Psyche Spacecraft Conducts Asteroid Science Rehearsal at Mars

NASA’s Psyche spacecraft swept past Mars at roughly 12,300 mph, closing to within 2,864 miles of the surface on May 15, according to a Jet Propulsion Laboratory release issued on July 17. The high-speed planetary flyby served as an operational rehearsal for the spacecraft’s primary mission: investigating a metal-rich asteroid located in the main asteroid belt, using the Red Planet’s gravity to steal speed without burning fuel.

Stealing Speed and Testing Instruments at Mars

The May encounter was not designed for planetary research. According to Lindy Elkins-Tanton, who leads the mission and directs the Space Sciences Laboratory at the University of California, Berkeley, the primary goal was to secure a gravity assist that bends the spacecraft’s path and adds velocity. However, mission planners utilized a month of approach time to power up onboard science instruments for critical testing and calibration.

None of the data collected during the flyby constitutes a peer-reviewed study, as the event served purely as instrument checkout data downlinked in the weeks following the encounter. Planners anticipated that Mars would be too distant for certain detectors to register planetary signals, but secondary targets yielded measurable results.

Detecting Neutrons and Measuring Magnetism

The gamma-ray and neutron spectrometer aboard Psyche is built to identify chemical elements on the target asteroid’s surface by eavesdropping on a collision. While Mars sat too far away for gamma-ray detection, the instrument successfully logged neutrons. David Lawrence, who leads spectrometer science at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, stated that the count rate climbed near closest approach and matched mission predictions.

“It was very gratifying to see,” Lawrence said of the instrument’s performance.

Meanwhile, the spacecraft’s magnetometer faced its first planetary body since launch in October 2023. Over nearly three years of flight, the sensor had only measured the magnetic field dragged along by the solar wind. During the Mars pass, the instrument captured the bow shock, where fast-moving solar wind stacks up against a planet’s magnetic resistance.

Ben Weiss, Psyche’s deputy principal investigator and magnetometry lead at MIT, noted that the pass tested the hardware under fast-changing conditions while revealing the physics of planetary magnetism on a world whose internal dynamo shut down billions of years ago.

Targeting the Metal Asteroid Psyche in 2029

The ultimate destination for the spacecraft is an asteroid that shares its name, an unusually dense and metallic body suspected to be the exposed nickel-iron core of a failed planetesimal. According to project manager Bob Mase at the Jet Propulsion Laboratory, the spacecraft flew the exact trajectory required to line up a rendezvous in the summer of 2029.

The spacecraft remains healthy, and its solar-electric propulsion system—which sips xenon gas to build speed gradually over years—is scheduled to resume sustained thrusting in the fall. Until then, the engineering data gathered during the Martian rehearsal remains filed away as the mission targets its distant metallic destination.

Frequently Asked Questions

Why did the Psyche spacecraft fly past Mars?

The spacecraft flew past Mars on May 15 to execute a gravity assist, gaining velocity without burning fuel, while simultaneously testing and calibrating its onboard science instruments.

What did the magnetometer measure during the Mars encounter?

According to MIT magnetometry lead Ben Weiss, the magnetometer measured the Martian bow shock where the solar wind slows against the planet’s weak magnetic resistance.

When will the Psyche spacecraft reach its target asteroid?

According to JPL project manager Bob Mase, the spacecraft is on a trajectory to rendezvous with the metal asteroid Psyche in the summer of 2029.