October 13, 2023

— NASA's first mission to a metal-rich world has gotten off to a proper heavy start.

The space agency's Psyche spacecraft, which shares its name with that of its target asteroid, launched atop a SpaceX Falcon Heavy rocket on Friday (Oct. 13). The 10:19 a.m. EDT (1419 GMT) liftoff from Pad 39A at Kennedy Space Center in Florida marked SpaceX's eighth Falcon Heavy flight since 2018, though it was the first with a NASA payload.

"This will be our first time visiting a world that has a metal surface," Lindy Elkins-Tanton, principal investigator for the Psyche mission at Arizona State University (ASU) in Tempe, said during a pre-launch press conference. "There aren't that many completely unexplored types of worlds in our solar system for us to go see, so that is what is so exciting about this."

"And here's the thing," Elkins-Tanton said, "we do not know what Psyche looks like."

Psyche launches to a metal asteroid. Click to enlarge video in new pop-up window. (NASA)

Hall pass

Located in the main asteroid belt between Mars and Jupiter, Psyche, the metal world, will take Psyche, the spacecraft, about six years to reach. The asteroid is approximately three times farther out from the Sun than Earth.

After separating from the Falcon Heavy's second stage about an hour after leaving Earth, the 16.1-foot-tall by 7.1-foot-wide (4.9-by-2.2-meter) Psyche spacecraft deployed two cross-shaped solar arrays, each consisting of five panels, increasing its span to about the size of a singles tennis court (81 feet long by 24 feet wide or 24.76 by 7.34 meters).

In addition to powering the science instruments that will study Psyche, the solar arrays enable the probe's propulsion system. Four Hall-effect thrusters will use the electricity to create electric and magnetic fields, which in turn will accelerate and expel charged atoms, or ions, of xenon at such high speed that it will produce a steady thrust.

"So you can think of this as getting thrust from sunlight, the ultimate in clean propulsion," said David Oh, the mission's chief engineer for operations at NASA's Jet Propulsion Laboratory in Pasadena, California.

Psyche is the first mission to use to use Hall-effect thrusters beyond the moon in deep space.

Mission to Mars... Psych(e)!

About 100 days after its launch, after all of its systems and science instruments have been activated, calibrated and checked out, the Psyche spacecraft will begin its first of two cruise periods on its way to the metal-rich asteroid. To reach its destination, though, it will need an assist from Mars.

In May 2026, the mission will fly by the Red Planet, using Mars' gravity to increase its own speed and to change its direction. The spacecraft will fly a safe distance above Mars, but close enough to get a gravity assist. Psyche will likely be traveling at about 13,000 mph (21,000 kph) relative to the surface of the planet.

Two days after swinging by Mars, the spacecraft will begin its second cruise, an approximately 29-month journey requiring near-continuous use of its thrusters. Cruise 2 will end as the probe starts its approach to the asteroid Psyche in the spring of 2029.

The core mission

Psyche (the asteroid) is an alluring target for study because it could be part or all of the iron-rich interior of a planetesimal, an early planetary building block, which was stripped of its outer rocky shell as it repeatedly collided with other large bodies during the early formation of the solar system. The Psyche spacecraft will be the first probe to directly examine the interior of a previously-layered planetary body, which scientists expect will shed additional light on how Earth and other rocky planets formed.

The Psyche spacecraft is outfitted with a pair of identical cameras equipped with filters and telescopic lenses to photograph the surface of the asteroid in different wavelengths of light; a gamma-ray and neutron spectrometer to determine the chemical elements that make up the surface material; and a magnetometer to look for evidence of an ancient magnetic field — a strong sign that the asteroid formed from the core of a planetary body.

"[Psyche] is going to surprise us once we get there," said Elkins-Tanton. "We're going to find out that our basic scientific understanding is going to be updated and that is why we need to go."

In addition to its "core" mission, Psyche is also carrying a technology demo that could greatly improve how missions into deep space communicate with Earth. NASA's Deep Space Optical Communications experiment, mounted to one side of the spacecraft, will be the first to use a near-infrared laser to test high-bandwidth transmissions at distances far exceeding the moon.