Building functioning thrusters should be a routine task, these are used on many spacecraft all the time. But rockets are hard. SpaceX blew up a capsule on the t

Building functioning thrusters should be a routine task, these are used on many spacecraft all the time. But rockets are hard. SpaceX blew up a capsule on the test stand, due to an issue with the propulsion system (thrusters). The only way they will risk astronaut lives and various reputations allowing them to return on the Boeing capsule is if they are 100% certain of a positive outcome. There are no rescue vessels in space right now, so even a minor problem can be deadly. It seems unlikely at this point 100% certainty will be reached. And I'm sure NASA is very annoyed that the capsule isn't configured to do an unmanned return. Boeing needs to upload and test software for unmanned return, otherwise it is stuck there until they have those issues worked out (1 of only 2 docking ports perhaps?).