Six months ago, as NASA's MAVEN probe flew past Mars, it continued to operate normally, studying the effects of solar wind on the Martian atmosphere. But during this 20-30-minute flyby of the Red Planet, out of communication with Earth, something went wrong, and nothing has been heard of the spacecraft since.
On Wednesday, after a coordinated effort to remotely reboot the spacecraft's onboard computer and send the probe into contact with the outside world, agency officials said the $582 million orbiter had failed to recover and that its highly successful mission had come to an end.
«"Our last successful communication with MAVEN occurred on December 6, 2025," said Mike Moreau, MAVEN project manager at NASA's Goddard Space Flight Center in Maryland. "The MAVEN spacecraft and all its subsystems were operating normally when it entered its scheduled eclipse, passing behind Mars.".
«"There were no signs of problems with the spacecraft in the week leading up to the signal loss, but when the spacecraft appeared beyond Mars on December 6, the deep space network detected no signal," Moreau said.
An artist's impression of the MAVEN spacecraft in orbit around Mars. / Source: NASA
Commands were sent blindly in an attempt to force MAVEN's onboard computer to reboot, but to no avail.
«"Unfortunately, all these attempts to re-establish communication with MAVEN were ultimately unsuccessful, and no telemetry or signals have been received from the spacecraft since December 6," Moreau said.
Launched on November 18, 2013, MAVEN (short for Mars Atmosphere and Volatile Evolution Mission) entered orbit around Mars in September of that year.
Equipped with a sophisticated suite of instruments, the probe was designed to study the Martian atmosphere to gain additional insight into how it is being stripped, or eroded, by particles from the solar wind.
Originally designed for just one year of operation around Mars, the MAVEN mission has been extended multiple times, allowing it to conduct the most extensive studies of the Martian atmosphere ever conducted.
Mars was once a warmer and wetter world, but the existence of water on its surface required much higher atmospheric pressure than today. MAVEN has provided crucial data on how charged particles from the solar wind eroded the Martian atmosphere over billions of years.
«"One of our most exciting discoveries was using 11 years of MAVEN data to observe for the first time on any planet a process called 'sputtering', a process that leaks out of the atmosphere," said Shannon Curry, the study's lead author from the University of Colorado Boulder.
«"This is where charged particles collide with the upper atmosphere and splash out of the neutral atmosphere, like a running jump into a swimming pool," Curry said. "Our team confirmed that this process has been the dominant atmospheric escape mechanism for billions of years, with incredible implications for other planets in our solar system and even exoplanets.".
In addition to studying the Red Planet's atmosphere, MAVEN also helped relay signals from NASA's two active Mars rovers, Curiosity and Perseverance, to mission controllers at the Jet Propulsion Laboratory. Three other Mars orbiters provide similar communications relay services.
Although the MAVEN spacecraft continued to operate significantly longer than initially expected, NASA is trying to determine what might have gone wrong to learn lessons for other missions. In February, the agency established an anomaly review committee to determine the root cause.
As part of the ongoing investigation, engineers reanalyzed recordings of what the Deep Space Network may have "heard" when MAVEN emerged from behind Mars as part of an ongoing radiophysics experiment. As expected, the usual telemetry data was missing, but fragments of data were found indicating the spacecraft was rotating at 2.7 revolutions per minute.
Except for periodic orientation changes necessary for scientific observations, communications, and power generation, MAVEN generally remained stationary, keeping its solar panels pointed toward the Sun and its antenna pointed toward Earth.
At the observed rotation rate, normal communication would likely be impossible, and the sensor arrays would be unable to generate sufficient power. In this case, the probe's batteries would quickly run out.
Moreau declined to speculate on what might have happened while the spacecraft was out of contact with Earth, saying he looked forward to the results of the ongoing investigation.
Whatever the cause, the rotation rate recorded in the recovered telemetry data was incompatible with life. The spacecraft is expected to remain in the same orbit around Mars for at least the next 50-100 years, but NASA will not make further attempts to restore communication.
«"It has been a great honor and privilege for me personally to lead this team," said Curry. "This team worked tirelessly to operate the spacecraft and achieve exceptional scientific results. It was their vision, their determination, and their curiosity that led to these amazing discoveries. I will greatly miss the spacecraft and this team.".
When asked by a reporter what should be written on MAVEN's tombstone, Curry replied: "Best Mars mission ever.".