How likely is an asteroid strike? 'Earth is constantly getting hit by stuff'

NASA's DART Mission is mankind's first attempt at redirecting an asteroid. In partnership with the Johns Hopkins Applied Physics Laboratory, NASA hopes the mission could one day save life on Earth.

AUSTIN (KXAN) — NASA's DART Mission is mankind's first attempt at redirecting an asteroid. In partnership with the Johns Hopkins Applied Physics Laboratory, NASA hopes the mission could one day save life on Earth.

The mission is pretty simple. We're going to crash a space probe into the side of a tiny asteroid, which poses no threat to Earth. The asteroid is currently in orbit around another asteroid. If the impact is strong enough, the orbit of the tiny asteroid could change.

KXAN spoke with Andy Rivkin, an astronomer with the Johns Hopkins Applied Physics Laboratory, about the mission, what's next for DART and how often Earth is struck by an asteroid.

You watch the interview above or read the transcript below to learn more. This conversation has been edited for clarity.

ERIC HENRIKSON, KXAN: How likely is it that the earth is going to get struck by an asteroid at some point during the span of human race?

ANDY RIVKIN, PLANETARY ASTRONOMER: Oh, well, the Earth is constantly getting hit by stuff, if you go out, you know, in the Pecos, or Big Bend or something, and you've got a meteor shower, or shooting star that's the earth getting hit by an asteroid. It's a tiny, tiny, sand-sized asteroid.

Obviously larger asteroid impacts have profoundly affected the history of life on earth, from the dinosaurs to the formation of the moon way, way back.

Nine years ago, the Earth was hit by something that was about 25 yards across that hidden Siberia. It injured about 1000 people just from breaking glass because people didn't see it coming.

Something the size of DART's target, Dimorphos, we think on average things like that hit every 20,000 to 25,000 years. Part of planetary defense is doing the search to find what's out there.

HENRIKSON: Speaking of that search, I know there's a lot of challenges you're facing trying to locate these near-Earth objects coming towards us. So what sort of things are y'all doing to prepare and to catch these things before they get too close, where we can't do anything?

RIVKIN: The search for near-Earth objects began in the 90s and as telescopes have gotten bigger and more capable and cameras have gotten bigger and more capable they we've been doing a better job. We have a much, much more data just because we have 30 years of data now.

But there are some directions that are still difficult to look in. And as silly as it might sound, we can't look during the day because the sun is up. So things like the impact in Siberia a few years ago came from the direction of the sun.

One of the things that is the community would like to see happen is a telescope in space doing this searching their ideas for having that happened.

HENRIKSON: DART collides with the asteroid. What happens after that, what's kind of the process after that?

RIVKIN: DART collides with the asteroid, it comes in at something like 14,000 miles an hour. So it's way too fast, you know, we don't have someone sitting there with a joystick, or an Xbox controller or whatever coming in. So there's onboard navigation, that will take the pictures from the Draco camera and analyze them and say, okay, point a little bit left and right.

Those images are also going to be streamed down to Earth, and those are going to be shown on NASA TV during a broadcast and, and during the rebroadcast.

After the impact, we expect the DART spacecraft to have to throw up a lot of debris from the impact, that debris will catch some sunlight.

We think that it will make the entire system get brighter as seen from the Earth, we don't know if it's going to be a little bit brighter or a whole lot brighter. That's one of the questions we're looking forward to answering.

In the days and weeks and months afterward, we have telescopes on all seven continents that are going to be watching the system. Up until now, what we've been using is the fact that from the point of view of Earth Dimorphos spins in front of Dynamos and then out behind Dynamos.

So the brightness of the single point of light, we see from Earth goes up and down.

We've been measuring how often it goes up and down, that tells us how rapidly dwarfs goes around in a mouse. And then after the impact in the days and weeks, months coming up, we'll do that again. And we'll compare it.

We'll say okay, here's here's how often it's happening now and then we will know that the DART impact is what caused the difference.

HENRIKSON: Is that the reason we chose these twin asteroids is because you're able to observe the light fluctuations and the changes in trajectory?

RIVKIN: Yeah, there's a few a few different reasons people originally conceived of this. Testing this technique, as you go to an asteroid in space and you hit it, you see what you did in its orbit around the sun.

There are a few different reasons including the one you mentioned why it's easier to do with this technique of a double asteroid on an asteroid moon. You only need one spacecraft. You can make the measurements from Earth. If you were hitting one object in space, you probably would need a second spacecraft to sit there. And then that's twice as twice as expensive in some ways.