A Kerbin orbit that's hard to reach from anywhere but the ground?

[cantab]

What would be an orbit around Kerbin that's reasonably easy to launch into but hard to reach from more typical orbits, for ships leaving the Mun or Minmus, and for ships coming in from interplanetary space?

My thought is a high polar orbit, but still lower than the Mun, oriented noon-mignight. It will certainly be tough to get to from a regular LKO, and the alignment (which will need stationkeeping to maintain since we can't do sun-synchronous orbits in KSP) is unlikely to be matched by an incoming interplanetary vessel. The only easy-ish transfers would be from the Mun or Minmus at the right time, but hopefully the altitude can be picked for the most expensive transfer, factoring that higher orbits make a cheaper direct transfer but lower orbits a cheaper aerobraking one.

Meanwhile if I make the orbit synchronous, or perhaps a period of say 2 or 3 Kerbin days, I may be able to facilitate an easy launch to a quick rendezvous from Kerbin.

In case you're wondering, I want it for a Kerbal prison. Don't want the miscreants being busted out by their former colleagues.

Edited May 2, 2014 by cantab
fixed a typo where "synchronous" should have been "polar"

[BudgetHedgehog]

Geosynchronous polar orbit. Want to keep checking up on them every so often, after all.

[Taki117]

you should have a look at Molniya orbits. They are highly eliptical and highly inclined.

http://en.m.wikipedia.org/wiki/Molniya_orbit

Edited May 2, 2014 by Taki117

[DeMatt]

I'm gonna go with "on the ground". I can't think of any possible Kerbin-SOI orbit that wouldn't be easier to reach from "approaching Kerbin SOI" than it would be from the ground.

Anyways... why imprison kerbonauts in the environment they've dedicated their lives to reaching?

[Skorpychan]

Leave them on Eve. That's downright impossible to escape from.

[Rokker]

I'm gonna go with "on the ground". I can't think of any possible Kerbin-SOI orbit that wouldn't be easier to reach from "approaching Kerbin SOI" than it would be from the ground.

Anyways... why imprison kerbonauts in the environment they've dedicated their lives to reaching?

Indeed, especially given the fact that takes much longer to walk anywhere on Kerbin than it does to launch into orbit.

[FenrirWolf]

lol I like the idea of an Eve prison

[Raven.]

Anyways... why imprison kerbonauts in the environment they've dedicated their lives to reaching?

The idea of an orbital prison has been tossed around quite a bit, especially in science fiction. The idea is that in the event of a jailbreak, there is nowhere to escape to. Prisoner gets out of hand? Just blow them out the airlock. The Mass Effect series had the Purgatory prison, which was more of a ship than an actual station, but still the same concept. Star Trek VI explored the idea of a prison on a cold, lifeless moon, of which unruly prisoners were left to die on the inhabitable surface (with no way of escape).

The issue in real life with an orbital prison is the cost. In addition, the purpose of a prison is to keep people in, not to keep people out. So, in my humble opinion, an orbital prison should be quite easy to access in order to keep the cost of maintaining the station down. If prisoners will only be coming from Kerbin, then you can put the station in whatever inclination you want. I'd probably put it in a 70 km circular orbit at an inclination of 60 degrees. This keeps the access from the ground at a minimal cost while making an intercept from a higher orbit difficult.

Also, I'd put a de-orbit engine on the thing. If there's a major jail break, de-orbit the thing and watch 'em burn .

If you go the route of the moon prison, then you want a moon of which has enough gravity that a kerbal cannot escape from with a jetpack. This leaves mainly the Mun and Tylo as candidates for this. Eve is a great location to, and it analogous to actual hell.

[Kasuha]

In terms of dv, any orbit within Kerbin SOI is easier reachable from anywhere else than from Kerbin surface.

Hardest to reach orbit is probably any circular polar orbit literally meters below the SOI boundary. But that one is also inconvenient to reach from surface.

[cantab]

I'm gonna go with "on the ground". I can't think of any possible Kerbin-SOI orbit that wouldn't be easier to reach from "approaching Kerbin SOI" than it would be from the ground.

Anyways... why imprison kerbonauts in the environment they've dedicated their lives to reaching?

Haha. A fair point, but I want to build a space prison. And yeah, I'm considering the somewhat fanciful idea of a bust-out being attempted from outside.

Eve would be good if I wasn't so hopeless at making precision landings on bodies with atmosphere, based on my performance on Kerbin at least. I'd end up with less a prison and more a light sprinkling of cells over the planet.

[Rokker]

but I want to build a space prison. And yeah, I'm considering the somewhat fanciful idea of a bust-out being attempted from outside.

I think the best thing would probably be a highly eccentric (think 90 km x 70000 km or less if you want to save time reaching it yourself), highly inclined (60-70 degrees), with a argument of periapsis of 90 or 270 degrees. The longitude of the ascending node should be as close to 180 degrees from Minmus' as possible. It would be fairly hard to intercept except at very select intervals and would need a good amount of delta V, the main drawback is, other than the delta v, it would take a long time to reach.

Now, the orbit itself might not be necessarily hard to reach, but interception would be.

Edited May 5, 2014 by Rokker

[Othuyeg]

I'd quess a very elliptical polar orbit would be a hard one to intercept easily.

[RSF77]

A polar orbit isn't much harder than an equatorial one if you are coming from as far out as the Mun or something, its a lot easier to change inclination the farther out you are. Like other posters said elliptical orbits would probably be the hardest to reach, but they can also be hard launching from the ground as well depending on how much time youre willing to warp through to get your prisoners there.

Surprised no one has mentioned this, but why not drag an asteroid into orbit and make that the perfect prison? Alcatraz... the asteroid.

Edited May 5, 2014 by RSF77