[amsat-bb] Listen for LightSail - transmissions stopped

[Robert McGwier]

Good grief.

On Tue, May 26, 2015 at 6:00 PM, JoAnne Maenpaa <k9jkm at comcast.net> wrote:

> Just read on-line at http://planet.ly/0gVop (Planetary Society) that the
> LightSail satellite stopped transmitting. The team is attempting a reboot.
> The telemetry data is sent on a downlink of 437.435 MHz, AX.25, 9600 bps
> FSK.
>
> Excerpt from their page ...
> 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 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 LightSail 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's automated chirps fell silent.
> The last data packet received from the spacecraft was May 22 at 21:31 UTC
> (5:31 p.m. EDT).
>
> A LightSail map tracking application is at:
> http://sail.planetary.org/missioncontrol
>
> --
> 73 de JoAnne K9JKM
> k9jkm at amsat.org
> AMSAT VP User Services
>
>
>
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-- 
Bob McGwier
Co-Founder and Technical Director, Federated Wireless, LLC
Research Professor Virginia Tech
Senior Member IEEE, Facebook: N4HYBob, ARS: N4HY
Faculty Advisor Virginia Tech Amateur Radio Assn. (K4KDJ)