Small Bodies, Big Future

And what do their chemistries tell us? Their history, and in that sense, our history: the history of the Solar System (including prehistory: various signs of the cloud that would, later, form the Solar System). And what does that history tell us? That most (but not all) asteroids are undifferentiated (primitive). All planets, the remaining (differentiated) asteroids, and Earth’s moon were hot after their formation, to the point of melting. Molten bodies then separate under gravity (“differentiation”), forming a core and crust. The core gathers the metals (and some metal-binding elements), the lightweight elements are mainly boiled off to space, and the remaining crust is formed from the lightweight minerals.

Most asteroids, being undifferentiated, did NOT lose nearly as much of the light elements, and did NOT have their metal content turn inaccessible, lost to a core hundreds of miles beneath solid rock. Therefore, the primitive asteroids tell us of the broader Solar System’s chemistry, its pre-chemistry and pre-history, and its future: accessible resources such as metals, organics, water, sulfur/sodium, propellants (reaction mass) and shield mass, buffer gases, etc.- asteroid mining. All this, while being more accessible than even Earth’s moon. That’s right, the closer of the near-Earth asteroids require less energy and less propellant than mining that differentiated, depleted crust that most people see in the sky.