NASA’s MAVEN spacecraft has been orbiting Mars since 2016. Parts of the spacecraft are beginning to show their age, and it has had its share of problems, most recently from February to May of this year. On February 22, 2022, MAVEN entered safe mode, a mode where it doesn’t do any science or other activities to protect itself.

The root cause of the most recent issue was a problem with the spacecraft’s Inertial Measurement Units (IMU). These tell the spacecraft what direction it is pointing in space. The issue began when the spacecraft computer could not get any data from either IMU. Following its programming, MAVEN first rebooted the main computer; just like a home machine, the first step was to turn it on and off again. The reboot didn’t work, though, so the spacecraft switched to its backup flight computer. Using the backup computer, the team was finally able to get data from the IMU but only from one of them and only for 78 minutes.

So the team ended up on IMU-2, a unit they’ve had problems with before and could not rely on for the next years of spacecraft life. This meant that a new method was needed, and it was one flight controllers were planning to implement eventually: all stellar navigation.

MAVEN has star trackers which helped it navigate from Earth to Mars; these tell the spacecraft what it’s pointed at by what stars are where. The original plan was to switch to all stellar navigation in October of this year, and the team worked really hard to develop the software faster, sending the new code to the spacecraft in April. After a month of testing, MAVEN was put in all stellar navigation mode full time on May 28.

With this new mode – and some occasional use of the IMUs as needed – the spacecraft can continue science and other duties through its next extended mission.

More Information

NASA press release