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www.southgatearc.org
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SwissCube newsProject Manager Muriel Noca has posted an update to the SwissCube mailing list on this Amateur Radio satellite that was launched in September Dear all, Well, days and weeks do fly-by fast! So, to keep up, here are a few news from the satellite… Over the week-end of Oct. 24-25, the satellite’s attitude control system experienced a “reset” of the microcontroller. The satellite has one microcontroller per subsystem (power, communication, payload…), but only the attitude control one was reset, which leads to think that some external event happened. That behavior had never been seen during the tests. The satellite’s communication still works well, as all its subsystems. We experienced communication difficulties due to some software anomalies on the ground and also due to the spinning of the satellite. We are currently resolving the ground software anomalies (related to the uplink TNC). Both the EPFL and the Fribourg ground stations are used for uplink and downlink of the data. We are also seeing perturbations on the I2C data bus aboard the satellite, also never seen during tests. But they do not prevent us from talking to the satellite. We are investigating the reasons. Our efforts to understand the rotation rates of the satellite are making progress. The new students working on it are improving models and getting close to making predictions. One of the students made Antenna Deployment Test in air, which shows that we do have a residual rotation after deployment. Further testing will be done in vacuum next semester at the EPFL LCSM laboratory. You will be able to see one video of the deployment tests on the SwissCube main website. Although this does not totally explain the initial high rotation rates, and although it is very counter-physical, it is one potential explanation. We will be investigating another reason with additional tests at DTU (Denmark Technical University) with measurements of the residual magnetic dipole of the satellite. We also had a discussion with the Radio Amateurs of Vaud to share our understanding and findings about the high rotation rates. Quite a few radio-amateurs are proposing very good explanations and solutions to this high rotation. Work is still in progress and we still have a few weeks of work before implementing a detumbling (de-spinning) procedure. We really want to thank all the Radio-Amateurs in the world sending us very valuable data every day. They allow us to check that the satellite is still in good health, and also participate in our understanding of the behavior of the satellite when it is far away from Switzerland . Till next week! Muriel Noca ISIS CubeSat launch blog
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