MICHELE NORRIS, host:
From NPR News, this is ALL THINGS CONSIDERED. I'm Michele Norris.
MELISSA BLOCK, host:
And I'm Melissa Block.
The space shuttle is back safely on Earth, which means it's time for the next great adventure in space. The U.S. military will attempt to shoot down an ailing spy satellite. It could be early as tonight that the Pentagon now says that's unlikely.
The military says it's worried the satellite otherwise might crash into a populated area. NPR's David Kestenbaum joins me now.
And, David, what is the Pentagon's plan?
DAVID KESTENBAUM: Well, this will actually be the first real-world, sort of, test of the U.S. missile defense system. And the plan is to fire one of these missiles off a ship somewhere near Pacific. It takes off and on the tip of it is something called a kill vehicle. Its job is to - using cameras and heat sensors - to home in on the target. It doesn't carry an explosive - it's just a force of the collision when it hits the satellite that's supposed to destroy - the satellite, by the way, has been described as more bus-like than truck-like in size, and the closing velocity is somewhere around 20,000 miles an hour.
BLOCK: And one question here, I gather, is even if they can confirm that the satellite has been hit, they can't necessarily confirm that the fuel tank has been destroyed and that's what's the main concern here.
KESTENBAUM: The concern is that it has fuel tank. It's about three feet across the spherical thing filled hydrazine, which is a propellant. It's not something you want to breathe in. There's also been some study linking long-term exposure to cancer but that's the main thing they're worried about that that's going to land somewhere and people might be near it.
BLOCK: Are they able to tack based on the satellite's pattern of where it would crash - if this test fails, where would it come down?
KESTENBAUM: That's a hard thing to predict far in advance because it can bounce off the atmosphere and the atmosphere swells, temperatures change, so once it's in the atmosphere and coming down, they have a better idea but when you're talking 10 days out there of an accuracy, it's something like a day for when it's going to land and they really have no idea where it's going to land.
BLOCK: Hmm. Now, once they do attempt this shoot down, how do we find out what the result has been?
KESTENBAUM: Well, the military will have a press conference but you can also talk to amateur astronomers because there is - I talked to one guy in Canada, he says about 20 friends around the globe - a lot of them men, sort of in their 60s - they like to go outside with their binoculars and track spy satellites. And he says a direct hit - they could certainly spot at some point in the future because it will be missing or you'll have small pieces there. Or even if they just nick it, it could start spinning and you could see that the light reflection was changing. So he thinks, you know, it could take some time but they'll be able to get a handle somewhat on what has happened.
BLOCK: David, you said that this would be a test of a missile defense system. What would it show exactly? How applicable would the lessons of this be?
KESTENBAUM: Well, if they missed, that definitely says something. I mean, that says that it's - even when you have a target that you have a long lead time to work on and you know exactly where it that it's not so easy to hit it. If they do hit it, you know, this missile has done pretty well in recent tests. But they are sort of waiting to have ideal conditions, for instance, the military has been discussing postponing the test because the seas are sort of choppy, and obviously in a real situation where you're being attacked, you're not going to wait to have some seas as smooth as glass.
BLOCK: If the shoot down fails, is there a plan B? Do they have a way of steering the satellite to some area that's not populated, sending it into an ocean?
KESTENBAUM: They lost contact with it almost immediately after it was put in orbit. And if they could steer it, they would steer it down into an ocean, though. They have no communication with it.
Plan B is basically to take a second shot on a subsequent day when it passes into view again.
BLOCK: Okay, NPR's David Kestenbaum. Thanks so much.
KESTENBAUM: You're welcome.