Is it possible to have 0 m/s velocity in space?

[AXCN_K.S.P]

I was thinking, if you launch a rocket into deep space, and then at a certain point you burn retrograde to kill off all your speed, would you be completely still (theoretically speaking)? Or would having engines pointing in all directions towards the CoM work better whilst in space? In other words, is it possible to stop the altimeter from increasing or decreasing and stay constantly at a specific altitude relative to the current object you are orbiting?

Edited June 27, 2015 by AXCN_K.S.P

[Crzyrndm]

1) 0m/s relative to what. To be really obviously picky, a vessel is always travelling at 0m/s relative to itself (and is never moving at 0m/s relative to all other objects either...)

2) Gravity has no limit (or rather, a limit you could probably hit in KSP. If you did somehow manage to get far enough out into deep space that gravity was being rounded to zero by floating point errors in a double precision value, I think you're likely to have bigger issues...) and does not stop accelerating objects, so unless you have some form of propulsive system you will never maintain 0m/s (relative to the star...) for more than a fraction of a second

[Evanitis]

Well, gravity would pull you towards the center of your current SoI. But it you pointed your engine towards that spot and managed to find the exact thrust to nullify the g-force... yes it should be working until you run out of fuel.

I'd probably try it with ion engines. As I recon gravity is a really weak force, so really weak engines feels best to find the sweet-spot.

[Cerbis]

Sorry, there's no "parking" in space!

In real life, gravity works over infinite distances. To put it simply; if there were only two objects in the universe, they would eventually fall towards each other. In Kerbal Space Program, it works a little bit differently (gravity is still functionally infinite as noted above) but not quite enough to make a difference.

Being a video game, KSP has an internal coordinate system. Objects exist in set, discrete locations that are so tightly packed that you don't see the 'jump' from one spot to another as you travel, it all looks smooth to you. It would be possible to cancel out your velocity with respect to this coordinate system in the game engine... for a moment.

The reason for that is that no matter where you are in the game world, you're always pulled on by gravity from some source. Even if you fly away from all other planets and bodies in the game, you'll always be under the influence of the Sun. All other objects around the Sun in the game also travel around it, so even if you cancel your velocity with respect to the coordinate system used internally by the game engine, you won't be going at 0 m/s compared to the planets, and you won't be able to stay stationary with respect to the coordinate system for very long either, as you'll be invariably pulled towards whatever you end up orbiting!

So like with so many things in life, the answer is "Yes, and no, depending on how you look at it".

But mostly "No"!

[Evanitis]

even if you cancel your velocity with respect to the coordinate system used internally by the game engine, you won't be going at 0 m/s compared to the planets

I feel you are nitpicking here... I'm pretty sure the OP didn't meant to become stationary relative to -every- object in space. That would require to nullify the orbit of all planets and asteroids. But even that is pretty easy to achieve - you just need to press 'esc'.

[Ripper2900]

In the RealWorld Lagrange points, it's possible to have an almost 0 velocity relative to the (orbiting) reference frame of the parent planet.

It doesn't work that way in ksp though.

These points are probably the closest you'll get to a "standstill in space". The fact that a velocity needs a reference frame makes it impossible to achieve a zero velocity situation, as space is not absolute (as far as science goes. Religious people may tell you there's a center of the universe)

[Sharpy]

Kudos for Lagrange Points. Note only two of them are stable, the others are in unstable balance so need powered stabilization. (plus other bodies disturb the system). OTOH you have surely tried building some hovercraft in KSP (who didn't?) and try to stay motionless relative to the ground by hovering with engines roaring at high thrust.

Move your hovercraft to the edges of Kerbin SOI and try the same. Your thrust requirements become suddenly very small: the Ant engine with thrust limiter pulled down to 5% and barely a few notches of throttle at that will keep you "hovering" opposing Kerbin's gravity at zero orbital speed.

...The LISA experiment by ESA will feature three satellites at a standstill relative to Earth.

To achieve that, they will have some very special ion engines: 0.001N of thrust, but ISp going into tens of thousands.

That way they can thrust against gravitational pull in specific locations near Earth's Hall Sphere (SOI in KSP terms) by staying in powered flight for years.

[carlorizzante]

I felt bad to ask her. She had to meditate for days, but finally my yoga teacher came back with an answer to your question, and she told me that no, it's impossible to stop the never ending flowing of happenings.

You can't achieve 0 m/s in space. Neither anywhere in this Universe. Perhaps in some other parallel Universe you could... but you cannot go there either.

[BlueCanary]

There was a proposal (not sure which agency, or whether they plan to do it) to put a spacecraft above the north pole of the sun, at a distance where the thrust from its solar sail would match gravity so it would stay in place. That's the closest I can think of to 0 orbital velocity without thrust (well, there is thrust, but no propellant on board)

[Mipe]

It would still have the Sun's velocity relative to the galaxy.

[Cerbis]

I feel you are nitpicking here...

Oh, I am most definitely nitpicking there, in the interest of completeness, and to make the point that even in the game you'll always be moving with respect to something else, no matter what you do! Indeed you cannot become stationary relative to every object in space, and I didn't think that's what the OP meant.

