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,

Sunny 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.

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 Sunny aboard the International Space Station

and bring the Boeing Starliner home uncrewed is a result of a commitment to safety.

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

So Miles, we know NASA has been weighing whether to try to bring Sunny and Butch home on the Boeing craft or a SpaceX

craft.

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

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 live 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 are 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 approach 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.

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