In addition to near-Earth objects, NEO Surveyor will likely detect more than a million asteroids in the Main Belt between Mars and Jupiter and about a thousand new comets.  By studying the physical and orbital properties of Main Belt asteroids and comets, we can better understand where the NEOs come from.

Unlike asteroids in the Main Belt, which have generally remained in place for billions of years, we know that NEOs are a transitory population. NEO orbits aren’t usually stable for longer than a few million years. After a few million years, one of three things will happen to most NEOs: either they will be pulled into the Sun, get ejected from the inner solar system, or they will crash into a planet.

The fact that we see so many NEOs today despite their transitory nature means that they must continually be resupplied from sources in the Main Belt or comet populations. NEO Surveyor will give us more detailed insight into how the NEOs are formed, and what will eventually happen to them.

NEO Surveyor will also yield valuable information about the numbers, sizes, and activity levels of comets, allowing us to better understand the hazard they may pose to Earth as well as their origins. NEO Surveyor’s science team includes experts on comet population studies and composition.

While NEOWISE discovered 21 new comets, NEO Surveyor would be expected to discover many times more.

Throughout our planet’s 4.6 billion year history, asteroids and comets have been agents of change for our planet: they may have delivered the ingredients needed for life, and they have caused mass extinctions. 

Today, asteroids spend most of their time harmlessly orbiting in the main belt between the orbits of Mars and Jupiter. These remnants from our solar system’s formation can still make their way into the inner part of our solar system, however, sometimes impacting the Earth. 

We now know that most of the very largest asteroids and comets that get close to Earth have been discovered, but many of the more numerous smaller ones (still capable of causing significant regional damage) remain to be found. 

The Near-Earth Object Surveyor is designed to discover and characterize a large fraction of the asteroids and comets throughout our solar system, including those that get close to Earth. NEO Surveyor will not only find asteroids and comets, but it will teach us about their physical properties, origins, and evolution. 

Our results suggest that the subset of NEOs that are most likely to cause impacts, the so-called potentially hazardous objects, are about twice as likely to occupy orbits in nearly the same plane as the Earth.  This may mean that they are more likely to impact the Earth. With NEO Surveyor, we can better quantify the risks of asteroid impacts simply by going out and discovering them.

Late Heavy Bombardment This illustration depicts a period early in the history of the solar system in which Earth and the inner planets were pummeled by cometary debris filling the young solar system. Scientists think this “Late Heavy Bombardment” was triggered in our solar system by the migration of our outer planets, which jostled icy comets about, sending some of them flying inward. The incoming comets scarred our moon and pummeled our inner planets. They may have even brought materials to Earth that helped kick start life. (Image credit: NASA/JPL-Caltech/R. Hurt)