A pair of NASA astronauts who have been stuck at the International Space Station since June

will have to wait a little longer to come back to Earth, as they wait once again for a new

capsule to send in their replacements. NASA says astronauts Butch Wilmore and Sonny Williams

won't return now until late March or even April, which means they will have lived and worked in orbit

for more than nine months. We're joined now by our science correspondent, Miles O'Brien. So,

Miles, this voyage was supposed to last about a week. Remind us why Butch Wilmore and Sunny Williams

have now been on the ISS for so long. Yeah, talk about a holdover. It's pretty extraordinary,

isn't it, Jeff? They arrived at the International Space Station on a spaceship,

manufactured by Boeing, called the Starliner. The arrival did not go well. There were all

kinds of problems with thrusters that fired when they shouldn't,

things that got stuck, things that failed outright. And NASA became very concerned about

whether those thrusters would do as they were supposed to on reentry, where it is very critical

that they do things precisely on time, precisely as

designed. They couldn't get comfortable with what was causing the problem, even though they

tried to simulate things on the ground. And so in the end, NASA administrator Bill Nelson

decided it was not safe to return that capsule with human beings on board. It ended up landing without

incident, but it was in his case, Nelson's case, the better part of valor, to leave them aboard.

But boy, it's been a long run for them. We know that Williams and Wilmore are veteran astronauts,

but still, what are the long-term psychological and health effects of those prolonged

stays in space? There's a lot to unpack here. They are both veterans. They're both troopers.

They have, you know, completely assimilated with the crew and have been doing the tasks that

astronauts do up there. But over the course of time, human beings who

...