Spacecraft Uses Mars Gravity Assist in Critical Test for 2029 Asteroid Arrival
NASA's Psyche spacecraft successfully executed a close flyby of Mars on Friday, March 28, 2025, using the planet's gravity to propel itself toward its ultimate target—the metal-rich asteroid 16 Psyche. The maneuver, conducted at a distance of just 2,864 miles (4,609 km) from the Martian surface, marks the most significant trajectory adjustment since the mission launched in October 2023.
The flyby served as a crucial dress rehearsal for the spacecraft's arrival at the largest metal asteroid in the solar system, scheduled for 2029. Mission navigators at NASA's Jet Propulsion Laboratory (JPL) in California carefully orchestrated the slingshot, ensuring the probe gained enough velocity to reshape its orbit around the Sun.
More Than Midway Through a 2.2 Billion Mile Journey
Psyche, which launched from Kennedy Space Center atop a SpaceX Falcon Heavy rocket, has been coasting through space for over two-and-a-half years. The spacecraft relies on innovative plasma engines to gradually build impulse over its six-year voyage, which spans roughly 2.2 billion miles (3.6 billion km). The Mars gravity assist provides a critical boost, cutting down travel time and fuel consumption.
“This flyby was a flawless execution of a complex orbital ballet,” said Dr. Lindy Elkins-Tanton, principal investigator of the Psyche mission at Arizona State University. “It gives us invaluable data for the final leg of the journey.”
Background: The Psyche Mission
The Psyche mission targets the asteroid 16 Psyche, a unique world believed to be the exposed core of an early planet. Located in the asteroid belt between Mars and Jupiter, the object may hold clues about the formation of terrestrial planets. The spacecraft carries a suite of scientific instruments to study the asteroid's composition, magnetic field, and topography.
Launched on October 13, 2023, Psyche initially entered a heliocentric orbit. Its plasma thrusters, also known as Hall-effect thrusters, have been firing intermittently to increase the spacecraft's momentum. The Mars flyby was planned years in advance as the most efficient way to reach the asteroid without requiring excessive propellant.
What This Means
With the Mars gravity assist now complete, Psyche is on a direct trajectory to intercept its target in August 2029. The successful maneuver demonstrates the robustness of the mission's design and navigation systems. It also provides an opportunity to test instruments in a martian environment, though the primary science target remains the asteroid.
The data from the flyby will help refine future navigation for the spacecraft, including precise timing for the asteroid arrival. “Every gravity assist is a high-risk, high-reward moment,” said Dr. Julia Stähler, JPL navigation team lead. “This one sets us up perfectly for the final approach to Psyche.”
The mission is expected to revolutionize our understanding of metal cores and planetary formation. As Psyche continues its journey, scientists eagerly await the unique insights it will bring back from an uncharted world.