NASA’s mission to protect our planet from dangerous space rocks
At a glance
NASA’s Near-Earth Object Surveillance Mission, NEOSM, is a mission that will launch as soon as 2025 to find near-Earth objects—asteroids and comets with orbits that come close to Earth.
NEOSM’s goal is to find 90 percent of near-Earth objects with diameters of at least 140 meters. An impact from an object that large could level an entire city.
Despite congressional orders to find dangerous asteroids and a NASA commitment to start the mission, NEOSM has yet to be fully funded. You can help The Planetary Society advocate to make the mission a reality.
Why do we need NEOSM?
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.
The Planetary Society is working to decrease the risk of Earth being hit by an asteroid or comet.
Know your foes
Meteor: Tiny bits of space rocks that burn up in Earth’s atmosphere.
Meteorite: A meteor that survives all the way to the ground.
Asteroid: A lumpy space rock left over from the formation of the solar system, ranging from around 10 meters to more than 500 kilometers in size. Mostly found between Mars and Jupiter.
Comet: Similar in size to an asteroid, but icier, and often forms a tail of dust and gas when heated by the Sun. Most come from the cold, outer fringes of our solar system.
Near-Earth Object (NEO): Any asteroid or comet with an orbit that comes close to that of Earth’s.
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.
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 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 NEOSM, NASA’s Near-Earth Object Surveillance Mission. NEOSM 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.
Asteroid Apophis radar images
These images of asteroid Apophis were captured by radar in 2012. In 2029, the 370-meter-wide space rock will come as close as 31,300 kilometers (19,400 miles) from Earth—closer than most communications satellites.
A truly awesome mission
Mission team members have been overheard pronouncing NEOSM as “nee-awesome.” Whether or not that pronunciation becomes official as the mission moves toward launch remains to be seen!
How NEOSM will look for potentially hazardous asteroids
NEOSM 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, NEOSM 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.
Wikimedia Commons / User Xander89
Sun-Earth Lagrange Points
Lagrange points, named after mathematician Joseph-Louis Lagrange, are locations around two bodies where the gravitational pull from each body balances out, allowing a spacecraft to hang around indefinitely without using much fuel.
NEOSM 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.
NEOSM 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 NEOSM 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.