[meteorite-list] Mars Express Back in Business at the Red Planet

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 16 Feb 2012 08:59:41 -0800 (PST)
Message-ID: <201202161659.q1GGxfaN002162_at_zagami.jpl.nasa.gov>

http://www.spaceflightnow.com/news/n1202/15marsexpress/

Mars Express back in business at the red planet
BY STEPHEN CLARK
SPACEFLIGHT NOW
February 15, 2012

Europe's Mars Express resumed full science operations in early February,
four months after scientists suspended research following persistent
glitches in the probe's solid-state mass memory unit, according to the
craft's mission manager.
 
"Mars Express has now been restored to full operational capability and
its potential mission lifetime remains unchanged," a European Space
Agency statement said.

Problems with the 12-gigabit memory unit, which contains data and
commands necessary for instrument operations, put Mars Express in safe
mode four times. The data system is required for the spacecraft to
conduct scientific reesearch, storing up to 50 individual commands for
each observation.

The safe mode events forced Mars Express to rapidy point toward the sun,
consuming six months' worth of propellant in a short time, according to
ESA.

After the data storage glitch showed up using two redundant controllers,
engineers halted scientific observations Oct. 16 to avoid burning more
propellant and preserve the mission's expected lifetime.

Officials turned to a hardware-based timeline store in a different
computer, bypassing the issue believed to have caused the safe modes
last year.

But the backup timeline store can only hold 117 commands, much less than
the thousands executable in the timeline in the faulty solid-state mass
memory unit.

Engineers found a way to write much shorter command sequences to fit in
the hardware-based short timeline, and although the suspect memory unit
continues to experience errors, none of them have triggered a safe mode,
according to ESA.

"This has recently been tested in real life, as the spacecraft
encountered a [solid-state memory unit] anomaly exactly like those in
late 2011, but this time was able to complete the observation and return
to Earth pointing without entering safe mode," an ESA statement said.
"This allowed a much faster recovery to nominal operations and avoided
wasting precious propellant."

Controllers continue working on a command scheduler to allow Mars
Express to function autonomously for up to a week, reducing the workload
for ground operators.

Fred Jansen, Mars Express mission manager, said the spacecraft has more
than 8 pounds of maneuvering propellant left in its tank, which should
be enough fuel to continue the mission for up to 14 more years.
Received on Thu 16 Feb 2012 11:59:41 AM PST