NASA’s MAVEN spacecraft was in excellent shape when it disappeared behind Mars on December 6 of last year. The routine passage, called an occultation, was supposed to last less than an hour, but ground teams didn’t hear from the spacecraft when it was supposed to regain contact with Earth.

The loss of communication triggered contingency plans for engineers to try to restore a link with MAVEN, which orbits Mars more than 200 million miles from Earth. To no avail, they listened for faint signals and uplinked commands in the blind. Hopes of saving the mission faded over time, and NASA officials announced Wednesday that they’re giving up on it.

“NASA has ceased efforts to search for the MAVEN spacecraft and are beginning activities to decommission the mission,” said Mike Moreau, MAVEN’s project manager at NASA’s Goddard Space Flight Center in Maryland. 

Loss of signal

It will take some time for engineers to try to unravel what happened to the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, which launched from Earth in 2013 and arrived in orbit around Mars in 2014 to study the interaction between the Martian atmosphere and the solar wind. MAVEN was an unqualified success, lasting 11 years at Mars and far outliving its original prime mission. But the spacecraft’s sudden failure was a surprise. Many of NASA’s planetary exploration missions operate for decades.

With the scant information available,  investigators may never determine exactly what went wrong with MAVEN. Investigators are combing through data the spacecraft transmitted before Mars blocked the signal, and engineers were able to recover fragments of telemetry from MAVEN after it reemerged from behind the planet.

“As part of this investigation, the team members at the Jet Propulsion Laboratory were successful in recovering some fragments of telemetry and Doppler shift data from the spacecraft,” Moreau said. “These data were extracted from recorded signals that were recovered during the hours following the loss of signal.”

Ground controllers didn’t see these faint signals in real time. They were recorded as part of a separate science campaign seeking to gather information about the density and dynamics of the upper Martian atmosphere, which can distort radio signals that pass through it.

“One of the bits of that we were able to confirm is an inertial rate measurement that told us the spacecraft was spinning at about 2.7 revolutions per minute,” Moreau said. “We also confirmed that that was consistent with a Doppler signature that we saw in the data. That’s faster than the spacecraft is expected to rotate, and that indicates a problem that the spacecraft probably couldn’t recover from.”

Without the ability to point its solar arrays toward the Sun, the tumbling spacecraft likely drained its batteries within hours.

“That was one of the data points that helped us understand that the spacecraft probably reached a power state that was not supportable to continue operations,” Moreau said. “Those are the facts that we know. The anomaly review board is still looking at the root cause of what actually initiated the failure.”

MAVEN is orbiting Mars on an oval-shaped, elliptical path taking it as close as 110 miles (180 km) and as far as 2,500 miles (4,000 km) from the planet’s surface. The spacecraft, about the size of a small car, will remain in this orbit for 50 to 100 years before naturally falling into the Martian atmosphere and burning up.

Artist’s illustration of the MAVEN spacecraft in its elliptical orbit around Mars (not to scale).

Credit: NASA/University of Colorado/LASP

What is lost?

There are two answers to this question. MAVEN was built as a research platform to help scientists understand how the atmosphere of Mars has changed over billions of years. Before MAVEN, scientists knew Mars must have been warmer and wetter and that it had a thicker atmosphere in the ancient past. The atmosphere on Mars today is too thin to support liquid water at the surface, and there is now widespread evidence of a network of lakes and rivers that covered Mars billions of years ago.

MAVEN found evidence of the mechanisms that stripped molecules from the upper layers of the atmosphere, a process known as atmospheric escape. The spacecraft’s science instruments monitored how the Martian atmosphere responded to blasts of charged particles emitted by massive eruptions from the Sun.

“One of our most exciting discoveries used 11 years of MAVEN data to observe, for the first time at any planet, an atmospheric escape process called sputtering,” said Shannon Curry, MAVEN’s principal investigator at the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder. “This is where charged particles crash into the upper atmosphere and splash out the neutral atmosphere, much like doing a cannonball in a pool. Our team used noble gas isotopes to confirm that this process has been a dominant escape mechanism for billions of years.”

A solar storm in 2024 hit Mars particularly hard. “We saw orders of magnitude more atmospheric escape, and we even captured images of glowing aurora across the planet,” Curry said.

MAVEN’s scientific legacy is secure, but the goodbye isn’t easy for teams working on the project, which scientists first proposed to NASA in 2006.

“I think the team has really experienced the loss of a loved one with the end of the mission,” Moreau said.

“At the same time, we are incredibly proud of the science we’ve accomplished over the last decade,” Curry said. “MAVEN was the best observer of atmospheric escape anywhere in the Solar System. We now have a better understanding of atmospheric escape at Mars than at any other planet, including Earth.”

The second answer is a little more uncertain. 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.”

NASA is asking commercial companies to develop a replacement for the existing Mars Relay Network. The new commercial system, called the Mars Telecommunications Network, is expected to provide higher throughput and broader coverage for NASA’s future missions to the red planet.

“Instead of each mission designing its own communications solution, we’ll build in a more capable architecture deliberately designed for Mars,” said Greg Heckler, deputy program manager for capability development at NASA’s Space Communications and Navigation office. “It will be built on the lessons from MAVEN, from the other orbiters, from every mission operating in this environment, including the current rovers, and from some of our growing endeavors around the Moon.”

NASA wants the Mars Telecommunications Network to be operational by the 2030s. The agency released a request for proposals last month.

“I think there’s … urgency,” Heckler said. “I think NASA establishing this infrastructure is going to be very important to continue science operations of the current missions here today and then enable us to execute on these newer, bigger missions yet to come.”