Lightsail spacecraft goes dead because programmers appended a data file instead of replacing it

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Lightsail spacecraft goes dead because programmers appended a data file instead of replacing it

A new spacecraft that was going to test out new technologies went dead soon after launch because the data file it sent back was being added to, and not replaced, every time it was sent. So it progressively grew larger until it crashed the system. Such a small issue with such a huge outcome.

The Planetary Society’s LightSail test mission is paused while engineers wait out a suspected software glitch that has silenced the solar sailing spacecraft. Following a successful start to the mission last Wednesday, LightSail spent more than two days sending about 140 data packets back to Earth.

But the long Memorial Day weekend here in the United States offered no respite for the LightSail team, as they scrambled to figure out why the spacecraft's automated telemetry chirps suddenly fell silent. It is now believed that a vulnerability in the software controlling the main avionics board halted spacecraft operations, leaving a reboot as the only remedy to continue the mission. When that occurs, the team will likely initiate a manual sail deployment as soon as possible.

What happened?

Inside the spacecraft's Linux-based flight software, a problem was brewing. Every 15 seconds, LightSail transmits a telemetry beacon packet. The software controlling the main system board writes corresponding information to a file called beacon.csv. If you’re not familiar with CSV files, you can think of them as simplified spreadsheets—in fact, most can be opened with Microsoft Excel.

As more beacons are transmitted, the file grows in size. When it reaches 32 megabytes—roughly the size of ten compressed music files—it can crash the flight system. The manufacturer of the avionics board corrected this glitch in later software revisions. But alas, LightSail’s software version doesn’t include the update.

Late Friday, the team received a heads-up warning them of the vulnerability. A fix was quickly devised to prevent the spacecraft from crashing, and it was scheduled to be uploaded during the next ground station pass. But before that happened, LightSail fell silent. The last data packet received from the spacecraft was May 22 at 21:31 UTC (5:31 p.m. EDT).

 http://www.planetary.org/bl...
By netchicken: posted on 31-5-2015








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