SpaceX is about to launch its riskiest and most critical mission to date. See how the rocket company hopes its first flight with NASA astronauts plays out.

• Eighteen years after Elon Musk founded SpaceX, the rocket company is preparing to launch its first people.
• On May 27, NASA astronauts Bob Behnken and Doug Hurley will board SpaceX's new Crew Dragon spaceship and ride it to space atop a Falcon 9 rocket.
• The Demo-2 test mission for NASA will launch from Kennedy Space Center in Florida and take about nine minutes to reach orbit.
• Behnken and Hurley will test out Crew Dragon's systems during a day-long journey to the International Space Station.
• The astronauts will live on the space station for about 3 months before they climb back inside the space capsule, return to Earth, and parachute into the Atlantic Ocean.
• Visit Business Insider's homepage for more stories.

Elon Musk formed SpaceX in 2002. Since then, the company has turned the spaceflight industry upside-down with dozens of reusable rocket launches.

For all its achievements, though, SpaceX has never flown a single person into space.

That will change on May 27 — weather and luck permitting — when NASA astronauts Bob Behnken and Doug Hurley put on spacesuits, climb aboard SpaceX's new Crew Dragon spaceship, and ride the gumdrop-shaped vehicle into orbit atop a 23-story Falcon 9 rocket.

The astronauts' Demo-2 mission will be SpaceX's first human-rated flight and its second full test flight for NASA's Commercial Crew Program. The goal of the roughly $8 billion effort is to restore American access to space with commercial partners; NASA retired all of its space shuttles in July 2011, and SpaceX is poised to achieve the feat before its competitor, Boeing.

Demo-2 will ferry the astronauts to the International Space Station (ISS), where they may stay for more than 100 days.

Here's every notable step of SpaceX's first crewed flight, which will be the company's most critical, dangerous, and historic mission to date.

A successful Demo-2 mission would also tee up a bright future for SpaceX, NASA, and the future of commercial spaceflight.

SpaceX's Crew Dragon spaceship approaches the International Space Station on March 3, 2019.      NASA

If all goes well, Demo-2 will set the stage for SpaceX's first operational mission with NASA astronauts Victor Glover and Mike Hopkins, who may fly to the ISS before the end of the year.

NASA astronauts Victor Glover (left) and Mike Hopkins (right). They will be the second to fly SpaceX's Crew Dragon capsule.      NASA

SpaceX's GO Searcher ship will be at the ready with a helicopter in case Behnken or Hurley need to be rapidly evacuated to land for medical attention.

Teams from NASA and SpaceX practice procedures for medical emergency evacuation onboard the GO Searcher ship, Friday, August 15, 2019 in the Atlantic Ocean off the coast of Cape Canaveral, Florida.      Bill Ingalls/NASA

Minutes later, Crew Dragon will deploy a series of parachutes to splash down in the Atlantic Ocean just off the coast of Cape Canaveral.

SpaceX’s Crew Dragon is guided by four parachutes as it splashes down in the Atlantic Ocean about 200 miles off Florida’s east coast on March 8, 2019, after returning from the International Space Station on the Demo-1 mission.      Cory Huston/NASA

This will expose the capsule's heat shield, which will plow through Earth's atmosphere, generate superheated plasma, and help bleed off the energy of moving at dozens of times the speed of sound.

An illustration of SpaceX's Crew Dragon spaceship returning to Earth with a blaze of plasma ahead of its heat shield.      SpaceX via YouTube

Crew Dragon will fly away from the ISS until it's in position to shed its tube-like trunk, a lower section outfitted with fuel tanks, solar panels, and other hardware the astronauts will no longer need.

An illustration of SpaceX's Crew Dragon spaceship shedding its trunk before returning to Earth.      SpaceX via YouTube

Their return to Earth is supposed to follow a timeline like this one.

A diagram showing the planned departure and landing sequence from International Space Station of SpaceX's Demo-2 mission with NASA astronauts Bob Behnken and Doug Hurley.      SpaceX via NASA TV

Back inside Crew Dragon and suited up, Behnken and Hurley will bid the space station farewell.

SpaceX

"I understand it's going to be sort of like a capture the flag moment here for commercial spaceflight. So good luck to whoever grabs that flag," then-President Barack Obama said on July 15, 2011.

President Barack Obama talks with the crews of the Space Shuttle Atlantis and the International Space Station during a phone call in the Oval Office on July 15, 2011.      Pete Souza/White House

Source: NASA via YouTube

Before Behnken and Hurley leave, though, they'll grab a historic memento: an American flag flown on the first space shuttle mission and left by the crew of NASA's final space shuttle flight, of which Hurley was a member.

