Engineers bring Psyche's thrusters back online

Diagnosing a borkage from a million miles away

NASA's Psyche spacecraft is back in business after engineers successfully switched to a backup fuel line in an impressive piece of remote maintenance.

The switch fixed a solar electric propulsion problem first detected in April - where engineers noticed a pressure drop in the line feeding the xenon gas to the thrusters. The electric thrusters – Psyche's thrusters ionize and expel xenon gas to propel the vehicle – were shut down while the team investigated the issue.

There was no immediate impact on the spacecraft's trajectory, yet engineers needed the thrusters to resume operation by mid-June.

NASA made the move to the backup after concluding that a faulty valve in the original line was to blame for the plunging pressure. The valve is responsible for managing the propellant flow, and the boffins reckon that a part within it is causing an obstruction.

The identical backup line naturally includes an identical valve, and the team have opted to leave it open so the problem doesn't recur. Completing the swap means that the thrusters can resume operation by mid-June.

The probe has already travelled a billion kilometers (628 million miles) according to NASA.

Psyche is set to reach its target, a metal-rich asteroid, in 2029 and is due to fly by Mars in 2026, using the planet's gravity to slingshot it towards its destination. The trajectory does, however, require the gentle propulsion of its electric thrusters.

The issue is the first major problem for the spacecraft, which launched in 2023 after multiple delays, including problems getting its software ready. The vehicle was used as a test bed for an optical communications demonstration during its journey, and some impressive data speeds were recorded.

The spacecraft will spend approximately two years in orbit once it reaches its destination. Scientists hope the data it collects from its observations will help them better understand how planets are formed. The asteroid is approximately 173 miles (280 kilometers) across at its widest point.

Psyche fired up its thrusters a year ago. According to NASA, "the pressure exerted by the thrusters is about what you'd feel holding three quarters in your hand." However, running them for an extended period should gently accelerate the vehicle to 124,000 mph (200,000 kph).

While the mission remains on track, the fact the agency needed to switch to a backup already is a concern. There are still another four years to go until the probe reaches its destination. ®