Grail

The Grail duo was launched on the 10th September 2011. The spacecraft have 6dB gain X-Band patch antennas radiating at 8451.5995MHz and 8451.7995MHz, and 5dB gain patch antennas radiating at 2279.511MHz and 2280.6MHz.

The telecom subsystem includes the following: 2 S-band transponder antennas to communicate with Earth, 2 X-band beacon antennas for Doppler ranging measurements from Earth of the Moon's near side, S-band time-transfer system antenna, which sends a time-synchronization code back and forth between the spacecraft and a Ka-band ranging antenna for precision distance measurement between the spacecraft.

The various RF links are used as follows:

Grail rf

S-Band downlinks:

Grail a 120911Grail b 120911

X-Band beacon downlinks:

Grail a xband 130911Grail b xband 130911