Solar Electric Propulsion Makes NASA’s Psyche Spacecraft Go

A Gentle Maneuver

Psyche will launch from the historic Pad 39A at NASA’s Kennedy Space Center. The Falcon Heavy will place the spacecraft on a trajectory to fly by Mars for a gravity assist seven months later, in May 2023. In early 2026, the thrusters will do the delicate work of getting the spacecraft into orbit around asteroid Psyche, using a bit of ballet to back into orbit around its target.

That task will be especially tricky because of how little scientists know about the asteroid, which appears as only a tiny dot of light in telescopes. Ground-based radar suggests it’s about 140 miles (226 kilometers) wide and potato-shaped, which means that scientists won’t know until they get there how exactly its gravity field works. As the mission conducts its science investigation over 21 months, navigation engineers will use the electric propulsion thrusters to fly the spacecraft through a progression of orbits that gradually bring the spacecraft closer and closer to Psyche.

NASA’s Jet Propulsion Laboratory in Southern California, which manages the mission, used a similar propulsion system with the agency’s Deep Space 1, which launched in 1998 and flew by an asteroid and a comet before the mission ended in 2001. Next came Dawn, which used solar electric propulsion to travel to and orbit the asteroid Vesta and then the protoplanet Ceres. The first spacecraft ever to orbit two extraterrestrial targets, the Dawn mission lasted 11 years, ending in 2018 when it used up the last of the hydrazine propellant used to maintain its orientation.

Partners in Propulsion

Maxar Technologies has been using solar electric propulsion to power commercial communications satellites for decades. But for Psyche, they needed to adapt the superefficient Hall thrusters to fly in deep space, and that’s where JPL engineers came in. Both teams hope that Psyche, by using Hall thrusters for the first time beyond lunar orbit, will help push the limits of solar electric propulsion.

“Solar electric propulsion technology delivers the right mix of cost savings, efficiency, and power and could play an important role in supporting future science missions to Mars and beyond,” said Steven Scott, Maxar’s Psyche program manager.

Along with supplying the thrusters, Maxar’s team in Palo Alto, California, was responsible for building the spacecraft’s van-size chassis, which houses the electrical system, the propulsion systems, the thermal system, and the guidance and navigation system. When fully assembled, Psyche will move into JPL’s huge thermal vacuum chamber for testing that simulates the environment of deep space. By next spring, the spacecraft will ship from JPL to Cape Canaveral for launch.

More About the Mission

ASU leads the mission. JPL is responsible for the mission’s overall management, system engineering, integration and testing, and mission operations. Psyche is the 14th mission selected as part of NASA’s Discovery Program.

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