AGU Abstract

American Geophysical Union

This August, our RamSat group submitted an abstract for the American Geophysical Union. Our abstract was selected to be presented at the conference this December 16th. We began planning our abstract in July when the satellite began experiences very high temperatures. This began our research into why these high temperatures were occurring. We discovered this was due to the angle between the satellite and the sun, which is caused by the inclined orbit of the satellite. While we cannot change these orbital parameters, adjusting the orientation of the satellite can help alleviate these overheating issues. We collected these findings and in August, our RamSat group submitted our findings in an abstract to the American Geophysical Union. Our abstract was selected to be presented at the AGU conference in New Orleans this December 16th.

Analysis of collected beacon telemetry from RamSat, in combination with orbital prediction from the General Mission Analysis Tool (GMAT), was examined to show the effect of solar beta angle on thermal regulation. Orbital prediction was accomplished through use of the two-line element (TLE) supplied by the Joint Space Operations Center (JSpOC), a subdivision of the United States Space Force. Data describing the status of satellite components were gathered through beacon telemetry, which was broadcast every minute and collected through the SatNogs database, an open-source global network of satellite ground stations. The inclination of the satellite's orbit is 51.6 °; therefore, changes to the longitude of the ascending node and solar beta angle are significant factors in the thermal regulation of the satellite. High beta angles subject the satellite to prolonged periods of sunlight and heating, negatively affecting the efficiency of solar panels and batteries on the satellite, as well as increasing core temperatures by 14.2 °C. The longitude of the ascending node of RamSat's orbit showed strong correlation with the rapid periodic changes in the beta angle, caused mainly by the nodal precession due to Earth’s oblateness. An underlying longer period in the beta angle is due to Earth's orbit around the Sun. The combination of RamSat’s orbital precession and seasonal changes led to the high beta angle, peaking on July 13th, 2021. Telemetry data reflects these temperature fluctuations. The exposed solar panel reached 91 °C during the highest beta angle on July 13th. Similar high beta angles are expected during the winter solstice. Activation of RamSat’s attitude control system provided spin around the axis parallel to the affected solar panel, significantly alleviating the overheating problems.

Altitude(y) vs. Time (x) from June-14-2021 to June-14-2022. I turned off the precession in this graph to just show how drag affects the satellite

Beta Angle (y) vs. Time (x) Graph from June-14-2021 to June-14-2022

There is also this graph of the longitude of the ascending node. It mainly just shows the ~60 day period of the nodal precession

Graph that predicts the orbital decay of the ISS. I noticed it looked similar to some of the RamSat altitude telemetry