Orbit Raising

Orbit raising increases a satellite's altitude through one or more prograde burns (firing in the direction of travel). A single burn at perigee raises the opposite side (apogee) of the orbit. A second burn at the new apogee circularises it. Starlink satellites are deployed at 300 km and use krypton-fuelled Hall-effect thrusters to slowly raise their orbits to 550 km over several weeks — this allows defective satellites to deorbit naturally before reaching their operational altitude. The reverse process (orbit lowering) uses retrograde burns.