NEO Surveyor, Protecting Earth from Dangerous Asteroids


  • NASA’s NEO Surveyor mission will launch in 2026 to find near-Earth objects, or NEOs — asteroids and comets with orbits that come close to Earth.
  • NEO Surveyor will find 90% of near-Earth objects with diameters of at least 140 meters. An impact from an object that large could level an entire city.
  • U.S. Planetary Society members pressed their congressional representatives to fund the mission during the Society’s 2021 Day of Action.

What are near-Earth objects?

Space may be vast, but it’s not empty. Earth is bombarded by tiny space rocks called meteors every day, most of which burn up in our atmosphere. Larger meteors, like the one that exploded over Chelyabinsk, Russia in 2013, can damage buildings and cause minor injuries. And on rare occasions, asteroids and comets strike Earth and cause global devastation—the dinosaurs perished when this happened 66 million years ago.

Fortunately, NASA and other space agencies are working on tests to deflect near-Earth objects (NEOs) on course to hit our planet. But before we can stop them, we have to find them. In 2005, the U.S. Congress ordered NASA to find 90% of the estimated 25,000 NEOs larger than 140 meters — the size threshold at which an object can level an entire city. The deadline was 2020. So far, we’ve found just 37%. At our current detection rate, it will take more than 30 years to meet this mandate.

What does NEO Surveyor do?

Right now, ground-based telescopes are the primary means of detecting NEOs, but they have limitations. They can’t search during bad weather, and there aren’t enough in the southern hemisphere. Furthermore, since they can’t scan the sky during the daytime, many objects coming from directions near the Sun often go undetected. The solution? Park a space telescope between Earth and the Sun and scan regions of space we can’t see well from Earth.

This is the impetus behind NEO Surveyor, NASA’s Near-Earth Object Surveillance Mission. NEO Surveyor would launch as soon as 2025 and within 10 years meet Congress’s goal of finding 90% of near-Earth objects 140 meters and wider. Finding and studying these objects will not only help us figure out if any are on course to hit Earth, but will also help lay the groundwork for survey and deflection missions if one is found.

Planetary Society members and supporters sent letters to their congressional representatives in 2020 urging them to fund NEO Surveyor for a 2025 launch. NASA's 2021 budget partially met that request; finally, in June 2021, NASA approved NEO Surveyor for further development. The launch is now slated for sometime in the first half of 2026.

How NEO Surveyor works
How NEO Surveyor works NASA's NEO Surveyor space telescope will scan for asteroids hidden in the Sun's glare. This infographic is free for media and non-commercial use with attribution.Image: The Planetary Society

How NEO Surveyor Works

NEO Surveyor will park itself at the Sun-Earth L1 point—a spot 1.5 million kilometers (930,000 miles) away from Earth where the gravitational pull from the Sun and Earth balance each other out, allowing spacecraft to hang around indefinitely without using much fuel. From this location, NEO Surveyor will look ahead of and behind Earth’s orbital path, spotting asteroids that we otherwise wouldn’t be able to see because of the Sun’s glare.

NEO Surveyor is a 50-centimeter-wide telescope. Its camera sees things in infrared wavelengths—a type of light not visible to human eyes. Infrared light reveals heat signatures, which is perfect for asteroids because they are very dark and hard to see against the blackness of space. In infrared light, they glow because they heat up in the Sun and re-radiate that heat back into space.

NEO Surveyor is both a replacement and an improvement upon NASA’s current asteroid-hunting space telescope, NEOWISE. NEOWISE launched in 2009 and was originally an astrophysics telescope before being repurposed as an asteroid hunter in 2013. Though NEOWISE has discovered hundreds of asteroids, it is not optimized for the job in ways NEO Surveyor will be. NEOWISE has a smaller telescope mirror and sits in Earth orbit, which limits its search capabilities. Its orbit is currently drifting to the point where it will soon be unable to observe asteroids without stray light entering the telescope.

NEO Surveyor Artist's Concept
NEO Surveyor Artist's Concept This artist's concept of NASA's Near-Earth Object Surveillance Mission shows the space telescope in front of a star field captured by the WISE telescope.Image: NASA/JPL-Caltech/The Planetary Society

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