Radio Science observations – gathered by tracking the spacecraft through its communications system – will precisely measure MESSENGER’s speed and distance from Earth. From this information, scientists and engineers will watch for changes in MESSENGER’s movements at Mercury to measure the planet’s gravity field, and to support the laser altimeter investigation to determine the size and condition of Mercury’s core. NASA’s Goddard Space Flight Center leads the Radio Science investigation.
The MESSENGER science and operations teams communicate with the MESSENGER spacecraft using the large ground-based antennas of the Deep Space Network (DSN). While sending commands and receiving data, the DSN antennas use sensitive receivers to measure the slight changes in frequency caused by MESSENGER's motion in Mercury's gravity field. The largest DSN antennas are 70 meters (230 feet) in diameter. These antennas have about as much surface area as a football field.
A view of the Canberra Deep Space Communications Complex, located outside of Canberra, Australia.