A mission to a metal world—The Psyche mission

A mission to a metal world—The Psyche mission
Artist’s concept of the Psyche spacecraft, a proposed mission for NASA’s Discovery program that would explore the huge metal Psyche asteroid from orbit. Credit: NASA/JPL-Caltech

In their drive to set exploration goals for the future, NASA's Discovery Program put out the call for proposals for their thirteenth Discovery mission in February 2014. After reviewing the 27 initial proposals, a panel of NASA and other scientists and engineers recently selected five semifinalists for additional research and development, one or two of which will be launching by the 2020s.

With an eye to Venus, near-Earth objects and asteroids, these missions are looking beyond Mars to address other questions about the history and formation of our solar system. Among them is the proposed Psyche mission, a robotic spacecraft that will explore the metallic asteroid of the same name – 16 Psyche – in the hopes of shedding some light on the mysteries of planet formation.

Discovered by Italian astronomer Annibale de Gasparis on March 17th, 1852 – and named after a Greek mythological figure – Psyche is one the ten most-massive asteroids in the Asteroid Belt. It is also the most massive M-type asteroid, a special class pertaining to asteroids composed primarily of nickel and iron.

For some time, scientists have speculated that this metallic asteroid is in fact the survivor of a protoplanet. In this scenario, a violent collision with a planetesimal stripped off Psyche's outer, rocky layers, leaving behind only the dense, metallic interior. This theory is supported by estimates of Psyche's bulk density, spectra, and radar surface properties; all of which show it to be an object unlike any others in the Belt.

A mission to a metal world—The Psyche mission
Artist’s impression of the size comparison between 16 Psyche, Eros, the Moon and Earth. Credit: Space.com/Karl Tate (artist)

In addition, planetesimals that formed earlier than 1.5 to 2 million years ago (which is believed to be the case with 16 Psyche) are believed to have had sufficient heat from short-lived radionuclides to differentiate into a metallic core and a silicate mantle.

Had such a planetesimal been struck by a large enough object, it would have been able to lose its lower-mass exterior while keeping its core intact. Thus, studying this 250 km (155 mile) wide body, offers a unique opportunity to learn more about the interiors of planets and large moons, whose cores are hidden beneath many miles of rock.

Dr. Linda Elkins-Tanton of Arizona State University's School of Earth and Space Exploration is the Principle Investigator of this mission. As she and her team stated in their mission proposal paper, which was originally submitted as part of the 45th Lunar and Planetary Science Conference (2014):

"This mission would be a journey back in time to one of the earliest periods of planetary accretion, when the first bodies were not only differentiating, but were being pulverized, shredded, and accreted by collisions. It is also an exploration, by proxy, of the interiors of terrestrial planets and satellites today: we cannot visit a metallic core any other way.

A mission to a metal world—The Psyche mission
The huge metal asteroid Psyche may have a strong remnant magnetic field. Credit: Damir Gamulin/Ben Weiss
"For all of these reasons, coupled with the relative accessibility to low- cost rendezvous and orbit, Psyche is a superb target for a Discovery-class mission that would characterize its geology, shape, elemental composition, magnetic field , and mass distribution."

A robotic mission to Pysche would also help astronomers learn more about metal worlds, a type of solar system object that scientists know very little about. But perhaps the greatest reason to study 16 Psyche is the fact that it is unique. So far, this body is the only -like body that has been discovered in the solar system.

The proposed spacecraft would orbit Psyche for six months, studying its topography, surface features, gravity, magnetism, and other characteristics. The mission would also be cost-effective and quick to launch, since it is largely based on technology that went into the making of NASA's Dawn probe. Currently in orbit around Ceres, the Dawn mission has demonstrated the effectiveness of many new technologies, not the least of which was the xenon ion thruster.

The Psyche orbiter mission was selected as one of the Discovery Program's five semifinalists on September 30th, 2015. Each proposal has received $3 million for year-long studies to lay out detailed mission plans and reduce risks. One or two finalist will be selected to receive the program's budget of $450 million (minus the cost of a launch vehicle and operations) and will launch in 2020 at the earliest.


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Source: Universe Today
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Oct 09, 2015
Couldn't they retask the Dawn orbiter to check out Psyche once it's other mission wraps up?

Oct 09, 2015
Couldn't they retask the Dawn orbiter to check out Psyche once it's other mission wraps up?


Depends if the Dawn orbiter will have enough Xenon fuel left for it's ion thruster.

Oct 09, 2015
Couldn't they retask the Dawn orbiter to check out Psyche once it's other mission wraps up?

Really depends on a number of things:
- where Psyche is in the asteroid belt with respect to the other two (not so much whether it's much further along, but whether it's further out or further in as the delta V is what eats up your fuel)
- how long the travel time would be and whether the onboard systems will keep working for that long (especially any battery buffered systems). I couldn't find a map that shows the realtive positions of these bodies in the asteroid belt. Anyone have one?

There's probably not a lot of spare fuel left as that would have been costly to get up there. It would be a nice bonus, but I think the chances of this working are slim.

Oct 09, 2015
aa_p: plus, as anyone who's played KSP knows, it may really depend most on the phase between Dawn and Psyche. Going further out or further in isn't nearly as hard as changing your position within the orbit you presently occupy.

