Electra is a telecommunications package that acts as a communications relay and navigation aid for Mars spacecraft.
Toward the end of the primary science phase, other Mars missions launched in 2007 and beyond will begin to arrive. Mars Reconnaissance Orbiter will use its Electra UHF radio to support any navigation, command, and data-return needs these missions may have. If the arriving spacecraft has an Electra communications payload, it can receive these signals and use them to determine its distance and speed in relation to Mars. This communication allows much more precise navigation.
After incoming landers or rovers have arrived safely on Mars, Electra can provide precise Doppler data which, when combined with Mars Reconnaissance Orbiter's position information, can accurately determine the location of the lander or rover on the surface of Mars.
Electra can also provide UHF coverage to Mars landers and rovers on the surface that may not have sufficient radio power to communicate directly with Earth by themselves, using its nadir-pointed (pointed straight down at the surface) antenna.