Editor’s note: Since one of NASA’s Mars rovers recently escaped the executioner’s axe, the Trivia Geek is using that as an excuse to recycle this Classic Geek, which originally ran on Jan. 3, 2006.
Two years ago this week, Spirit — the first of NASA’s twin Mars Exploration Rovers — touched down on the Red Planet, inaugurating a period of unbounded surface exploration that continues even as we speak. The sheer amount of Geek Trivia (and, of course, science) provided by this mission could fill dozens of articles — indeed, Spirit has proven so remarkable that scientists renamed asteroid 37452 in its honor — but we’ll try to hit the high spots.
While a number of NASA missions have made photographic history, Spirit has made its own historic contributions to the astronomic photographic archives. On Jan. 6, 2004, the rover’s panoramic camera (or “pancam”) took the highest resolution image ever captured on the surface of another planet. (It was also the first color photo taken by Spirit.) Twelve million pixels (4000 x 3000) imbued the wide-frame image of the Sleepy Hollow crater.
One month later, Feb. 6, 2004 marked the first grinding of a rock on Mars using artificial, mechanical means. Spirit’s Rock Abrasion Tool (RAT) ground out a 2.65-millimeter deep impression on a rock sample designated Adirondack, illuminating the inner layers for observation by the rover’s spectrographic sensors.
On March 9, 2005 — after more than a year on the Martian surface — Spirit received some unexpected ad hoc maintenance from Mother Nature, combined with a rather momentous scientific opportunity. The rover’s solar panels suddenly jumped from roughly 60 percent efficiency to more than 90 percent.
The cause was a flyby from a Martian dust devil, which likely swept a year’s worth of grime from Spirit’s solar panels and offered scientists a chance to review accidentally captured data on the rarely seen Martian meteorological phenomenon.
Yet, for all its myriad and marvelous technical achievements (to say nothing of help from the winds of good fortune), not even so fine an instrument as Spirit is beyond the need for tech support. On Jan. 21, 2004 — less than three weeks after touchdown — Spirit suffered a crippling technical glitch that baffled operators and engineers for days, despite the deceptively simple solution.
WHAT TECHNICAL GLITCH CRIPPLED THE MARS SPIRIT ROVER MERE DAYS AFTER TOUCHDOWN, BUT HAD A DECEPTIVELY SIMPLE TECHNICAL SOLUTION?
What technical glitch crippled the revered Mars Exploration Rover Spirit mere weeks after its deployment on the Red Planet — and what unexpectedly simple solution allowed the plucky probe to resume its historic explorations unimpeded?
On Jan. 21, 2004, the Spirit rover crashed. Not physically, but computationally — ceasing all communications with NASA mission control. A day later, it sent out an interplanetary error code, presenting its operators with the equivalent of Windows’ dreaded Blue Screen of Death.
Like any good tech, Spirit’s controllers rebooted the system — only to find the rover stuck in an error loop, constantly reloading the onboard flight software and then crashing before the boot cycle was complete. (For the record, Spirit and its twin, Opportunity, both use the VxWorks embedded operating system found on many recent space probes, so don’t go blaming this mess on Linux or Windows.)
Again, following the universal tech support playbook, engineers instructed Spirit to boot into “crippled mode,” the rough equivalent of Windows Safe Mode. Crippled mode meant Spirit was operating using only RAM, rather than its onboard 256-MB flash memory systems.
Once in crippled mode, the rover became responsive, suggesting that the problem had to do with the flash memory. However, diagnostics and deduction illustrated that the flash memory module was physically fine. This was a software bug — and apparently a major one.
NASA engineers immediately launched into a series of software diagnostics that, ironically enough, actually made the problem worse. Only after making Spirit less responsive with their repair efforts did NASA realize the simplicity of the problem: Too many files on the file system.
The software diagnostics had actually aggravated the situation by dropping more files on the system. Most of the culpable files were leftover in-flight data that were no longer necessary.
A quick batch of deletes, a software patch to perform some regular garbage collection, and a complete reformat of the flash memory — in tech speak, smoke the system and load a clean image — put Spirit back at full strength. Engineers applied the same remedy to the Opportunity rover before it had a chance to lock up, and that probe has never suffered from the same problem.
It just goes to show that sound tech support principles — and Geek Trivia — apply no matter which planet you’re on.
The Quibble of the Week
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