Mars Probe Loses Some Data in Memory Glitch
This panoramic view taken by NASA's Phoenix Mars Lander shows the sweeping plains of the Martian polar north. Phoenix's robotic arm scoop is visible. It was released May 29, 2008.
Credit: NASA/JPL-Caltech/University of Arizona.

NASA?s Phoenix Mars Lander has lost some science observations in an odd glitch after generating too much housekeeping data, mission managers said Wednesday.

Phoenix engineers are investigating why the anomaly, which affected only unessential science data, occurred. It shouldn't be a problem today, they added, because they've planned activities for Phoenix that do not require the probe to store science data overnight.

"The spacecraft is healthy and fully commandable, but we are proceeding cautiously until we understand the root cause of this event," said Phoenix project manager Barry Goldstein of NASA's Jet Propulsion Laboratory.

The spacecraft normally accumulates a small amount of data everyday having to do with maintaining its computer and normal functioning. This data is classified as high priority and gets stored in the spacecraft's flash memory.

For some reason, Phoenix gathered so much housekeeping information on Tuesday that it crowded out science data from being stored in flash memory. The excess science was lost Wednesday after the spacecraft powered down for the Martian night after completing its 22nd Martian day, or sol, since landing May 25.

The lost data was not high-priority, NASA said, and the images can mostly be retaken.

To save Phoenix's memory from being overburdened, mission managers told the spacecraft not to pursue any new science investigations on Wednesday and to lower the priority for the kind of housekeeping data that overwhelmed it on Tuesday.

"We can continue doing science that does not rely on non-volatile memory," Goldstein said in a status update. 

This has not been a problem until now because Phoenix usually downlinks most of the science data it collects back to Earth the same day it is gathered. Occasionally, the spacecraft collects more data than can fit in the afternoon package sent down, and this data is stored overnight, to be sent the following Martian morning.

While mission managers are investigating the reason for the flood of housekeeping data, they will tell Phoenix to refrain from storing any science data overnight. They have also added extra communication-relay opportunities during the Martian day on Thursday so Phoenix can send back as much science data as it can gather. The spacecraft plans to spend today digging trenches, taking pictures and monitoring the weather.

The $420-million mission is set to study the Martian arctic for three months to determine if the region could have once been habitable to life.