97 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
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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
  • 6,926
25 votes
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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
  • 15k
24 votes
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What is the reason for the Ariane 5 launcher with Intelsat 29e losing altitude?

Altitude drops like that are common when the orbital stage has a high-efficiency, low-thrust engine. It takes a few minutes for the upper stage to bring the craft up to orbital speed. During that ...
Russell Borogove's user avatar
24 votes
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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
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Tethered geostationary orbit

At the geostationary orbit, the growth (gradient) of tension will be practically zero, but the value will be far, far from zero. Actually, it will be the highest in the whole tether. After all, the ...
SF.'s user avatar
  • 54.9k
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
  • 7,216
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
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20 votes
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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
19 votes
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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
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
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17 votes
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How do communication satellites remain positioned above a particular region?

Such satellites are in a geosynchronous orbit (GSO), orbiting at an orbital altitude where orbital period matches Earth's rotation on its axis. Their orbital speed is roughly 3 km/s at mean orbital ...
TildalWave's user avatar
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14 votes
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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
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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
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

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

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
  • 9,504
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
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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
  • 6,220
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
  • 7,216
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
  • 9,504
10 votes

What's salvageable from a dead satellite?

It really depends on what stage the satellite is in. If the satellite still functions at a reduced capacity, then likely everything except the batteries, and fuel, is salvageable. Some of the ...
PearsonArtPhoto's user avatar
  • 121k
10 votes

What is the reason for the Ariane 5 launcher with Intelsat 29e losing altitude?

We know that the tough part of getting to space isn't getting there, it's going fast enough to stay there. One of the key reasons is that the rocket is concentrating more on gaining horizontal speed ...
PearsonArtPhoto's user avatar
  • 121k

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