NASA’s Psyche spacecraft will execute a close gravity-assist flyby of Mars on Friday, passing within 2,800 miles of the planet’s surface — roughly the distance between the U.S. east and west coasts — at a velocity of 12,333 mph as it slingshots toward the asteroid belt between Mars and Jupiter.
The maneuver marks the midpoint of the uncrewed explorer’s six-year voyage to asteroid Psyche, a potato-shaped body roughly 173 miles long and 144 miles wide that scientists suspect is the exposed nickel-and-iron core of a fledgling planet stripped down by cosmic collisions during the solar system’s formation 4.6 billion years ago. The spacecraft launched in October 2023 and should arrive at its target in 2029, where it will spend two years in orbit studying the asteroid.
“We’re getting just plain beautiful photos,” Arizona State University’s Jim Bell, the imaging team leader, said in a statement, noting that the flyby serves double duty — allowing operators to fine-tune instruments while capturing striking imagery.
All of the spacecraft’s science instruments will be active during the Mars pass. NASA’s two Mars rovers, along with a small fleet of U.S. and European orbiters, will make simultaneous surface and atmospheric observations for comparison with Psyche’s instrument readings. The spacecraft’s cameras are already photographing Mars, which appears as a crescent on approach and will show as a nearly full sphere once the flyby is complete.
Asteroid Psyche orbits three times farther from the sun than Earth, on the outer fringes of the asteroid belt. Most of the millions of objects in the belt are made of rock or ice; only a small percentage are thought to be metal-rich like Psyche, making the mission a rare opportunity to study a type of body that may reveal how terrestrial planets like Earth formed and differentiated into core, mantle, and crust. Studying such an object up close, NASA scientists have said, can yield information about why and how Earth spawned life.
The van-sized spacecraft runs on solar electric propulsion, using xenon gas thrusters for the journey — a fuel-efficient system that allowed engineers to plot the six-year trajectory including the Mars gravity assist that will accelerate Psyche toward its final destination.