Near the end of his third orbit, Glenn fired other rockets to slow his speed.
VOA: special.2009.06.17
Once the two GRAIL satellites are in orbit, their next step is to begin a five week phase in which they increase the speed at which they orbit the Moon.
The craft is meant to speed off a runway and accelerate gracefully into orbit in a single blast, perform a task like launching a satellite and then glide back home to its hangar.
Alongside the HTC-made handset are an altitude and orbit control system, two propulsion setups and a Linux-based computer with a "high-speed" processor.