Planetary Society's LightSail bricked due to a software bug. Needs physical reset button pressed

I’m a little sad and disappointed about this, bacause as a Kickstarter supporter I felt a wholly-unwarranted slight sense of ownership.

From the Planetary Society

As of late Friday afternoon, LightSail was continuing to operate normally. The spacecraft’s ground stations at Cal Poly San Luis Obispo and Georgia Tech were receiving data on each pass. Power and temperature readings were trending stably, and the spacecraft was in good health.

But every time LightSail transmitted a packet, it stored a copy in a datafile file called beacon.csv. This continued until the file reached 32 megabytes and crashed the system.

There was a patch already in place, but the version they sent didn’t include it. They were going to beam the patch up, but by the time they got around to it it was already dead…

Apparently it would work if it were reset. There is a physical reset button…

“There’s nobody in outer space to push that reset button,” says [Bill] Nye.

Since we can’t send anyone into space to reboot LightSail, we may have to wait for the spacecraft to reboot on its own. Spacecraft are susceptible to charged particles zipping through deep space, many of which get trapped inside Earth’s magnetic field. If one of these particles strikes an electronics component in just the right way, it can cause a reboot.

So their only hope is a convenient passing cosmic ray.

I worry this is to be expected with citizen science. It’s awesome that the Planetary Society did this, but I think if this were a NASA project the chances of a stupid error like this would have been miniscule. NASA has had a few famous examples of software bugs, but their recent stuff is just about the most well-tested, perfectly running software in the world.

From a FastCompany article about NASA software a few years ago:

But how much work the software does is not what makes it remarkable. What makes it remarkable is how well the software works. This software never crashes. It never needs to be re-booted. This software is bug-free. It is perfect, as perfect as human beings have achieved. Consider these stats : the last three versions of the program — each 420,000 lines long-had just one error each. The last 11 versions of this software had a total of 17 errors. Commercial programs of equivalent complexity would have 5,000 errors.

And guys, a physical button? Not a second system that you can beam to as an external rebooting service?

(Paging @frauenfelder as it’s an interesting topic.)

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I’m more than a trifle surprised that there isn’t a watchdog timer in the picture.

Writing Totally Bulletproof code is serious business; but watchdog timers are widely available even for relatively boring systems(some PCs have them, lots of microcontrollers at least offer a version that has one, it’s hardly a hugely expensive or exotic thing); and, while not 100% painless to incorporate into a software design; they are a great deal easier than building nearly perfect software; and a great deal more reliable than hoping for a cosmic ray, or including a button that nobody will be able to press.



Oh man, Bill Nye is gonna be soooooo mad.

But I’m sure Neil deGrasse Tyson will be able to play it off as no big deal. That cat is so chill. I don’t think I’ve ever seen him fired up and angry about anything. Although I’ve seen him get progressively more annoyed with Dale McGowan (I think? Could easily have been someone else) asking him why he doesn’t call himself an atheist or even an agnostic while also stating that he has no belief in the supernatural.

Anyway, huge bummer about the solar sail thing. I listened to an episode of the Skeptics Guide to the Universe a week or two ago with Bill Nye as the guest explaining all the kinks they’ve worked out for the prototype, and how they’ve fixed the problems that caused JAXA’s solar sail to overshoot its Venus capture window sending it into a solar orbit of about the same altitude as Venus. Nye was so excited and fired up and confident that this little cubesat thing was so simple and foolproof and well-tested that it couldn’t possibly fail.

The Planetary Society attempted to launch one of these earlier (Cosmos 1 in 2005) on top of a refurbished missile, but the damn thing ended up having an inadvisable and unexpected transfer of momentum to the Barents Sea. After that they attempted to launch a second one in 2008, but the launch vehicle “failed to attain orbit” as well, so the planetary society has had a string of nasty luck with 3rd party rockets not doing the whole rocket thing very well.

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They’ve gotten back into contact with their little solar sail cubesat!



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Nice! Turns out waiting for a passing cosmic ray wasn’t so fun after all.

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Seriously, did anyone not mentally read that in Professor Farnsworth’s voice?


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