Skip to main content
104 votes
Accepted

Are there any satellites in geosynchronous but not geostationary orbits?

Are there any satellites in geosynchronous but not geostationary orbits? Yep, lots! Apparently there are various advantages to being synchronous even when oscillating wildly in position above/below ...
uhoh's user avatar
  • 149k
71 votes
Accepted

Name for geostationary orbit around another planet

I'll go with Emily Lakdawalla who in her blog post about stationkeeping in Mars orbit wrote (emphasis mine), What is a geostationary orbit like at Mars? I have to pause here for a brief discussion ...
David Hammen's user avatar
30 votes

Why aren't space telescopes put in GEO?

Spacecraft are placed into the orbits that they need to be in, given the objectives of the mission and the constraints during design. Nothing in space is arbitrary, since there is so much at stake if ...
Michael Stachowsky's user avatar
28 votes

Name for geostationary orbit around another planet

Geostationary orbits are synchronous orbits, which are also circular and equatorial. You could describe orbits around other planets in the same way, as circular, equatorial & synchronous orbits. ...
Polygnome's user avatar
  • 6,956
25 votes
Accepted

Why are obsolete geostationary satellites re-orbited above the geostationary belt?

Orbits at the altitude of GEO are stable for very long times (millions of years). There is no significant decay of the orbital height due to some kind of drag, so the risk of these satellites ...
asdfex's user avatar
  • 15.1k
24 votes
Accepted

Why aren't space telescopes put in GEO?

It wouldn't need to turn as fast to stay focused, maybe increasing the lifetime of its reaction wheels. On Earth when you "turn" a telescope, you are really keeping it pointed in one direction! It's ...
uhoh's user avatar
  • 149k
23 votes

Could an areostationary satellite help locate asteroids?

Could NASA put an artificial radar telescope satellite in geosyncronous orbit around Mars to help locate dangerous asteroids on a trajectory that would place them on a path to strike Earth? The "...
uhoh's user avatar
  • 149k
20 votes

Why are obsolete geostationary satellites re-orbited above the geostationary belt?

Actually, it makes a lot of sense to raise the orbit of end-of-life geostationary satellites: Coming from Earth you have to cross through a lower orbit to transfer from low earth orbit to a ...
1337joe's user avatar
  • 7,206
20 votes

Dangle a cable down to earth - fundamental Physics question

You're asking about an idea that's been around for a long time: the Space Elevator or the Sky Hook. Konstantin Tsiolkovsky wrote about a similar concept in 1895, though his concept was for a standing ...
Tom Spilker's user avatar
  • 18.3k
20 votes
Accepted

Delta-v to move from GEO to GEO

Theoretically, you can go anywhere in GEO for an arbitrarily small ∆v - you raise your apogee a little bit, which slows you down, wait until you've phased to your destination latitude, then re-...
Russell Borogove's user avatar
20 votes
Accepted

Launch system to get a 75,000 kg object to geostationary orbit?

Is there any current launch system that could get a 75,000 kg object to geostationary orbit? No. (Starship/Super Heavy can, of course, do anything, but it's not a current launch system.) If ...
Russell Borogove's user avatar
18 votes
Accepted

Are commercial communications satellites in GEO being constantly monitored by telescopes?

It seems that the company ExoAnalytic Solutions regularly observes high- orbiting satellites (MEO, HEO, and GEO), using the data to provide tracking, ensure they are at the right spot, and provide ...
PearsonArtPhoto's user avatar
  • 121k
18 votes

Have there ever been cubesats in GEO?

tl;dr As of June 2019, there are zero CubeSats in GEO The Union of Concerned Scientists has a great database of satellites orbiting the Earth, the smallest satellite that they have in GEO orbit is the ...
Mark Omo's user avatar
  • 5,291
14 votes
Accepted

Why does Himawari-8 have problems with the Sun from 19th February to 19th April?

Why around midnight... Because then the sun will be on the exact opposite site of the earth, from the satellites point-of-view. A=Satellite, E=Earth, S=Sun (not to scale ;) ) ...
Infrisios's user avatar
  • 894
14 votes
Accepted

Are all or some geostationary satellites tidally locked to the Earth?

But I wonder whether they're also tidally locked, meaning a certain side of the satellite always points to the same direction relative to Earth I can not write a definitive answer about satellites in ...
uhoh's user avatar
  • 149k
14 votes

Does it economically cost the same to launch a satellite into LEO and GTO?

