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In the “Star Trek” universe, most of the good real estate is on “Class M” planets — worlds like Earth, which can support human life. Present-day scientists don’t use that classification — not yet, anyway. But they do classify some asteroids as type M. And NASA is about to send a spacecraft to study the largest of them.

Psyche — named for the Greek goddess of the soul — is in the asteroid belt, between the orbits of Mars and Jupiter. It’s shaped a bit like a potato, with an average diameter of about 140 miles.

An asteroid is a member of type M if it has a high concentration of metals — especially iron and nickel. And that’s true of Psyche. Originally, scientists said it might be almost completely metal. They even estimated the value of that metal at around 10 billion billion dollars. More-recent observations say the proportion of metals could be around half, with much of the asteroid consisting of empty space.

Psyche might once have been part of a small planet. Its gravity was strong enough to melt the interior, so heavy elements — like iron and nickel — settled in the core. Lighter elements floated upward, forming the mantle and crust. Psyche would have been part of the core. A collision could have shattered the original body, blasting Psyche into space.

Studying Psyche could tell us more about how planets with metallic cores formed, especially the most famous class-M planet of all: Earth.

More tomorrow.

Script by Damond Benningfield

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