Inverted Orbit

[pikmin2faner]

Hi I have been wondering about this for a long time and I was wondering

if you could create a inverted orbit going in the other way than Kerbin.

Like this:

-Kerbin->

<-Vessel-

And while doing that, going in the same speed as Kerbin is going in the other way. Is it by that way possible to "Stay" at the same place above Kerbin?

Please reply.

http://www.youtube.com/watch?v=Ys5xApSO7tg&feature=g-upl

[Felsmak]

Sure, but you'd have to bring lots of fuel since the delta-V required for attaining such an orbit is twice the orbital speed of Kerbin. First you have to cancel out the speed you inherited from Kerbin, and then you'd have to accelerate back up in the other direction.

You can't stay above Kerbin that way, just like you can't stay next to a meeting car on the road. Your relative velocities are simply too high.

[N_las]

Unsinn answer ist simply wrong. During the ascent of the Rocket, just head to 270° (west), not the usual 90° (east). You need just a little bit more fuel.

If you orbit Kerbin at the right altitude, your orbital periode matches a day on kerbin, and you "stay" over the same spot. http://en.wikipedia.org/wiki/Geosynchronous_satellite

[draeath]

The only way to "stay" above in one spot, relative to Kerbin, is an equatorial (inclination = 0.0°) at geostationary orbit (I believe 2844km). It's not possible to do it at any other inclination.

To adjust your inclination, circularize your orbit and burn perpendicular to your existing orbit while pointing at the horizon on your nav ball. Eg, if you were orbiting in a currently South-Easterly direction (North-West on the other side), you'd want to burn North-East (or, South-West on the other side). Your apoapsis might shift by a few KM while you do this, so I recommend doing this at 100km or greater, so you don't accidentally aerobrake. Once your engines get you within a degree, use your RCS (if you have it, default key for "forward" is 'H') to fine-tune.

Note, if you get yourself close to a polar orbit (90° or 180°) SAS will spaz out and put you in a roll, so don't use it while you are =/- 5° of 90° or 180°.

[EndlessWaves]

Unsinn answer ist simply wrong.

Not necessarily, it depends on whether pikmin2faner is asking relative to a spot on the planet's surface or relative to the planet as a whole.

The only spots you can stay fixed with respect to the planet as a whole is ahead of and behind in it's orbit if you orbit the sun in the same orbit as kerbin.

A 270° orbit that was a year long to stay in the same place relative to kerbin is possible under some conditions but not those currently in game as you'd leave kerbin's sphere of influence and end up orbiting the sun before you make it to such a large orbit.

As far as I know there's no way to stay between Kerbin and the sun permanently.

Edited September 30, 2012 by EndlessWaves

[Felsmak]

Oh, wait. You meant staying above the same spot in a retrograde orbit around Kerbin? I thought you meant staying near Kerbin in a retrograde orbit around the Sun. My bad.

Edited September 30, 2012 by Felsmak

[Will_hynes]

I don't know what you guys are talking about, but going in the opposite direction of Kerbins rotation would make it impossible to "stay" over one spot. In order to do that, you have to following the rotation, so going the other way would like like you're orbiting Kerbin twice as fast.

[-Gamah]

If I'm understanding, the OP wants to be in a kebol orbit equal to that of kerbin, but behind it by a phase angle of a few degrees.

[Ziff]

You can only stay in a geosynchronous orbit (your view of Kerbin won't change) by orbiting in the same direction as Kerbin at a very specific orbit height(that I can't remember off the top of my head). However, you can certainly orbit opposite Kerbin's direction of rotation by launching with a heading of 270° and maintain a specific altitude, but your view will continuously be changing.

Edit: Fixed 270°, thanks Vanamonde.

Edited October 1, 2012 by Ziff

[Yeomans]

If you're asking if it's possible to be orbiting the sun while constantly "above" kerbin, it's impossible.

Newton's Law of Universal Gravitation states this explicitly.

F = G((m₁m₂)/(r²))

F is the force of gravity, G is the Gravitational Constant, m1 is the mass of the first object, m2 is the mass of the second object, and r is the distance between the two objects.

The force of gravity increases when the distance between two objects becomes closer, and decreases when the objects are further apart. When the force is higher, more speed is required for a stable orbit, and less speed is required when the force is lower. Therefore, to orbit the sun at the same speed as Kerbin, you have to be the exact same distance from the sun as Kerbin. You cannot obviously be above kerbin and orbiting the sun, because then your distance from the sun is not the same.

Now, if you're asking if you can orbit the sun in the opposite direction of kerbin, and stay "above" kerbin, also impossible.

You're travelling in different directions around the sun. If you were travelling around the sun in the opposite direction of kerbin, you would only meet at the point of the escape burn. Furthermore, if you did your escape burn close enough to kerbin, upon your first encounter with kerbin, you would be pulled back into kerbin's sphere of influence, which would either alter your solar orbit greatly, or even possibly put you back in orbit around kerbin.

I hope this all makes sense.

[Bluejayek]

Sure, but you'd have to bring lots of fuel since the delta-V required for attaining such an orbit is twice the orbital speed of Kerbin. First you have to cancel out the speed you inherited from Kerbin, and then you'd have to accelerate back up in the other direction.

You can't stay above Kerbin that way, just like you can't stay next to a meeting car on the road. Your relative velocities are simply too high.

Actually if you are smart about it, the delta V required is far less then twice kerbins delta V.

See my posts in the following thread.

http://kerbalspaceprogram.com/forum/showthread.php/18877-Kerbol-polar-orbit?highlight=Polar+kerbol

It takes only around delta V equal to kerbins orbital speed if you do a high bi-elliptic transfer.

Also, with the new nuclear engines I have managed to build a craft that has enough delta-V to brute force this anyways.

[phoenix_ca]

The geostationary orbit altitude of Kerbin is 2870km (displayed as 2.870Gm by MechJeb). Getting a satellite up there in a stable circular orbit will mean it's orbit is geosynchronous (it's orbital period is equivalent to the rotational period of Kerbin). Having it also at an inclination of 0º means it's geostationary (it's always above the same longitude and latitude of Kerbin).

[mrdest21]

It's like 3 threads ran into each other and only one came out...

[phoenix_ca]

Well it's hard to know exactly what the OP meant by staying in a place relative to Kerbin, because even that can be interpreted in a number of ways. Relative to Kerbin's surface or center? Relative to it in relation to another celestial body (e.g. the sun) or not? Too many variables, need more data.