It took work across three presidencies, those of George W. Bush, Barack Obama and Donald Trump, but the United States is at last prepared once again, after nearly a decade, to launch American astronauts into orbit from American soil on an American-built rocket.

“This is a unique opportunity to bring all of America together in one moment in time and say, look at how bright the future is,” Jim Bridenstine, NASA’s administrator, said during a news conference on Tuesday.

Lori Garver, who served as NASA’s deputy administrator during the Obama administration, said in an interview that she hoped this moment would have come sooner. But she also said she was “really pleased with how, even in the pandemic, much attention and excitement there is for it.”

The United States sent astronauts to the moon in the 1960s and 1970s and then built the world’s only space shuttle fleet for trips into and out of orbit. But the destruction of the shuttle Columbia in a 2003 accident eventually left NASA dependent on costly Russian spacecraft to ferry astronauts to and from the International Space Station.

The replacement that the U.S. space program finally settled on is an innovation not of technology, but philosophy and policy.

Instead of building its own replacement for the shuttle, NASA is handing over responsibility for carrying astronauts to a private company, SpaceX, one of the obsessions of serial entrepreneur Elon Musk. If Musk’s engineers succeed on Wednesday in sending Douglas G. Hurley and Robert L. Behnken to orbit, it will forever change how the world thinks about getting people to space.

If a private company can loft humans to orbit today, why not the moon next or Mars some years in the future? A successful launch could ignite a future long imagined by science fiction writers in which space is a destination for more and more people.

Almost everything about the journey to space scheduled on Wednesday is different from earlier eras of human spaceflight.

The launchpad at the Kennedy Space Center in Florida where the mission will blast off — the same one used by the last shuttle mission in 2011 — has been rebuilt to handle Musk’s Falcon 9 rocket.

Instead of riding to the spacecraft in Astrovan, a modified Airstream motor home that NASA used to transport shuttle crews, Hurley and Behnken will take a trip in a gull-winged Model X SUV, manufactured by Musk’s other major company, Tesla.

Wearing stylish SpaceX spacesuits, the two will walk across a sleek walkway about 230 feet above the ground to board the SpaceX-built capsule, which sits on top of the Falcon 9.

This launch will be the first time a private company and not a governmental space agency will be in charge of sending astronauts to orbit. Even though the passengers are still NASA astronauts, and the agency’s officials certainly could call off the launch if they saw something concerning, it is a SpaceX control room with SpaceX employees scanning the monitors who will be directing the launch.

“We’re really looking to be a customer to SpaceX, and to other companies, in the future,” said James Morhard, NASA’s deputy administrator. “That’s what we’re trying to do is to create an expanse, really expand the economy in low-Earth orbit. That’s really what this is about.”

Already, two companies have announced plans to buy launches in SpaceX’s capsule, the Crew Dragon, to take non-NASA passengers to space. Those missions might fly as soon as a year from now. One would take space tourists on a visit to the International Space Station; the other would be a trip on an elliptical orbit around Earth that might view the planet from an altitude two to three times as high as the space station’s orbit. Tom Cruise has even expressed interest in using the space station for a film.

A successful launch could also instill confidence that a similar approach will work for the lunar landers NASA hopes will be needed to take astronauts to the surface of the moon as soon as 2024. One of the proposals NASA is financing is from SpaceX for a giant spacecraft called Starship that the company hopes to eventually send to Mars.

Another proposal comes from Jeffrey P. Bezos, founder of Amazon and another billionaire with space dreams. Bezos’ rocket company, Blue Origin, is leading the development of Blue Moon, a lander that looks like a larger version of the lander used by NASA’s Apollo program in the 1960s and 1970s.

But the approach also includes potential pitfalls.

Boeing, the other company NASA selected to carry astronauts, stumbled in December during an uncrewed test of its spacecraft called Starliner. A software problem scuttled a planned docking at the International Space Station. An investigation revealed systemic problems with Boeing’s software development and testing, and questions about whether NASA was keeping a close enough eye on its contractors.

SpaceX has also encountered technical hurdles, including an explosion last year that destroyed one of its capsules during a test of the escape engines, and failures during parachute tests. But it was able to recover more quickly.

Today, Musk’s rocket company, with Gwynne Shotwell handling much of the day-to-day management as president and chief operating officer, has largely avoided controversy and the distractions that Musk sometimes creates around Tesla.

SpaceX routinely launches and lands reusable rockets for numerous customers, and it has captured about 70% of the market. A decade ago, U.S. aerospace companies had lost almost all of the business of launching commercial satellites to competitors in countries such as Russia and China.

SpaceX is also in the process of deploying hundreds, if not thousands of satellites, to create Starlink, a space-based network to provide high-speed internet service to almost anyone anywhere in the world.

But before the company got involved with NASA, it nearly went out of business after failures of its first three attempts to launch its first rocket. The cargo contract it won in 2006 helped finance development of the Falcon 9, the rocket now used for launches, and Dragon, the cargo container that became the basis for the capsule that will carry NASA’s astronauts.

The company has now successfully launched 19 cargo missions for NASA and successfully bounced back from the one failure in 2015.

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