Scientists, looking deep into space, have long voiced their concerns that satellites are encroaching on their ability to study the cosmos.
Scientists, looking deep into space, have long voiced their concerns that satellites are encroaching on their ability to study the cosmos.
ELI5 - why do satellites need to be bright? Do they have some kind of lights? Can’t they just be dark and beam internet around?
They’re metal things sitting up there where the sunlight hits them. What you’re seeing is the sun reflecting off them. Its like how you can look up and see a plane all bright and in the sun even at dusk when its starting to get dark on the ground.
I read the original question as “why can’t they make them black/nonreflective”
Thermal management is a huge issue for spacecraft. In atmosphere, the bulk of cooling for things like electronics would be convective, from transferring the heat into a fluid (air/water/etc) which then moves away with the heat. In space, you don’t have a fluid for convective cooling, so your cooling is all radiative - essentially just emitting infrared energy. This is far, far less efficient - you need much more material and surface area to get the same cooling.
Dark objects are better at radiative cooling… unfortunately, they’re also far better at absorbing radiative energy. Like the oodles of it coming out of the sun. That’s why dark objects are dark - they’re absorbing the energy. However, it also means that your thermal management is far more difficult because you’re absorbing a lot more heat. It can be worked around, but it makes the spacecraft larger and heavier, which is the antithesis of space work. So spacecraft have traditionally tried to reject as much absorbed energy as possible, which by definition makes them reflective.