Rocket for today’s SpaceX flight on the pad at Cape Canaveral. Notice the landing legs folded up against the bottom part of the first stage booster. Photo: SpaceX.

If all goes will with the countdown, Space Exploration Technologies, or SpaceX, will attempt its most ambitious flight yet today.

Not content with merely providing the lowest-cost flights to orbit, the company, headed by extreme innovator Elon Musk, is on a mission to create reusable rocket boosters. Airline-style flights to space is the Holy Grail of the commercial spaceflight industry as a whole, and SpaceX is farthest along in realizing the dream.

After making a cargo run to the International Space Station for NASA at 4:58 pm ET from Cape Canaveral in Florida, the plan is to have the first stage of the SpaceX Falcon 9 rocket turn around and fly itself back to a soft water landing off the Florida Coast.

SpaceX spokesperson Hannah Post gave me the rundown via email on how the attempt will go.

“During this test, SpaceX will attempt to execute first a reentry burn and then a landing burn with the Falcon 9 first stage. For the first burn, we will relight three engines to do a supersonic retro propulsion burn to slow the vehicle down and help ensure it survives atmospheric reentry. Assuming successful reentry, SpaceX will relight the center engine to stabilize the stage and reduce the vehicle’s velocity prior to contact with the water. About 10 seconds into the landing burn, SpaceX will attempt to demonstrate successful deployment of the legs in preparation for future land landings.”

Post emphasized that this is an extremely high-risk maneuver, is not the primary objective for this mission, and she put the chances for a successful fly-back of the booster at only 30-40%.

I actually think the odds are better than that, given the successful restart and reentry of a Falcon 9 on a previous flight, and the successful takeoffs and landings of a Falcon 9 first stage closer to the ground. Put the two together, Musk said after the last fly back attempt, and we’ll have a winner.

Watch commentary and live coverage by SpaceX engineers starting at 3:30 pm ET today at