NASA’s Psyche is now thrusting almost nonstop at more than 100,000 mph toward a metal asteroid

NASA’s Psyche spacecraft has been firing its electric thrusters almost without a break since Sept. 28, and the agency says it is now moving at more than 100,000 mph (160,900 kph). The destination is the metal-rich asteroid Psyche, roughly 173 miles (280 kilometers) across at its widest, where arrival is planned for summer 2029.

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The status comes from a mission blog post dated Oct. 22, 2026. Don Han, the Psyche navigation lead at NASA’s Jet Propulsion Laboratory (JPL), summed up the phase in a line that gave the post its name: it is now “pedal to the metal” to the asteroid. After a Mars gravity assist, the spacecraft stopped coasting and went to near-continuous thrusting, pausing only about once a week to check in with mission controllers.

What 100,000 mph is measured against

The number needs its frame. In the NASA Psyche blog post, the figure is given at maximum cruise speed and relative to an observer on Earth: more than 100,000 mph. It is not a closing speed on the asteroid, and the post gives none. Psyche the asteroid is also moving around the Sun, so the rate at which the gap between the two shrinks is a different quantity that NASA does not state in this post.

The distinction matters because a speed that large is mostly borrowed motion. A spacecraft launched from Earth inherits Earth’s orbital velocity around the Sun, and gravity assists such as the Mars flyby add or bend that motion at almost no propellant cost. NASA describes the Mars encounter as giving a propellant-saving speed boost and a slight change of trajectory. For a general explanation of the technique, see this overview of the gravity assist.

Lindy Elkins-Tanton, the mission’s principal investigator at the University of California, Berkeley, said the Mars flyby also gave the team a chance to calibrate instruments and practice procedures before the long cruise. The spacecraft launched in October 2023, and the post says about one-third of its propellant has been used in the three years since.

Hall-effect thrusters: a push the weight of one AA battery

The engines are solar-powered Hall-effect electric thrusters that expel ions of xenon gas; the mechanism is covered in this reference on the Hall-effect thruster. Psyche carries four of them and fires one at a time. Each can produce up to 250 millinewtons of thrust, which NASA compares to roughly the weight of one AA battery. That is a feeble push at any instant, yet applied for around nine hours in every ten for years it adds up to a velocity change chemical rockets could not deliver on the same propellant.

Han said the thrusters will run “nearly 90% of the time” until arrival. Steve Snyder, lead engineer for propulsion operations at JPL, said they will run at full power for three months and then gradually step down to about half power as sunlight weakens with distance from the Sun. The power comes from two five-panel, cross-shaped solar arrays with about 800 square feet (75 square meters) of collecting area, so a dimmer Sun directly means weaker thrust. The arrays are the reason the throttle comes down at all: the farther the spacecraft travels toward the asteroid belt, the less sunlight reaches the panels, and the less electrical power the engines can draw.

Snyder also called the torque measurements the first of their kind for a Hall thruster in space. The swirling ions create a slight torque on the spacecraft, which reaction wheels absorb. Periodically the spacecraft shuts off its main thruster, rotates and fires a low-power thruster in another direction to offload the momentum the wheels have built up, which is part of why the thrusting is almost nonstop rather than continuous.

Xenon budget, 2029 arrival and the metal target

Psyche launched with about 2,400 pounds (1,090 kilograms) of xenon in seven tanks, and about a third is gone after three years. Xenon is the working fluid for the ion engines: the solar arrays supply the electricity that ionizes it, and the thrusters accelerate the ions to produce thrust, so every kilogram spent is a kilogram that cannot be recovered. The remainder has to carry the spacecraft through the rest of a cruise that ends with arrival at the asteroid in the main asteroid belt in summer 2029. NASA says orbit insertion comes in 2029, followed by a two-year prime science mission.

The asteroid itself is the reason for the trip. NASA describes it as thought to be the partial core of an early planetesimal, a building block of the kind that merged into rocky planets. Studying that kind of exposed metal could reveal what the interior of rocky planets such as Earth is like, which cannot be sampled directly. The target is catalogued as 16 Psyche.

The planned arrival is a plan, not an event, and the post offers no firm calendar day. What the blog does establish is the present state of the cruise: engines on almost around the clock, full power for three months, a gradual reduction after that, and a navigation team led by Han that checks in about weekly. Those three phases, and the weekly pause for contact with controllers, are the working rhythm of the next stretch of the trip, which began on Sept. 28 and runs, with the throttle-down Snyder describes, all the way to the 2029 arrival. The spacecraft shares its name with the target, and its background is summarized on a reference page for the mission.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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