[AXCN_K.S.P]

Ok, to be specific all I'm asking for is that in space can you hover in a certain spot, without changing the position on the map (it doesn't matter really about the velocity since the universe is expanding at a rate of 74.3 plus or minus 2.1 kilometers per second per megaparsec (Googled it)). It doesn't matter if cheats, plug-ins or mods were needed, I just wanted to orbit around Kerbin while being completely still as the solar system revolves around.

[Murph]

Ok, to be specific all I'm asking for is that in space can you hover in a certain spot, without changing the position on the map (it doesn't matter really about the velocity since the universe is expanding at a rate of 74.3 plus or minus 2.1 kilometers per second per megaparsec (Googled it)). It doesn't matter if cheats, plug-ins or mods were needed, I just wanted to orbit around Kerbin while being completely still as the solar system revolves around.

Synchronous orbit

Not sure, as you're making a rather odd request and the descriptions are not entirely unambiguous, but that might be what you're looking for. "…without changing the position on the map" doesn't really mean anything, without defining "relative to <some other thing>". If you want to be stationary relative to the surface of the body you are orbiting, then you want a synchronous equatorial orbit.

KSP does not model the expansion of the universe.

[Red Iron Crown]

While under the influence of gravity in a 2-body model while flying in vacuum and not thrusting it is impossible to remain at 0m/s speed relative to the parent body, full stop. You can hit 0m/s instantaneously but can't remain there.

[Cerbis]

You could try to go into an orbit around the Sun in the game universe at the exact distance and speed that Kerbin orbits at. That would let you be free of Kerbin's gravity while still watching all the planets move with respect to Kerbin; Kerbin would stay at the same distance away from you.

Alternatively, you could put yourself in any other orbit around the Sun, I'd suggest a closer one, so all the planets would move at different velocities compared to your craft. Inner planets would go faster than you, outer ones would go slower.

If you want to just watch the planets spin, you can go into the Tracking Station, double-click on the Sun to change focus to it, and then use Timewarp to watch the planets go round and around!

[GoSlash27]

Ok, to be specific all I'm asking for is that in space can you hover in a certain spot, without changing the position on the map (it doesn't matter really about the velocity since the universe is expanding at a rate of 74.3 plus or minus 2.1 kilometers per second per megaparsec (Googled it)). It doesn't matter if cheats, plug-ins or mods were needed, I just wanted to orbit around Kerbin while being completely still as the solar system revolves around.

AXCN,

Sorry, I'm trying to follow, but this question involves mutually- exclusive concepts. You can't orbit a body *and* be completely still. Orbiting requires motion.

Also, you have to define what "being still" means. Zero velocity in reference to what?

Best,

-Slashy

[BlueCanary]

If you mean stationary relative to a point on the surface of a body, you need a synchronous orbit.

If you mean stationary relative to a planet, you need an orbit around the sun at the same altitude as that planet, so you will remain at the same distance from that planet at all times.

If you mean an orbit with 0 velocity around it's parent body, that's by definition impossible, like GoSlash27 said. The nearest thing to it requires some sort of continuous force - from an engine, a solar sail, from buoyancy if you're in atmosphere - to oppose the unavoidable gravity of the body who's sphere of influence you are in. In KSP this would require that the vessel in question stay focused, as otherwise it would stop providing thrust.

To hold a certain position on the map you would need 0 relative velocity to the sun, which would be impossible without continuous thrust, which would be extremely impractical if not impossible in KSP, and definitely not possible in stock. So, if I am interpreting you're question right, it's impossible, but for whatever practical purpose you need this for there is probably an alternative you can use. What did you have in mind to do with 0m/s velocity?

[Mastikator]

If you put yourself in a perfect kerbin stationary orbit and set the velocity meter to surface mode you'll read 0m/s while also not having your altmeter vary.

That's the only way to have no velocity in space.

[Snark]

It would still have the Sun's velocity relative to the galaxy.

Which is just another way of saying that in the real world, there's no such thing as "absolute velocity of zero" because "absolute velocity" is a meaningless concept. Velocity is always relative to something-- there is no fixed frame of reference.

But now we're in the realm of actual science and/or philosophy, not KSP.

[GDJ]

Personal slowest after leaving Kerbin: 3 m/s for about 5 minutes before it started it's slow fall back down.

In space terms, that's pretty much stopped.

[Xannari Ferrows]

It would be very difficult, but you could apply retrograde thrust while having no lateral velocity. That thrust-to-weight would have to be exactly equal to 1, so good luck.

EDIT: But, you are moving 0 m/s relative to the coordinate system, if you want to count that, even though it has no bearing on reality.

[Specialist290]

It's already been stated in greater or lesser degrees throughout the rest of this thread, but the big takeaway is: In matters dealing with space travel, your frame of reference is important. That principle applies in many situations beyond this specific one, so it's a quite handy one to remember.

[rofltehcat]

I had a bug with a (badly designed) craft that some fairings got stuck on. It started to vibrate so I thought I'd at least salvage the satellite and flew its to its orbit. After I was done I switched back to the space plane (which was marked as "landed" in map view) and it was stuck in space with 0 m/s relative speed to Kerbin. If you can do that in a solar orbit you'd have 0 relative speed (well, galaxy still moves but not in game)