Re:James Webb is fully deployed
by ianai on Saturday January 08, 2022 @04:31PM
(#29856505)
Agree. A replica wouldn’t have to be sent to L2 for that matter. Pretty sure a lot of science could be done with even a slow trajectory leaving the solar system, if orbiting something else is infeasible.
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As I understood the engineering of the JWST requires it to be at L2 so it's in permanent shadow of the sun and can keep the very low temperatures necessary for good infrared image quality.
It has solar panels, so it can't be in shadow. IIUC the advantage of earth-sun L2 is it's away from the light and shadow of the earth and moon, while being reachable by radio year round.
I didn't check for sources again earlier, but this NASA article [1] explains it.
Yea shadow was the wrong word and doesn't actually apply because of the relative size of the sun and earth. However the L2 point is by definition in a straight line Sun -> Earth -> L2, so if the sun would be a single point light source that would block the sun and place the JWST in the permanent shadow thrown by the earth. The point is actually that the sunscreen is always facing earth and sun at the same time to block/reflect a maximum of heat.
It's orbiting L2, not at it. It will have basically constant sunshine, which is good - solar panels provide all its power. (no RTG)
Re:James Webb is fully deployed
by richardwhiuk on Saturday January 08, 2022 @08:43PM
(#29858934)
It has constant sunshine on one side, and constant darkness on the other.