Currently, about 16,000 satellites are orbiting Earth, providing everything from GPS service and weather reports to phone service in remote locations to people across the globe.

In contrast, the highest-ever number of active satellites in orbit around Mars, one of the best-explored other planets in our solar system, is eight.

Starting in 2021, there were three from NASA, two from the European Space Agency and one each from the Indian Space Research Organization, the UAE Space Agency and the China National Space Administration. The oldest of these is still 2001 Mars Odyssey, which has now spent 25 years in space, with Mars Express, at 23 years, and the Mars Reconnaissance Orbiter, at 20 years, hot on its heels.

But in December 2025, NASA lost contact with its Maven spacecraft, bringing the total number of active satellites down to seven, and NASA’s to two.

The cause of the loss of Maven has still not been publicly released, and NASA officially declared the mission over in June 2026. A final report on the cause of the loss is due later this year.

NASA is exploring potential commercial solutions to supplement the current fleet of Mars orbiters. In September 2026, NASA selected Jeff Bezos’ Blue Origin to provide a Mars telecommunication satellite no later than Dec. 31, 2028.

These satellites are important because future missions will rely on them to communicate with Earth and select safe landing sites on Mars. Planetary scientists like me rely on the data they’ve taken over the past few decades to learn more about our close, red neighbor.

Maven loss and implications

The Mars Atmosphere and Volatile EvolutioN, or Maven, spacecraft arrived at Mars in 2014, making it NASA’s youngest orbiter. It was only briefly the youngest in the international Mars family, as the Indian space agency’s Mars Orbiting Mission spacecraft arrived a few days later.

The longer any satellite spends in space, the greater the toll of the harsh environment – from extreme temperature swings to solar radiation. Maven, however, appeared generally healthy until it missed a radio check-in – a sign of trouble – after emerging back from behind the planet.

Whatever happened to Maven last December was only the second time in the 21st century that NASA had lost contact with an orbiter during otherwise ordinary operations. The other time was in 2006, with Mars Global Surveyor, which NASA ultimately lost, likely due to issues with uploaded software commands.

The Mars exploration community, myself among them, is waiting with bated breath to understand why one-third of NASA’s Mars fleet lost contact seemingly overnight. The loss ends a stellar, almost two-decade-long track record of missions ending when expected, not before.

Science impact

Mars science has been in a golden age since 2001 Mars Odyssey arrived at the red planet 25 years ago. NASA has had a Mars rover of some type operating on the surface continuously since 2004 with the Exploration rover landings, so there have been only a handful of years in the 21st century where scientists couldn’t access nearly simultaneous views of Mars from the surface and from orbit.

This access gives Mars scientists the ability to study how both the surface and atmosphere change over time. In particular, we can follow changes with Mars’ seasons, which drive about a quarter of its atmosphere onto its surface as seasonal ice. And we have found laundry lists of these changing features, including “spiderlike” araneiform features in the soil that likely develop from carbon dioxide geysers.

Learning about rare events like global dust storms, which obscure Mars’ entire surface, also opens up many new questions. We still don’t know what triggers the start of a global dust storm, and they only occur every several Mars years. In Maven’s 11 years at Mars, it was only able to observe one global dust storm, in 2018.

Mars exploration impact

From a practical standpoint, Mars orbiters have their own science missions. However, their powerful radios are also critical for delivering data from landers and rovers, like Perseverance or Curiosity, back to Earth. In the past, NASA has adjusted the Mars Reconnaissance Orbiter and Maven orbits to support landings and surface operations.

HiRISE (High-Resolution Imaging Science Experiment) aboard the Reconnaissance orbiter, is the highest-resolution camera in orbit to date. Engineers have used data from HiRISE to ensure they could deliver the Mars rovers Curiosity and Perseverance to the surface, as well as the InSight lander.

While Mars orbiters and their instrument suites are selected for their science value, they have come to participate in infrastructure that is essential for getting all the possible data back to Earth. These tasks, which go beyond science data collection, make the orbiter fleet critical to Mars exploration.

The future

The Dec. 31, 2028, delivery date for the Blue Origin telecommunications Mars orbiter to NASA represents the earliest a new orbiter could be launched for Mars. Mars launch opportunities happen at an approximately 2-year cadence, when Mars and Earth get closest to each other in their respective orbits. During this window, less fuel is needed for the journey.

If a new Mars orbiter for science or telecommunications is not launched by the 2028 window, the next opportunity would be in 2030 or 2031. While the Blue Origin telecommunications orbiter would support future exploration missions, the announcement did not outline plans for any science instrumentation onboard.

Mars Odyssey will be around 30 years old by then, and the Mars Reconnaissance Orbiter around 25. NASA hardware tends to be hardy, often greatly exceeding expectations. For example, the Mars Exploration rovers were meant to last for 90 days, with Spirit ending its mission after over six years and Opportunity after over 14 years. However, orbiters may slowly lose capability over time – the Mars Reconnaissance Orbiter’s spectrometer instrument ceased operations in 2023, while its other instruments are still active.

But three or four decades in a space environment is a long tour of duty for any hardware in space, let alone hardware that is pulling double-duty as scientist and radio broadcaster.

Much like driving your first car for far longer than you had planned on, the NASA orbiter fleet is waiting to see if the next repair bill means it’s time for an upgrade, or if it’ll have to catch rides from its friends.

Until NASA releases its report, scientists and engineers will be waiting to understand what happened to end the Maven spacecraft’s mission early, and how those details can help them keep the current fleet flying until reinforcements finally arrive.

Margaret Landis receives funding from NASA, including as a Co-Investigator on the HiRISE Mars camera instrument. She is a long-term member of the Planetary Society, and formerly worked at the University of Colorado, Boulder, the lead organization for the MAVEN mission.