For most of its time at Mars, the MAVEN spacecraft provided a relay for scientific data uplinked from NASA’s rovers and landers on the Martian surface. The relay allowed NASA to return significantly more data and imagery from rovers like Perseverance and Curiosity than would be possible through a direct-to-Earth radio connection.

With MAVEN out of the picture, NASA has four other orbiters it can use to provide this critical radio link. But officials aren’t sure how much longer they will last. Three of the four remaining relay orbiters are older than MAVEN, which played an outsized role in the relay network thanks to its higher orbit.

“Over the life of the mission, MAVEN supported more than 8 percent of all of our relay sessions planned by our rovers and landers, but it accounted for nearly 18 percent of all of the data returned, illustrating its usefulness when returning large data volumes,” said Tiffany Morgan, director of NASA’s Mars Exploration Program.

The network still has plenty of capacity to support the Perseverance and Curiosity rovers, with some minor caveats.

“We do have remaining assets, and those assets have adjusted the amount of data that they return, and the rovers have also adjusted their planning for how they connect to those assets,” Morgan said. “There is a slight delay on occasion, because we don’t have as many assets in view, to getting our science data back, and MAVEN was critical in returning science data versus operational data. But the Mars Relay Network is resilient enough at this point in time to accommodate, for the most part, the loss of MAVEN with the added delay.” //

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jlredford said:
It's interesting that they're able to use so many different orbiters to do this relay function. Interesting and resilient! It's great that it can handle dropouts like MAVEN. As the system gets upgraded, I hope they keep all this inter-operability to handle the next failure. The Mars Reconnaissance Orbiter is the main link these days, and it's now 20 years old, almost twice the age of MAVEN.

That’s because most of them (at least those launched after 2005) fly the JPL developed Electra software defined radio (they’re manufactured by L3, but the hardware design and the software is JPL). The landers also use Electra radios (or Electra Lite). MER was the first Mars lander to use relay ops with an orbiter to return data, and after a week or two, it had returned more data through the relay link than all previous Mars missions combined. It’s that effective (compared to basic X-band Direct to Earth at 8 kbps)

And as far as interoperability goes, that’s part of the Prox-1 standard from the Consultative Committee on Space Data Standards (ccsds.org) - most people flying a relay payload use it (as will the new Mars Telecom Network, and similar spacecraft planned for the Moon). 400 MHz UHF at Mars for now, but S-band is coming, as is Ka-band.