Why do we study asteroid composition?
Asteroid composition is important because it can teach us about the early Solar System. All of the planets and moons we know of have changed since their initial formation, with their surfaces dramatically reshaped by processes like volcanism, erosion, and tectonics. Asteroids and comets, by contrast, can offer pristine records of the early Solar System.
By studying what asteroids are made of, we can learn about the building blocks of planets, how the Solar System has changed over time, and even how Earth itself evolved over time. For example, an analysis of samples of the asteroid Ryugu returned to Earth by Japan’s Hayabusa2 mission showed that water locked in the asteroid’s rocksis similar to water found in Earth’s oceans. Chondrite meteorites coming from C-type asteroids like Ryugu could have brought Earth much of its water.
Asteroid composition is also important to study if we want to protect ourselves from asteroid impacts. Knowing whether an incoming asteroid is dense and metallic or a loose, rocky rubble pile would have a huge effect on how we try to deflect it.