<p>SpaceX's historic first crewed launch was set to proceed as scheduled Wednesday, NASA announced at midday, but some uncertainty remained over weather conditions just over four hours before takeoff.</p>.<p>"We are go for launch!" tweeted NASA chief Jim Bridenstine.</p>.<p>"@SpaceX and @NASA will continue monitoring liftoff and downrange weather as we step into the countdown. We are proceeding toward a 4:33 launch."</p>.<p>The mission will see the California-based company send astronauts Bob Behnken and Doug Hurley on a voyage in SpaceX's Crew Dragon capsule to the International Space Station.</p>.<p>It will be a first for the private sector and the first crewed mission to blast off from US soil in almost a decade following the shuttering of the Space Shuttle program in 2011.</p>.<p>A thunderstorm lashed the Kennedy Space Center in the morning, and the National Hurricane Center announced a tropical storm was forming off South Carolina, a possible risk if astronauts are forced to carry out an emergency landing in the Atlantic shortly after takeoff.</p>.<p>But a NASA announcer later announced that conditions were improving, placing the odds at launching on time at around 50-50. The next window is Saturday.</p>.<p>For the moment, launch is scheduled for 4:33 pm (2033 GMT) from the Kennedy Space Center's Launch Pad 39A, the same from which Neil Armstrong and his Apollo 11 crewmates lifted off on their historic journey to the Moon.</p>.<p>The mission has proceeded despite shutdowns caused by the coronavirus pandemic, with the crew in quarantine for the past two weeks.</p>.<p>Founded in 2002, Space Exploration Technologies Corp. has torn up the rules to produce a lower-cost alternative to human spaceflight that has gradually won over skeptics.</p>.<p>By 2012, it had become the first private company to dock a cargo capsule at the ISS, resupplying the station regularly ever since.</p>.<p>Two years later, NASA ordered the next step: to transport its astronauts there, starting in 2017, by adapting the Dragon capsule.</p>.<p>"SpaceX would not be here without NASA," Musk said last year, after a successful dress rehearsal without humans for the trip to the ISS.</p>.<p>The space agency paid more than $3 billion for SpaceX to design, build, test and operate its reusable capsule for six future space round trips.</p>.<p>The project has experienced delays, explosions, and parachute problems -- but even so, SpaceX has beaten aerospace giant Boeing to the punch.</p>.<p>Boeing's NASA entry, the Starliner, is still not ready.</p>.<p>The move by NASA to invest in privately developed spacecraft -- a more economic proposition than spending tens of billions of dollars developing such systems itself, as it had done for decades -- was begun under the presidency of George W. Bush for cargo, and then under Barack Obama for human flight.</p>.<p>At the time, there was immense hostility in Congress and NASA to the start-up's claims of what it could achieve.</p>.<p>A decade on it is another president, Donald Trump, who will attend Wednesday's launch in Florida.</p>.<p>The Republican is trying to reaffirm American domination of space, militarily but also by ordering a return to the Moon in 2024.</p>.<p>If NASA can entrust "low Earth orbit" space travel to the private sector, it would free up dollars for its more distant missions.</p>.<p>"We envision a future where low Earth orbit is entirely commercialized, where NASA is one customer of many customers," NASA's Bridenstine said.</p>.<p>Crew Dragon is a capsule like Apollo, but updated for the 21st century.</p>.<p>Touch screens have replaced switches. The interior is dominated by white, more subtle lighting.</p>.<p>It looks entirely different than the huge winged space shuttles that carried astronauts into space from US soil from 1981 to 2011.</p>.<p>"We're expecting a smooth ride but we're expecting a loud ride," said Behnken, who, like Hurley, also flew in the shuttles twice.</p>.<p>Unlike the shuttles, one of which -- the Challenger -- exploded in 1986 after launch, Dragon can eject in an emergency if the Falcon 9 rocket has a problem boosting it into space.</p>.<p>Crew Dragon will catch up with the space station on Thursday at an altitude of 400 kilometers, and will probably remain docked there until August.</p>.<p>If it fulfils its mission and is certified safe, it will mean the Americans will no longer depend on Russia for access to space: since 2011, the Russian Soyuz rockets were the only space taxis available.</p>
