WA8LMF Mirror of WB4APR Website - 21 July 2008 Telemetry

ANDE Final Months Telemetry Trends

This page displays all of the meaningful telemetry values for the last month of the ANDE-MAA mission. It should be noted however that ANDE telemetry is gathered very very sparsely and over widely distributed ground stations, so remember these are only sample points and the lines that connect the points are not to be considered continuous.

CORE TEMPS: . These plots reveal the long term trends. . First, the average core temperature (the central electronics and Batteries) show the changes in orbit Sun beta angle. . The final heating was mostly due to beta angle, until the last day when some frictional heating was noted.

SHELL TEMPS: . In contrast to the relatively stable internal temperature of the Batteries and lasers above, the shell temperature varies considerably as much as 30 degrees on each orbit between sun and dark as shown below on the X temperature sensor data. Again, the locations of our ground stations means we may not be capturing the oribt extremes during certain phases of the orbital period. The other shell temperatures look similar:

BATTERIES: . Next you can see that battery voltage is relatively constant so far, though there appears to be a slight Temperature dependency on voltage during the higher temperatures. . ANDE runs on primary Lithium cells (no solar power) so this next plot gives us an idea of mission life remaining.

LASER/VOICE USAGE: . The next plot indicates when we have turned on either the Voice module or the Lasers. . Notice how activity picked up towards the end as more stations were monitoring and collecting telemetry.

SUN SENSORS: . The most revealing data concerns the Sun sensors. The +Y Sun sensor was known to be failed before launch as an open circuit. Its telemetry is useful because it shows the temperature dependency of the late-integration telemetry system fix that was added to compensate for the positive-grounded solar cells. This plot should be a flat line of "no Sun" yet its baseline shows a temperature dependence on the core tempertature of the spacecraft. We can use this data to subtract out the temperature effects of all the other Sun sensors.

But the other Solar sensors are also revealing. The +X and +Z sensors show activity early on but they both taper as the mission progresses. The +Z sensor degrades very quickly in the first week while the +X sensor degrades over the first month. Ignore off-scale bad-data-hits.

Similarly, all of the sun sensors on the B side system have been flatlined since launch. Comparing the plots below to the only original working sun sensor (+X above) you can see that the only change in the flat-line data occurs at high temepratures of the overall spacecraft. This shows baseline temperature dependence of the telemetry system diodes on the Sun sensors, but no real sensor data as shown below. Be aware that side B data is very sparse, since it only wakes up for command stations while side A wakes up for any user activity on the channel.

Our assessment to date indicates ANDE was rotating at about 0.17 RPM on deployment. The early failiure of all the sun sensors yields no other spin data, but by February, close observations of shell temperatures yields a similar rotation rate of about 0.17 RPM.

Bob Bruninga
USNA Satellite Lab WA8LMF Mirror of WB4APR Website - 21 July 2008