The Psyche spacecraft will orbit the asteroid in four staging orbits and perform science investigation for 21 months, between 2015 and 2028. Credit: JPL.

Deep in outer space, orbiting the Sun between Mars and Jupiter, is a massive metal asteroid named 16 Psyche.

Discovered in 1852, the asteroid is mostly composed of metallic iron and nickel. Scientists believe it has a diameter of 226 kilometres and a surface area of 641,800 km².

The asteroid landed on NASA’s radar in January 2017, when the space agency and Arizona State University’s School of Earth targeted it for exploration through the Discovery Program.

The latter mainly aims to understand the solar system with the launch of modest cost-capped space missions, thus giving birth to the planned Psyche orbiter, according to a report in Aerospace Technology.

NASA’s Jet Propulsion Laboratory (JPL) is responsible for the management, testing and mission operations, while Maxar Technologies will provide a high-power solar electric propulsion spacecraft chassis, the report said.

“The Psyche team is not only elated that we have the go-ahead … more importantly we are ready,” said principal investigator Lindy Elkins-Tanton of Arizona State University in Tempe.

“With the transition into this new mission phase, we are one big step closer to uncovering the secrets of Psyche, a giant mysterious metallic asteroid, and that means the world to us.”

The spacecraft will be launched onboard a Falcon Heavy rocket from Cape Canaveral, Fla., in July 2022 and is expected to reach the asteroid in early 2026, the report said. The estimated cost of the mission is US$850 million, including US$117 million for the launch and secondary payloads.

The mission will mainly determine if 16 Psyche is a core or unmelted material. It will also characterize topography and look inside terrestrial planets, including Earth, providing insights into planet formation, the report said.

Psyche will sport a body, two solar arrays and the instrument payload. It will have a length of 24.76m, including solar panels, and a width of 7.34m.

The spacecraft will orbit the asteroid in four staging orbits and perform science investigation for 21 months, between 2015 and 2028.

“The state of the art is profound ignorance about what we expect to find,” Jim Bell, the deputy principal investigator of the Psyche mission, told Smithsonian magazine. “We are trying to prepare for any eventuality, no matter what it’s like. Our instruments will make interesting measurements, observations and discoveries that will allow us to put the history of that object back together.”

The team’s leading hypothesis is that the asteroid is the once-molten metallic core of some planetary body destroyed long ago, the Smithsonian said.

No one knows what it looks like — whether chunks of mantle still hang from it; whether it will appear distinctively metal, a hunk of iron in space; or whether it will be covered in rock, indistinguishable by the untrained eye from any other asteroid in the solar system.

Scientist suspect Psyche might have had ferrovolcanoes in its past, the Smithsonian said.

“The idea is that Psyche might have retained much of its heat after the impact process that ripped off its mantle and crust,” Bell says.

“One way that planets get rid of their heat is through volcanism. On Earth its silicate volcanism. On [Jupiter’s moon] Io, there is silicate and also sulfur-rich volcanism. On Psyche, we may be looking at a place where it’s mostly dominated by molten iron, or iron and nickel, and maybe sulfur.” Different metals melt at different temperatures, and pockets of molten liquid from Psyche’s subsurface might have erupted long ago onto the surface.

“Maybe we will see evidence of that. Maybe there won’t be any at all. But it’s fun to speculate,” Bell says.

If the team proves that Psyche is a planetary core, then everything learned at the asteroid can be extrapolated to planetary bodies across the solar system — including Earth, the Smithsonian said.

The spacecraft will use a magnetometer and a gamma ray and neutron spectrometer to make chemical and magnetic measurements of the asteroid in order to determine its composition, and whether it is, in fact, a planetary core.

The asteroid lacks an atmosphere, and whether it has a magnetic field is yet to be determined. What is certain, however, is that it is exposed to the radiation environment of space, the Smithsonian said.