Rovers and landers on Mars produce large amounts of science data, but they rarely send it straight to Earth. Instead, a network of orbiters acts as a relay. This Mars telecommunications network is essential for every surface mission, and NASA is now planning a dedicated next generation network. This article explains how the system works today.
The Mars Relay Network today
According to NASA, the Mars Relay Network is an international constellation of four spacecraft orbiting Mars that send science data from surface rovers back to Earth:
- NASA: Mars Odyssey, launched in 2001, and Mars Reconnaissance Orbiter, launched in 2005.
- ESA: Mars Express, launched in 2003, and the ExoMars Trace Gas Orbiter, launched in 2016.
NASA's MAVEN orbiter was also part of the network. According to NASA, it ceased operations in June 2026.
How the relay works
Instead of transmitting directly to Earth over hundreds of millions of kilometres, a rover sends its data to an orbiter passing overhead. NASA states that rovers can transmit to the orbiters at data rates of up to 2 megabits per second. The orbiters store the data and forward it to Earth. This lets rovers use small, low power radios and spend more of their energy on science.
How much data the orbiters relay
NASA lists the average daily relay volumes through 2025. The Trace Gas Orbiter relayed the most, about 1,562.7 megabits per day, followed by MAVEN with 897.5, Mars Reconnaissance Orbiter with 447.5 and Mars Odyssey with 170.4 megabits per day.
The link to Earth: the Deep Space Network
On Earth, the data arrives through NASA's Deep Space Network, three groups of large radio antennas about 120 degrees apart in California, Spain and Australia. As the Earth rotates, at least one site can always see Mars. Read more in our article on satellite ground systems.
Why a new Mars telecommunications network is needed
Most relay orbiters are well beyond their original design lifetimes, and MAVEN has already ended operations. Future missions, and eventually crewed exploration, will need more capacity. In September 2026, NASA selected Blue Origin to provide a Mars telecommunications network, as covered in our article on the Blue Origin selection.
Sources
- NASA Science: Mars Relay Network
- NASA: Deep Space Network
- NASA: NASA Selects Blue Origin as Mars Telecommunications Network Provider
Cover image: Artist's concept of NASA's Mars Reconnaissance Orbiter over the Martian polar region. Credit: NASA/JPL (PIA04918), public domain.