Psyche’s Mars Gravity Assist: Slingshot Toward a Metal Asteroid

NASA's Psyche spacecraft is scheduled to pass about 2,800 miles (4,500 kilometers) from the surface of Mars on May 15, 2026, travelling at 12,328 mph (19,840 kph). The encounter is a gravity assist meant to carry the spacecraft toward its namesake target, a metal-rich asteroid in the main asteroid belt, with arrival planned for 2029.

The journey so far

The Psyche mission launched from NASA's Kennedy Space Center on October 13, 2023. The video describes the launch and deployment as flawless, and the spacecraft has since been cruising through deep space toward the asteroid Psyche, which the narration calls the largest metal-rich asteroid in the solar system. It orbits the sun between Mars and Jupiter.

Scientists think the asteroid could be an exposed core of a planetary building block, which may unlock secrets to the origin of planets like Earth and the solar system. The spacecraft carries instruments to image, detect, measure and map the asteroid's geology, composition, topography, and gravitational and magnetic fields.

Why Mars is needed

The maneuver is known as a gravitational slingshot, a propellant-saving move that uses Mars' gravity. A mission speaker says it will increase the spacecraft's speed, but more importantly change the plane of its orbit. Another explains that the plane of Earth's path around the sun and the plane of the asteroid Psyche differ by about 3 degrees, so the spacecraft has to align with the asteroid's plane to reach it. In the team's words, they cannot do it without the gravity assist.

What the instruments will do

During the flyby all of Psyche's instruments will be fully operational, with the imagers particularly active. The spacecraft will approach with high phase, so Mars will appear as a crescent. The team plans time-lapse images to make a short video of the planet as the spacecraft arrives and departs.

The mission team will also use the encounter to calibrate the instruments. By capturing thousands of observations of Mars with the multispectral imager, engineers can hone the imaging and navigation techniques needed to orbit Psyche and study what scientists believe is the asteroid's exposed nickel-iron core of an ancient planet.