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NASA has launched its first mission to a mysterious world made largely of metal, on a journey to find out whether the asteroid is the exposed core of an early planetary building block from the beginning of the solar system.
The Psyche mission lifted off at 10:19 a.m. ET Friday aboard a SpaceX Falcon Heavy rocket from NASA’s Kennedy Space Center in Florida. Psyche will be the first of many upcoming NASA science missions slated to launch aboard the Falcon Heavy rocket.
The mission, named for the 16 Psyche asteroid it will observe, will travel about 2.2 billion miles (3.6 billion kilometers) over the next six years to reach the space rock, located in the outer part of the main asteroid belt between the orbits of Mars and Jupiter, said David Oh, Psyche chief engineer for operations at NASA’s Jet Propulsion Laboratory in Pasadena, California.
“We’re launching a mission to an object that humankind has never before studied up close,” said Lindy Elkins-Tanton, Psyche principal investigator and foundation and regents professor at Arizona State University’s School of Earth and Space Exploration. “This will be our first time visiting a world that has a metal surface. 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.”
Scientists believe the large M-type, or metallic, asteroid could be the exposed core of an early planetary building block and may resemble the cores of rocky planets in our solar system, such as Earth, Mars, Venus and Mercury. The core may have been exposed due to violent collisions with other rocky bodies early in the solar system’s formation.
Ground and space-based telescopes have observed Psyche in the past, mainly detecting radiation bouncing off the reflective metal on the asteroid’s surface. Together, these observations have helped scientists develop a model of the asteroid’s shape, which is about the size of Massachusetts without Cape Cod, and a surface area equivalent to California, Elkins-Tanton said.
But even using the Hubble Space Telescope, Psyche only appears as a few pixels.
“We do not know what Psyche looks like,” Elkins-Tanton said. “I always joke that it’s shaped like a potato because potatoes come in many shapes, so I’m not wrong. But we’re going to find out when we get there.”
The long road to Psyche
The Psyche mission, originally scheduled to launch in October 2022, has faced its share of delays.
Last year, there wasn’t enough time to conduct a full checkout of the spacecraft’s flight software to ensure it was ready before the 11-week launch window closed. And this year’s launch window was pushed from October 5 to October 12 to give engineers enough time to adjust the temperature limits of the nitrogen cold gas thrusters on the spacecraft, which will be used to orient it in space.
“There would have been a potential risk of overheating the thrusters and so it was a serious issue that we had to deal with,” said Henry Stone, Psyche project manager at NASA’s Jet Propulsion Laboratory. “And we would have probably discovered that right away had we not caught this and done the due diligence.”
The Falcon Heavy rocket powered the beginning of the spacecraft’s long cosmic journey before separating. Falcon Heavy’s side boosters landed back at Cape Canaveral Space Force Station in Florida, causing a sonic boom that could be heard by local residents, and will be used for future missions.
Once in space, the team will spend three to four months going through initial checks of the spacecraft and its instruments.
To accomplish the rest of the mission, the van-size spacecraft will rely on its new solar electric propulsion system, powered by Hall-effect thrusters, Oh said. The thrusters will utilize the spacecraft’s large solar arrays and “use electricity to ionize xenon gas and accelerate those charged ions through an electric field to very, very high speeds,” Oh said.
The result: a speed five times faster than that of the fuel released in a regular chemical rocket.
The Psyche spacecraft will arrive at Mars in May 2026 and use the planet’s gravity to effectively slingshot its trajectory to Psyche. The mission will arrive at the asteroid in late July 2029 and spend 26 months orbiting the asteroid to map its surface, take images and determine whether Psyche truly is a metal core. The spacecraft will use different orbits around the asteroid, going from 440 miles (708 kilometers) away to just 40 miles (64 kilometers) above the surface.
The Psyche mission’s imagers will begin transmitting data to Earth as soon as the spacecraft spots the asteroid.
Also along for the ride is the Deep Space Optical Communications technology demonstration, or DSOC. Occurring during the first two years of the journey to Psyche, it will be NASA’s most distant experiment of high-bandwidth laser communications, testing the sending and receiving of data to and from Earth using an invisible near-infrared laser.
The laser can send data at 10 to 100 times that of traditional radio wave systems NASA uses on other missions. If the tech demo is successful, DSOC could one day be used to communicate with humans exploring Mars.
Secrets of a metal world
The spacecraft’s instruments will help scientists determine the asteroid’s chemical and mineral composition, topography, mass, gravitational field and rotation. The mission’s magnetometer will attempt to detect evidence of a magnetic field around Psyche, which could suggest that the space rock initially formed as a planetary core.
Psyche, which has a high density, is largely made of iron and nickel, along with something else, which may be rock, sulfur or carbon-based, Elkins-Tanton said.
If Psyche isn’t a core, it could be a rare, leftover object from the formation of the solar system that has never been observed.
“The other idea is Psyche is a kind of primordial unmelted body basically formed from the very first materials in the solar system that came together under gravity and was preserved in this primordial state ever since,” said Ben Weiss, Psyche deputy principal investigator and magnetometer lead. Weiss is a professor of planetary science at the Massachusetts Institute of Technology.
Psyche may have formed near the sun and then was reduced to metal over time as oxygen atoms were stripped away from iron atoms — an object hypothesized but never found.
The science team is eager to see the surface features of the asteroid. Radar indicates that there are two large craters on the surface. But what does a metal crater look like? Psyche may have little metal spikes, spires and even tiny pieces that resemble a type of metal sand within the crater, said Elkins-Tanton. It’s also possible that Psyche experienced volcanic eruptions, creating huge cliffs and greenish-yellow lava flows due to their sulfur content.
“This is our scientifically motivated idea, almost certain to be completely wrong,” Elkins-Tanton said. “It’s going to surprise us when we get there. I think there’s a very good chance that it’s going to be outside of our imaginings, and that is my fondest hope.”