When counting photons, the noise in your signal scales with the square root of the total count. If the satellite is dumping 100 ± 10 photons in every pixel it p

When counting photons, the noise in your signal scales with the square root of the total count. If the satellite is dumping 100 ± 10 photons in every pixel it passes through, you can no longer distinguish objects so faint that they'd only leave 10 photons in a pixel during your exposure.