SpaceX set up for a sky-lighting Florida doubleheader Monday, prepping a powerful Falcon Heavy rocket for launch to put an X-37B spaceplane into orbit for a classified military mission with a workhorse Falcon 9 following a few hours later carrying 23 Starlink internet satellites.
Both launchings had been planned for Sunday, but were delayed 24 hours because of predicted bad weather and to give engineers more time to complete additional checkouts.
With much better weather on tap Monday evening, the X-37B mission was targeted for liftoff from historic pad 39A at the Kennedy Space Center at 8:14 p.m. EST. The Starlink flight, not confirmed until Monday afternoon, was set for launch from nearby pad 40 at the Cape Canaveral Space Force Station at 11:05 p.m.
Two on-time launchings would mark the shortest interval between two U.S. orbital flights — two hours and 51 minutes — in decades.
The Falcon Heavy, using a central reinforced Falcon 9 core stage and two nearly identical strap-on boosters, is the most powerful operational rocket in SpaceX’s inventory, capable of generating more than 5 million pounds of thrust at liftoff.
For the X-37B mission, the flight plan called for the two side boosters, both making their fifth flight, to peel away from the core stage after helping push the vehicle out of the dense lower atmosphere. They were programmed to fly themselves back to landings at the nearby Space Force station, the 40th and 41st to touch down in Florida.
The central core stage’s nine engines were expected to continue firing for another minute and a half before shutting down. Unlike the two side boosters, the core stage was expected to use up all of its propellant and no recovery was planned.
No details about the second stage’s climb to the spaceplane’s intended orbit have been released. As usual with such classified military missions, SpaceX planned to end its launch commentary after the side booster landings about eight-and-a-half minutes after liftoff.
Two virtually identical X-37B Orbital Test Vehicles, or OTVs, are operated by the Pentagon’s Rapid Capabilities Office for the U.S. Space Force. The vehicles are designed to serve as test beds for avionics and advanced sensors, to evaluate reusable spacecraft components and to provide a platform for experiments that can be returned to Earth for analysis.
The Boeing-built X-37B operates like a miniature space shuttle, complete with delta wings, heat shield tiles and a compact payload bay. Unlike NASA’s space shuttle, which relied on fuel cells for power in orbit, the X-37B is equipped with an extendable solar array that allows extremely long flights.
The compact orbiters are designed to end their missions with runway landings at Vandenberg Space Force Base in California or the Kennedy Space Center in Florida using a 3-mile-long runway built for the space shuttle.
The most recent flight of an X-37B began with launch atop a United Launch Alliance Atlas 5 rocket on May 17, 2020. It ended Nov. 12, 2022, with touchdown at the Kennedy Space Center after 908 days and 21 hours in space.
Through the program’s six previous flights dating back to the first launch in April 2010, the two X-37Bs logged a combined 10.3 years in space. The planned duration of the latest mission has not been announced.