<p>SpaceX's historic first crewed launch was set to proceed as scheduled Wednesday, NASA announced at midday, but some uncertainty remained over weather conditions just over four hours before takeoff.</p>.<p>"We are go for launch!" tweeted NASA chief Jim Bridenstine.</p>.<p>"@SpaceX and @NASA will continue monitoring liftoff and downrange weather as we step into the countdown. We are proceeding toward a 4:33 launch."</p>.<p>The mission will see the California-based company send astronauts Bob Behnken and Doug Hurley on a voyage in SpaceX's Crew Dragon capsule to the International Space Station.</p>.<p>It will be a first for the private sector and the first crewed mission to blast off from US soil in almost a decade following the shuttering of the Space Shuttle program in 2011.</p>.<p>A thunderstorm lashed the Kennedy Space Center in the morning, and the National Hurricane Center announced a tropical storm was forming off South Carolina, a possible risk if astronauts are forced to carry out an emergency landing in the Atlantic shortly after takeoff.</p>.<p>But a NASA announcer later announced that conditions were improving, placing the odds at launching on time at around 50-50. The next window is Saturday.</p>.<p>For the moment, launch is scheduled for 4:33 pm (2033 GMT) from the Kennedy Space Center's Launch Pad 39A, the same from which Neil Armstrong and his Apollo 11 crewmates lifted off on their historic journey to the Moon.</p>.<p>The mission has proceeded despite shutdowns caused by the coronavirus pandemic, with the crew in quarantine for the past two weeks.</p>.<p>Founded in 2002, Space Exploration Technologies Corp. has torn up the rules to produce a lower-cost alternative to human spaceflight that has gradually won over skeptics.</p>.<p>By 2012, it had become the first private company to dock a cargo capsule at the ISS, resupplying the station regularly ever since.</p>.<p>Two years later, NASA ordered the next step: to transport its astronauts there, starting in 2017, by adapting the Dragon capsule.</p>.<p>"SpaceX would not be here without NASA," Musk said last year, after a successful dress rehearsal without humans for the trip to the ISS.</p>.<p>The space agency paid more than $3 billion for SpaceX to design, build, test and operate its reusable capsule for six future space round trips.</p>.<p>The project has experienced delays, explosions, and parachute problems -- but even so, SpaceX has beaten aerospace giant Boeing to the punch.</p>.<p>Boeing's NASA entry, the Starliner, is still not ready.</p>.<p>The move by NASA to invest in privately developed spacecraft -- a more economic proposition than spending tens of billions of dollars developing such systems itself, as it had done for decades -- was begun under the presidency of George W. Bush for cargo, and then under Barack Obama for human flight.</p>.<p>At the time, there was immense hostility in Congress and NASA to the start-up's claims of what it could achieve.</p>.<p>A decade on it is another president, Donald Trump, who will attend Wednesday's launch in Florida.</p>.<p>The Republican is trying to reaffirm American domination of space, militarily but also by ordering a return to the Moon in 2024.</p>.<p>If NASA can entrust "low Earth orbit" space travel to the private sector, it would free up dollars for its more distant missions.</p>.<p>"We envision a future where low Earth orbit is entirely commercialized, where NASA is one customer of many customers," NASA's Bridenstine said.</p>.<p>Crew Dragon is a capsule like Apollo, but updated for the 21st century.</p>.<p>Touch screens have replaced switches. The interior is dominated by white, more subtle lighting.</p>.<p>It looks entirely different than the huge winged space shuttles that carried astronauts into space from US soil from 1981 to 2011.</p>.<p>"We're expecting a smooth ride but we're expecting a loud ride," said Behnken, who, like Hurley, also flew in the shuttles twice.</p>.<p>Unlike the shuttles, one of which -- the Challenger -- exploded in 1986 after launch, Dragon can eject in an emergency if the Falcon 9 rocket has a problem boosting it into space.</p>.<p>Crew Dragon will catch up with the space station on Thursday at an altitude of 400 kilometers, and will probably remain docked there until August.</p>.<p>If it fulfils its mission and is certified safe, it will mean the Americans will no longer depend on Russia for access to space: since 2011, the Russian Soyuz rockets were the only space taxis available.</p>