Hard-Impossible Orbit

[spadeking12]

I just made a random space craft and well it is still going around Kerbol. Not Kerbin, Kerbol. If I was to put this on the time warp of x1 it would take about 2 years before it returned to Kerbin I wrote down a few facts about it.

Ap:14,211,806,219m

Pe:8,881,223,989m

It takes 84 irl days to rotate Kerbol.

I just wanted to share this in the forums. Can someone tell me it something even close to this has happened to them before. I only launched from kerbin and came nowhere close to hitting the mun.

[Cykyrios]

Oh, I have a friend playing on the demo who cannot yet orbit, but has already reached escape velocity and drifted around Kerbol

If you have some fuel left, now's your chance to try and get back to Kerbin safe!

[Ted]

Welcome to the forums!

I would say that most active users have probably reached Kerbol orbit at some point (normally due to a badly timed burn to try and get to Minmus).

Now the real challenge is to try and get change orbit so that you hit the Sun!

PS; Watch out for the 'Space Kraken'

[spadeking12]

I ran out of fuel when I made the orbit around Kerbol trying to target the Mun so It will take a long time but it will crash into Kerbin or at a very low chance the Mun and now it is past 2 years so my estimate was off.

[maltesh]

Getting back to Kerbin can be difficult, but not impossible... unless you don't have any fuel.

If you don't have any fuel, and didn't plan your departure very carefully, the most likely result is /extremely/ long periods between passes through the Kerbin SOI, on the order of decades to centuries, and and a decent chance of ultimately being thrown by one of these rare passes onto an escape trajectory of the Kerbol system entirely.

[Vostok]

I find it easier to get back to kerbin than to do a sundive manoeuvre. Getting back to kerbin is just like rendezvousing in orbit, but sundiving requires a ton of fuel. I see no real point in sundiving, personally

[Emphursis1]

Welcome to the forums!

I would say that most active users have probably reached Kerbol orbit at some point (normally due to a badly timed burn to try and get to Minmus).

I've sent more crafts into Kerbol orbit than I have Kerbin :|

[TheDarkStar]

IF you want to know that orbital period, it's

T = 2pi sqrt(a^3/u)

a is the semimajor axis in meters, and u is the standard gravitational constant.

Edited August 18, 2012 by TheDarkStar

[Winter Man]

I find it easier to get back to kerbin than to do a sundive manoeuvre. Getting back to kerbin is just like rendezvousing in orbit, but sundiving requires a ton of fuel. I see no real point in sundiving, personally

Doesn't really need that much fuel to do, you just incrementally increase your apoapsis and decrease your periapsis. I did it in an average shuttle. Still though, you're right in saying there's no point (any more).

[maltesh]

I find it easier to get back to kerbin than to do a sundive manoeuvre. Getting back to kerbin is just like rendezvousing in orbit, but sundiving requires a ton of fuel. I see no real point in sundiving, personally

Sometimes, you've just got to dump things into the sun.

A bi-elliptic transfer sundive can cost less than half the delta-V of a hohmann transfer sundive, at the cost of taking much, much, much longer. If your Munlander has a reasonable amount of fuel on landing, it's probably capable of a bi-elliptic sundive.

[flaillomanz]

And given epic timing, you may even propel yourself at nullspeeds into Kerbin. Good luck with that; the odds of that are indeed heavily stacked. Why, at those speeds it's probably possible to pass on a tangent to the ground, all the way through the atmosphere. We need to test this.

[CobraA1]

Nullspeeds? What's that?

[flaillomanz]

Ludicrous ones. Usually seen after a sundrop, when the speedo isn't long enough to contain all the numbers.

[spikeyhat09]

once i got a rocket (without exploiting the fuel bug) to venture within 2,000,000 meters of Kerbol. its speed at periapsis was like 180,000 m/s or something

[spikeyhat09]

Doesn't really need that much fuel to do, you just incrementally increase your apoapsis and decrease your periapsis. I did it in an average shuttle. Still though, you're right in saying there's no point (any more).

No point? i thought successful Kerboldives resulted in a bug that makes you go at like 20,000,000 m/s or something. did they fix that?

[maltesh]

In the free version, Kerbol had no collision surface, and was treated as a gravitational point in space. You could pick up speeds in excess of several thousand kilometers per second by passing near its center, and floating point errors compounded by the Oberth effect made it possible to carry huge amounts of that velocity back out.

In the paid version,there's an invisible solid surface at an altitude of about 4500km above Kerbol's defined surface. Nearly all objects that smack into that will do so at a couple hundred kilometers per second, and be destroyed. Scraping (or hitting) Kerbol at over 200km/s is probably only barely in the realm of possible now.

Though if the Kraken is slain, a bi-elliptic sundive into a sunscraping powered gravitational slingshot would be a pretty good way to carry very large velocities into the interstellar void.

Edited August 18, 2012 by maltesh

[spikeyhat09]

In the free version, Kerbol had no collision surface, and was treated as a gravitational point in space. You could pick up speeds in excess of several thousand kilometers per second by passing near its center, and floating point errors compounded by the Oberth effect made it possible to carry huge amounts of that velocity back out.

In the paid version,there's an invisible solid surface at an altitude of about 4500km above Kerbol's defined surface. Nearly all objects that smack into that will do so at a couple hundred kilometers per second, and be destroyed. Scraping (or hitting) Kerbol at over 200km/s is probably only barely in the realm of possible now.

Though if the Kraken is slain, a bi-elliptic sundive into a sunscraping powered gravitational slingshot would be a pretty good way to carry very large velocities into the interstellar void.

thank you for the explanation