Only one. If more, then no solutions at all.
And we can not change shape of asteroid belt. We must choose one of 4.
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and this is automaticly remove any gliphs inside the star.
I think we can narrow down the possibilities more than that as far as how the asteroid glyphs might look and, more importantly, how they affect the solution of the bottom left.
The two columns have 3 and 5 "bits" available respectively - we know 6 of these are to be used to depict the belts due to the Y axis totals. The two bits left over have to fit in the 3 slots available at the bottom. And no two bits can be adjacent horizontally or vertically (in either the belt or the bottom left). Considering each permutation of asteroid pattern:
Option #1: use 3 from left column, 3 from right column
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This leaves 0+2 bits to be arranged in the bottom 3 slots. Note that it doesn't matter which way around these glyphs are arranged - in term of the bits left over for the bottom it has no impact, it is essentially cosmetic.
Option #2: use 2 from left column, 4 from right column
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This leaves 1+1 bits to be arranged in the bottom 3 slots.
I don't see how any other option will work - the maximum number of bits in either asteroid column can be 4 - a fifth will be adjacent to one of the others. And the first column only has a total of 3 bits to use at all. So in terms of "bits" left over for the bottom left there are only these two possibilities.
EDIT: he he, looks like I was beaten to the punch several times while I was typing this [noob]