Psyche could reveal secrets about Earth

There is a small minor planet, only 210 kilometres across, that could unlock some of the secrets of our own planet. This is Psyche, which orbits in the asteroid belt between the orbits of Mars and Jupiter.

There is a lot that we don’t know about the origin and inner structure of Earth. In particular, we do not know exactly how the planet came to be formed or what the composition is of its solid metal core. We cannot examine this directly because it is surrounded by thousands of kilometres of molten metal and magma.

So where does Psyche come into the picture?

Observations of the asteroid reveal that it is composed almost entirely of solid metal, and there is nothing else in the solar system – as far as we know – of which this can be said. The implication is that Psyche is a remnant of a former planet that was once considerably larger, but was so battered about by collisions with other objects that all the outer layers were knocked off to leave only the solid metal core. Could this therefore be similar to what lies at the heart of Planet Earth?

Astronomers are keen to send a probe to Psyche to find out. A launch date for a mission to Psyche has been set for 2022, with the destination reached in 2026.

The spacecraft will be equipped with a range of instruments to enable the nature of Psyche’s gravity to be established, which will in turn allow deductions to be made about its composition and structure. There will also be a gamma ray and neutron spectrometer on board, which will be used to discover the exact range of metals of which Psyche is composed. It is thought that the main elements will be iron and nickel, but there is a distinct possibility that silver, gold, palladium, copper and iridium will also be present.

The purpose of the mission is to gain knowledge, from which inferences will be made about Earth’s interior. The assumption is that the early solar system contained many similarly composed lumps of metal, most of which coalesced and ended up as planetary cores.

However, there is also room for speculation about how such a world might be a source of future benefit to mankind in terms of its content. All that metal, just sitting there doing nothing! An estimate has been made of what Psyche might be worth in terms of monetary value, and it is a truly staggering figure, namely ten quintillion dollars – a one followed by nineteen zeros!

If anyone imagines that all that metal could be transferred to Earth and the value realized, they need to think again. For thing, the idea is pure fantasy. For another, the value of something like gold depends on its scarcity – make vast quantities of it available and it will no longer be valuable!