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[TheBronzePickle]

The thing about a hyperbolic orbit is that if there's no other gravitational mass, the hyperbolic 'orbit' will become a literal orbit. It would just take an incredibly long amount of time, one which most people would never have the patience (or lifetime) to wait for.

[Gimhalos]

So I played for a few hours last night. I made a giant rocket that reached over 4600 m/s at it's top speed. I ran it overnight out of curiosity. 185,120 km and climbing, still going 3.8 km/sec, and I can no longer see the earth. I think I can make it more efficient, actually. I bet I can hit 7 km/sec if I do a complete redesign.

[Sirian]

According to wikipedia, it IS in fact possible to escape gravity, even with only one source of gravity in the entire universe. But yea, 10km of altitude is not enough at slow speeds. Just for comparison, our moon is around 400 000 km away from earth, and is still strongly bound (although the kerbal moon should be closer to the planet).

Mathematically speaking, it is possible to calculate the limit towards which your speed tends as you move away from the planet. if the limit is superior to 0, you have effectively reached escape velocity (but "escape speed" is more correct). The only time it's impossible (at least with normal physics) to reach escape velocity, is inside a black hole's event horizon, because you'd need to go faster than light to escape.

Also, Kerbal seem hard to escape because it has an unnatural density, so what may feel like an escape speed for earth won't always be enough here. It's like the slope is steeper or something.

[Leyic]

The thing about a hyperbolic orbit is that if there's no other gravitational mass, the hyperbolic 'orbit' will become a literal orbit. It would just take an incredibly long amount of time, one which most people would never have the patience (or lifetime) to wait for.

Hyperbolic and parabolic orbits are not closed like elliptic orbits. If you are on such an orbit and moving away from Kerbal, you will never again head towards Kerbal*. There's absolutely no need for another mass to continue pulling you away from it.

*Assuming you don't use your rocket to push you onto a different orbit.

[Soulwynd]

You should have read under the misconception paragraph:

Escape velocity is sometimes misunderstood to be the speed a powered vehicle, such as a rocket, must reach to leave orbit and travel through outer space. The quoted escape velocity is commonly the escape velocity at a planet's surface, but it actually decreases with altitude. It is the speed above which an object will depart on a ballistic trajectory, i.e. in free-fall, and never fall back to the surface nor assume a closed orbit. Such an object is said to "escape" the gravity of the planet.

Notice escape is in quotes because you never escape gravity. Ever. You can be at one "end" of the universe and an object at the other "end" will still have an irrelevant tiny bit of gravity affecting you. The effect of gravity is inversely proportional of the square of the distance... So yeah. There's always some background gravity, just never 0.

[breadbocks]

Yeah, in theory, you could go 10000000000000 km away, and if you let time run long enough, you'd find you'd crashed into kerbal.

[Leyic]

Yeah, in theory, you could go 10000000000000 km away, and if you let time run long enough, you'd find you'd crashed into kerbal.

Unless your speed relative to Kerbal is commensurate with the escape velocity of Kerbal at 1e13 km.

The thing to remember here is that escape velocity always applies; you can't just "escape" and then reduce your velocity to zero.

[breadbocks]

Nup. Can't escape. It'll slowly but surely slow you down, and bring you home.

[Leyic]

Once you've reached infinity. Good luck with that.

[Sensei]

Yeah, in theory, you could go 10000000000000 km away, and if you let time run long enough, you'd find you'd crashed into kerbal.

Unless your speed relative to Kerbal is commensurate with the escape velocity of Kerbal at 1e13 km.

The thing to remember here is that escape velocity always applies; you can't just "escape" and then reduce your velocity to zero.

If you had ACCELERATION, you could be unaffected. No amount of speed will ever cause you to escape gravity. Gravity will accelerate you and make your speed change.

[Rakonas]

You're all forgetting that you'll actually just end up in an extremely elliptical orbit and never actually hit the planet again.

