Assuming it happens, this is a day I’ve been anxiously awaiting for almost a decade, along with many other Americans. Elon Musk’s SpaceX team is scheduled to launch one of their Crew Dragon capsules mounted atop a Falcon-9 rocket with two American astronauts onboard at 4:33 pm eastern time today. It would mark the first time astronauts have been put into orbit from an American spaceport on an American-made rocket since the last shuttle launch. (NBC News)

“We as a nation have not had our own access to the International Space Station for nine years,” NASA Administrator Jim Bridenstine said earlier this month in a news briefing. “This is a very exciting time.”

Over the past nine years, NASA has awarded lucrative contracts to private companies such as SpaceX and Boeing to take over routine flights to the space station. Wednesday’s launch is a critical step in that direction. It will be the first time a commercially built vehicle carries NASA astronauts into orbit and the first time that SpaceX attempts to ferry human passengers to the space station.

NASA isn’t sending rookies to ride the Dragon. Doug Hurley and Bob Behnken have both been to space before. In a nod to our previous space program, Hurley was the pilot on the last flight of space shuttle Atlantis in 2011. But this time he’ll be piloting a much sleeker and more technologically advanced craft. The Crew Dragon has already made multiple trips to the International Space Station, though until now it’s only carried supplies and the occasional mannequin.

The reason I said “assuming it happens” is that the late spring weather is rather unstable and SpaceX needs good weather and relatively calm seas all the way from Florida to Ireland. Currently, meteorologists are giving us a 60% chance of the conditions being favorable for a launch. That’s better than yesterday, but far from a sure thing.

And the reason they need such a wide expanse of favorable conditions? It’s because one of the more exciting and promising features of the Crew Dragon is its ability to separate itself from the rocket in the event of a failure during ascent and safely bring the astronauts back to Earth. SpaceX has tested the abort capabilities of the Dragon extensively and even intentionally blew up one of their own Falcon-9s to demonstrate this capability. In the past, if a rocket started to go off course, catch fire or just fall apart during ascent, the astronauts were basically doomed.

Now, in the event of a significant failure on the way up, SpaceX should be able to separate the capsule from the Falcon-9, whereupon it will deploy some huge parachutes and begin the trip back down. But that means that Hurley and Behnken could land anywhere from just off the Florida coast to the eastern end of the Atlantic. And one of the SpaceX rescue ships would need to be able to reach them quickly and extract them from the vehicle. Hence the need for good weather and calm seas across the entire Atlantic Ocean.

I’m crossing my fingers and toes and hoping that you all will join us in keeping these brave men in your prayers today. Godspeed, gentlemen. Today you take the final steps in freeing us from our dependence on the Russians to put our people into space.