The crews of STS-135 and Expedition 28 hold up a US flag that flew on the first space shuttle mission, STS-1, returned to Earth, and flew again on STS-135. The flag was left on the International Space Station for the next crewed launch from American soil.      NASA

The Demo-2 crew will begin a stay in orbit that may last up to 110 days. Future SpaceX crews may linger for more than six months.

The Aurora Australis seen from the International Space Station in September 2011.      NASA

The three-person crew of Expedition 63, commanded by fellow NASA astronaut Chris Cassidy, will be waiting to greet Behnken and Hurley once the hatches open.

Expedition 63 crew members Chris Cassidy, Anatoly Ivanishin, and Ivan Vagner.      NASA

Once they show the new interface works, Crew Dragon's computer will resume control, propel the spaceship to its port, and berth it to the ISS.

An artist's illustration shows the SpaceX Crew Dragon spacecraft docking to the International Space Station.      SpaceX via NASA

At that point, the astronauts will try out their spaceship's all-new touchscreen docking controls — just in case there's a problem with the automated system.

SpaceX's training simulator for docking Crew Dragon with the International Space Station.      SpaceX vis YouTube

Crew Dragon will pull up to a spot about 220 meters (722 feet) in front of the ISS.

SpaceX's Crew Dragon spacecraft — the first of NASA's Commercial Crew vehicles — prepares to dock with the International Space Station on March 3, 2019.      NASA

After about 15 hours of flying above Earth, the space station will come into view.

The International Space Station (ISS).      NASA

The phases for this stage of SpaceX's Demo-2 mission look like this.

A diagram showing the planned flight sequence to the International Space Station of SpaceX's Demo-2 mission with NASA astronauts Bob Behnken and Doug Hurley.      SpaceX via NASA TV

Once Behnken and Hurley safely reach orbit, they'll climb out of their spacesuits, begin a series of tests, eat, and get some much-needed rest.

An illustration of SpaceX's Crew Dragon, also known as Dragon 2 or Dragon V2, orbiting Earth. (The first Dragon was a cargo and supply ship not designed to carry people.)      Kennedy Space Center/SpaceX via Flickr

If there's a major problem with the rocket en route to orbit, the escape system is designed to automatically pull Crew Dragon away from danger.

An illustration of SpaceX's Crew Dragon spaceship for firing its engines during an abort from a Falcon 9 rocket launch.      SpaceX via Twitter

The crew's journey to space will look something like this. Once the Falcon 9 rocket booster expends most of its fuel, it will detach from the upper stage and attempt to land on a boat at sea to fly another day.

A diagram showing the planned launch sequence of SpaceX's Demo-2 mission with NASA astronauts Bob Behnken and Doug Hurley.      SpaceX via NASA TV

The force of launch will press them into their seats as the Falcon 9 spends roughly the next nine minutes accelerating Crew Dragon to 17,500 mph. That's about 10 times as fast as a bullet and the speed required to orbit Earth at the space station's altitude.

A SpaceX Falcon 9 rocket lifts off from Launch Complex 39A at NASA’s Kennedy Space Center in Florida at 10:30 a.m. EST on Jan. 19, 2020, carrying the Crew Dragon spacecraft on the company’s uncrewed In-Flight Abort Test.      Tony Gray/SpaceX

Once the rocket is fueled and the clock counts down, Behnken and Hurley will wait through some of the longer seconds of their lives.

SpaceX's astronaut spacesuit inside a Crew Dragon capsule.      Elon Musk/SpaceX; Instagram

SpaceX showed the escape system works by launching a Crew Dragon atop a Falcon 9 rocket on January 19. During the most strenuous part of the flight, the ship — empty save for a mannequin — safely flew away from the doomed rocket.

SpaceX's Crew Dragon spaceship separating and speeding from an intentionally failed Falcon 9 rocket on January 19, 2020.      SpaceX via Twitter

About 45 minutes before liftoff, the astronauts will arm a launch escape system — just in case anything goes wrong during a roughly half-hour fueling procedure called "load and go," which NASA approved in 2018.

Elon Musk.      Steve Nesius/Reuters

Source: Space News

Next comes a thorough checklist of items before launch.

NASA astronauts Bob Behnken (foreground) and Doug Hurley (background) train inside SpaceX's Crew Dragon spaceship.      SpaceX

SpaceX staff will buckle the astronauts into their reclined seats, wave goodbye, and seal the hatch.

NASA astronauts Bob Behnken (left) and Doug Hurley (right) inside SpaceX's Crew Dragon spaceship.      NASA

... And crawl into the white cabin of the Crew Dragon spaceship.

