Software Patch Fixes Mars Curiosity Rover's Auto-focus Glitch

An anonymous reader writes: Scientists from Los Alamos National Laboratory have successfully uploaded and applied a software patch to NASA's Curiosity Rover on Mars. The patch fixes a focusing problem that cropped up in November when the laser that helps to focus one of its cameras failed. "Without this laser rangefinder, the ChemCam instrument was somewhat blind," said Roger Wiens, ChemCam principal investigator at Los Alamos. "The main laser that creates flashes of plasma when it analyzes rocks and soils up to 25 feet [7.6 meters] from the rover was not affected, but the laser analyses only work when the telescope projecting the laser light to the target is in focus." Before the fix, scientists had to shoot images at nine different focus settings to distill a decent set of data. Now, they say the new software results in better images in a single shot than even before the laser broke down. The program that runs the instrument is only 40 kilobytes in size.

Comments

Source code?

[Anonymous Coward]

Apollo space program is documented in great detail. Even the software running in the flight computers is nowdays available and you can run the whole thing in a virtualized guidance computer. http://www.ibiblio.org/apollo/

Does anyone have any idea what's the case with probes and landers? I know they are mostly running VxWorks, but I'd love to take a peek on how some of the routines are actually implemented.

Still a hack, but way better than nothing.

[Mal-2]

This fix still requires much of the resources of the previous method, essentially bracketing the shot and picking the best one. This means it will still take just as long to obtain each image, but apparently that wasn't a huge problem. What this saves is something precious though: bandwidth. Now the rover is picking the best shot, instead of sending a bunch of blind guesses and making us sort it out. I suspect that if the bandwidth wasn't precious, they wouldn't have bothered improving on the existing workaround, so it must have been worth all the trouble.

Re:Still a hack, but way better than nothing.

[Anonymous Coward]

Technically you don't even need a range finder.

It's possible to do autofocus through-the-lens with phase detection or contrast detection:

Contrast detection places different constraints on lens design when compared with phase detection. While phase detection requires the lens to move its focus point quickly and directly to a new position, contrast detection autofocus instead employs lenses which can quickly sweep through the focal range, stopping precisely at the point where maximum contrast is detected. This means that lenses designed for phase detection often perform poorly on camera bodies which use contrast detection.

From a link in TFA:

They figured out that if they discarded a lot of the old code on board their distant subject, they could make room for software that could command the instrument to take the nine images on its own and analyze them on-board to find the best focus.

I guess they didn't have room on the device to code up a binary search of the contrast method before acquiring a single image?

To the editors

[Crashmarik]

If you are going to have a story like this it would be good form to remember the H, aka HOW from who,what,when,where, why and HOW of a journalism article. At some point in the past this was a site oriented to the technical community, most of whom are very interested in the how. You might even think that for the most part the when, why, where and who are all at the who cares level. (Mars being an exception)