According to the United States space agency, this is a demonstration mission which, if successful, will allow SpaceX to take part in more manned missions.
The private company will attempt to launch two NASA astronauts from Kennedy Space Center - a first from the USA since the end of the Space Shuttle Program in 2011. Launch is scheduled for 4:33 p.m. EDT.
Now, SpaceX is looking to become the first private company to carry NASA astronauts to the ISS and - if this test flight is successful - eventually to the Moon and Mars.
All that's standing in this latest mission's way is the weather, with the US Air Force's 45th Weather Squadron predicting there is a 60pc chance of "unfavourable weather conditions" including thick clouds for the Demo-2 mission on launch day. Bob and Doug completed a dress rehearsal Saturday, ahead of the launch attempt Wednesday.
Although, according to Cape Canaveral forecasters the weather forecast stays unfavorable. They try to make the unbelievable thing into believable by ferrying two NASA astronauts into space.
SpaceX and NASA scheduled at 4:33 pm (20:33 GMT) on Wednesday Falcon9 set to launch from Pad 39A with the Crew Dragon capsule.
The odds of acceptable launch weather improved Tuesday to 60%.
US President Donald Trump will be among the onlooker at Kennedy Space Center in Florida to observe the launch given the positive green light despite months of shutdowns due to the COVID-19 pandemic.
But the Crew Dragon's first piloted test flight has more down-to Earth objectives: proving the capsule and safely put astronauts in orbit, rendezvous and dock with the space station and return to Earth with an ocean splashdown.
NASA hired SpaceX and Boeing in 2014 to transport astronauts to the space station, after commercial cargo shipments had taken off. Development of SpaceX's Dragon and Boeing's Starliner capsules took longer than expected, however, and the US has been paying Russian Federation to launch NASA astronauts in the interim.
Although familiarity with the trip, this will be the first time that SpaceX will send an actual human being all the way into space. After extensive leak checks, Hurley and Behnken will be welcomed aboard the space lab by Expedition 63 commander Chris Cassidy and cosmonauts Anatoly Ivanishin and Ivan Vagner.
The mission duration has not been announced yet.