In regards to the James Webb telescope(congrats, NASA!): How does the solar shield NOT act like a solar wind sail, which would cause the telescope to be steadily pushed away from us and require frequent re-alignment?

Question

In regards to the James Webb telescope(congrats, NASA!): How does the solar shield NOT act like a solar wind sail, which would cause the telescope to be steadily pushed away from us and require frequent re-alignment?

In: 143

Answer 1

Good question. You gotta see which force is acting against that pressure. The telescope is not at the L2 exactly, but slightly “before” so it has the ever slightest tendency to get pulled towards the sun. This gravitational force is bigger than the solar wind pressure, so you need fuel to ever stay as close to L2 as possible, not overshot.

The aft momentum flap is to counteract rotation caused by the wind pressure, and not to act against the outward force of the wind pressure: the shield is rarely perpendicular to the sun rays, which causes a rotation as the sun beam is reflected off.