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I wonder if there is any consideration for high quantities of LEO satellites affecting ground based telescope operations? I guess one question would be "how man

by xt00 8y ago

I wonder if there is any consideration for high quantities of LEO satellites affecting ground based telescope operations? I guess one question would be "how many LEO objects are up there that are the size of say more than 1 cubic meter in size right now?".. if SpaceX would be doubling the total number up there right now that does sound concerning.. I personally love the idea of the global internet constellation they are working on.. just worry that there could be other ramifications..

gpm 8y ago
In my opinion even if this was a huge problem for ground base telescopes it wouldn't matter, that negative externality would be tiny compared to the potential benefits. That said, this project will approximately double the number of man made satellites. I believe these satellites will be smaller than normal, but also closer than normal. I'm not an expert, but I think number of satellites is actually a really bad predictor for impact. In particular there was one set of satellites that had really bad effects for some reason. See more here [0]. [0] https://en.wikipedia.org/wiki/Satellite_flare https://en.wikipedia.org/wiki/Satellite_flare
- xt00 8y ago
  Yea I wonder if with modern telescopes that they do digital integration so effectively they just delete the errant frames from the recorded captures and carry on from there. In the old days with film capture the entire exposure would be toast if a satellite flew through the frame..
aerophilic 8y ago
I think something that most people don’t comprehend is just how HUGE space is. For context, at 550km orbit, the “surface area” of the sphere surrounding the earth is ~601 BILLION square kilometers. Suppose we had 40,000 (double the number of objects larger than a softball we have been tracking) objects up there, in that exact orbit, we would still only have one object every 15 MILLION square miles. So, while it is a valid concern... until we put up “millions” of items, I think astronomers will be pretty safe. However, orbital debris avoidance... much bigger issue.
- smueller1234 8y ago
  I agree with your conclusions. Just a nit: the r² increase in surface of a sphere that makes this so much bigger an area to scatter the satellites across also applies to the field of view of telescopes and thus cancels out. Edit: Clarification. The above is only true if having a satellite in the field of view is enough to be a problem.

by xt00 8y ago

gpm 8y ago

In my opinion even if this was a huge problem for ground base telescopes it wouldn't matter, that negative externality would be tiny compared to the potential benefits. That said, this project will approximately double the number of man made satellites. I believe these satellites will be smaller than normal, but also closer than normal. I'm not an expert, but I think number of satellites is actually a really bad predictor for impact. In particular there was one set of satellites that had really bad effects for some reason. See more here [0]. [0] https://en.wikipedia.org/wiki/Satellite_flare https://en.wikipedia.org/wiki/Satellite_flare

xt00 8y ago
Yea I wonder if with modern telescopes that they do digital integration so effectively they just delete the errant frames from the recorded captures and carry on from there. In the old days with film capture the entire exposure would be toast if a satellite flew through the frame..

aerophilic 8y ago

I think something that most people don’t comprehend is just how HUGE space is. For context, at 550km orbit, the “surface area” of the sphere surrounding the earth is ~601 BILLION square kilometers. Suppose we had 40,000 (double the number of objects larger than a softball we have been tracking) objects up there, in that exact orbit, we would still only have one object every 15 MILLION square miles. So, while it is a valid concern... until we put up “millions” of items, I think astronomers will be pretty safe. However, orbital debris avoidance... much bigger issue.

smueller1234 8y ago
I agree with your conclusions. Just a nit: the r² increase in surface of a sphere that makes this so much bigger an area to scatter the satellites across also applies to the field of view of telescopes and thus cancels out. Edit: Clarification. The above is only true if having a satellite in the field of view is enough to be a problem.