The interior of SpaceX's Dragon v2 or Crew Dragon capsule showing seats for five astronauts, though the craft can support up to seven.      SpaceX/Flickr (public domain)

The arm will connect to a rectangular hatch on the side, where Behnken and Hurley will worm their way through...

A closed-circuit TV camera's view of SpaceX's Crew Dragon hatch on January 1, 2019, ahead the Demo-1 mission. (The "you must be this tall to ride" sign was digitally added.)      Elon Musk/SpaceX via Twitter

... Then walk down an access arm to their spaceship. Just before boarding Crew Dragon, the astronauts will give a family member a traditional phone call. "Hopefully, we get a person and not an answering machine," Behnken said on May 1.

NASA astronauts Bob Behnken (left) and Doug Hurley, wearing SpaceX spacesuits, walk through the Crew Access Arm connecting the launch tower to the SpaceX Crew Dragon spacecraft during a dress rehearsal at NASA’s Kennedy Space Center in Florida on January 17, 2020.      SpaceX

Source: Business Insider

The crew will get a ride out to the launch pad and ascend an elevator to the top ...

SpaceX

A few hours before launch, Behnken and Hurley will be helped into their spacesuits. The garments are made to protect the astronauts from a sudden loss of air pressure and even fire.

NASA astronauts Doug Hurley (foreground) and Bob Behnken don SpaceX spacesuits during a dress rehearsal in the Astronaut Crew Quarters at Kennedy Space Center in Florida on Jan. 17, 2020      NASA/Kim Shiflett

NASA gets one more chance to call off the mission on May 25 with a launch readiness review. If the weather holds and the review goes well, SpaceX — and the astronauts — will have a green light to make history on May 27. (The backup launch day is May 30.)

NASA Administrator Jim Bridenstine at a post-launch news conference for SpaceX on January 19, 2020.      Steve Nesius/Reuters

If the test-firing goes well, Behnken and Hurley will drive out to the launchpad on May 23 to conduct a full launch dress rehearsal with SpaceX to ensure everyone and everything is ready for flight.

Astronauts Doug Hurley (left) and Robert Behnken pose in front of a Tesla Model X at a SpaceX launch dress rehearsal at Kennedy Space Center in Florida on January 17, 2020.      Kim Shiflett/NASA via AP Photo

During static-fire tests, SpaceX pumps super-chilled liquid oxygen and kerosene fuel into the rocket's tanks. Then they fire the rocket booster's nine Merlin engines for a few seconds to ensure there are no problems.

A photo of the bottom of a Falcon 9 rocket, showing its nine Merlin engines.      SpaceX/Flickr (public domain)

After it's clamped down and checked out, SpaceX will conduct a static fire test on May 22.

LC-39A, which SpaceX heavily retrofitted, is the same site that NASA's Apollo moon missions and final space shuttle launched from — so Demo-2's flight will continue its historic tradition.      SpaceX via Twitter

Source: Spaceflight Now

... And lift the rocket into a vertical position on the launchpad.

A SpaceX Falcon 9 rocket with the company's Crew Dragon spacecraft onboard is seen as it is raised into a vertical position on the launch pad at Launch Complex 39A as preparations continue for the Demo-1 mission, Feb. 28, 2019 at the Kennedy Space Center in Florida.      Joel Kowsky/NASA

A few days before liftoff, SpaceX will roll the stacked Crew Dragon spaceship and Falcon 9 rocket out of its hangar at Launch Complex 39A ...

A SpaceX Falcon 9 rocket with the company’s Crew Dragon attached, rolls out of the company’s hangar at NASA Kennedy Space Center’s Launch Complex 39A on January 3, 2019.      SpaceX

NASA will give Demo-2 a flight readiness review around May 21. If it goes well, SpaceX will kick off a series of final preparations for launch.

SpaceX's Crew Dragon spaceship being mated to its trunk on April 30, 2020, at Cape Canaveral Air Force Station in Florida. The spacecraft was built for NASA's Demo-2 test mission.      SpaceX via NASA

Source: Spaceflight Now

On May 20, Behnken and Hurley will fly to Kennedy Space Center (KSC) in Cape Canaveral, Florida, to finish up quarantine there.

NASA astronaut Doug Hurley prepares for a flight in a T-38 trainer on his way from Houston to the Kennedy Space Center in Florida, June 20, 2011.      NASA Photo / Houston Chronicle, Smiley N. Pool

Although NASA and SpaceX are moving forward with Demo-2 during the coronavirus pandemic, quarantines are standard: They help prevent crew members from getting sick while orbiting 250 miles away from the nearest hospital.

