NASA budgeted US$496 million for the program to include spacecraft and instrument development, launch, mission operations, and science support.

The winning names, Ebb and Flow, were suggested by 4th grade students at Emily Dickinson Elementary School in Bozeman, Montana.

By measuring the change in distance between the two spacecraft, the gravity field and geological structure of the Moon was obtained.

[21] The knowledge acquired will aid understanding of the evolutionary history of the terrestrial planets and computations of lunar orbits.

The propulsion subsystem consisted of a main fuel tank and a Re-repressurization system which were activated shortly after lunar orbit insertion.

This extended and circuitous trajectory enabled the mission to reduce fuel requirements, protect instruments and reduce the velocity of the two spacecraft at lunar arrival to help achieve the extremely low 50 km (31 mi) orbits with separation between the spacecraft (arriving 25 hours apart) of 175 to 225 km (109 to 140 mi).

[27] The initial lunar orbits were highly elliptical near-polar, and were later lowered to near-circular at about 25-86 km altitude with a period of about 114 minutes.

[30] The spacecraft were operated over the 88-day acquisition phase, divided into three 27.3 day long nadir-pointed mapping cycles.

Twice each day there was an 8-hour pass in view of the Deep Space Network for transmission of science and "E/PO MoonKam" data.

[39] NASA has announced that the crash site will be named after GRAIL collaborator and first American woman in space, Sally Ride.