NASA’s Psyche spacecraft will explore unique asteroid looking for clues to the early solar system

Launch planned for next year, NasaThe Psyche mission marks the agency’s first time exploring an asteroid richer in metal than rock or ice.

More than 150 years have passed since novelist Jules Verne wrote “Journey to the Center of the Earth”, but reality has yet to catch up with this sci-fi adventure. While humans can’t make their way to our planet’s metallic core, NASA aims to visit a giant asteroid that may be the frozen remains of the molten core of a bygone world.

Called Psyche, this asteroid orbits the Sun in the main asteroid belt, between March and Jupiter. Using data collected from land-based radars and optical telescopes, scientists believe that Psyche is largely made of metal. It could be some or all of the iron-rich interior of an early planetary building block that was stripped of its outer rocky shell when it repeatedly collided with other large bodies during the early formation of the solar system.

The asteroid, which is about 173 miles (280 kilometers) at its widest point, could also be something else. It could be the remnant of a completely different iron-rich body type that formed from metal-rich materials somewhere in the solar system.

NASA’s Psyche mission hopes to find out. Scheduled for launch in August 2022, the spacecraft will orbit for two years around the asteroid it is named after, taking photos, mapping the surface and looking for evidence of an ancient magnetic field. Psyche will also study neutrons and gamma rays coming from the asteroid’s surface to help determine its elemental makeup.

The first mission to explore an asteroid whose surface contains substantial amounts of metal rather than rock or ice, Psyche seeks to better understand the cores of iron, an unexplored building block in the formation of planets. The mission also potentially offers the first opportunity to directly examine the interior of a rocky planet by offering a glimpse into the interior of a previously layered planetary body that otherwise could never be seen. What scientists are learning could shed additional light on the formation of the Earth and other rocky planets.

“There are a lot of fundamental questions about Psyche that remain unanswered,” said mission principal investigator Lindy Elkins-Tanton of Arizona State University. “And with every detail added from the data we can collect on Earth, it’s getting harder and harder to make a meaningful story. We really don’t know what we’re going to see until we visit, and we’re going to be surprised.

For example, previous observations on the ground have led scientists to believe that the asteroid contains up to 90% metal. Recent research by Elkins-Tanton used updated density measurements to estimate that the asteroid is more likely between 30% and 60% metal.

And scientists are wondering why Psyche appears to be low in iron oxides, which are chemical compounds made up of iron and oxygen. Mars, Mercury, Venus, and Earth has them all. “So if we’re correct that Psyche is a mixture of metal and rock, and rock contains very little iron oxide, then there must be a weird story about how it was created – because it does not correspond to the standard stories of planetary creations, ”said Elkins-Tanton.

Mystery of Psyche

Scientists also don’t know where Psyche formed. He may have been born inside the main asteroid belt, but it’s also possible that he was born in the same area as inner planets like Earth – or in the outer solar system, where now resides giant planets like Jupiter. Neither of the original two stories follows a straightforward path to where Psyche now lives, 450 million kilometers from the Sun.

Asteroids in general can provide insight into how planets were formed and how the early solar system worked 4.6 billion years ago. But Psyche is of particular interest to scientists because of its unusual character, with its metal content, high density, and low concentration of iron oxides.

“The fact that it’s so unusual tells us a new story that we’ve never seen before about the evolution of asteroids,” said Bill Bottke, Psyche Mission Scientist at the Southwest Research Institute in Boulder, Colorado. “It’s a part of the story that we don’t have right now. By putting this piece together with all the others we have, we continue to refine our story about how the solar system formed and evolved very early on. “

Tools of the trade

To help understand the origins of the asteroid, the mission’s scientific investigation will rely on a magnetometer, gamma-ray and neutron spectrometer, and multispectral imager. Scientists know that the asteroid doesn’t generate a magnetic field like the Earth does, but if Psyche had a magnetic field in the past, it could still be recorded in the asteroid’s material today. With sensors mounted on a 2-meter (6-foot) boom, the magnetometer can determine if Psyche is still magnetized. If so, it would confirm that the asteroid is part of the nucleus of a primitive planetesimal, the cornerstone of a primitive planet.

The orbiter’s gamma-ray neutron spectrometer will help scientists determine the asteroid’s chemical elements. When cosmic rays and high energy particles impact the surface of Psyche, the elements that make up the surface material absorb energy. The neutrons and gamma rays they emit in response can be detected by the spectrometer, allowing scientists to match their properties to those emitted by known elements to determine what Psyche is made of.

Meanwhile, a pair of color cameras make up the multispectral imager. The imager is sensitive to light just beyond what humans can see, using filters in the ultraviolet and near infrared wavelengths. The light reflected in these filters could help determine the mineralogy of any rock material that may exist on the surface of Psyche.

The spacecraft’s telecommunications system will also contribute to science. The X-band radio system is mainly used to send commands to the spacecraft and receive technical and scientific data from it. But scientists can also analyze subtle changes in these radio waves to measure the body’s rotation, oscillation, mass, and gravity field, providing additional clues to the composition and structure of Psyche’s interior.

Eyes on Psyche

But before this scientific analysis begins, there will be pictures. By the end of 2025, three years after launch, Psyche will be in sight of the asteroid and the imaging team will be on high alert.

“Before we even get into orbit, we will start to get much better images than those obtained with terrestrial telescopes. We will begin to solve the features, see large craters, basins of craters – maybe mountain ranges. Who knows what we’ll see? Said Jim Bell of Arizona State University, Psyche associate principal investigator and head of the imaging team. “All we know is that the reality of Psyche is going to be even stranger and more beautiful than we can imagine.”

Learn more about the mission

ASU is leading the Psyche mission. NASA’s Jet Propulsion Laboratory in Southern California is responsible for overall mission management, system engineering, integration and testing, and mission operations. The mission phase known as assembly, test and launch operations is currently underway at JPL. By next spring, Psyche will be fully assembled and ready to ship to NASA’s Kennedy Space Center.

JPL is also providing a technology demonstration instrument called Deep Space Optical Communications that will also fly on Psyche, which will test high-speed laser communications that could be used by future NASA missions.