It’s incredible that it still has fuel left.

Big Money Thrustas

NASA engineers have pulled off an incredible feat: switching the agency’s ancient Voyager 1 probe — the farthest human-made object in existence — to a different set of thrusters. The feat, heavily complicated by the record 15.3 billion miles of outer space separating the probe from ground control, took weeks of careful planning.

Some of the 46-year-old spacecraft’s thrusters started getting gunked up with silicon dioxide, the apparent result of a rubber diaphragm breaking down inside its fuel tank. The material reduced the thrusters’ efficiency, forcing NASA to come up with a workaround.

Their solution: reactivate a different set of thrusters to keep it going.

The feat, successfully completed in late August, gives Voyager 1 yet another lease on life. The probe has been on life support for quite some time now — but it’s still not giving up.

Dead Space

Voyager 1 has three sets of thrusters, which were designed to help it perform several planetary flybys. However, now that it’s on a straight path away from the solar system, “its thruster needs are simpler, and either thruster branch can be used to point the spacecraft at Earth,” according to NASA.

It’s not the first time engineers have had to switch to a different set of thrusters. Both in 2002 and 2018, teams swapped the probe to a different branch due to similar material buildup.

The team’s latest move was to swap to an attitude propulsion thruster branch, which had already been partially clogged, but to a lesser degree.

Complicating matters are power supply and temperature issues. Having “turned off all non-essential onboard systems, including some heaters” to conserve power, both Voyager 1 and its twin Voyager 2 have grown colder.

Consequently, engineers had to warm up the thrusters before bringing them back online to avoid any damage. However, turning on the heater could put too much stress on the spacecraft’s dwindling power supplies.

Fortunately, the team confirmed on August 27 that their final plan — turning off one of the main heaters to free up power for the thruster heaters — had worked, allowing Voyager 1 to keep edging into interstellar space.

“All the decisions we will have to make going forward are going to require a lot more analysis and caution than they once did,” said Voyager’s project manager Suzanne Dodd in a statement.

Nobody knows how long Voyager 1 will hold on. The spacecraft has more than exceeded expectations, having fulfilled its original mission to explore Jupiter, Saturn, and Saturn’s largest moon, Titan, decades ago.

But NASA remains optimistic.

“My motto for a long time was 50 years or bust,” astronomer Stamatios Krimigis, who has worked on the Voyager 1 mission since the 1970s, told NPR in March, “but we’re sort of approaching that.”

More on Voyager 1: NASA’s Ingenious Hack Brings Dying Voyager Probe Back Online