$50sat update

Tuesday, April 21, 2015 marked the 17 month anniversary of the launch of $50SAT/MO-76/Eagle-2, and believe or not, it is still operating.
Unfortunately, the battery capacity has degraded to the point where the satellite spends a significant amount of time with the battery voltage below
the 3300 mV minimum required for enabling the transmitter. As a result, those of us who live in the northern hemisphere no longer hear any
transmissions during the evening passes, and for now, rarely hear any during the daytime passes as well. The last telemetry packet I captured here in
EN82 land was April 21, and the last one which was error-free on April 10. Fortunately, I have been able hear it operate over Anton’s (ZR6AIC) WebSDR station in South Africa during the evening passes (which occur between 4:00 and 6:00 PM Eastern Daylight Time), and occasionally am able to capture error-free telemetry packets. The last one available is from April 24 at 21:25 UTC.


This situation was fully expected; when looking at the battery voltage chart (which, along with all the other telemetry, is available from our Dropbox, the readings took a large drop sometime after February 12. Given this was a $10 camera battery that had gone through over 6,000 orbits, each with temperature swings of -30 degrees C to +30 degrees C, it is surprising it has lasted this long! At this point, it is starting to behave more like a large capacitor than a battery.


As we get closer to summer here in the northern hemisphere (and after this winter, it cannot come soon enough), $50SAT/MO-76/Eagle-2 will spend more
time in the sun before it makes each pass; this means it will be warm enough to enable solar power sooner in the pass, and makes it more likely it we
will be able to hear it transmit before it disappears over the southern horizon. Those of you who live in the southern hemisphere, however, should
still be able to hear it during both daytime and evening passes. If you could, we would certainly appreciate any telemetry you could gather and
post. In the meantime, I will continue to update the Dropbox with any new telemetry gathered. Please keep it coming, even if it has errors or is
incomplete. At this point, we are happy to simply know that it is still operating.

Michael Kirkhart, KD8QBA
$50SAT/MO-76/Eagle-2 team


Leave a Reply