At roughly 12,333 mph, NASA’s Psyche spacecraft will skim just 2,800 miles above the surface of Mars on Friday, May 16, 2026, threading a gravitational needle that will bend its course toward one of the strangest objects in the solar system: a 140-mile-wide asteroid that appears to be made largely of metal.
The flyby is the single most consequential navigational event of the entire mission. By borrowing momentum from Mars’ gravitational pull, the probe gains the velocity shift it needs to reach asteroid 16 Psyche without burning through propellant reserves it cannot replace. If the maneuver works as planned, the spacecraft will arrive in orbit around the asteroid in August 2029, where it will spend nearly two years studying what scientists believe may be the exposed core of a protoplanet that was stripped of its rocky outer layers by violent collisions billions of years ago.
How the gravity assist works
The concept is straightforward, even if the execution is not. As Psyche falls toward Mars, the planet’s gravity accelerates the spacecraft and redirects its trajectory around the Sun. Engineers at NASA’s Jet Propulsion Laboratory designed the approach to bring the probe within about 2,800 miles (4,500 km) of the Martian surface at a speed of roughly 19,848 kph. That close pass delivers the velocity change the spacecraft needs without firing its Hall-effect thrusters for a costly deep-space burn, conserving the xenon propellant that powers its solar electric propulsion system for the years of maneuvering still ahead.
Gravity assists have been a staple of interplanetary navigation for decades, used by missions from Voyager to Cassini. But each one is custom-engineered, and the margins are tight. A slight error in approach angle or timing could alter the post-flyby trajectory enough to require corrective burns that eat into the mission’s propellant budget. NASA has not publicly detailed contingency plans for the encounter, though JPL’s navigation teams have extensive experience with this type of maneuver.
The flyby also serves as an engineering shakedown. During the close approach, the spacecraft’s instruments will image Mars and run calibration tests, giving the operations team a real-world check on hardware performance before the probe reaches its primary target. One early result is already public: Psyche captured an image of Mars on May 3, 2026, from a distance of about 3 million miles (4.8 million km), confirming that its multispectral imager was functioning and properly aimed.
A long road to a strange destination
Psyche launched on October 13, 2023, after a one-year delay caused by late delivery of the spacecraft’s flight software and testing equipment. The postponement pushed the mission past its original 2022 launch window and forced engineers to recalculate the trajectory, ultimately adding the Mars gravity assist as the most efficient way to reach the asteroid on the revised timeline. According to NASA’s official mission overview, the Mars flyby is the pivotal midcourse event between launch and arrival.
The spacecraft travels using solar electric propulsion, a system that ionizes xenon gas and expels it at high speed to generate thrust. The force is gentle, roughly equivalent to the weight of a AA battery resting in your palm, but it operates continuously over months and years, gradually building enormous velocity changes that chemical rockets achieve in short, fuel-guzzling bursts. A peer-reviewed paper on the mission’s trajectory design explains how the gravity assist was engineered to close the velocity budget that solar electric propulsion alone could not cover. Without the Mars flyby, the mission would have required significantly more propellant or a larger launch vehicle.
After Friday’s encounter, Psyche will spend the next three years on a long arc through the inner solar system before entering orbit around its target in August 2029. Once there, it will spend at least 21 months mapping the asteroid’s surface with a magnetometer, a gamma-ray and neutron spectrometer, and the same multispectral imager now photographing Mars.
What makes 16 Psyche so unusual
Most asteroids are rubble piles of rock and ice. Asteroid 16 Psyche, orbiting in the main belt between Mars and Jupiter, appears to be something fundamentally different. Ground-based radar and spectral observations suggest it is rich in iron and nickel, and its bulk density supports that picture. Research led by Lauri Siltala and Mikael Granvik, available as a preprint on arXiv, estimated the asteroid’s density at approximately 3.88 grams per cubic centimeter, plus or minus 0.25. That is far denser than typical stony asteroids (which cluster around 2 to 3 g/cm³) and consistent with a significant metal fraction.
The leading hypothesis is that 16 Psyche is the remnant core of a protoplanet, a body that began forming into a full-sized planet early in the solar system’s history but was shattered by collisions before it could finish. If that is correct, studying Psyche up close would offer a direct look at the kind of metallic interior that lies buried and unreachable beneath the rocky mantles of Earth, Mars, and the other terrestrial planets.
But the picture is not settled. The density measurement, while suggestive, does not rule out a porous structure with a mix of metal and silicate rock rather than a solid iron-nickel mass. Scientists will not have definitive answers until the spacecraft’s instruments begin mapping the surface composition and measuring the asteroid’s magnetic field in 2029.
About that $700 quintillion price tag
The figure that has followed this mission through every headline is $700 quintillion, a number so large it dwarfs the entire global economy by orders of magnitude. It originates not from NASA or any peer-reviewed study but from back-of-the-envelope calculations that multiply the asteroid’s estimated metal content by current commodity prices for iron and nickel.
The math has a fatal flaw: it assumes you could sell that volume of metal at today’s prices. In reality, flooding Earth’s markets with even a fraction of that material would collapse commodity prices to near zero. NASA has never endorsed the valuation. The agency frames the mission entirely around science, describing 16 Psyche as a window into planetary formation, not a mining prospect.
That does not make the asteroid uninteresting from a resource perspective. The fact that a body this metal-rich exists and can be studied up close is genuinely significant for the long-term future of space resource utilization. But the $700 quintillion figure tells us more about how viral numbers travel through media than it does about the asteroid’s actual economic relevance.
What Friday’s flyby will and won’t reveal
The Mars encounter will not answer the big scientific questions about 16 Psyche. Those answers are still three years and hundreds of millions of miles away. What the flyby will do is lock in the trajectory that makes those answers possible and generate engineering data that confirms the spacecraft is ready for the work ahead.
Navigation tracking during the close approach will tell JPL’s flight dynamics team exactly how the spacecraft’s orbit has changed, allowing them to verify that Psyche is on course for its 2029 rendezvous. Engineering telemetry will reveal how the spacecraft’s systems performed under the gravitational and thermal stresses of a planetary flyby. And the images of Mars, while not the mission’s primary science, will help calibrate the imager that will eventually photograph the asteroid’s surface in detail.
For now, the spacecraft is healthy, its instruments are working, and the math says the flyby will deliver the gravitational kick it needs. What happens over the next 24 hours above Mars will determine whether Psyche stays on schedule for its appointment with one of the solar system’s most enigmatic objects, a world that may preserve, frozen in metal, a record of how planets are built.
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*This article was researched with the help of AI, with human editors creating the final content.
