From time to time, some non-experts come up with strange suggestions for satelli
ID: 121134 • Letter: F
Question
From time to time, some non-experts come up with strange suggestions for satellite missions, which reveal a very limited understanding of remote sensing techniques. Explain in concise and convincing sentences:
a)Why it is not feasible to have a geostationary remote sensing satellite over the North Pole for continuous observations of the Arctic Ocean sea ice?
b)Given that an atmospheric correction algorithm can be devised based on different path lengths through the atmosphere, such as for the ATSR series of satellite radiometers, would it not be a good idea to have two satellites in adjacent orbits each carrying a MODIS type radiometer, with a constant horizontal cross-track separation of 500 km measured orthogonally to the orbital planes of the satellites? This would allow the ocean temperature at the same place in the overlapping part of each satellite radiometer swaths to be measured by the two radiometers through two atmospheric path lengths, but why is this not feasible?
c)Why is it not currently possible to have a microwave radiometer and an infrared radiometer on satellites for surface temperature measurement with the same high spatial resolution?
Explanation / Answer
A) A geostationary satellite rotates as same with Earth's rotation so there relative position is fixed with each other as the Earth and satellite rotates at same speed. The rotational velocity keeps satellite from falling in the Earth's gravity. Also the fixed position helps in calculating weather data precisely.
At North pole, there is no rotational velocity acting on Earth's surface, meaning the North pole is at rest having very less (approximately zero) rotational velocity. Now to stay on top of this area, geo stationary satellite has to stay at one place i.e. with zero rotational velocity which is not possible as it will be pulled in the Earth's gravity. This is the reason geo stationary satellite remote sensing is not possible over North pole.
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