Since then, scientists have long acknowledged that Verne’s literary journey was only science fiction. The extreme temperatures of the Earth’s interior – around 10,000 degrees Fahrenheit (5,537 Celsius) at the core – and the accompanying crushing pressure, which is millions of times more than at the surface, prevent people from venturing down very far.
Still, there are a few things known about the Earth’s interior. For example, geophysicists discovered that the core consists of a solid sphere of iron and nickel that comprises 20% of the Earth’s radius, surrounded by a shell of molten iron and nickel that spans an additional 15% of Earth’s radius.
Although most are rocky, icy or a combination of both, perhaps 20% of asteroids are worlds made of metal, and similar in composition to the Earth’s core. So it’s tempting to imagine that these metallic asteroids are pieces of the cores of once-existing planets, ripped apart by ancient cosmic collisions with each other. Maybe, by studying these pieces, scientists could find out directly what a planetary core is like.
Psyche is the largest-known of the metallic asteroids. Discovered in 1852, Psyche has the width of Massachusetts, a squashed spherical shape reminiscent of a pincushion, and an orbit between Mars and Jupiter in the main asteroid belt. An amateur astronomer can see Psyche with a backyard telescope, but it appears only as a pinpoint of light.
About the Psyche mission
In early 2017, NASA approved the US$1 billion mission to Psyche. To do its work, there’s no need for the uncrewed spacecraft to land – instead, it will orbit the asteroid…