Linked Questions

16 votes
4 answers
986 views

Why is the US building a Lunar Orbital Platform-Gateway (LOP-G)?

An excerpt taken from the Wikipedia page on LOP-G says space-experts have criticized it: The Deep Space Gateway has received criticisms [...] for lacking a proper scientific goal. Former NASA ...
Magic Octopus Urn's user avatar
18 votes
2 answers
2k views

Is this what station keeping maneuvers look like, or just glitches in data? (SOHO via Horizons)

I've been enjoying the JPL Horizons web interface and after I discovered the incredibly extensive database associated with SOHO (Solar and Heliospheric Observatory, also see sohowww.nascom.nasa.gov) ...
uhoh's user avatar
  • 149k
15 votes
1 answer
18k views

What is a near rectilinear halo orbit?

A proposed option for the lunar orbit of a Lunar Orbital Platform-Gateway (formerly known as Deep Space Gateway) is a near rectilinear halo orbit, or NRHO. This excellent answer discusses the ...
uhoh's user avatar
  • 149k
18 votes
1 answer
7k views

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? ...
daniel.sedlacek's user avatar
13 votes
1 answer
7k views

Why is a near rectilinear halo orbit proposed for LOP-G (formerly known as Deep Space Gateway?)

Why is a near rectilinear halo orbit a good place for a Lunar Orbital Platform-Gateway (formerly known as Deep Space Gateway)? Are there specific logistical and orbital-mechanical advantages over ...
uhoh's user avatar
  • 149k
5 votes
2 answers
4k views

How far would the Mars L1 Lagrangian Point be from Mars?

I am a sci-fi writer, and I've heard about the concept of putting some type of magnetic deflector near the Sun-Mars L1 point to deflect charged particles from the Sun to reduce radiation effects on ...
Dorothy Piper's user avatar
6 votes
1 answer
2k views

Are there any natural circular orbits?

I just saw How does orbital eccentricity affect positions of Lagrange points $L_4$ and $L_5$? and it questions the difference between circular and elliptical orbits. We know the Moon does not have a ...
James Jenkins's user avatar
4 votes
4 answers
395 views

Why are the Trojan libration points equidistant and not mass weighted?

The locations of the collinear Lagrange points L1, L2, L3 are mass weighted, so for example Sun-Earth-L1 is only 1% of the distance to the Sun from Earth. But L4 and L5 are one AU from both the Sun ...
LocalFluff's user avatar
5 votes
1 answer
987 views

Why is Queqiao's dish antenna so big? (Chang'e-4 relay satellite) Largest ever on/near the Moon?

Source: Chinese language blogpost The NASA Spaceflight article Queqiao relay satellite launched ahead of Chang’e-4 lunar mission describes the communications relay satellite that will be used to ...
uhoh's user avatar
  • 149k
4 votes
2 answers
1k views

How will the Lunar Gateway go to L2 and L1; how much delta-v is needed?

In a talk to the press which can be heard in the YouTube video NASA Administrator Jim Bridenstine Explains the Lunar Gateway, NASA director Jim Bridenstine says after about ...
uhoh's user avatar
  • 149k
3 votes
1 answer
809 views

How to calculate the Lagrangian points positions?

I have two bodies, one rotates around another on orbit. For i.e. Earth and Sun or Moon and Earth. If we know masses, velocity, distance and keplerian elements of orbit, how can we find the positions ...
Robotex's user avatar
  • 604
2 votes
0 answers
2k views

What is a "synodic frame"? Can one be defined for an elliptical orbit?

A description of a "synodic frame" was one of the main ingredients in this excellent answer to a question about an animation of a funky-looking orbit that several different and distinctly interesting ...
uhoh's user avatar
  • 149k