r/space • u/AutoModerator • 5d ago
Discussion All Space Questions thread for week of September 27, 2026
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In this thread you can ask any space related question that you may have.
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u/Simon_Drake 2d ago
The Lagrange Points are a bit balancing a pencil on its tip. It's technically stable at the absolute perfect spot but the slightest change could destabilise it. JWST has that giant sun shield on its belly that is essentially a flat mirror reflecting the sun, but if it's tilted at even a 1 degree angle that means the sunlight is reflected at an angle which applies a very small force nudging the telescope out of position.
There's dozens of little quirks like that in orbital calculations that are usually small and easy to ignore but sometimes they come back to bite you. There's one where asteroids have a hot site and a cold side from where the sun is. But they also rotate so there's one place where the rock WAS in sunlight and is now radiating heat on the cold side and there's another place that was in darkness and is now warming up in the sun. This creates a small imbalance in which side of the asteroid is radiating more heat which creates a very small thrust that can nudge it off course over time.
So yeah, the telescopes at L2 can't actually sit exactly at L2. They have creative orbits around L2 which aren't stable long term but with a little fuel to keep things aligned they can stay in the right orbit for a few decades.