It’s not often that a NASA mission is still up and running over four decades after launch, but the space agency’s Voyager twins are anything but ordinary. The twin spacecraft were launched way back in 1977 and they’ve been speeding away from Earth the entire time.

Lately, however, one of the spacecraft began acting up. Voyager 2 signaled its handlers back on Earth that it had encountered a problem with its autonomous systems. This is exactly what the spacecraft is designed to do when it runs into an issue, and NASA engineers back on Earth are working on getting Voyager 2 back on its feet, so to speak.

Here’s how NASA breaks down the glitch:

On Saturday, Jan. 25, Voyager 2 didn’t execute a scheduled maneuver in which the spacecraft rotates 360 degrees in order to calibrate its onboard magnetic field instrument. Analysis of the telemetry from the spacecraft indicated that an unexplained delay in the onboard execution of the maneuver commands inadvertently left two systems that consume relatively high levels of power operating at the same time. This caused the spacecraft to overdraw its available power supply.

When this happened, the spacecraft’s fault detection software alerted NASA that something was wrong, and mission engineers began working to restore the spacecraft to its fully functional state.

As NASA’s Jet Propulsion Laboratory reports, commands issued to Voyager 2 have already been sent, but it takes nearly two full days for signals to make the round trip, meaning that NASA won’t know if the commands have “the desired effect” for at least 34 hours. In any case, NASA’s bright minds are working on a fix, and with a little bit of luck, Voyager 2 will continue its decades-long mission shortly.

Mike Wehner has reported on technology and video games for the past decade, covering breaking news and trends in VR, wearables, smartphones, and future tech. Most recently, Mike served as Tech Editor at The Daily Dot, and has been featured in USA Today, Time.com, and countless other web and print outlets. His love of reporting is second only to his gaming addiction.