Why NASA’s Psyche probe is embarking on humanity’s first journey to a metal asteroid

Why NASA’s Psyche probe is embarking on humanity’s first journey to a metal asteroid
  • PublishedOctober 8, 2023

In the swirling ring of asteroids between Mars and Jupiter, one space rock has attracted far more attention than any other.

It’s known as 16 Psyche.

The metal-rich asteroid has made headlines because scientists once estimated, if mined, it could be worth way more than all the cash on Earth today.

But the metal that gives 16 Psyche such an eye-popping valuation is interesting to scientists for other reasons.

The dense little world can provide a window into what was happening during the earliest epoch of our Solar System.

Michael Shepard, geoscientist at Bloomsburg University of Pennsylvania, has a special interest in the asteroid and has helped produce 3D models of the rock.

“Psyche will add a big missing piece in our understanding of how the Solar System formed,” he said.

The upcoming Psyche mission, led by NASA’s Jet Propulsion Laboratory in Southern California, is designed to get up close and personal with 16 Psyche and examine its mysterious exterior.

Building on years of Earth-based observations, scientists hope to reveal exactly what 16 Psyche is: The remnant core of a failed planet? A tiny planet that was crashed into and reassembled? Or a cosmic body shaped by something more exotic, like iron-spewing volcanoes?

With Psyche, those questions could finally be answered.

A spacecraft with X-shaped solar panels against a starfield
An artist’s illustration of the Psyche spacecraft en route to the asteroid 16 Psyche. (Supplied: NASA/JPL-Caltech/ASU)

What’s Psyche?

Psyche can refer to three things, making it a little confusing.

It starts with 16 Psyche, the official name of the asteroid that was discovered in 1852 by Italian astronomer Annibale de Gasparis. It’s named after the goddess of the soul in Greek mythology.

The “16” denotes that the rock was the 16th minor planetary body discovered. Most of the time, scientists just call it Psyche.

Next, there’s the Psyche mission, which consists of a NASA-built orbiter that’s also named Psyche.

The mission was selected as part of NASA’s Discovery program in 2017.

When it reaches orbit around Psyche, it will be the first time that humans have visited a metal asteroid.

When is NASA launching the Psyche mission?

Psyche’s launch window was intended to open on October 5 but NASA delayed the launch by a week, to October 12, to allow more time to fine-tune the spacecraft’s thrusters.  

The potential launch time is 1:38am AEDT every day. If the window is missed because of weather or other factors, it gets pushed to the following day.

The spacecraft will be launched from the Kennedy Space Center in Florida, aboard a SpaceX Falcon Heavy, one of the world’s most powerful rockets. 

The mission was originally scheduled to launch in September 2022 and arrive at Psyche in 2026. However, mission development and workforce issues forced NASA to postpone and re-evaluate the timeline.

The route for the Psyche spacecraft to the asteroid 16 Psyche, which takes it on just over two laps of the solar system
The Psyche mission timeline includes a Mars gravity assist in 2026. It’s scheduled to arrive in August 2029. (Supplied: NASA/JPL-Caltech)

The mission has now been given the green light to continue but the delay means the spacecraft is now expected to reach 16 Psyche in 2029.

It will travel around 3.6 billion km on its journey, about 1.4 million km further than its route had it launched in 2022.

The new course will see the Psyche spacecraft make a close pass of Mars, slingshotting around the planet to gather speed on its journey to the full metal asteroid.

What do we already know about 16 Psyche?

The study of 16 Psyche has, so far, been limited to observations from Earth and in low-Earth orbit.

The asteroid is the largest member of the M-class, a group of metal-rich asteroids. These are a rare breed; there are less than 40 in JPL’s Small Body Database.

Compared with many other asteroids, 16 Psyche is very, very reflective.

That reflectiveness has enabled scientists to build a fuzzy picture of 16 Psyche’s structure and key features, Professor Shepard said.

“We know its size, shape, rotation period, and rotation pole to a pretty high degree — within 5 per cent or so.”

It’s about 220km wide — you could fit two side-by-side between Melbourne and Launceston — and shaped like a bumpy, flattened potato.

The Psyche spacecraft will hover about 75km from its surface.

