What Time Is the SpaceX Launch on Wednesday?

An historic mission being spearheaded by NASA and SpaceX has been given the green light and is scheduled to take place Wednesday.

Weather dependent, liftoff of the SpaceX Falcon 9 rocket and Crew Dragon spacecraft is scheduled for May 27 from Kennedy's Launch Complex 39A in Florida.

According to SpaceX, the instantaneous launch window will open at 4:33 p.m. EDT, or 20:33 UTC. Backup launch opportunities are set for Saturday, May 30 at 3:22 p.m. EDT, or 19:22 UTC, and on Sunday, May 31 at 3:00 p.m. EDT, or 19:00 UTC.

Coined Launch America by the agency, but officially known as the Demo-2 test flight, it will see two veteran NASA astronauts, Robert Behnken and Douglas Hurley, sent to the International Space Station (ISS) as part of the Commercial Crew Program.

It marks the first flight into orbit of American astronauts on American rockets from American soil since the end of the "space shuttle era" in 2011.

There is a lot at stake for Elon Musk's rocket company, as it is the final test flight before its technology is validated by NASA—and the first with humans aboard.

From a Crew Dragon capsule, the two astronauts will be sent into Earth's orbit by the Falcon 9, a powerful reusable rocket already used in dozens of launches.

On Monday, the U.S. Air Force 45th Weather Squadron predicted there could be a 60 percent chance of unfavorable weather conditions for the mission, warning of possible thick cloud coverage. It was later lowered to a 40 percent chance of violation.

For now, astronauts Behnken and Hurley remain in quarantine, which is a routine part of pre-launch preparations for humans journeying into space, NASA has confirmed.

The mission, explained

The crew will take off from Launch Pad 39A, with the Falcon 9 speeding the astronauts to approximately 17,000 mph and putting them on intercept course with the ISS.

In orbit, the crew and SpaceX mission control will verify the spacecraft is performing as intended. Within about 24 hours, NASA says the Crew Dragon capsule will be in position to autonomously "rendezvous and dock" with the international station.

The astronauts can take control of the craft if necessary. After docking, the men will be welcomed aboard the ISS and will become members of the Expedition 63 crew.

Length of the mission will be determined once on station. The Crew Dragon spacecraft will be capable of staying in orbit for at least 210 days, per NASA requirements.

Eventually, the Crew Dragon will autonomously undock with the astronauts on board, depart the space station and re-enter the Earth's atmosphere. The capsule will touch down on Florida's Atlantic Coast, with the two astronauts being recovered and returned to Cape Canaveral. A date is to be determined.

Looking to the future, NASA said the launch is the "final major step" before the Crew Dragon is certified for operational, long-duration missions to the space station, laying the groundwork for future exploration of the Moon and Mars including the Artemis program, the plan to land the first woman and next man on the moon in 2024.

The ongoing pandemic will limit the number of in-person viewers. However, the launch will broadcast live and in real-time to computers, tablets and phones. Here is a full run-down of what you can expect to see during the mission, and when.

Live coverage will be widely available on YouTube via the official NASA and SpaceX accounts. NASA TV video coverage and countdown commentary begins at 12:15 p.m. EDT on Wednesday, also being sent out across Facebook, Twitter and Twitch.

NASA says its official hashtag will be #LaunchAmerica.

The space agency has already been posting some behind-the-scenes glimpses from the site of the launch. Elon Musk confirmed he will be watching from mission control.

Discovery and Science Channel will show the launch live, with coverage starting on Wednesday (2 p.m. ET/11 a.m PT) featuring live commentary from astronauts, engineers and celebrity guests. Its social media hashtag will be #SpaceLaunchLIVE.

Watch live on NASA TV, liftoff scheduled for 4:33 p.m. (EDT):

Here is the program schedule, courtesy of NASA:

Wednesday, May 27

• Noon: Live views of the SpaceX/Falcon 9 rocket on launchpad
• 12:15 p.m - Live countdown coverage begins
• 4:33 p.m (EDT) - Lunch expected
• 6 p.m (EDT) - Demo-2 post-launch news conference

Thursday, May 28

• 11:39 a.m - Docking of the SpaceX Crew Dragon to the ISS
• 1:55 p.m. – Hatch opening to the International Space Station
• 2:25 p.m. – Mission crew media event aboard the space station

Friday, May 29

• 11:05 a.m. – News conference with astronauts Bob Behnken and Doug Hurley
• 12:50 p.m - In-flight event for SpaceX to mark arrival of the Demo-2 crew