Oct 09, 2015
I'm interested in knowing why, what with the limited resources available for missions, we have to be so interested in what might have happened billions of years ago. IMHO, answering that type of question is something you'd do if you have excess funds because it really makes very little difference to us today. It is almost purely academic, not practical. Sending missions to icy moons, to me, would be far more useful and interesting, unless someone is thinking about mining that metallic asteroid. But enough with the "gobs of money for geologists only" missions = let the geologists fund this stuff if they think it is so important to the human race.

Oct 09, 2015
LariAnn, do you realize how much a metal asteroid would be worth? I have heard some estimates beyond 1 trillion dollars for precious metals contained in asteroids. BTW Geologists do focus on things important to the human race, like volcanoes, earthquakes and finding fuel reserves. So by gaining insights on how planets form, geologists back here on earth can learn more about plate tectonics (see volcanoes and earth quakes) and other things that are important for human survival. People always bash NASA for spending money they use up like 1% of our budget. NASA's projects have had real payback in terms of technology, many technologies would not exist w/o their inovation.

Oct 09, 2015
I'm interested in knowing why, what with the limited resources available for missions, we have to be so interested in what might have happened billions of years ago

Because some people find questions like "where did we come from?", "how does everything work?" and "what nasty surprises that could snuff us out of existence at any moment does the universe hold in store for us?" interesting (and important)

Others, like you, are only interested in "where's my paycheck". Your mental horizon extends 2 meters above ground level in a vat, vast universe. Think how limited that makes you appear to others.

Not everything that is found is immediately practical. Most things you take for granted today were decryed as 'not practical' in their day (quantum physics, relativity, electricity, magnetism, steam engines, medical research, you name it.). Yet here you are using them because people didn't listen to people like you. Isn't that great?

Oct 09, 2015
The Russians don't even need a space program. We give them, free of charge, all the science they could wish for and more.

I'm reminded of the scene from Mary Poppins where the kids had the choice to spend the money to feed some pigeons, or to invest the money in their future, and they wanted to feed the birds...

lol... U.S. space program...

If this is preliminary for corporate mining projects, then make the corporations pay for it. Just giving them this stuff, especially foreign corporations, is ridiculous. It might even qualify as treason in this case. After all, China is going to have a manned space program of its own soon, and they get to take all the short cuts because America shares all our knowledge with everybody for free.

idiots.

God damn idiots.

Oct 10, 2015
When was the last time Russia just handed over something like planetary science data?

Venus? 30 years?

Yeah, yah, right now they are ferrying our astronauts to the ISS because NASA extended the shuttle program too long before developing a replacement program, so we're stuck with them a few more years.

I'll be glad to see the new SLS in action. It's supposed to be the largest rocket the U.S. has ever made. Going to be one hell of a show when that thing goes off...

I'm not saying we don't do things for the good of humanity, but the U.S. spends the most money on space. If there are resources to be claimed on these objects, the U.S. should get a guaranteed rights to claim those resources for our own economy, since we're the ones doing most of the discovery and exploration.

ESA helps.

Russia hasn't had a successful Mars mission in ages.
India got to Mars on their first try! For peanuts compared to Russia or the U.S. but primitive orbiter in comparison.

Oct 10, 2015
@antialias_physorg
I couldn't find a map that shows the realtive positions of these bodies in the asteroid belt. Anyone have one?

Hard to find one of those. Play with the JPL database, may be enough anyway (java required). You can check current position, one by one.
Just set the asteroid ID number (Ceres: 1, Vesta: 4, Psyche: 16) in the "Search" box, then switch to "Orbit Diagram" from the link (above the chart). The ">>" button sets them in motion:
http://ssd.jpl.na...sbdb.cgi

I suppose Dawn has "slowed down" to catch up with Ceres rather than "speed up" for it. 16 Psyche is way harder, either way.

Oct 10, 2015
Couldn't they retask the Dawn orbiter to check out Psyche once it's other mission wraps up?

Depends if the Dawn orbiter will have enough Xenon fuel left for it's ion thruster.

It depends on other factors too. For eg. Dawn may lack the required instruments:
The proposed spacecraft would orbit Psyche for six months, studying its topography, surface features, gravity, *magnetism*, and other characteristics.

"A *magnetometer* and laser altimeter were considered for the mission, but were not ultimately flown." https://en.wikipe...#Payload

(cont..)

Oct 10, 2015
(cont...)

However, you're right about the Xenon fuel issue if you suggested that it could be the "ultimate obstacle". Look at the fact sheets:

At Dawn's launch time: http://www.nasa.g...unch.pdf
-Fuel: 937 pounds (425 kilograms) of xenon propellant
-Estimated days of thrusting for entire mission: 2,000

Arrival at Vesta: http://www.jpl.na...esta.pdf
-Estimate of fuel remaining at the start of Vesta approach: 417 pounds (189 kilograms)
-Estimated days of thrusting up to the start of Vesta approach: 909 days

Arrival at Ceres: http://www.jpl.na...2015.pdf
-Fuel remaining at Ceres orbit entry: 88 pounds (40 kilograms)
-Days of thrusting up to orbit at Ceres: 1,885

Oct 20, 2015
Just think about how it would make the value of something like gold, uranium, or platinum would plummet if we were ever to able to harvest a meteor made of solid metal like this one. When you consider that the entire amount of gold ever mined on Earth is only about the volume of the Washington Monument, it really puts into perspective how massive something 150 miles across really is.

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