SpaceX is looking to launch its Crew Dragon spacecraft using a Falcon 9 rocket today, in a crucial test of the human-rated spacecraft's In-Flight Abort (IFA) system. This safety feature will separate the Crew Dragon from the Falcon 9 rocket early, propelling the spacecraft (and any astronauts who would be on board, during a real mission) to a safe distance at extremely high speed.
The test was originally scheduled for Saturday, but weather prevented that from being a workable option. Now, SpaceX's launch window opens today at 8 AM EST (5 AM PST) and lasts for six hours. SpaceX and NASA are currently aiming for a 10:30 AM EST (7:30 AM PST) liftoff time during that window, in order to ensure that weather both for launch and for recovery of the Crew Dragon spacecraft in the Atlantic Ocean are optimal. Depending on conditions, that time could slip again, or if they exceed the launch window, push to a backup date on Monday.
SpaceX and NASA are making sure everything is as good as it can be for this mission in terms of weather conditions, so it's subject to stricter criteria than SpaceX's average cargo launch. This reflects what the private space company and its government agency partner would do were their actual astronauts on board, too, since astronaut safety is the number one priority to consider when performing crewed launches.
During the mission, the In-Flight Abort process is set to trigger automatically at about 84 seconds into the launch, when the rocket and its payload are roughly 60,000 feet above the Earth. In real crewed mission conditions, this would be used in case something was going wrong with the rocket, in order to give the astronauts on board the best possible chance to escape in the unlikely event of anything potentially dangerous happening like a rocket exploding within the atmosphere.
The goal here is to study the Crew Capsule, and to recover it quickly in order to gather the data that's being collected on board, which should provide key info about what a human astronaut would've experienced were they inside during the IFA process. That means conditions on the ocean are pretty much as important as conditions on the launch pad, since recovery crews will be working to retrieve the capsule and NASA and SpaceX want to ensure their safety, too.
The broadcast should begin about 15 minutes prior to the target liftoff time, so currently that means 10:15 AM EST (7:15 AM PST). We'll update this post if weather conditions cause further delays.