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Emily LakdawallaMarch 4, 2013

Very brief Curiosity update, sol 205: Memory anomaly and a swap to the "B-side"

Hopefully many of you have been following Curiosity's mission to Mars through the rapid release of its raw images. But there haven't been any new images since sol 200 because the mission has been working its way through its first major (not life-threatening, just really inconvenient) anomaly: a memory problem in its main computer. I will let other outlets attempt to explain what's known about the bad news, like National Geographic and CBS News. JPL just announced that they brought the rover out of safe mode on its backup set of electronics, and that they've resumed communication using the high-gain antenna, but that they still need a few days to perform housekeeping operations before they can resume science activity.

Since landing, Curiosity has been employing its "A-side" set of electronics. It has a fully redundant set of electronics, the "B-side," with some connections between the two that would, in theory, permit its controllers to use some parts of A with some parts of B, but for the most part the preferred way of doing things is to have one side running the show and the other side available as a backup. With this swap to the B-side, then, Curiosity's B-side electronics will be considered the main system and the A-side the backup. They'll continue to work on fixing the memory problem on the A-side while they rely on the B-side for operations.

One of the things that'll make the switch a little bit interesting is that it's not just the brains that are redundant; the B-side computers are connected to a second set of engineering cameras that haven't been used yet, as far as I know. Curiosity's new point of view out its B cameras will produce a very slight shift in the perspective of Navcam panoramas (the B cameras are just below the A cameras but have the same horizontal position with respect to the mast). There will be a much larger shift in the perspective of Hazcam views.

Locations of Curiosity's cameras


Locations of Curiosity's cameras
Locations of all of Curiosity's cameras: the two Mastcams; Chemcam Remote Micro-Imager (RMI); the left and right Navcams (set A, used from landing, on top, and set B, used after the A-side anomaly, on the bottom); the left and right front Hazcams (in A-B-A-B order, so that pair A has a view that is shifted slightly to the right of pair B, but they overlap); and the left and right rear Hazcams (with pair A located on the port side and pair B located on the starboard side, so that pair A has a point of view shifted to the right with respect to pair B's point of view).
Curiosity's forward Hazard Avoidance Cameras (Hazcams) as seen from MAHLI, sol 34

NASA / JPL / MSSS / Emily Lakdawalla

Curiosity's forward Hazard Avoidance Cameras (Hazcams) as seen from MAHLI, sol 34
On sol 33, Curiosity used its Hand Lens Imager (MAHLI) to take the first views of previously unseen parts of the rover, including the two pairs of Hazard Avoidance Cameras (Hazcams). Curiosity uses only one pair at a time. On sol 33, Curiosity was using the first and third of these (images from these two have filenames beginning with "FRA" and "FLA"); the second and fourth form a backup pair attached to the B-side computer ("FRB" and "FLB").

The lack of new images from Curiosity's side of Mars has given me time to explore the goodies among the mission's first release of archival data to the Planetary Data System. I'll have more on that later this week, but feel free to explore it for yourselves! Or just explore this cool interactive 3D panorama of the landing site, produced by Andrew Bodrov.

Mars Panorama - Curiosity rover: Martian solar day 177 in Out of this World

Read more: mission status, Curiosity (Mars Science Laboratory)

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Emily Lakdawalla

Senior Editor and Planetary Evangelist for The Planetary Society
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Emily Lakdwalla
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