Orbit Insertion - Deceleration

Deceleration

The first kind of orbit insertion is used when capturing into orbit around a celestial body other than Earth, owing to the excess speed of interplanetary transfer orbits relative to their destination orbits. This shedding of excess velocity is typically achieved via a rocket firing known as an orbit insertion burn. For such a maneuver, the spacecraft’s engine thrusts in its direction of travel for a specified duration to slow its velocity relative to the target body enough to enter into orbit. Another technique, used when the destination body has a tangible atmosphere, is called aerobraking, which uses the friction of atmospheric drag to slow a spacecraft. Generally aerobraking is used to circularize a highly elliptical capture orbit while minimizing the use of on board fuel. To date, only a handful of aerocapture maneuvers have been attempted by NASA.