That’s about eight times closer than a Starlink satellite in low-Earth orbit.

At this height, the spacecraft will be able to image the surface features, creating a map of Psyche and providing our first real glimpse of its surface features — a real-world equivalent of the “zoom and enhance” trope used in TV crime dramas.

What metals are on 16 Psyche?

The surface of 16 Psyche remains a riddle wrapped in an enigma adorned with a coating of rare metals — we think.

Data from large telescopes and radar imaging have shown some patches reflect more light than others, suggesting those metals are distributed haphazardly over Psyche’s surface.

What those metals are remains elusive

We do know that many meteorites — the rocks that fall to Earth from space — come from asteroids. Scientists can study their chemical composition and structure to determine which asteroids they may have originated from. 

“We use the metals that have been observed in iron meteorites as examples for what metal Psyche might be made of,” said Fiona Nichols-Fleming, a PhD candidate at Brown University in the US studying 16 Psyche. 

It’s very likely the asteroid is rich in iron and nickel and there’s also likely to be trace elements of cobalt, titanium and rare metals, like platinum and palladium. 

But while this provides the best guess at what metals might be on the asteroid, the truth is scientists aren’t yet sure of their abundance. 

What don’t we know about 16 Psyche?

The biggest question is: What is 16 Psyche?

There are a number of competing theories.

One of the earliest theories suggest the asteroid might be a remnant core of a planet, left over from the earliest days of the Solar System. Later measurements of the rock’s density have suggested this is less likely, Professor Shepard said.

“I don’t think any theory has been completely ruled out, but the earliest idea that Psyche is a remnant metal core is probably the least favoured right now.”

If it is a remnant core, the Psyche spacecraft will find out. It carries a magnetometer, hoping to sense any remnant magnetism the asteroid might exhibit.

Another theory suggests 16 Psyche may have been moulded by an extreme type of volcanism that is no longer active.

There are so many unanswered questions about Psyche’s formation and evolution, Ms Nichols-Fleming said.

“Regardless of what the mission finds, we’ll have a new piece of the puzzle for understanding the early Solar System and the formation of planetary bodies.”

How much is 16 Psyche worth?

That’s the $US10,000 quadrillion ($15,600 quadrillion) question.

Lindy Elkins-Tanton, lead mission scientist, once suggested the asteroid could be worth that amount.

That number is highly speculative, as Professor Elkins-Tanton noted in a 2017 interview, and the bigger problem is we’d have to find a way to mine its minerals.

16 Psyche would be a great resource, said Andrew Tomkins, an earth and planetary scientist at Monash University, “if you can find a way to bring it down to the Earth’s surface … without making a big hole in the ground”.

The idea of mining the asteroid remains a pipe dream, though, because scientists don’t know enough about Psyche’s surface features and composition. 

Professor Shepard noted it would be foolhardy to rush to the asteroid with a stack of mining equipment before we have this type of preliminary information to plan our journey.

Artist's impression of Asteroid 16 Psyche
An illustration of what Psyche might look like when NASA gets up close in 2029.(Supplied: Arizona State University)

Rebecca Allen, an astronomer at Swinburne University of Technology, says “there are going to be insane challenges you have to overcome, and advancing technology to do that is going to come back to us and benefit us on the planet”. 

There are other issues at play, too. Who owns an asteroid? Under the conditions of the 1967 United Nations Outer Space Treaty, the answer is “nobody”.

Signatories to the treaty, including the US, Russia, India, China and Australia, can’t claim sovereignty over asteroids, the Moon or Mars.

However, the Treaty does not explicitly deny countries access to resources they’ve mined.

And while turning space rocks into space mines remains hypothetical and exorbitantly expensive, missions like Psyche could pave the way for developing the technological know-how and understanding that could come back to benefit us on Earth, Dr Allen noted.

But sustainability, safety and the ethical considerations of asteroid mining must be considered, too. 

“We have to think about the consequences of what we’re doing there,” Dr Allen said.

How can I watch the launch?

NASA and SpaceX will both be streaming the launch live on October 12, but you’ll need to be up late. 

The launch time is 1:38am AEDT, but broadcasts generally start 30 to 60 minutes prior to lift-off.


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