(CAPE CANAVERAL, Fla.) -- Millions are expected to tune in on Saturday as NASA and SpaceX go forward with their second attempt to launch astronauts to the International Space Station.

The history-making SpaceX Demo-2 launch was originally scheduled for Wednesday, but it was called off less than 20 minutes before liftoff due to inclement weather.

SpaceX confirmed Saturday morning that its launch is going ahead as planned.

"All systems go for Crew Dragon’s test flight with @NASA astronauts @AstroBehnken and @Astro_Doug," the company tweet. "Teams are keeping an eye on weather."

SpaceX CEO Elon Must echoed the weather concern, tweeting "Proceeding with countdown today, weather cancellation risk ~50%."

If all goes well Saturday, it will be the first time Musk's private space firm, SpaceX, will launch a human crew. It will also mark the first time in nearly a decade the U.S. has launched American astronauts from U.S. soil, ending an expensive reliance on Russia for seats to space.

"We're at the dawn of a new age, and we're really leading the beginning of a space revolution," NASA Deputy Administrator James Morhard said at a news conference Friday.

He said the aim for the launch is to "give hope for many people who need it right now, and also to unite our country and the world."

You can learn more about the NASA astronauts, Doug Hurley and Bob Behnken, who are headed to the ISS, here.

'50-50 chance': Weather forecast includes possible thunderstorms, showers

The weather forecast for Cape Canaveral, Florida, at the time of the launch includes scattered showers and thunderstorms.

"It sounds like we got a 50-50 chance with the weather again," Bob Cabana, the director of the Kennedy Space Center, said in a news conference Friday.

NASA Administrator Jim Bridenstine added that despite all the VIP's coming to watch the launch, including President Donald Trump, and the national hype they will feel "no pressure" and "we will launch when we are ready," emphasizing the safety of Behnken and Hurley as a top priority.

According to the Launch Mission Executive Forecast, there is a 50% probability of violating weather constraints. Meanwhile, there is a 40% of probability of violating weather constraints on the backup launch date of Sunday.

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