If you have a digital camera you’re familiar with reformatting your memory card after you’ve filled it up and downloaded your images. Reformatting clears the card and allows you to write to it again. But after maybe a hundred of these digital lobotomies a card will often begin to malfunction. Now unreliable, it can’t be trusted, so you toss it and pop in a fresh one.
NASA’s now in the same situation with the flash memory drive in the Mars rover Opportunity. The drive, which stores data when the rover “sleeps” at night, is wearing out after more than 11 years on the Red Planet. As with any camera memory card there are limits to how many times you can write to and erase data.
Over the past six months NASA has had difficulties getting the rover to store commands sent from Earth. Commands, data and photos are normally stored in Opportunity flash memory or hard drive. But the rover’s has lately taken to moving some of that information into its “volatile” or RAM (random access memory) like that found in your computer.
When you shut down your computer, the important stuff remains on the hard drive while all the temporary settings or RAM memory’s erased. But when Opportunity powers down at night, commands and data that shouldn’t have been moved to RAM are deleted along with all the temporary stuff.
Before Christmas, mission control sent three days’ worth of commands to the rover, but memory troubles meant that only the one day’s activities were kept and completed.
Since the trouble began, the mission’s operations team has been avoiding using the flash system and is currently working on a software fix. In the meantime, they’ve been downloading everything into RAM memory every day before the rover’s nightly shuteye.
That might not be the end of Opportunity’s woes. There’s no money in the proposed federal budget to fund the rover beyond the current budget year. Unless additional funding is found by NASA, Opportunity will bite the Martian dust sometime this fall.
The agency has the difficult task of deciding how to divide a limited amount of money between new missions and continuing to fund old ones.
Opportunity landed on Mars on January 25, 2004 and was only designed to operate for 90 days. The rover is presently sniffing around on the west rim of Endeavour Crater heading towards “Marathon Valley,” where abundant clay minerals may lie just about 984 feet (300-m) away from its present position. Then it’s off to the “Spirit of St. Louis” crater.
Opportunity has truly run a marathon in its 11-plus years with 26 miles of roving to its credit, the farthest any machine has driven on the surface of another world besides Earth. It snatched the record last July from the former Soviet Union’s remote controlled Lunokhod 2 rover, which ambled across 24.2 miles (39 km) of the moon back in 1973.
So yes, Opportunity has outlived its original design lifetime more than 44 times over. And yes, it’s starting to lose its nimble mind, but I believe the relatively small amount of money (its 2014 budget was $14 million) it would take to keep it going another year or two is well worth it if only because of the potential for additional discoveries and opportunities. Remember, only Opportunity got a decent photo of Comet Siding Spring when it passed close to Mars last fall. Once it’s shutdown, the only feet on Martian ground will be the Curiosity rover’s.