Rubin Observatory is going to be our best tool yet for detecting asteroids. Why is that so important? In addition to studying their composition to learn more about the formation of our Solar System, it’s important to know what asteroids are doing, just in case they’re on an orbit path that brings them close to Earth.
Asteroids, made of rock, metals, and other elements, are remnants from the formation of our Solar System. They don’t emit their own light, but they do reflect light from the sun.
Most asteroids are found in a belt between Mars and Jupiter, and the vast majority of them pose absolutely no threat to Earth.
Some asteroids, however, have orbits that bring them close to Earth. These asteroids are sometimes referred to as Near Earth Objects, or NEOs, and the ones that could come especially close to Earth at some point (less than 20x the distance to the Moon) get classified as Potentially Hazardous Asteroids.
Although the chance of Earth being struck by a Potentially Hazardous Asteroid asteroid in the near future is low (there’s only about a 1% chance that it could happen in the next century), we know from studying the fossil record that large asteroid impacts have caused major atmospheric, geological, and biological changes to our planet.
In 1998, the United States Congress directed NASA to prioritize finding the asteroids that could pose a threat to Earth. Since then, NASA-directed projects have made great progress in addressing the Congressional mandate to catalog at least 90% of the estimated population of NEOs larger than 140 meters across. But because they’re so faint, even some of those larger asteroids are pretty good at hiding from us…until now.
Asteroids won’t be able to hide from Rubin Observatory—it will detect more asteroids in its first year of observations than all previous telescopes combined.
The large size of Rubin Observatory’s telescope and its wide field of view make it great for seeing objects that are very far away from Earth. Rubin Observatory will also be able to detect objects that are closer to Earth but very dim—like asteroids.
Rubin Observatory will image the same object twice each night, so astronomers will be able to determine the direction of any object that is moving. That makes it a lot easier to find the object in later images and eventually determine its orbit. Once we know an asteroid’s orbit, we know if it’s likely to come close to Earth. And the further in advance we know, the more time we have to make a plan to deflect it.
Rubin Observatory is poised to discover a few million asteroids, compared with the fewer than one million we know today. Although Rubin Observatory isn’t a dedicated asteroid-finding machine, it's the only ground-based observatory that can significantly contribute towards the goal of finding all the asteroids that pose a potential threat to Earth. And while Rubin Observatory is discovering and cataloging asteroids, it'll be contributing to all kinds of other science too!
