Orbits - Possible?

[Kar]

Is it possible to establish a orbit around a planet, be that Kerbin or whatever, closer to the poles with a inclination of 0 (zero) degrees? In a way parallel to a equatorial orbit ?

[Snark]

59 minutes ago, Kar said:

Is it possible to establish a orbit around a planet, be that Kerbin or whatever, closer to the poles with a inclination of 0 (zero) degrees? In a way parallel to a equatorial orbit ?

No.

Every orbit-- whether it's circular or elliptical-- always is in a plane that passes through the center of the planet.  If you want to go over the north pole, then you'll have to go over the south pole, too.

If you want to loiter as much of your time over the north pole as possible, you could put yourself into an elliptical orbit that has a high apoapsis over the north pole, and a low periapsis over the south pole.  That way, on each orbit the satellite will make a long, slow, high pass over the north pole, then a quick whip round the south pole, so it's spending most of its time in the north.  But there's no way to just orbit around the north pole parallel to the equator.

[Temstar]

No it's not possible in KSP, your orbit always cross the equator at two points.

In real life it may be possible with fun tricks like statite, which continuously modify its orbit.

[Snark]

16 minutes ago, Temstar said:

In real life it may be possible with fun tricks like statite, which continuously modify its orbit.

..where by "real life" you mean "has never been done but is theoretically possible, though practical considerations are severe enough to make it unlikely for the foreseeable future." 

The main issue is that doing that would require some form of continuous propulsion that doesn't require spending reaction mass, and the only ways we know to do that (i.e. solar sails) have such vanishingly tiny thrust that it would be a big challenge to keep the craft lightweight enough to maintain the relatively large accelerations needed for a statite.

[worir4]

An orbit is centred on the bodies centre of mass. In KSP that is the centre of the planets/moons. So the craft must always be an elipse around that point.

In real life there are non spherical bodies such as astroids and some moons. (See wiki for Mars' moons).

For these a craft still orbits the centre of mass but this point is not always in the centre of the body so an orbit that you describe is possible.

[swjr-swis]

27 minutes ago, Temstar said:

No it's not possible in KSP, your orbit always cross the equator at two points.

Except when it crosses it at all points.

[Temstar]

7 minutes ago, Snark said:

..where by "real life" you mean "has never been done but is theoretically possible, though practical considerations are severe enough to make it unlikely for the foreseeable future." 

Yes, hence the "may" part

Another way to look at it is a nuclear ramjet that's circling the polar region ala Project Pluto. It's also continuously modifying its "orbit" by sucking air in at the front, heating it up in its reactor and shooting it out the back. It also uses its wings to deflect air to create upwards thrust to counter gravity. Nuclear power means it's really good at this which allows it to "orbit" at way below normal orbital velocity and way deep in the atmosphere for months.

Rather extreme example right? But the idea is the same: if you use thrust to modify your trajectory constantly you can go into all sort of funny orbit.