Space. So close and yet so far.

Elon Musk's SpaceX on Friday is expected to launch a rocket to the International Space Station for the first time since a weak support strut tipped a mission into catastrophe two minutes after launch in June.

The rocket awaiting liftoff at Cape Canaveral will deliver to the space station an experimental inflatable module of a type that may someday house space travelers. Astronauts will activate the module within a few months of its arrival and test its safety and performance over two years. If it works, it will be a handy thing to have, but secondary to something even more critical: a reliable way to ferry people to and from space.

Since NASA retired its Space Shuttle fleet in 2011, the U.S. has relied on Russian vehicles to send professionals aloft. SpaceX and another company, Orbital Sciences, have contracts to restock the station and may begin taxiing astronauts back and forth as soon as 2017. SpaceX is out to slash the cost of flight to a small fraction of its historic levels by safely guiding launch vehicles back to earth and reusing them.

That's what makes every SpaceX launch a double dare, and impossible not to watch. Lifting machines into orbit is one thing. Now the rockets are going to have to stick their landings.