While I was going through the question What happens to Insight's parachute? I learned of the role of the Mars Reconnaissance Orbiter to provide reliable communication between other Mars spacecraft and/or landers with Earth.

The Mars Reconnaissance Orbiter has been in place for over 12 years now. Yet it is handling communications with Mars' newest visitor InSight, which just landed.

How are the programmers and controllers able to configure MRO to communicate with these new arrivals?


1 Answer 1


MRO uses the Electra software-defined radio:

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.

See also Wikipedia's Electra (radio) Key Features:

  • Transceiver that runs the free open source RTEMS operating system.
  • Electra's software-defined radio (SDR) provides flexible platform for evolving relay capabilities.
  • Fully reprogrammable software/firmware functionality by using field-programmable gate array (FPGA) technology.
  • CCSDS Proximity-1 Space Link Protocol for interoperable, reliable data transfer.
  • Frequency-agile operation across UHF band (390–450 MHz).
  • Integrated Doppler navigation and timing services.
  • Data rates up to 1 Mbit/s

When Curiosity arrived, the radio on MRO was reprogrammed to use new transmission modes.

All missions since then have used Electra-compatible radios.

I don't know if reprogramming will be necessary for InSight. If not, it's just a matter of adjusting the schedule.

The InSight UHF radio seems to be similar to the ones used on Spirit, Opportunity and Phoenix. That suggests reprogramming isn't necessary.

Finding details on the InSight communications system is surprisingly difficult.

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    $\begingroup$ +1 Electra seems like quite a snazzy bit of technology! I hope you don't mind the edit, I've just added key points from your links back into the answer itself to avoid link-only-ness and the risk of link rot for future readers. $\endgroup$
    – uhoh
    Commented Nov 28, 2018 at 1:33
  • $\begingroup$ @Hobbes Thanks for the answer. Does satellite on the earth orbit use something like Elactra which can be reprogrammed when needed? $\endgroup$ Commented Nov 28, 2018 at 5:22
  • $\begingroup$ Electra seems to have been designed specifically for Mars missions. Software-defined radio (SDR) is common in satellites, I suspect. Good question though, go ahead and ask it as a new question because there's more to this than fits in a comment. $\endgroup$
    – Hobbes
    Commented Nov 29, 2018 at 8:08

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