rover sequencing team, which develops and checks each day’s set of commands.
“We decided not to wait until finishing the investigations before trying to drive again. Given Spirit’s limited power and the desire to make progress toward destinations to the south, there would be risks associated with not driving.”
Hopefully keeping the rover mobile will help NASA troubleshoot the recent computer problems, but so far, she’s still rolling over the Martian dirt…