Congratulations are in order for the National Aeronautics and Space Administration for its decision to clear Discovery for lift off despite objections from some safety officers. We don’t make that statement flippantly; the dangers ahead are enormous, as we were taught by Apollo 1 in 1967, Challenger in 1986, and Columbia in 2003. The latter was caused by a piece of foam breaking off during liftoff, eventually compromising the heat shield, causing the shuttle to break up on re-entry. Discovery’s launch last year, the first shuttle mission after Columbia, saw signs of progress, but two members of the 25-member Discovery team worried that the progress has not been sufficient to warrant another flight quite yet.

Space travel is still dangerous. Travel into space may have become so routine that television stations rarely carry more than a few minutes of coverage, but the risk has never really gone away. Which is why we admire our astronauts so much. The men and women who will board that shuttle July 1 will be taking a big risk, as have their predecessors before them, and so will the men and women who back them up on the ground. As the mission’s head, Wayne Hale, noted in an interview with the Associated Press, no one can calculate how big a risk it is. This is the kind of risk that has always been a requisite of scientific progress, and we can all be grateful that, even as it strives to manage the dangers more effectively, NASA is prepared to risk all for greatness.