Let’s Get Metal – Getting Psyched for Psyche

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I know I was just all hyped about the OSIRIS-REx asteroid mission and believe me, I still am. But now there’s a new asteroid mission on the block and it’s only fair I get all hyped up about that one too. NASA is preparing this coming Thursday, October 12^th, to launch Psyche, a spacecraft destined to explore one of the strangest worlds in the asteroid belt, the asteroid…Psyche.

Yes, the spacecraft and the asteroid have the exact same name. Was that a good idea? No. No, it was not. But NASA does not consult me about how to name their spacecraft (otherwise I’d give them a lesson in how acronyms actually work). So just to keep things clear, I’ll be referring to them as Spacecraft Psyche and Asteroid Psyche from here on. I blame NASA.

Anyway, let’s meet this new spacecraft, and find out just why this asteroid is cool!

The Asteroid

NASA only gets to build so many missions per year, so when they pick a target to explore you know there must be something special about it, and that definitely holds true for Asteroid Psyche. It is among the largest asteroids in the belt, with its roughly 140-mile diameter putting it 17^th in terms of size. That may sound low on the list, but keep in mind the belt contains millions of rocks, so being number 17 puts you pretty high up there.

It may be 17^th in terms of size, but it’s only 10^th in terms of mass. That’s because Asteroid Psyche’s makeup isn’t quite like any other asteroid—it’s extremely dense. We suspect that a lot of this rock—somewhere between 30-60%--is actually metal, mostly likely iron. As a result it’s classified as an M-type asteroid, a class that contains higher-than-normal concentrations of metal (random nerd side note: as a Star Trek fan, the designation of “Class M” for this asteroid has always delighted me, since Starfleet considers a “Class M” planet to be one that is suitable for humanoid life. That definitely does not apply to Asteroid Psyche, but it pleases me all the same).

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Asteroid Psyche sits firmly in the main part of the asteroid belt between Mars and Jupiter, so it’s orbiting the Sun about three times farther away than Earth is. At that distance it takes this metallic rock about five Earth years to complete a single orbit.

As another fun aside, Psyche was discovered early enough (it was the 16^th asteroid ever discovered, back in 1852, so its full designation is 16 Psyche) that astronomers were still giving things symbols as well as names. 

 “Psyche” means “soul” in Greek, and apparently the Greek symbol for the soul is a butterfly, so the symbol for Asteroid Psyche is a semi-circle, to represent a butterfly’s wing, crowned by a star, which I find delightfully lovely and whimsical. The semi-circle for the butterfly wing was then incorporated into the patch for Spacecraft Psyche’s mission. 

What’s Going On With Psyche (The Asteroid)?

So just how did an object like Asteroid Psyche form? Wonderful question! We don’t know. My personal favorite theory, not necessarily because it’s the most likely but because it’s very definitely the coolest, is that Asteroid Psyche was once the core of something that attempted to become Planet Psyche and failed. In this scenario, extreme impacts stripped the forming outer layers of this theoretical planet away, leaving the core behind. It’s hard to beat the idea of the exposed metallic core of a failed planet. If that’s the case, it would be a chance for us to see what the core of a terrestrial planet would look like with our own eyes (well, with the spacecraft’s anyway). We can’t usually do that because, well, these things are cores, they’re usually on the inside. 

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There are, of course, other ideas. One is that Asteroid Psyche isn’t a solid object at all, but rather a rubble pile similar to Bennu, the asteroid visited by OSIRIS-REx, although Asteroid Psyche would still be significantly more metallic. A metal rubble pile would be very weird and a very cool find, although I’m still holding out for the exposed planetary core.

Another idea is that Asteroid Psyche is a differentiated object. What that means is that it has different layers made of different materials. Earth, for instance, with its crust and mantle and core, is a differentiated object. We know some of the larger asteroids are, and Asteroid Psyche might be a metal core with a silicate mantle on top of it. In this case Asteroid Psyche might have undergone a sort of volcanism that we haven’t seen evidence of anywhere else: ferrovolcanism, the eruption of molten metal. We’re not expecting to see it actively happening on Asteroid Psyche, but we think it’s possible that this could have happened in its past, and we want to find evidence for it. Eruptions of molten iron isn’t quite as cool as the exposed core theory, but it’s definitely a close second.

The potential worth of this asteroid is another topic that’s often brought up. The idea of asteroid mining is something that humanity has toyed with in the past, since there are certain materials that are much more commonly found in the asteroid belt than on Earth. In theory this could make the process worthwhile, if we can overcome all of the challenges. We don’t actually know how much everything inside Asteroid Psyche is worth, but some estimates put it at $10,000,000,000,000,000,000. That is, for the record, around 100,000x the estimated worth of the entire global economy. You can see why some folks get dollar signs in their eyes when they think of this rock.

