Update 1:49 p.m.: SpaceX's launch webcast is now posted above, right below our countdown clock. Liftoff is scheduled in four minutes from Cape Canaveral Space Force Station. SpaceX to launch NASA's Pandora satellite mission Update 1:40 p.m.: In a Monday tweet, SpaceX officials announced a Falcon 9 rocket will launch the Pandora small satellite on a NASA mission, perhaps as early as this fall. Pandora will observe at least 20 different exoplanets — or worlds beyond our solar system — during its yearlong astrophysics mission, NASA reported. "Pandora will study planets discovered by other missions using transits, events where planets passing in front of their stars cause tiny dips in starlight. Scientists are interested in further observing these worlds because transits can also reveal information about the planet’s atmosphere," a NASA mission website said. SpaceX booster to land on drone ship Update 1:31 p.m.: Today's afternoon mission marks the Falcon 9 first-stage booster’s 18th flight, SpaceX reported. This much-traveled booster previously launched Crew-5, CRS-28, Intelsat G-37, Optus-X, Immarsat I6-F2, GPS III-6, NG-20 and 10 Starlink missions Following stage separation, crews expect the booster to land on the SpaceX drone ship Just Read the Instructions in the Atlantic Ocean 8 minutes, 11 seconds after liftoff. SpaceX Falcon 9 fueling underway Update 1:22 p.m.: Falcon 9 fueling procedures are underway at Launch Complex 40, as evidenced by billowing water vapor emitting from the rocket. That means this afternoon's Starlink mission countdown is now locked in to lift off at 1:53 p.m. without any delays, or else the launch must be postponed. SpaceX Falcon 9 launch countdown Update 1:11 p.m.: Here's a rundown of SpaceX’s upcoming behind-the-scenes countdown timeline. T-minus: 38 minutes: SpaceX launch director verifies “go” for propellant load. 35 minutes: Rocket-grade kerosene and first-stage liquid oxygen loading begins. 16 minutes: Second-stage liquid oxygen loading begins. 7 minutes: Falcon 9 begins engine chill prior to launch. 1 minute: Command flight computer begins final prelaunch checks; propellant tank pressurization to flight pressure begins. 45 seconds: SpaceX launch director verifies “go” for launch. 3 seconds: Engine controller commands engine ignition sequence to start. 0 seconds: Liftoff.