Can asteroids be veered away from Earth? New NASA spacecraft aims to find out

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• Amna Nawaz:

  Well, NASA has launched a satellite into orbit on a mission to smash itself into an asteroid.

  It's a test to see whether it is possible to knock a speeding space rock off-course if one were on a collision course with Earth. We should say, the asteroid targeted in this case is not a threat to our planet.

  But to break it all down, I'm now joined by "PBS NewsHour" science correspondent Miles O'Brien.

  Miles, welcome back. Always good to see you.

  Tell us a little bit about this mission and what NASA hopes to accomplish here.

• Miles O’Brien:

  Well, as you just mentioned, it's the first spacecraft launched to test the idea of defending Earth against an asteroid or a comet that puts a bullseye on us.

  It's a refrigerator-sized spacecraft. It was launched on top of a Falcon 9 rocket in the early hours of the day from Vandenberg Space Force Base in California. So far, no problems. It's a $310 million mission and 10-month journey, millions of miles to an asteroid.

  And they're focused on its tiny moon. DART is expected to impact that asteroid on September 6. So, mark your calendars.

• Amna Nawaz:

  And DART, of course, stands for?

• Miles O’Brien:

  It is the dual — no, excuse me — the Double Asteroid Redirection Test.

  And called that because it's a binary system of asteroids. Didymos, the big one, is 2, 500-feet-long. That's epic. And its moon, Dimorphos, is about 500 feet in length. That's about the size of the Washington Monument.

  DART is aiming for Dimorphos. And the idea is to just nudge it, crash in and change the speed just enough, by literally about a centimeter per second, or 2/100ths of a mile-per-hour. That doesn't sound like much, but if you nudge something like that far enough ahead of a date of impact, it could turn a city killer into a near miss and a fun night for astronomers.

  (LAUGHTER)

• Amna Nawaz:

  So, it's traveling a very long way to hit a very, very small bullseye.

  How are they going to pull this off? And how will we know if it actually works?

• Miles O’Brien:

  Well, we're going to have some photographic proof.

  I will tell you about that in a sec. It is 6.8 million miles away. And it's a tiny little rock. It is a feat of navigation ingenuity, but there's — it's not hand flying. There's no way you could do that. So it will home in on the little asteroid autonomously.

  It has a camera on board, some imaging software to identify its target, and then just crash right in, we hope. There is a tiny CubeSat that's attached to the big spacecraft. It will separate right before the impact. It's got a couple of cameras on board, and it will document it.

  And that's — as you know, we call that the money shot, Amna. We know what this might look like. In 2005, there was a spacecraft called Deep Impact. It plowed into a comic called Tempel 1. The goal of that mission wasn't planetary protection, but rather just to kick up some dust and look and see what the comment was made of.

  But they found out he did change its orbit.

• Amna Nawaz:

  So, Miles, we should be clear, this asteroid, this particular asteroid is not a threat. But how big is the concern about an asteroid like it or a comet striking Earth and causing some kind of calamity?

• Miles O’Brien:

  Yes, Dimorphos is the size of a kind of object that hits Earth every few 1,000 years, Amna. It would cause regional devastation. It's a big deal.

  We do live in a rough neighborhood. You want proof, take a look at the moon and the craters. Most of them get covered up here on Earth, including the giant crater that was created 65 million years ago after a big asteroid wiped out the dinosaurs.

  City killers are more common. In February of 2013, we saw a shot across the Bow. A 60-foot-wide asteroid exploded over Chelyabinsk, Russia. It's equivalent to 30 atomic bombs, and it injured 1, 500 people, because they all went to their windows. And the windows broken. And many people got cut.

  The most important thing really is to catalog all these objects. We know where 90 percent of the Earth-enders are, so we're ahead of the dinosaurs. But we still have a lot of work to do on the larger, but not-that-large objects. Only 30 percent of those regional disaster rocks have been identified.

  So we have a lot of work to do.

• Amna Nawaz:

  So sending the refrigerator sized spacecraft millions of miles away to nudge an asteroid off-course, is that the best plan we have if something were to target Earth?

• Miles O’Brien:

  Well, we could recruit a team of misfit oil roustabouts by Bruce Willis, send them out there to blow it up. But maybe we should leave that one to Hollywood.

  The impact idea actually is just one idea. There's another idea to use a so-called gravity tractor. That's a spacecraft that would be near an object, hover it, or orbit, and that would just perturb its trajectory just enough to move it out of harm's way.

  And if the chips are really down, and there wasn't much time, and Bruce Willis was holding out for more money, you could launch a nuclear bomb into space and explode it near a big object, hoping to nudge it out of our direction and out of harm's way.

  Let's hope that doesn't happen.

• Amna Nawaz:

  Here is hoping. Here is hoping.

  Miles O'Brien, "PBS NewsHour" science correspondent, thanks, and always, always good to see you.

• Miles O’Brien:

  You're welcome, Amna.