Orbit velocity adjustments

[LoganMalone]

I noticed that when I maneuver retrograde that after my orbit velocity reaches to almost zero, it slowly begins to increase. If I leave it alone, it will go well past 31 m/s or higher. Is this a game design or a game programming bug that needs fixed?

Thank you!

[Red Iron Crown]

If you burn retrograde long enough, you will stop moving in that direction and start moving in the opposite direction, so the old retrograde becomes the new prograde.

[LoganMalone]

Correct. I have seen that. My inquiry is why does the orbit velocity not stay at 2 m/s if you burn down to that level. I slowly increases over time with no user input. Any ideas whats causing this? Thank you!

[blizzy78]

Because you're falling towards the planet/moon and go faster at the same time due to gravity.

[Red Iron Crown]

You start falling toward the body you're orbiting, increasing speed.

Edit: Ninja'd

[blizzy78]

Look at it this way: Just because you decreased your lateral velocity over the surface to zero, it doesn't mean you stop being in an orbit. From the mathematical standpoint, you're still in orbit around a single point (the center of the body.) And thus, you will get faster when approaching that point, and get slower when getting away from it. Your previous action of "stopping" does not change that.

[Streetwind]

The slowest point of your orbit is at apoapsis, the fastest point of your orbit is at periapsis.

If you decelerate all the way to near complete standstill, your apoapsis is where you currently are, and your periapsis will be somewhere close to the center of mass of the body your're orbiting, well inside of the body itself. The game never shows you a periapsis that's underground (you can never reach it, because well, lithobraking), but technically it's still there.

EDIT: also ninja'd!

[Yasmy]

You have put yourself in the middle of "What goes up, must come down.", i.e., the apex of a suborbital trajectory.

So what were you trying to achieve?

[Red Iron Crown]

New forum account, likely a new player. I'd bet he was just seeing what would happen.

[Pecan]

Maybe trying to get a Kerbin-stationary orbit?

If you are trying to get a synchronous orbit, so that your ship/probe stays over the same point on the surface you need to take into account that the world is turning (every 6 hours) and, therefore, you need to orbit at sufficient altitude (2 868.75 km) and speed to go 'around' in the same time.

[LoganMalone]

Actually, I'm having a fun time trying to figure all this stuff out. I have a Kerbal stranded on the moon as I write this. The sun is passing and nightfall will soon occur, thus my kerbal will have a very cold night in the darkness inside his new crater home. I was trying to get a rescue mission underway to get him back home with his kerbal family. I made a successful landing on the Mun, however I totally forgot that my capsule had only one seat. Thanks for the replies, they helped me think in a different manner.

[xcorps]

I think the only thing I haven't forgotten to take on a mission at some point or another is fuel. I actually forgot to place radially mounted engines for one flight.

[Streetwind]

My favorite thing to forget is batteries. I like to put probe cores on things I want to deorbit after decoupling, but more often than not they're out of energy before I even stage the decoupler...

[cantab]

The only thing I really tend to forget is REMOVING Kerbals from flights that are meant to be unmanned tests.

[Kryxal]

Better yet, not removing Kerbals from rescue or offloading flights, then having no space for whoever you went to pick up...

[MarvinKitFox]

Stand up.

You are stationary, relative to the ground, right?

Now lift up your feet.

wow, your velocity is increasing!