• SpaceX plans to launch a new spaceship for NASA astronauts, called Crew Dragon , early Saturday morning at 2:49 a.m. ET.
  • The experimental launch won't carry any people, just cargo and a dummy. However, NASA says it's "a very critical mission" to proving the vehicle is safe to fly.
  • Crew Dragon will rocket toward the International Space Station, arrive at the orbiting laboratory early Sunday morning, then depart and land in the Atlantic Ocean a few days later.
  • If this dress rehearsal for NASA's $8 billion Commercial Crew Program goes well, Elon Musk's rocket company may fly its first astronauts as soon as July.
  • Here's what to expect and when from the demonstration mission, which is called SpaceX Demo-1.

SpaceX is about to launch one of the most critical space missions in the company's 17-year history.

After years of delays, NASA and its partners have given SpaceX a "go" to launch itsnew spaceship for astronauts, called Crew Dragon (or Dragon 2), for the first time ever.

Elon Musk's rocket company seeks to show that it can safely fly astronauts in its commercial spaceships. NASA, for its part, describes the mission as a "critical step" in resurrecting the ability to launch astronauts from US soil in American spaceships.

Crew Dragon is scheduled to launch atop a Falcon 9 rocket on Saturday at 2:49 a.m. ETfrom Kennedy Space Center in Cape Canaveral, Florida. No people will fly inside the spaceship for this first demonstration just cargo and sensor-laden dummy.

The mission is called SpaceX Demo-1 in formal circles, and if all goes well, the spaceship will travel to the International Space Station, dock with the $150 billion laboratory, then return to Earth a few days later.

"Demo-1 is a flight test, it absolutely is, although we view it also as a real mission, a very critical mission," Kirk Shireman , who manages the space station program at NASA's Johnson Space Center, said during a press briefing about the upcoming launch. "The ISS still has three people on board, and so this vehicle coming up to the ISS for the first time has to work. It has to work."

Here's what to expect and when from the first experimental, orbital-class flight of SpaceX's Crew Dragon space capsule.

SpaceX has been working for years with NASA toward the first launch of Crew Dragon.

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Associated Press

Following series of thorough tests including blasts of sound to simulate the vibration of launch, and exposure in a vacuum chamber Crew Dragon was shipped to Florida late last year.

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Marcia Dunn/Associated Press

There it was then integrated, or attached, to SpaceXs partly reusable Falcon 9 rocket.

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SpaceX

The spacecraft will be flown into orbit by the latest and arguably safest version of the Falcon 9, a model called "Block 5."

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Elon Musk/SpaceX via Instagram

SpaceX has wheeled the entire launch system out to a site called Launch Complex 39A.

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SpaceX

No astronauts will fly in this demo the spaceship is designed to be autonomous. But Crew Dragon will hold a spacesuit-clad dummy, or articulated mannequin. The plan is for a crew to fly the vehicle in the coming months.

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SpaceX

The test flight is part of a larger effort called the Commercial Crew Program, or CCP, which aims to find a way to fly NASA astronauts to and from the space station. NASA lost that capability in July 2011, after it retired its space shuttle system. Astronauts currently fly in Russian Soyuz spacecraft.

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Dave Mosher

In 2014, after developing and launching uncrewed cargo spaceships for NASA, SpaceX was awarded a $2.6 billion contract to develop and certify its Crew Dragon space capsule, then launch at least two (but up to six) operational missions to the space station.

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SpaceX

Musks company has worked closely with NASA astronauts to refine the controls and functionality of Crew Dragon before it was finalized.

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SpaceX

Boeing also won a $4.2 billion CCP contract for its CST-100 Starliner spaceship. After each company performs an uncrewed mission to the space station, and a series of abort tests, NASA will let eight of its astronauts and one retired astronaut (now a Boeing employee) fly them into space.

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NASA via AP

SpaceX is launching its vehicle first. The Demo-1 mission is scheduled to launch at 2:49 a.m. ET on Saturday from Cape Canaveral, Florida, though theres a 20% chance of a weather delay.

