NASA Voyager mission engineers are preparing a software patch that will allow thrusters on the Voyager 1 and 2 interstellar probes to continue operating for another five years, thus maintaining the probes' communications with Earth. The Voyager probe has been in service since its launch in 1977 and has exceeded its expected lifespan many times. They are a testament to the design team, but nearly half a century later, their longevity has created new problems that were never anticipated.
One problem is that the hydrazine-fueled thrusters used to keep Voyager's high-gain antenna pointed at Earth are showing their age. While the thrusters still have enough propellant to last until 2037 under careful protection at the Jet Propulsion Laboratory (JPL) Mission Control Center in Pasadena, California, the thrusters themselves are in need of a good cleaning.
The problem is that each thruster firing leaves residue in the system that has been slowly building up over the years. If too much builds up, the fuel lines will become clogged and the detector's fate will be doomed.
To prevent this, NASA engineers are developing a software patch that will command Voyager to fire its thrusters less often but for longer to maintain the probe's attitude. In addition, the probes will be told that their fixed point on Earth will drift further than before before going into emergency mode, which will result in some data being lost, but in the long run more data will be returned.
Additionally, the patch will fix a glitch that caused Voyager 1's Attitude Articulation and Control System (AACS) to issue incorrect commands in 2022. Software updates are not without risks. Not only was Voyager outdated, but it was also traveling in extremely harsh environments, with signals taking 18 hours to travel from Earth to the probe. This means it will take at least 36 hours before Mission Control discovers there is a problem with the upload. Therefore, before trying to send a signal to Voyager 1, a signal will be sent to Voyager 2.
It is hoped that the upgrade will extend the life of the thrusters by at least five years. Since the nuclear battery on board the probe is only expected to last another two years, this will leave considerable room for error.
JPL project scientist Linda Spilker said: "The engineering team has faced many challenges so far in the mission, and we do not yet have solutions to these challenges. But creative solutions continue to be proposed."