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REAL LIFE NEWS: VESTA, THE STRANGE ASTEROID

by Hazed

Isaac Asimov wrote a great science fiction story called "Marooned Off Vesta" in 1938 - the third story he ever wrote. In it, three men survive the wreck of the spaceship they are travelling on, but find themselves trapped in orbit around the asteroid Vesta. They have to use their ingenuity to find a way to rescue themselves.

I read the story in my teens, and it was the first time I had heard of the asteroid Vesta. At the time, all that was known about it was that it was the second largest body in the asteroid belt (the largest being Ceres).

Now, scientists are discovering just how strange Vesta really is.

First, there's the question of how to designate it. Is it as asteroid? A dwarf planet? A protoplanet?

Under the current definition, by which Pluto was demoted from its status as a planet to a mere dwarf planet, Vesta counts as a Small Solar System Body - along with all the other asteroids (except Ceres which is another dwarf planet). But Vesta is much bigger than any other object in the asteroid belt - its neighbours are all 100km wide or less, but Vesta has a diameter of 530km.

But although its mass accounts for about 9% of the total asteroid belt, it's not anything like massy enough to have become spherical, which is one of the requirements for planet-hood (even the dwarf variety).

What makes it really strange, though, is what's underneath its surface. Unlike the other asteroids, which are just chunks of rock, Vesta is what's known as an "evolved object" - it has a distinct core, mantle and crust that make it a lot more like Earth or Mars. This means that at the time it was formed it had sufficient radioactive material inside it to create the heat to melt rocks, and form these distinct layers. So it's more like a proto-planet.

We will learn more about this unusual body in the summer, when the NASA probe Dawn arrives there to spend a year examining it.

You can read more about Vesta, and the plans for Dawn, here: http://www.space.com/11467-vesta-asteroid-planet-debate-dawn-spacecraft.html.

Source: http://io9.com/#!5795681/the-strange-case-of-the-asteroid-planet-vesta

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