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The problem is believed to be the spinning mirror which scans the image sensor's viewpoint across the Earth. The motor driving the mirror has a problem, so it d

The problem is believed to be the spinning mirror which scans the image sensor's viewpoint across the Earth. The motor driving the mirror has a problem, so it doesn't spin consistently any more. It is supposed to spin at 360 RPM. Could it be possible to spin the entire satellite and get intermittent coverage and reception?

msl 7y ago
Satellites usually need to point their solar panels and high-gain antennas properly in order to stay powered to be able to communicate with ground stations, although this particular satellite seems to have been unable to use its high-gain antenna anyway and relied on an omnidirectional one anyway. Another issue would be thermal management as it is possible that not all parts of the satellite were designed to deal with direct sunlight. I would be more worried about all the sensors, though. The days of secondary electron conduction tubes [1] might be long over, but many instruments still prefer not to be pointed directly at the sun. Speaking of those other sensors, spinning the satellite would mean pointing all of them away from where they are supposed to be looking – not necessarily a net win. Finally, trying to spin the satellite at anything approaching 360 RPM might end up dramatically shortening the mission [2]. [1] https://en.wikipedia.org/wiki/Apollo_12#EVAs https://en.wikipedia.org/wiki/Apollo_12#EVAs [2] https://youtu.be/AqeJzItldSQ?t=90 https://youtu.be/AqeJzItldSQ?t=90 EDIT: In case you do not feel like watching the video, [2] shows a Little Joe II rocket (https://en.wikipedia.org/wiki/Little_Joe_II https://en.wikipedia.org/wiki/Little_Joe_II) breaking up due to an excessive roll rate (around 56 RPM) (https://en.wikipedia.org/wiki/A-003 https://en.wikipedia.org/wiki/A-003).
- orbital-decay 7y ago
  >trying to spin the satellite at anything approaching 360 RPM might end up dramatically shortening the mission A recent, quite a spectacular example of that was the Hitomi X-Ray observatory which went into uncontrolled spin due to a faulty inertial unit. https://en.wikipedia.org/wiki/Hitomi_(satellite)#Loss_of_spacecraft https://en.wikipedia.org/wiki/Hitomi_(satellite)#Loss_of_spa...

msl 7y ago

Satellites usually need to point their solar panels and high-gain antennas properly in order to stay powered to be able to communicate with ground stations, although this particular satellite seems to have been unable to use its high-gain antenna anyway and relied on an omnidirectional one anyway. Another issue would be thermal management as it is possible that not all parts of the satellite were designed to deal with direct sunlight. I would be more worried about all the sensors, though. The days of secondary electron conduction tubes [1] might be long over, but many instruments still prefer not to be pointed directly at the sun. Speaking of those other sensors, spinning the satellite would mean pointing all of them away from where they are supposed to be looking – not necessarily a net win. Finally, trying to spin the satellite at anything approaching 360 RPM might end up dramatically shortening the mission [2]. [1] https://en.wikipedia.org/wiki/Apollo_12#EVAs https://en.wikipedia.org/wiki/Apollo_12#EVAs [2] https://youtu.be/AqeJzItldSQ?t=90 https://youtu.be/AqeJzItldSQ?t=90 EDIT: In case you do not feel like watching the video, [2] shows a Little Joe II rocket (https://en.wikipedia.org/wiki/Little_Joe_II https://en.wikipedia.org/wiki/Little_Joe_II) breaking up due to an excessive roll rate (around 56 RPM) (https://en.wikipedia.org/wiki/A-003 https://en.wikipedia.org/wiki/A-003).

orbital-decay 7y ago
>trying to spin the satellite at anything approaching 360 RPM might end up dramatically shortening the mission A recent, quite a spectacular example of that was the Hitomi X-Ray observatory which went into uncontrolled spin due to a faulty inertial unit. https://en.wikipedia.org/wiki/Hitomi_(satellite)#Loss_of_spacecraft https://en.wikipedia.org/wiki/Hitomi_(satellite)#Loss_of_spa...