[Soulwynd]

At a certain distance, the force exerted to your ship by a body's gravity can be so minimal you can rule it out, as the time it would take to accelerate you back on to the planet would be ridiculous and in certain cases, could be countered by other gravities.

Such as how the moon's gravity doesn't overrule earth's gravity even when you have a high orbit (even tho it does cause the orbit to be elliptical).

[Gimhalos]

The escape velocity is the velocity at which an object can escape the gravitational pull of an object, i.e. make it to infinity. As far as we know, it is not possible to escape a gravitational pull (physics assumes that things have a pull on each other at infinity. This is not experimentally verified and we have not discovered the all-elusive graviton) since the distance "infinity" does not actually exist.

The confusion in this thread, I believe, is that people are mistaken on the definition of escape velocity. If your kinetic energy exceeds the potential energy FROM YOUR CURRENT POSITION TO INFINITY, you have reached the escape velocity whether or not you can actually clear the gravitational field. It's a defined, arbitrary term, not something that should be taken literally.

[Soulwynd]

You're all forgetting that you'll actually just end up in an extremely elliptical orbit and never actually hit the planet again.

No such thing in reality. The value required for an orbit to last forever is so precise and actually varies so much, any given orbit is always falling or escaping. It can be by a minimal amount, but it's happening.

Eg. The moon is distancing itself from us by 38mm every year.

The escape velocity is the velocity at which an object can escape the gravitational pull of an object, i.e. make it to infinity. As far as we know, it is not possible to escape a gravitational pull (physics assumes that things have a pull on each other at infinity. This is not experimentally verified and we have not discovered the all-elusive graviton) since the distance "infinity" does not actually exist.

The confusion in this thread, I believe, is that people are mistaken on the definition of escape velocity. If your kinetic energy exceeds the potential energy FROM YOUR CURRENT POSITION TO INFINITY, you have reached the escape velocity whether or not you can actually clear the gravitational field. It's a defined, arbitrary term, not something that should be taken literally.

We don't know about infinity either. Any age/size of the universe is hypothetical. It could be literally infinite or it could not be. Bigbang is just the most acceptable theory right now, but we all better keep an open mind.

There's no confusion really, we're just talking about literally escaping gravity. A ballistic trajectory can have a speed of no return where it will simply not come back to the planet, but that doesn't mean the planet's gravity isn't affecting you.

[Rakonas]

You're all forgetting that you'll actually just end up in an extremely elliptical orbit and never actually hit the planet again.

No such thing in reality. The value required for an orbit to last forever is so precise and actually varies so much, any given orbit is always falling or escaping. It can be by a minimal amount, but it's happening.

Eg. The moon is distancing itself from us by 38mm every year.

The escape velocity is the velocity at which an object can escape the gravitational pull of an object, i.e. make it to infinity. As far as we know, it is not possible to escape a gravitational pull (physics assumes that things have a pull on each other at infinity. This is not experimentally verified and we have not discovered the all-elusive graviton) since the distance "infinity" does not actually exist.

The confusion in this thread, I believe, is that people are mistaken on the definition of escape velocity. If your kinetic energy exceeds the potential energy FROM YOUR CURRENT POSITION TO INFINITY, you have reached the escape velocity whether or not you can actually clear the gravitational field. It's a defined, arbitrary term, not something that should be taken literally.

We don't know about infinity either. Any age/size of the universe is hypothetical. It could be literally infinite or it could not be. Bigbang is just the most acceptable theory right now, but we all better keep an open mind.

There's no confusion really, we're just talking about literally escaping gravity. A ballistic trajectory can have a speed of no return where it will simply not come back to the planet, but that doesn't mean the planet's gravity isn't affecting you.

I don't personally understand why you're all discussing reality instead of kerbality and I think there's a mix of some people discussing the game's physics and some discussing real life physics. Personally I don't believe there was a big bang, I think some programmer designed everything and it's still in an alpha stage.