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SpaceX

On the launch pad, SpaceX briefly test-fired the Falcon 9 rockets engines to ensure the system was working correctly.

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SpaceX

The Block 5 version of SpaceXs Falcon 9 rocket was redesigned to improve the reuse of its expensive 16-story booster. The improvement also aimed to correct a problem that arose with a previous version of the rocket, which exploded during a launch pad fueling test on September 1, 2016.

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Launch Report/Handout via REUTERS

The Crew Dragon will be loaded up with about 400 pounds of cargo, including a dummy crewmember.

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SpaceX/Twitter

The dummy will be packed with sensors to gather data for SpaceX and NASA. It will help determine if Crew Dragons automated life support systems function as designed.

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SpaceX

The last dummy SpaceX flew into space was a mannequin in a spacesuit called "Starman," which the company launched in a Tesla Roadster out to Mars orbit.

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SpaceX/Flickr via YouTube (public domain)

If the weather cooperates and there are no glitches, the rocket should lift off promptly at 2:49 a.m. ET under the cover of darkness.

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SpaceX

In just over 1 minute, the rocket will accelerate faster than the speed of sound.

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SpaceX/Flickr (public domain)

About 80 seconds into the launch, Crew Dragon and its rocket will enter a phase called "maximum dynamic pressure" or "Max Q." Thats when there is the most stress on the rocket due to its high speed and the relative thickness of Earths atmosphere.

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SpaceX

Approximately 2 minutes and 30 seconds into flight, the Falcon 9s booster or first stage the biggest section of the rocket will separate from the upper stage, which will continue flying Crew Dragon to space.

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SpaceX/Flickr (public domain)

The booster will then turn around, re-light its rocket engines, and slow down. This will cause it to fall back to Earth. A little more than 8 minutes after launch, it will try to land on a robotic ship in the Atlantic Ocean.

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SpaceX/Flickr (public domain)

Landing the booster is not critical to the mission, but if all goes smoothly, it will get towed back to land for use in a future launch, saving SpaceX millions of dollars in rocket hardware.

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SpaceX/Flickr (public domain)

Around the same time as the booster landing, the upper stage will help send the Crew Dragon into orbit, then detach from the spaceship.

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Kennedy Space Center/SpaceX via Flickr

On Sunday morning, Crew Dragon will catch up to the football-field-size International Space Station.

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NASA

In SpaceXs previous launches of its uncrewed Cargo Dragon (or Dragon V1), the spaceships have been captured by a robotic arm on the space station.

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REUTERS/NASA

But this time, Crew Dragon has to prove it can safely dock with the roughly $150 billion orbiting laboratory.

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SpaceX

A crew of three crew members is already aboard the space station: NASA astronaut Anne McClain, Roscosmos cosmonaut Oleg Kononenko, and Canadian astronaut David Saint-Jacques. They will welcome the cargo and dummy if all goes according to plan.

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NASA

Around 2 a.m. ET on March 8, Crew Dragon and its dummy passenger, along with what NASA says are "critical research samples" loaded up by the space station crew, will depart from the ISS.

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NASA

Then Crew Dragon will scream through Earths atmosphere at dozens of times the speed of sound, then slow down using its ablative heat shield. Finally, it will deploy three landing parachutes.

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SpaceX on Flickr

If that all happens according to plan, the space capsule will splash down in the Atlantic Ocean near Cape Canaveral around 7:30 a.m ET on March 8.

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NASA Langley Research Center/Ron Beard

A boat will then recover the spaceship, its cargo, and the dummy passenger, and return them to land for SpaceX and NASA to scrutinize.

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SpaceX

If the Demo-1 mission is successful, SpaceX will then have one more uncrewed flight-abort test to complete before turning its attention to flying astronauts.

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SpaceX

As soon as July of this year, SpaceX may launch Demo-2: The companys first-ever crewed mission.

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NASA

"Human space flight is basically the core mission of SpaceX," Hans Koenigsmann, SpaceXs vice president for build and flight reliability, said on February 22. "There is nothing more important for us than this endeavor."

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Joey Roulette/Reuters

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