Print SpaceX carried two dozen satellites into space early Tuesday aboard a Falcon Heavy rocket and spread them across the sky in a marathon mission that Chief Executive Elon Musk had described as the company’s “most difficult launch ever.” It marked the first time the U.S. Air Force had launched satellites on a Falcon Heavy rocket, and also the first time the military had relied on previously flown SpaceX rockets — those that have been launched and returned to Earth. Tuesday’s successful mission could bolster SpaceX’s case to win more Air Force contracts to launch sensitive military satellites. Advertisement The Air Force said after the launch that the mission enabled it to get insight into SpaceX’s booster recovery and refurbishment process, paving the way for future military-satellite launch missions to use previously flown boosters. In this mission, SpaceX landed the Falcon Heavy’s two side boosters again, but the rocket’s center core crashed into the ocean. SpaceX has not yet been able to recover a center core for its Falcon Heavy rocket. The Falcon Heavy rocket lifted off from Kennedy Space Center in Florida at 2:30 a.m. Eastern time. Almost nine minutes later, the Falcon Heavy’s two side boosters — which were used during an April mission — landed at Cape Canaveral Air Force Station. Advertisement The rocket’s center core ended up crashing into the ocean instead of landing on its intended target: a floating platform in the Atlantic Ocean. The company said during a live-stream of the launch that the center core’s landing was the most difficult landing it had ever attempted. During this mission, the booster needed to propel the rocket’s second stage higher and faster than on previous flights, meaning the booster came back to Earth hotter and moving faster than usual, SpaceX said. Musk tweeted early Tuesday that a boat outfitted with a large net caught the rocket’s fairing — a clamshell-like covering that protects the satellites as the rocket hurtles to space. Advertisement