www.thespacewriter.com/wp

In just over two years, NASA will launch a probe to Psyche, an asteroid often dubbed as a “metal world”. Instead of being made mostly of ice, this asteroid’s composition is rocky-metallic. Why is it so important to study such a place? In short, the planet you stand on is made of the same materials.

Long ago, in the earliest epochs of the solar system, little bits of metallic rock like Psyche collided to form bigger worlds. These planetesimals are the building blocks of Earth, Venus, Mercury, Mars, and probably the cores of the giant planets. So, looking at this asteroid is like looking at the pieces that formed our planet.

About Psyche

An artist concept of the Psyche orbiter studying the surface of asteroid 16 Psyche. — An artist concept of the Psyche orbiter studying asteroid 16 Psyche during one of its orbits. Courtesy Psyche Mission/NASA.

Psyche was discovered in 1852 by Annibale de Gasparis. Its full official name is 16 Psyche, and it’s one of the ten most massive asteroids known in the solar system. It’s small, but it more than makes up for that with its interesting makeup. Psyche is very massive and has about 1 percent of the mass of the Asteroid Belt tied up in its 200-kilometer-wise body. It’s very likely to be the leftover iron core of a protoplanet, which would explain its massive properties. There has been water ice detected on its surface, probably delivered by impacts with other meteorites carrying ices.

Astronomers are still figuring out Psyche’s history, but the general story is that it probably was larger at one time (very early in the history of the solar system). As we all know, the infant solar system was a busy place. There were countless impacts among objects; some of them created larger objects. Some of them blew others apart.

That’s likely what happened to Psyche’s parent body. What was left is the current “version” of Psyche, and the rest of the pieces are scattered among the belt, or probably shattered into smaller ones by subsequent collisions. Another possibility is that the parent asteroid was leftover from the formation of the inner planets, and its outer layers battered away by continued collisions with other leftovers. Either story would explain why this asteroid is not much more than a metallic iron core with a layer of silicate rocks as a “surface”.

Asteroid Studies Teach about Past and Present

Planetary scientists are interested in asteroids for the role they play in the solar system. Certainly, they were part of our formational and collisional history. That “collisional part” is still a concern today, particularly about the asteroids that come close to our planet. Psyche isn’t one of those, however. The real value is in helping us understand that ancient time when Earth and other planets were still babies themselves.

The Psyche Orbiter

To explore this little world, NASA’s Psyche orbiter has to launch on 2022. If that happens, then it will head out on a trajectory that takes it past Mars for a gravity assist in 2023. The spacecraft arrives at Psyche in 2026. It will orbit for just under two years, studying the surface from ever-closer orbits.

The Psyche team has put together an interesting outreach plan. It’s called the “Innovation Toolkit”. First, if you want to learn more about the mission and spacecraft, they have a class for that! You sign up online and take the course at your own pace. The five-hour course gives a peek behind the scenes at what it’s like to plan a mission and carry it out.

The second course is a team-building exercise aimed at showing how diverse people can come together to focus on a single mission and “get ‘er done”. It’s all about collaboration and inclusivity to achieve some remarkable science goals.

The mission team plans to add other courses in the next couple of years, as the time for launch gets closer. There are also some very interesting videos and other activities available on the Psyche mission site. Check it out and follow along with the mission team as they closer to launch, and the exploration of Psyche.

A few weeks ago I wrote about the “Betelgeuse problem” which asks the question: why is it dimming? A lot of people are really in love with the idea that it’s going to blow up soon. I have to admit, it’s a fascinating thought, that we would get to see a giant star blow itself to smithereens from a safe distance of about 700 hundred light-years. But, it’s probably not what’s going to happen. At least, not just yet.

Taking a Direct Look at Betelgeuse

Figuring out exactly what IS happening with this star is complex. We know it’s an old star. Those aged, dying supergiants get a little eccentric in their final epochs of life. Astronomers have a general idea of what’s going on inside Betelgeuse, but that doesn’t explain why its appearance is changing. It could be due to some kind of stellar activity affecting its appearance and apparent size and shape. Could the surface be cooling for some reason? If so, what would explain that?

Another idea is that the star is ejecting dust away from itself. It ends up as clouds in the line of sight between us and the star. Such clouds could affect the star’s appearance pretty drastically. They would also absorb some of the light, which makes it look dimmer.

To figure this out, we need direct images of the star. So, astronomers used the Very Large Telescope in Chile to look directly at the star. They deployed special instruments to get a direct view of its surface in visible light as well as infrared light. Of course, Betelgeuse, like the Sun, is a massive ball of superhot gas. So, there’s not really a surface like we have on Earth. On the Sun, the “surface” is the “photosphere”. We can “see” all the way through the solar atmosphere to that region, and below that, we can’t see because it’s opaque to visible light.

December’s View of Betelgeuse

The “surface” on Betelgeuse is a similar region. The VLT showed astronomers the surface, and also let them study the material surrounding the star. That cloud of “star stuff” has been ejected from Betelgeuse in its later life. The December images of Betelgeuse show it not as a rounded sphere of hot gas, but a somewhat squished-looking thing. The infrared images of the dust look even stranger, showing clumps of star-stuff nearby the star.

The red supergiant star Betelgeuse, in the constellation of Orion, has been undergoing unprecedented dimming. This stunning image of the star’s surface, taken with the SPHERE instrument on ESO’s Very Large Telescope late last year, is among the first observations to come out of an observing campaign aimed at understanding why the star is becoming fainter. When compared with the image taken in January 2019, it shows how much the star has faded and how its apparent shape has changed. Credit:
ESO/M. Montargès et al.)

That image of dust around Betelgeuse may be providing an important clue to understanding the dimming we’re seeing at the star. It could well be that those dust clouds are playing a role in blocking light from the star. That could be why it appears to be getting dimmer.

This image, obtained with the VISIR instrument on ESO’s Very Large Telescope, shows the infrared light being emitted by the dust surrounding Betelgeuse in December 2019. The clouds of dust, which resemble flames in this dramatic image, are formed when the star sheds its material back into space. The black disc obscures the star’s center and much of its surroundings, which are very bright and must be masked to allow the fainter dust plumes to be seen. The orange dot in the middle is the SPHERE image of Betelgeuse’s surface, which has a size close to that of Jupiter’s orbit. Credit: ESO/P. Kervella/M. Montargès et al., Acknowledgement: Eric Pantin)

Betelgeuse’s Future

The ejection of dust from older (and dying) stars, called “mass loss”, is one part of Betelgeuse’s aging process. It’s actually part of what many stars experience. The Sun itself will go through a period of mass loss as it ages, and will gently blow its atmosphere out to space. In the case of Betelgeuse, it may go through several epochs of mass loss. Eventually, it could end up with several surrounding shells of gas and dust. When it does go through the final collapse (in perhaps 100,000 to a million years), the outbursting material from the torn-apart star will encounter those shells. It’ll heat them up, cause them to sparkle and glow, and make the death of Betelgeuse quite spectacular.

But, for now, if the images from VLT are to be believed, we’re still in for some episodes of mass loss. They’ll continue as Betelgeuse makes its way through old age. It’s actually pretty cool that astronomers can capture views of the star at this point. What they see gives a much better idea of the things that happen to supergiant stars before they explode as Type IIa supernovae and light up our night sky.

The Spacewriter's Ramblings

Exploring Psyche, the Metal World