Tag Archives: Mars Exploration Rovers

Opportunity — can you hear us?

The Mars Exploration Rover B “Opportunity” has been such an amazing success story.  From a remarkable “hole-in-one” landing in January of 2004….

…to record-shattering traverses of Meridiani Planum for over 14 years, currently taking it to a location aptly named Perseverance Valley, Opportunity has far outlived all of the expectations for it.  It has outlived its sister vehicle, Spirit, which became mired and unable to orient its solar panels for optimal illumination in the long Martian winter, and seen remarkably fortuitous weather events — dust devils that cleared the pernicious accumulation of dust from its solar panels.

But now, the rover’s been going on so long it almost seems unstoppable.  XKCD’s Randall Munroe took this its logical extreme:

We all remember those famous first words spoken by an astronaut on the surface of Mars: It really has seemed as if Opportunity is unstoppable.

The Martian Terminator of rovers, if you will.

But it’s possible it’s now met its match in the form of what is shaping up to be the biggest dust storm on Mars in a long time, possibly since the staggering dust storm that enveloped Mars just before Mariner 9 arrived in 1971, lasting months before the probe was able to begin usefully photographing the red planet.  If this storm also lasts months, it will surely kill Opportunity; it’s summer in Meridiani Planum, which helps a lot, but this storm is likely blotting out the sun almost completely.  A few days ago, NASA lost the signal from Opportunity.  Over the previous few days, the probe’s telemetry had reported plummeting power output from the solar panels, so at present, it is certainly subsisting on battery power, running only its mission clock so it can periodically wake up and check to see if there is light again.  If the storm lifts soon, we may hear from Opportunity again.  But if not . . . .

Well.  Cross your fingers.  😉  This plucky little robot has surprised us before.

PS If you’re wondering about Curiosity, well, that probe is on the other side of the planet, in Gale Crater.  But the storm is so massive that Curiosity is beginning to see the effects as well.  Unlike Opportunity, though, Curiosity runs off of a Pu-238 radioisotope thermoelectric generator; it can run just as well in the dark as in daylight.  (Well, except for the fact that it doesn’t have headlights so can’t see where it’s going.)  Curiosity may eventually find its science operations impeded by the weather, but at least it won’t have to worry about power for a good long while.

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Mangalyaan (MOM) and Curiosity (MER): minor snags, but still trucking!

First off, Mangalyaan continues its slow climb up out of Earth’s gravity well, pushing its apogee higher and higher with each burn.  Last weekend, the fourth burn was aborted prematurely, resulting in an apogee of 78,722 km instead of the 100,000 km target.  The problem was studied; ISRO had attempted to use the primary and secondary coils of a flow control valve in the main propulsion system in parallel; if this would be successful, it’s a method that could be used to increase confidence for the critical Mars orbit insertion burn, for which any Mars spacecraft usually* only gets one chance.   However, the parallel mode did not work as expected, and the two coils energized simultaneously.  The main computer detected this condition and terminated the burn.  A sequential method could be used instead once they reach the red planet, but for now they have plenty of time to decide; there are two more burns coming up, and then the long cruise to Mars.

Meanwhile, Curiosity also hit a minor hiccup when the R11 version of its onboard software was uploaded.  A catalog file was still listing a file which was now absent with the new software in place; the computer concluded that this meant the memory was corrupt and rebooted.  JPL switched it back to the R10 software and is preparing a fix.  It’s an easy fix, but you don’t rush things when you’re working in deep space.

Ultimately, however, both spacecraft have weathered their glitches just fine.  As  legendary spacecraft engineer Dave Akin said, “To design a spacecraft right takes an infinite amount of effort. This is why it’s a good idea to design them to operate when some things are wrong .”  Both Mangalyaan and Curiosity have demonstrated this beautifully, and though these were relatively minor snags, it is not in times of flawless operation that a mission is measured, but in how it responds to failures.  So, onward and upward!

 

* The one exception was Japan’s Kaguya probe, which failed to perform its Mars orbit insertion and so went sailing on past into heliocentric orbit.  It wasn’t dead, though, and a few years later, when it came by Mars again, they tried a second time.  Unfortunately, the same fault occurred again, and it continued on in heliocentric orbit.  A third attempt is out of the question; it was already beyond its design life by the second attempt.

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