AMNA NAWAZ: NASA's initial test launch with the Boeing Starliner capsule has not worked out well, to say the least.

The space agency announced this weekend it's finally decided that the two astronauts stuck at the International Space Station, Suni Williams and Butch Wilmore, will come back on a SpaceX Dragon capsule next year instead.

The pair were initially sent on an eight day mission in early June.

NASA Administrator Bill Nelson said the priority has to be safety of the astronauts.

BILL NELSON, NASA Administrator: Spaceflight is risky, even at its safest and even at its most routine.

And a test flight, by nature, is neither safe nor routine.

And so the decision to keep Butch and Suni aboard the International Space Station and bring the Boeing Starliner home uncrewed is a result of a commitment to safety.

AMNA NAWAZ: So, here to discuss the latest now is our science correspondent, Miles O'Brien.

So, Miles, we know NASA's been weighing whether to try to bring Suni and Butch home on the Boeing craft or a SpaceX craft.

What do we know about why they ultimately decided to go with SpaceX?

MILES O'BRIEN: Well, Amna, they just couldn't be certain about the thrusters, which are key here.

Now, all of the people making these decisions, we should point out, lived through the searing tragedy of Columbia back in 2003, when the orbiter disintegrated on reentry.

It's really important that these thrusters work as advertised when they're supposed to, because it's a very unforgiving, risky portion of the flight, to say the least.

If they come in too hot, that's a problem.

If they come in with not enough speed, they could skip off the atmosphere.

So since they went through the testing, they tried to understand the problems with these thrusters, which manifested as they approached for docking, and they just don't feel confident that they know enough about why they failed to understand if they might be reliable enough to get the crew home.

And so, at that point, there was no logical or safety rationale to put two human beings at risk for this return of the Boeing Starliner.

So it will go back uncrewed.

AMNA NAWAZ: So, Miles, if they can't be sure it's reliable, what does this mean for the future of the Starliner and also for Boeing's relationship with NASA?

I mean, will they still work on missions together?

MILES O'BRIEN: Yes, I mean, Boeing and its predecessor companies goes back to the very beginning of NASA, the first spacecraft.

They have been contractors on, you name it, just about every program, including the shuttle and the International Space Station for that -- for example.

There's no indication that there's going to be a separation of these two entities.

Boeing and NASA will probably continue to work together, highly likely.

Both -- leaders of both organizations are saying so.

What's really interesting right now is, what happens on the next flight for Starliner?

Will that be an uncrewed mission to test out these thrusters, which are so bulky?

Or will they allow astronauts to be a part of that next flight?

That's an open question.

AMNA NAWAZ: So an eight-day mission has now turned into a several-months-long mission.

If the decision has now been made about how Suni and Butch are going to get home, why will it take so long to actually bring them home?

Why until 2025?

MILES O'BRIEN: Yes, why is it "Gilligan's Island," people are asking, for sure.

Basically, there are no seats for them to return home on the spacecraft which are attached to the International Space Station.

They're not going home in the Starliner.

There's a SpaceX Dragon there, but no seats for them.

So what are the options?

Well, they could build a whole rocket for them to come pick them up, or, much more efficiently, a crew which is set to arrive next month is -- has -- it's a four-person crew.

Two of those crew members will stay home now, opening up two seats.

And Suni and Butch, for all intents and purposes, have been volunteered to be a part of this mission, which lasts six months into February.

So it's the most efficient for the flow of the space station, but probably not the most convenient for Butch or Suni.

(LAUGHTER) AMNA NAWAZ: To say the least.

What do we know about -- this is what's always top of my mind -- do they have what they need, Suni and Butch, who, again, planned for an eight-day mission?

Do they have what they need to get through these next several months, or is there going to be some kind of resupply mission to get them supplies?

MILES O'BRIEN: Yes, it's worth pointing out they went up without suitcases.

They had to make room for a piece of equipment to haul up to the space station to fix the water recycling system.

So they didn't even have a change of clothes.

Well, there's been a cargo mission arrive just a week or so ago with 8,600 pounds of stuff.

And at any given time, NASA has enough clothing, food, consumables for a four-person crew to last four months.

So there's plenty of stores up there.

That's not really the problem.

They will be fine.

They're not going to go hungry.

They will have clothing, et cetera.

But they do have a long mission ahead that they didn't anticipate.

AMNA NAWAZ: And what about that mission to come home as well?

I mean, the fact that they trained to go up and come back on a completely different craft than the one they will actually be coming back on, what does that mean logistically?

MILES O'BRIEN: Yes, well, the Dragon spacecraft is highly automated, and, obviously, the two-person crew which will fly up will be fully trained in SpaceX and Dragon functionality and the checklist, so to speak.

Suni and Butch are test pilots with a lot of experience.

They have flown on the shuttle, they have flown on the Soyuz, now the Boeing Starliner, and they will be in the history books when they go back on the Dragon, having flown in all four vehicles.

But given the fact that they have an experienced crew with them, and they are well-versed as test pilots, and they have plenty of time right now, I guess, to read the manual, I guess it'll be OK. (LAUGHTER) AMNA NAWAZ: Our science correspondent, Miles O'Brien.

Miles, always good to speak with you.

Thank you.

MILES O'BRIEN: Pleasure.