For the record, NASA is not going to Asteroid Psyche with an eye towards starting up mining operations. There are currently no plans in NASA’s future for such an endeavor. Asteroid Psyche is simply a world unlike any other, something NASA’s never been able to resist when given the chance.

The Spacecraft

Okay, so that’s why we want to go. What are we sending? Spacecraft Psyche is a surprisingly small ship for such a big mission. The entire thing is about the size of a tennis court, and most of that is solar panels. Out where Asteroid Psyche lives, Spacecraft Psyche will only be getting around 10% as much solar energy as it would at Earth, so big panels are required to make sure it gets the power it needs, especially since Spacecraft Psyche doesn’t use a traditional propulsion system. Most things we send into space use chemical thrusters to move about, but Spacecraft Psyche will use its solar panels to charge an electrically-powered rocket instead. We’ve never used such a propulsion system past lunar orbit before, so Spacecraft Psyche will be something of a testbed. 

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The spacecraft itself, the business part of it, is about 10 feet by 8 feet, or a little bigger than a minivan. That’s not a ton of space, but it’s enough to put in four instruments and a communications experiment. Spacecraft Psyche will carry a spectrometer, for figuring out what exactly Asteroid Psyche is made of, a magnetometer to map out the ragged remnants of Asteroid Psyche’s magnetic field, an x-band radio telecommunications system that will help Spacecraft Psyche map Asteroid Psyche’s gravitational field and figure out what its insides look like, and of course a camera so we can all feast our eyes on Asteroid Psyche’s tortured, pitted surface.

It will also carry a laser communication experiment, Deep Space Optical Communications. The hope is that this communications method will increase spacecraft communications efficiency 10-100 times over the usual methods. If we can prove that it works well so far from Earth it could have big implications both for future robotic exploration and for the day we finally get to send humans to Mars.

Spacecraft Psyche may be small, but it is stacked.

What’s Going On With Psyche (The Spacecraft)?

Spacecraft Psyche’s path to the launchpad has been anything but smooth. It was originally supposed to launch a year ago, by October 2022. In June 2022, NASA had to announce that the spacecraft was not going to be ready in time. This led to a major review of the mission development process and it was nearly canceled.

In the end it was determined that, with the spacecraft so close to completion, the best thing to do was to pull resources from a different mission, VERITAS, to get Spacecraft Psyche ready to go when the next launch window rolled around in October 2023. VERITAS was a truly amazing mission to Venus that was still in the early phases of development. With the resources lost to Spacecraft Psyche, it remains a question if VERITAS will ever become a reality (I really hope so, this mission is awesome). The rocket carrying Spacecraft Psyche was also originally supposed to carry a smaller, secondary spacecraft, Janus. When Spacecraft Psyche was delayed, Janus lost its chance to fly and has been “shelved”. It is not expected at this time that Janus will ever fly, though one should never say never.

Just when everything seemed set and Spacecraft Psyche would make its October 5^th, 2023 launch date, trouble struck again. On September 28^th, NASA announced they were pushing the launch by a week to this coming Thursday, October 12^th after discovering that the spacecraft’s thrusters were going to run hotter than expected. For a moment there was the possibility that the thrusters would have to be replaced and that the mission would not make its launch window. Instead it has been determined that the spacecraft can operate by using its thrusters at only 30% of rated thrust and avoid the overheating problem. This aside cost the spacecraft a week of its launch window, and considering the entire window is only 20 days long, ending on October 25^th, losing a week is no small thing.

Heading On Out

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Once Spacecraft Psyche actually launches, it has a long journey ahead of it, about 2.2 billion miles all told (spacecraft are rarely able to take a direct trip out to their targets). It will swing past Mars for a gravity assist in 2026, and is expected to reach Asteroid Psyche in August 2029, nearly six years after its launch. Once there, Spacecraft Psyche is expected to spend at least 26 months in orbit around the asteroid, steadily moving into lower and lower orbits to capture all the information it can.

When Spacecraft Psyche’s mission is over, it’s going to simply shut down, remaining forever (or at least for the foreseeable future) as a new, artificial moon of Asteroid Psyche, the body that gave the spacecraft its name and its purpose. There’s something kind of poetic about that.

In the meantime, keep your fingers crossed that Spacecraft Psyche starts its journey on Thursday as currently planned!