Linked Questions

5 votes
1 answer

Why did we think that the object was gonna hit the Moon March 4th 2022? Who's been tracking and predicting it so closely?

The Guardian's 'Out-of-control' Chinese rocket falling to Earth... Oops, I mean Out-of-control SpaceX rocket on collision course with moon says that Bill Gray's Project Pluto/DSCOVR says that the 2015 ...
5 votes
2 answers

Where is the Wind going? Where has it been? (Global Geospace Science spacecraft 1994-071A)

This excellent answer to Why put DSCOVR in a Lissajous orbit? Wouldn't a halo orbit completely avoid the Sun exclusion zone? explains that the Global Geospace Science or Wind spacecraft ...
7 votes
3 answers

What is the required burn to keep a satellite at a Lagrangian point?

When a satellite reaches a Lagrangian point, it has a non-zero velocity $v_1$ because of the transfer orbit in which it had already been. What burn, say, $\Delta v$, one needs if the satellite is ...
17 votes
4 answers

Could JWST stay at L2 "forever"?

Using only reaction wheels powered by solar panel and the sunshield as a sail (in continuous active attitude control) to generate thrust from solar photon pressure in the desired direction, could JWST ...
18 votes
1 answer

What happens to JWST after it runs out of propellant?

JWST will be orbiting L2 which is unstable equilibrium thus will require propellant for station keeping. JWST will carry propellant for 5-10 years. What will happen once it runs out of propellant? ...
3 votes
1 answer

Was Queqiao in a halo or Lissajous orbit? Why do sources disagree?

Wikipedia's Lissajous orbit says that sources disagree on the nature of Queqiao relay satellite's orbit; if it was in a proper halo orbit or just a Lissajous orbit. Proper halo orbits have the same ...
9 votes
1 answer

How would you identify when an object in a Lissajous orbit needs station keeping?

Obviously, with the international space station you need to do some station keeping when you're falling into the atmosphere. However, I saw the following image showing the Halo orbit that the Deep ...
16 votes
3 answers

Why would a mission to Sun-Earth L1 have an instantaneous launch window?

I was watching the webcast for Falcon 9 Flight 15 (launching DSCOVR) when they scrubbed their first launch attempt due to some issues during the terminal countdown. Before the scrub, the narrator ...
10 votes
1 answer

What exactly is the interaction that blocked Juno's data downlink near solar conjunction?

According to's article Juno Phones Home: Jupiter Probe Reconnects with Earth After 8th Flyby, Juno's recent close flyby of Jupiter and data collection happened while Jupiter was too close to ...
11 votes
1 answer

What is the difference between halo orbits and Lissajous orbits?

The Wikipedia articles for halo orbit and Lissajous orbit leave me wondering how these two orbits are different from an orbital mechanical point of view. Could they be discussed together here, so I ...