Basic orbit maneuvers

Understanding Kepler's laws

Kepler defined his laws before Newton found out how gravity causes these laws, so it is a nice set of rules of thumb for spaceflight.

1. The first law defines what a orbit in Keplers eyes is: An ellipse (or circle) with the central body in the focal point of it.
2. The second law describes the change in velocity with changing distance to a planet. The further you go away from the planet, the slower you get on the same orbit. It comes from the law of conservation of angular momentum.
3. The third and last law defined the changes in Orbit period.

Raising/lowering periapsis

Raising the periapsis of your orbit is an important maneuver, and is used in a variety of ways, ranging from achieving a stable orbit to rendezvousing with another craft. Along with being quite important, it is also a relatively easy maneuver, so you should take the time to master it. To raise your periapsis, you must fire your main thrusters while facing prograde at your apoapsis. To do this, wait until the ApT (Time to Apoapsis) readout on your Orbit MFD approaches about 90 seconds. At this point, it is necessary to engage the prograde autopilot ([), and wait until your craft has turned completely prograde. If it has not already, wait until ApT reads about 60 seconds before engaging you main thrusters. Watch your periapsis altitude rise (PeA on your Orbit MFD), and kill the thrust when it has reached your desired altitude. As a general rule, anything above 200 km in LEO is safe.

Deorbit

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