Can NASA and Elon Musk lift off?

A lot will be riding on the 230-foot rocket that lifts off this week from Cape Canaveral: The lives of two NASA astronauts. The United States’ ambitions to reclaim its independence as a spacefaring nation. And hopes for a reimagined era of space travel in which private companies ferry humans to low-Earth orbit and beyond.

The consequences of failure would be equally historic — for both NASA and its contractor SpaceX, the 18-year-old startup founded by the tech entrepreneur Elon Musk.

SpaceX beat the competition to the finish line for Wednesday’s 4:33 p.m. liftoff — ahead of more-established rivals like Boeing — and for the chance to become the first private business to fly humans into orbit. The mission would also be the first to launch astronauts from U.S. soil since the shuttle Atlantis took its final flight in 2011, triggering nine years of America’s total reliance on Russian spacecraft.