Technicians work on the MAVEN spacecraft at NASA's Kennedy Space Center in Florida prior to launch in 2013.
Credit: NASA/Kim Shiflett
But NASA's two other Mars orbiters have been in space for more than two decades. The older of the two, called Mars Odyssey, has been on Mars since 2001 and will soon run out of fuel, probably sometime in the next few years. NASA's Mars Reconnaissance Orbiter, which launched in 2005, is healthy for its age and has enough fuel to last until 2030. MRO is also important to NASA because it has the best camera on Mars, with the ability to map landing sites for future missions.
Two European spacecraft, Mars Express and the ExoMars Trace Gas Orbiter, carry radios to relay data between mission controllers and NASA landers on the surface of Mars. Mars Express, now 22 years old, suffers from the same aging problems as Mars Odyssey and MRO. The ExoMars Trace Gas Orbiter is newer, having arrived on Mars in 2016, but has also functioned beyond its original lifespan.
China and the United Arab Emirates also have orbiters orbiting Mars, but neither spacecraft is equipped to serve as communications relays.
NASA's Curiosity and Perseverance rovers have the capability for direct communication with Earth, but the orbiting relay network can support much higher data throughput. Without above-ground satellites, much of the scientific data and many of the spectacular images collected by NASA's rovers might never leave the planet.
MAVEN's unique orbit, which extends up to 2,800 miles above Mars, has some advantages for data transmission. In that orbit, MAVEN could relay science data from surface rovers for up to 30 minutes at a time, longer than the relay periods available from NASA's lower-altitude orbiters. This allowed MAVEN to support the largest data volumes of any other relay option.
