NASA working to fix Opportunity's memory

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Artist's concept of the Opportunity rover (Image: NASA)

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NASA's Opportunity rover landed on Mars in 2004 and its 90-day mission has now lasted almost 11 years. Unfortunately, its age is beginning to show with the unmanned robotic explorer beginning to display signs of memory loss. Mission control at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, reports that Opportunity's computers have been resetting as its flash memory banks suffer fits of "amnesia," which engineers back on Earth are trying to repair.

Opportunity may be an extremely sophisticated piece of rolling scientific hardware, and it may be functioning a decade beyond its specifications, but its "brain" is still a computer relying on much the same components as any PC circa 2003. As anyone who uses computers on a regular basis knows, these components have a limited service life, which is why junk drawers inevitably fill up with dead tech. Worse, the Martian environment is extremely hostile to electronics, and microelectronics especially, because the incredibly dry, dusty climate generates static electric charges, and the thin atmosphere and almost non-existent magnetic field lets in dangerous levels of cosmic radiation.

Whether due to time or radiation, NASA says that Opportunity is now suffering from bouts of computer senility. Like most computers, the rover's uses a combination of volatile Random Access Memory (RAM), and a non-volatile memory – in this case, a set of seven flash memory banks. The latter are especially important because Opportunity is solar powered. This means that it can't spare the power to keep the RAM operating at night because the batteries are needed to keep the electronics warm, so data collected during the day is stored in the flash memory until it can be transmitted to Earth.

This arrangement has worked fine until now, but in recent weeks the flash memory has refused from time to time to record new data, causing the computers to reset like a cranky tablet. To prevent this from happening again and to avoid lost data, mission control tried re-formatting the flash memory, but with little success, so in early December it ordered Opportunity to carry out a more extensive repair, including using the RAM to collect data and transmitting it to Earth before sunset. However, the space agency says that the main problem has been located in one of the seven flash banks, which NASA plans to isolate.

"The mission can continue without storing data to flash memory, and instead store data in volatile RAM," says Mars Exploration Rover Project Manager John Callas of JPL. "While we're operating Opportunity in that mode, we are also working on an approach to make the flash memory usable again. We will be sure to give this approach exhaustive reviews before implementing those changes on the rover."

Launched on July 7, 2003, Opportunity is the twin of the now defunct Spirit rover. It landed on January 25, 2004, three weeks after Spirit, in the Meridiani Planum region of Mars for a mission scheduled to last 90 Martian days, but ten years later, it's still going strong. It continues to study Martian soil and provide surface calibration for orbital observations by the Mars Reconnaissance Orbiter, and has traversed over 25 miles (40 km).

Source: JPL

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