On May 15, 2026, at approximately 3:28 PM Eastern time, NASA's Psyche spacecraft reached its closest point to Mars: 4,500 kilometres above the Martian surface, traveling at 12,333 mph (19,848 kph). The pass carried the probe inside the orbits of Mars's two moons, Phobos and Deimos — closer to the planet than any of its natural satellites.
The manoeuvre was not discretionary. Mission planners at NASA's Jet Propulsion Laboratory designed the entire 2.2-billion-mile (3.6-billion-kilometre) trajectory around this single gravitational exchange. Mars's orbital velocity did what xenon-gas ion thrusters alone could not: it tilted Psyche's orbital plane and accelerated the spacecraft toward the main asteroid belt, where its target, 16 Psyche, orbits between Mars and Jupiter. Mission controllers confirmed the flyby's success by monitoring the Doppler shift in radio signals exchanged between Psyche and NASA's Deep Space Network — changes in frequency that reveal changes in speed, providing an independent velocity check without requiring the spacecraft to report back directly.
Sarah Bairstow, Psyche's mission planning lead at JPL, had described the preparation as months of precise programming: "We are now exactly on target for the flyby, and we've programmed the flight computer with everything that the spacecraft will do throughout May."
From Mars's Night Side: Thousands of Images in Processing
Because Psyche approached Mars from its shadowed hemisphere, early images capture a crescent rather than the familiar rust-coloured disc. Jim Bell, the mission's imager lead at Arizona State University, described the approach geometry: "We are approaching Mars at a very high phase angle, which means we are catching up with the planet from its night side with only a sliver of sunlight creating a thin crescent." He added that after the closest pass, when Psyche swung around to the sunlit side, the spacecraft would have the opportunity to photograph a near-fully illuminated Mars — "just plain beautiful photos," in his words.
Thousands of multispectral observations were collected during the encounter. Engineers have not yet finished processing the imagery; a time-lapse sequence is expected to be released publicly in the coming weeks. The images serve a purpose beyond aesthetics: this is the first time Psyche's imager has been calibrated against a target larger than a few pixels, and the data will be used to refine the imaging techniques the team will need when the spacecraft approaches 16 Psyche in 2029.
Several existing Mars orbiters — NASA's Mars Reconnaissance Orbiter, Mars Odyssey, ESA's Mars Express, and the ExoMars Trace Gas Orbiter — provided coordinated observations and navigation data during the encounter. Cross-referencing Psyche's sensor readings against measurements from those established spacecraft allows engineers to validate the probe's instruments against known benchmarks.
The Hunt for Mars's Hidden Dust Ring
One secondary objective of the flyby was a search for a hypothesised faint dust ring surrounding Mars. Scientists have proposed that micrometeorites striking the surfaces of Phobos and Deimos continuously eject particles into Martian orbit, gradually building a diffuse torus. Whether that ring exists — and how dense it might be — has implications for understanding the erosion rate of the Martian moons and the broader dynamics of small-body debris in the inner solar system.
Psyche's approach geometry, coming in from the anti-sunward direction, placed it in a configuration where scattered sunlight could potentially illuminate ring particles during long-exposure observations. Whether any signal was detected is not yet known; analysis of the relevant imaging data is ongoing.
Magnetometer and Spectrometer Both Active During the Pass
Psyche's three-axis magnetometer was active during the flyby, measuring interactions between the solar wind and Mars's weak, irregular magnetic field. The instrument's primary scientific job will be to characterise the magnetic signature of 16 Psyche itself — a world that may carry a remnant field from its ancient history as a differentiating protoplanetary body. Calibrating the magnetometer against Mars's better-understood magnetic environment provides a useful baseline.
The gamma-ray and neutron spectrometer monitored changes in cosmic-ray flux during the pass, a secondary calibration exercise ahead of the instrument's primary role at the asteroid. At 16 Psyche, the spectrometer will attempt to identify the chemical elements at the asteroid's surface by detecting the gamma rays and neutrons emitted when cosmic rays strike it.
The Asteroid That May Not Be What NASA Thought — and Why That Makes 2029 More Significant
The core premise of the Psyche mission — that 16 Psyche is the exposed iron-nickel core of a long-destroyed protoplanet — has been under scrutiny for years. Researchers at Brown University and the University of Arizona have argued, based on density measurements and spectral analysis, that the asteroid may be less metallic than originally assumed, possibly harbouring a substantial rocky component that keeps its bulk density lower than a pure iron body should allow.
NASA's own mission overview now describes 16 Psyche as likely composed of "a mixture of rock and metal, with metal comprising 30% to 60% of its volume" — a significantly wider range than the near-pure metallic core hypothesis that originally defined the mission's scientific pitch. Whether the asteroid is a remnant core, a differentiated body that was repeatedly disrupted and re-accreted, or something stranger is precisely what the 2029 orbital campaign is designed to resolve.
That uncertainty is not a failure of the mission concept — it is its justification. As Lindy Elkins-Tanton, principal investigator for the mission at the University of California, Berkeley, has put it: "Ultimately, though, the only reason for this flyby is to get a little help from Mars to speed us up and tilt our trajectory in the direction of the asteroid Psyche." What arrives at 16 Psyche in 2029 will be the most capable set of scientific instruments ever sent to characterise a metal world.
Solar-Electric Propulsion's Deepest Test Yet
The Mars flyby is also a milestone for the propulsion system Psyche carries. The spacecraft is the first interplanetary mission to use Hall-effect electric thrusters, which ionise xenon gas and expel it to generate thrust. The force is gentle — far less than a chemical rocket — but it operates continuously over months and years, building velocity gradually across vast distances without the weight penalty of carrying large fuel reserves.
The gravity assist from Mars was a propellant-conservation measure as much as a navigational one. By letting Martian gravity do the work of tilting Psyche's orbital plane, the mission team preserved xenon for the roughly 29-month "Cruise 2" phase — continuous thruster firing from now until orbital insertion at 16 Psyche in August 2029.
The mission had already survived one propulsion crisis. In early 2025, all four thrusters were paused while engineers investigated an unexpected pressure drop in the primary xenon propellant line. After switching to the backup line in May 2025, full operation resumed by June 16, 2025, and the trajectory to Mars was maintained. That the probe arrived precisely on target for the flyby — after a thruster anomaly and more than two years into a six-year journey — represents a significant validation of the redundancy built into the spacecraft's design.
A Successful Flyby in the Shadow of Repeated NASA Budget Battles
The Psyche flyby arrives at a contested moment for the agency that operates it. In 2022, an independent review board found that workforce and management problems at JPL had caused Psyche to miss its planned 2022 launch window, a delay that also pushed back the VERITAS Venus mission indefinitely.
More recently, the Trump administration's proposed FY2027 budget — released in early April 2026 — called for a 47% reduction in NASA's science funding, which would cancel or end dozens of active and planned missions. The Planetary Society described the proposal as "a horrible threat to our future" in space exploration. The proposal mirrors a nearly identical FY2026 request that Congress rejected on bipartisan grounds, with the House voting 397-28 and the Senate 82-15 to preserve science funding at $24.4 billion. The FY2027 version is already facing similar congressional resistance.
Jack Kiraly, the Planetary Society's director of government relations, has warned that any deep cuts to the science directorate would undermine "outer solar system programs, astrophysics, heliophysics — all things that feed into the human program and enable the human program."
For now, Psyche is flying. Its trajectory is confirmed. Its destination is August 2029. What scientists will actually find at 16 Psyche — whether a planetary core, a disrupted metal world, or something the models haven't anticipated — remains the open question that makes the remaining 39-month journey worth following.
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