SPACE ROCKS

Exploring the Asteroid Belt's Ancient Rocks

- AUDREY PAVIA

Millions of miles from Earth, a horde of ancient rocks swirl around the Sun.This spinning band of randomly shaped objects fills the orbital space between Mars and Jupiter, providing us with clues to how our Solar System was created.

Known as the Asteroid Belt, this conglomerate of small stellar bodies contains around 1.5 million asteroids, all of varying sizes. Ranging from 327 miles in length to 33 feet, asteroids are made up of a variety Of metals. Too small to be considered planets, they do not have enough gravity to hold an atmosphere. Many are as old as the Solar System itself.

Believed to be made up of 4.6 billion-year-old primordial material that did not coalesce into planets when the Solar System was forming, the total mass of all asteroids orbiting the Sun is estimated to be less than half the size of the Moon. Yet, using Earth-based remote sensing, data from the Galileo mission and laboratory analysis of meteorites—fragments of asteroids that have struck the Earth—the National Aeronautics and Space Administration (NASA) has developed a good understanding of the ancient objects.

ASTEROID TYPES

NASA has been studying asteroids for decades and has categorized three different types of these interplanetary rocks, based on their composition:

C-type (Carbonaceous): The vast majority of known asteroids are the dark C-type. Their composition is clay and silicate rock, and they can be found in the Asteroid Belt's outer regions. They are the oldest asteroids in the Solar System.

S-type (Silicaceous): Made from silicate materials and nickel-iron, the S-type is the most common type of asteroid on the inner side of the Asteroid Belt. About 17% of known asteroids fall into this category.