Height of a 'kerbinl stationary' orbit?

[Callmedave]

Id like to set up a station directly above the kerbal space center, Does anyone know what altitude it would need to be at to stay directly above a fixed point on the equator (geo-stationary?)

[eurybaric]

the KSP wiki has all the info you need for these kinds of things. Kerbin Synchronous Orbit = 2 868.75 km.

Cheers!

[Callmedave]

Great! thanks!

[joppiesaus]

Yeah, I had a messed-up-synchronous-orbit thanks to my separator just an hour ago while making(may not be the correct word) synchronous orbit.

[dr_jt]

Consider Kerbals

Edited June 6, 2013 by dr_jt

[tomf]

You can only have stationary orbits above the equator, basically you orbit at teh exact height where you go round the planet exactly once a day. As you are moving the same speed that the planet rotates, for someone standing on the ground you appear not to move. To pick a particular longitude you would go to an orbit slightly above/below the stationary orbit and when you are in the right place you move to the stationary orbit.

[nyrath]

This is also called a "Clarke" orbit, after Sir Arthur C. Clarke who first proposed it. He often wistfully wondered if he could have patented the idea.

Around Earth real-estate in the Clarke orbit is next to non-existent. Everybody and his brother wants to put communication satellites there, and the satellites cannot be too close or their radio broadcasts interfere with each other. The orbit is packed to the gills with satellites, and competition for empty slots is beyond cut-throat.

[Jason Patterson]

This is also called a "Clarke" orbit, after Sir Arthur C. Clarke who first proposed it. He often wistfully wondered if he could have patented the idea.

That would have been a neat trick, considering the fact that he wasn't the first to come up with the idea, or even the first scifi author to use it.

[Fyrem]

.... I was pretty sure he was.

[Crown]

the KSP wiki has all the info you need for these kinds of things. Kerbin Synchronous Orbit = 2 868.75 km.[...]

Don't spend too much time on making your Apoapsis and Periapsis to exactly 2'868.75 km. What defines your orbital period is the Semi-Major-Axis (SMA), calculated by (Ap + Pe + 2 * PlanetRadius )/2.

Get your SMA to 2'868.75+600km and your satellite will stay above the same location more precisely. It will jitter a little bit over that point because of the altitude difference of Ap & Pe. But Apoapsis and Periapsis are more stable in this case than by trying to get them to the same value (which is almost impossible).

With inclined Geosynchronous Orbits you can get satellite track like these:

note that this an earth picture. Kerbin inclinations might differ

[Trueborn]

So, assuming one gets a satellite into a roughly kerbalsynchronus orbit, is there a way to get it to continuously point to the nadir vice having it not rotate? That would seem to be a somewhat important aspect of a comm satellite. Would just the right amount of trim in pitch (for example) do the trick, or would I need something more advanced?

[Jason Patterson]

No, it's not possible in game without constant monitoring. When you go to non-physics timewarp, move more than 2.2km away from a vehicle, or go to the space center or tracking station or quit the game, the vehicle is 'packed' and 'put on rails.' The relative positions and orientations of all of the parts of the vehicle are recorded and the properties of the center of mass of the ship are used to calculate the orbit that the ship is moving along.

The upside of this process is that it allows the game to simulate dozens of vehicles simultaneously without having to actually simulate all of their individual parts. The downside is that the game ignores all physics other than straightforward orbital mechanics (and hitting the ground.) It will not retain the rotational properties of the vehicle, it sometimes turns it in unexpected directions, and it will not perform any aerodynamic calculations for a vehicle in a planet's atmosphere (though it will auto-destruct any vessel that gets too low, ~22km on Kerbin, as I recall.)

If you really wanted your vessel to always point downward, you would have to introduce a rotation (an incredibly incredibly slow rotation) to it so that it spun once per orbit, in exactly the same way that the moon does as it orbits Earth. It's impractical to actually do this, since you'd be talking about moving 1 degree per minute.

[Jason Patterson]

.... I was pretty sure he was.

No, he certainly popularized it, but he was nowhere near the first to come up with the idea of a geostationary orbit (which is what a Clarke orbit is.) I don't remember who was the first, but I bet google knows...

Arthur C Clarke wrote about worldwide communications satellites in this type of orbit in 1945 in Wireless World magazine.

Prior to that, George O Smith wrote a series of scifi stories called the Venus Equilateral series that featured communications satellites in geostationary orbits (as well as satellites placed at the Lagrangian points.) Clarke apparently wrote an introduction to the collected stories noting the idea.

Prior to that, in 1928 Herman Potocnik wrote about inhabited space stations in geostationary orbits. According to wikipedia this was also the first description of the architecture of a space station.

Prior to that, Hermann Oberth (yes, that Oberth) wrote about satellites in geostationary orbits in 1922.

Prior to that, Konstantin Tsiolkovsky (yep, that Tsiolkovsky) apparently wrote about the orbit in the late 1800's-early 1900's. I can't find the exact paper where this was supposed to have happened, but there are a bunch of sources that mention it.

Clarke's contribution to the thing was to suggest that widespread communication could be done from these satellites. He didn't realize that such an orbit existed, or that it would be a good place to put a satellite, or a space station, or that it would be particularly useful for communications satellites.

Edited May 11, 2013 by Jason Patterson
poor wording

[Trueborn]

No, it's not possible in game without constant monitoring. When you go to non-physics timewarp, move more than 2.2km away from a vehicle, or go to the space center or tracking station or quit the game, the vehicle is 'packed' and 'put on rails.' The relative positions and orientations of all of the parts of the vehicle are recorded and the properties of the center of mass of the ship are used to calculate the orbit that the ship is moving along.

The upside of this process is that it allows the game to simulate dozens of vehicles simultaneously without having to actually simulate all of their individual parts. The downside is that the game ignores all physics other than straightforward orbital mechanics (and hitting the ground.) It will not retain the rotational properties of the vehicle, it sometimes turns it in unexpected directions, and it will not perform any aerodynamic calculations for a vehicle in a planet's atmosphere (though it will auto-destruct any vessel that gets too low, ~22km on Kerbin, as I recall.)

If you really wanted your vessel to always point downward, you would have to introduce a rotation (an incredibly incredibly slow rotation) to it so that it spun once per orbit, in exactly the same way that the moon does as it orbits Earth. It's impractical to actually do this, since you'd be talking about moving 1 degree per minute.

I was thinking that was the case, but thanks for the confirmation.

[Pugspaceprogram]

Just so EVERYONE knows, the EXACT height is 2868723 meters.