The crew of the International Space Station usually consists of six people at most. This is them before the arrival of three people on Friday.      ESA/NASA

Source: Business Insider

Behnken and Hurley's mission will begin in earnest on May 13: when the astronauts check into quarantine at a living facility on the grounds of Johnson Space Center in Houston, Texas.

NASA astronauts Bob Behnken (left) and Doug Hurley (right) sit inside SpaceX's Crew Dragon spaceship.      NASA

"On more than one occasion [Musk] has looked both Bob and I right in the eye and said, 'Hey, if there's anything you guys are not comfortable with or that you're seeing, please tell me and we'll fix it,'" Hurley said during a NASA briefing on May 1.

From left: SpaceX founder Elon Musk, NASA astronauts Victor Glover, Doug Hurley, Bob Behnken, NASA Administrator Jim Bridenstine, and astronaut Mike Hopkins speak inside the crew access arm with the SpaceX Crew Dragon spacecraft visible behind them during a tour of Launch Complex 39A. The spacecraft launched the Demo-1 mission on March 1, 2019.      Joel Kowsky/NASA

Source: Business Insider

They've also met with Musk many times to discuss ideas for Crew Dragon's improvement.

SpaceX founder Elon Musk (left) speaks with NASA astronaut Bob Behnken on the fixed service structure of Launch Complex 39A on March 1, 2019.      Joel Kowsky/NASA

The duo, along with other astronauts, have worked closely with SpaceX to provide critical feedback about Crew Dragon.

NASA astronaut Robert "Bob" Behnken evaluates SpaceX's Crew Dragon mock-up.      SpaceX

Source: Business Insider

Both are engineers who've flown on space shuttle missions to the space station. Gwynne Shotwell, SpaceX's president and COO, has described the men as "badass" test pilots, astronauts, and dads.

NASA astronaut Robert "Bob" Behnken aboard the International Space Station in February 2010.      NASA

Source: Business Insider

On August 3, 2018, NASA announced it had selected Hurley and Behnken to fly SpaceX's Demo-2 mission.

NASA astronauts Doug Hurley (left) and Bob Behnken during a 2018 Commercial Crew Program crew unveiling.      David J. Phillip/AP

Source: Business Insider

SpaceX is the first company to jump through all of NASA's hoops to convince the agency it's ready to fly astronauts.

NASA Administrator Jim Bridenstine (left) and SpaceX founder Elon Musk on January 19, 2020.      Kim Shiflett/NASA

But NASA has worked with SpaceX, Boeing, and others since 2012 to build all-new American spaceships through the Commercial Crew Program.

A view of SpaceX's Crew Dragon capsule atop a Falcon 9 rocket in Cape Canaveral, Florida. The spacecraft is part of NASA's Commercial Crew Program to launch astronauts into orbit from US soil.      SpaceX/Twitter

But Russia has made use of its monopoly on spaceflight. When NASA still launched space shuttles, a round-trip ticket on Soyuz cost about $20 million. In May, NASA agreed to pay Russia more than $90 million per Soyuz seat.

Astronauts and a cosmonaut buckled into a cramped Soyuz descent module make for a very tight fit.      ESA/NASA

Sources: Business Insider, Irene Klotz/Aviation Week

Soyuz is necessary to get astronauts to and from the International Space Station, which not only represents a $100 billion US investment, but is a football-field-size laboratory where NASA performs research for future crewed missions to the moon and Mars.

The International Space Station.      NASA

Sources: Business Insider (1, 2)

Since then, the only approved ride for NASA astronauts to and from space has been Russia's Soyuz launch system.

The Soyuz MS-10 spacecraft carrying NASA astronaut Nick Hague and Roscosmos cosmonaut Alexey Ovchinin from the Baikonur Cosmodrome in Kazakhstan on October 11, 2018. The rocket failed in mid-flight, but an escape system saved the crew.      Shamil Zhumatov/Reuters

Source: Business Insider

The stakes are immense for NASA as well as SpaceX. In July 2011, NASA flew its last space shuttle mission, effectively ending crewed spaceflight from American soil.

Space shuttle Atlantis at Launchpad 39A in Cape Canaveral, Fla.      Dave Mosher

On May 27 at 4:33 p.m. ET, the two men are schedule ride SpaceX's Crew Dragon ship into orbit — a risky test flight called Demo-2 — and become SpaceX's first human passengers.

An illustration of SpaceX's Crew Dragon space capsule for NASA astronauts launching toward space on a Falcon 9 rocket.      SpaceX

Source: Business Insider

NASA astronauts Doug Hurley and Bob Behnken are poised to make spaceflight history, both for the US and SpaceX.

NASA astronauts Doug Hurley (left) and Bob Behnken (right), who are scheduled to be the first people that SpaceX launches into orbit.      SpaceX