Engineers are trying to fix a problem with one of Voyager 1’s three onboard computers, called the flight data system (FDS). The spacecraft receives and executes commands sent from Earth; however, the FDS is not communicating properly with one of the probe’s subsystems, called the Telemetry Modulation Unit (TMU). As a result, no scientific or engineering data is sent to Earth.

FDS is designed to collect data from science instruments as well as engineering data on the health and condition of the spacecraft, among other things. It then combines this information into a single data “packet” that the TMU sends back to Earth. The data is in the form of ones and zeros or binary code. Different combinations of two numbers form the basis of all computer languages.

Recently the TMU has started transmitting a pattern of repeated ones and zeros, as if it were “stuck”. After eliminating other possibilities, the Voyager team determined that the source of the problem was FDS. Over the weekend, the team tried restarting the FDS and returning it to the state it was in before the problem occurred, but the spacecraft still did not return usable data.

It may take several weeks for engineers to come up with a new plan to fix the problem. The spacecraft, launched in 1977, and its twin, Voyager 2, are the two longest-running spacecraft in history. Finding solutions to problems facing research often requires looking at original documents from decades ago, written by engineers who could not foresee the problems that arise today. As a result, the team needs time to understand how the new team will affect the spacecraft’s operation in order to avoid unintended consequences.

Additionally, it takes 22.5 hours for commands from flight controllers on Earth to reach Voyager 1, which is exploring the outer reaches of our solar system more than 15 billion miles (24 billion kilometers) from Earth. This means the engineering team must wait 45 hours to hear back from Voyager 1 and determine whether the team has achieved the expected result. Source