Does NASA know about ALL the asteroids? Not exactly. We know about the vast majority of larger ones and none of those pose an impact threat to Earth, but space is big, so we’re always on the lookout. NASA asteroid expert Dr. Amy Mainzer explains.
Does NASA know about all the asteroids? Well, no. The good news is we know where most of the really big asteroids are that get closest to the Earth, and we’ve found more than 90 percent of these big asteroids. However, there are a lot of smaller pieces that are still out there that we haven’t found, and that’s where our planetary defense experts come in.
It’s really challenging to find asteroids and comets because even though some of them are as big as mountains, space is incredibly huge, and they can be really far away. In fact, we want to find them when they’re very far away from the Earth so that if necessary, we have lots of time to take action if we ever find one that’s really headed in our direction.
Asteroids are a source of fascination as they are relics from the birth of our solar system, and it is incredibly unlikely that a significant asteroid impact will occur in our lifetimes. Regardless, our planetary defense experts monitor the skies to look for near-Earth asteroids and comets and make sure that the Earth and an asteroid never get too close for comfort.
At NASA, we know what we have to do to find the remaining unknown asteroids. We’re on the job and really glad to be part of the ongoing mission of planetary defense.