Ars takes a clean room tour of JPL’s asteroid-orbiting Psyche spacecraft

Ars Technica was given the chance to tour NASA's Jet Propulsion Laboratory in California this week, and was able to take a sneak peek at the Psyche spacecraft. The mission will be launched in August on a Falcon Heavy rocket. Scientists are hopeful that learning more about this asteroid will help them understand planet formation and the earliest days of our solar system.

16 Psyche is an M-type asteroid that is in the main asteroid belt and has a potato-like shape. Psyche is the exposed metallic core of a planet from the earliest days of our solar system, with the crust and mantle stripped away by a collision with other objects. Scientists have concluded that the mass and density estimates are not consistent with a metallic remnant core. It is more likely a mix of metals and silicates.

The asteroid may have once been a parent body for a particular class of stony-iron meteorites, one that broke up and re-accreted into a mix of metal and silicate. 16 Psyche may have experienced a period of iron volcanism while cooling, leaving highly enriched metals in those volcanic centers.

Scientists have long suspected that metallic cores are present on Earth. Researchers can't find the cores beneath the rocky mantles and crusts. Psyche is the only metallic core-like body that has been discovered, and it is the perfect opportunity to shed light on how rocky planets formed in our solar system. The Psyche mission was approved by NASA in order to collect data about the asteroid.

Linda Elkins-Tanton of Arizona State University, principal investigator of the Psyche mission, told Ars that their understanding of what Psyche might be has not changed in the last few years. It could be the metal core of a tiny planet from early in the solar system, or it could be something that never melted and formed a core but has metal mixed into it. We won't really know until we get there.

Psyche will have several instruments on board to collect scientific data. Scientists can use a multi-spectral imager to tell the difference between the asteroid's metallic and silicate minerals. The asteroid's composition is mapped by a gamma ray and neutron spectrometer. A magnetometer can be used to measure and map the magnetic field. A microwave radio telecommunications system will be able to measure the asteroid's gravity field, gleaning clues about its interior structure.

The Maxar Technologies company delivered the Chassis in April of last year. It is roughly the size of a passenger van and was built largely from commercial, off-the-shelf technology.

Engines powered by chemical propulsion are great for getting rockets off the surface of the Earth when you need a brawny burst of energy to break out of the planet's gravitational well. But chemical rocket engines are not the most fuel-efficient machines in the world, as they guzzle propellant. And once a spacecraft is in space, there are more fuel-efficient means of moving around. NASA has been experimenting with  [solar electric propulsion] technology for a while. The space agency first tested electric propulsion technology in its Deep Space 1 mission, which launched in 1998, and later in the Dawn mission in 2007 that visited Vesta and Ceres in the asteroid belt.

These spacecraft used ion thrusters. Hall thrusters, by contrast, use a simpler design, with a magnetic field to confine the flow of propellant. These thrusters were invented in the Soviet Union and later adapted for commercial purposes by Maxar and other companies. Many of the largest communications satellites in geostationary orbit today, such as those delivering DirecTV, use Hall thrusters for station-keeping.

Using Hall thruster-based technology enabled the mission's scientists and engineers to design a smaller and more affordable spacecraft. Each of the Hall thrusters on Psyche will generate three times as much thrust as the ion thrusters on the Dawn spacecraft and can process twice as much power. This will allow the spacecraft to reach the Psyche asteroid, located in the main belt, in January 2026, after a 3.5-year journey.

In March, the Psyche team attached the solar panels to the body of the craft and then unfolded them to make room for the August launch. The largest solar array at JPL is 800 square feet. They are designed to work in low-light conditions far away from the sun.