The cost of a rocket launch is dependent on many factors. It depends what payload you are launching – some payloads require special services such as gas purges, helium or propellant top up, clean room ...
Slarty's user avatar
  • 9,720
13 votes

How stationary is geostationary?

Generally, the GEO satellites are to keep their desired position above ground within +/- 0.05 deg (both N and E) which translates into a 70 km 2D projection corridor at GEO altitude. The laser ...
Kuldeep Barad's user avatar
13 votes

How much is a geostationary satellite expected to deviate from the geostationary orbit?

Regulatory limits The deviations depend upon the radio frequency licensing agreement applicable to each satellite. This is a feature of the International Telecommunications Union, ITU. Limits in ...
Puffin's user avatar
  • 9,684
13 votes

Is the risk of explosion-induced damage to operational spacecraft in GEO actually reduced substantially by raising Spaceway-1 by 300 km?

Apparently the battery is only prone to explode while used. So when turning the satellite off, the risk appears to be mitigated sufficiently (I expect the battery to be discharged. A battery storing ...
Infrisios's user avatar
  • 894
13 votes
Accepted

Could a near earth asteroid perturb a satellite out of earth's orbit?

I think the maximum velocity change from a flyby would help quantify this. $$\Delta v \leq \sqrt{\frac{GM}{r_P}}$$ That is, with perfect relative velocity and angle, the change in velocity from such a ...
SE - stop firing the good guys's user avatar
12 votes

Why aren't space telescopes put in GEO?

At least one space telescope has been put into a geosynchronous orbit (but not geostationary) due to its unique mission: The Solar Dynamics Observatory (SDO) (Wikipedia)(Official mission site). One ...
Ghedipunk's user avatar
  • 1,167
12 votes
Accepted

When and why did three-axis stabilization become prominent in geostationary satellites?

Partial answer: The Symphonie satellites A and B were the first communications satellites built by France and Germany (and the first to use three-axis stabilization in geostationary orbit with a ...
blobbymcblobby's user avatar
11 votes

Thrust and rotation strategy to circularize a standard GTO orbit using ion propulsion?

TL; DR: Trajectory optimization for continuous thrust is difficult and this field is very active in research. 2021 clarifications: Methodology For the least amount of fuel, the best is the thrust the ...
ChrisR's user avatar
  • 6,180
11 votes

Is there a synchronous orbital height for Phobos?

No, or at least there isn't a useful synchronous orbital height. As you pointed out in your question, the mean radius of Phobos is 11.26 km, but if you look closer the sphere of influence of Phobos ...
1337joe's user avatar
  • 7,206
11 votes

Name for geostationary orbit around another planet

Perhaps "Clarke orbit"? The definitions always talk about Earth but at least it's not in the term. https://en.m.wiktionary.org/wiki/Clarke_orbit
Organic Marble's user avatar
10 votes
Accepted

How is the launch window decided for GTO launches?

When I was a bit more active supporting GTO launches, 15 years ago, the following constraints helped shape the launch window (not in any order and I may have forgotten some important points completely)...
Puffin's user avatar
  • 9,684
10 votes
Accepted

Have there ever been cubesats in GEO?

Edited update: Have there ever been cubesats in GEO? Yes, 5 in the period 2021-2023. As of 2023, there are two operational cubesats in GEO, and three that were operational in GEO: Ascent, launched ...
blobbymcblobby's user avatar
10 votes
Accepted

When is the supersynchronous orbit more efficient than a typical Hohmann transfer where inclination change and circularization are simultaneous?

(mostly recycled from What are the benefits of supersynchronous transfer orbits?) Excuse the wall of plots but I really do think they describe it better than my words ever could :) The total $\Delta ...
BrendanLuke15's user avatar
10 votes

How to attain an equatorial orbital inclination from a non-equatorial launch site?

Changing the orbital inclination of an orbit is very energy intensive. But the people making that stuff happen have a few tricks up their sleeve to reduce the amount of energy (Δv to be precise) ...
TrySCE2AUX's user avatar
  • 3,255
9 votes
Accepted

Determine orbit type from TLE

According to Wikipedia, field 8 of TLE line 2 is the "mean motion in revolutions per day"; you can determine the orbital period from this. For geosynchronous orbit, you should expect 1.0 ...
Russell Borogove's user avatar

Only top scored, non community-wiki answers of a minimum length are eligible