The space shuttle is back. Discovery stands waiting on launchpad 39B at Kennedy Space Center. It has taken more than two years to get here. Nasa has listened and changed. After all these months of work, this should be one of the safest missions ever flown.

But as Discovery finally rises skyward, the Challenger disaster is on everyone’s mind. There are unspoken questions about the very future of spaceflight.

https://www.bbc.co.uk/programmes/w3ct80bt