USSF-52: SpaceX Super Heavy Launches X-37B To Orbit For US Space Force

X-37B lifted off atop a SpaceX Falcon Heavy rocket at 0107 UTC on Friday(Dec. 29), from NASA's Kennedy Space Center (KSC) in Florida, as the United States Space Force's secretive space plane embarked on its latest clandestine Orbital Test Vehicle-7(OTV-7 or USSF-52) mission.

Falcon Heavy's two reusable outer boosters returned safely, touching down about 8.5 minutes after liftoff, at Cape Canaveral Space Force Station, next door to KSC. This was the fifth launch and landing for both boosters, whose resume also includes the launch of NASA's Psyche asteroid probe, which took flight this past October.

"We have successfully landed both Falcon Heavy side boosters at Landing Zone 1 and Landing Zone 2," said Jessie Anderson, SpaceX's mechanical production and engineering manager, in a live webcast. "With these two side boosters, this marks the 257th and 258th overall successful landings of an orbital class rocket."

Heavy consists of three modified, strapped-together first stages of SpaceX's Falcon 9 rocket. The central booster carries a second stage, which is topped by the payload in this case the X-37B. The booster which flew for the first and only time on Friday's mission, ditched intentionally into the Atlantic Ocean after launch, having expended too much of its fuel to return to Earth for recovery and reuse.

At the request of the U.S. Space Force, SpaceX shut down its livestream of Friday's launch before the X-37B space plane was deployed in its final orbit. The OTV-7 mission will take advantage of Heavy's muscle; the flight's main objectives "include operating the reusable space plane[X-37B] in new orbital regimes," Space Force officials wrote in a mission preview last month.

China and Russia have raised concerns the X-37B could be a weapons platform, which US denies.

X-37B looks like a much smaller version of NASA's retired space shuttle. The uncrewed vehicle is 8.8 meters long, with a wingspan of 4.6 meters( by contrast each shuttle orbiter  was 37 m long and had a wingspan of more than 24 m).

The Space Force is thought to own about two X-37B vehicles, both built by Boeing. The space planes are used primarily as orbital testbeds, allowing the military to see how  instruments perform and behave in the space environment. Details about X-37B missions tend to be classified. In addition to the "new orbital regimes" goal of OTV-7, the flight "will expand the United States Space Force's knowledge of the space environment by experimenting with future space domain awareness technologies," SF officials wrote in the mission description. "These tests are integral in ensuring safe, stable and secure operations in space for all users of the domain."

Among the unclassified payload hauled to orbit on OTV-7, is a NASA experiment called Seeds-2. 

Seeds-2 "will expose plant seeds to the harsh radiation environment of long-duration spaceflight," SF officials wrote. The project "will build upon the successes of prior experiments, paving the way for future crewed space missions," they added.

It's unclear how long OTV-7 will last in space. The previous six X-37B missions lasted more than seven months apiece, and each one bested its predecessors' duration:

• OTV-1: 224 days (launched on April 22, 2010, landed on Dec. 3, 2010)

• OTV-2: 468 days (launched on March 5, 2011, landed on June 16, 2012)

• OTV-3: 674 days (launched on Dec. 11, 2012, landed on Oct. 17, 2014)

• OTV-4: 718 days (launched on May 20, 2015, landed on May 7, 2015)

• OTV-5: 780 days (launched on Sept. 7, 2017, landed on Oct. 27, 2019)

• OTV-6: 908 days (launched on May 17, 2020, landed on Nov. 12, 2022)

The previous six missions all flew in low Earth orbit, just a few hundred kilometers above Earth. Falcon Heavy could take the X-37B much higher, potentially all the way to geosynchronous orbit, about 35,000 km up. But it's unclear if that's the plan for OTV-7.

Friday's early morning launch was X-37B's first ride on Falcon Heavy, the third-most powerful active rocket(after Starship and NASA's Space Launch System). The first five flights lifted off atop United Launch Alliance(ULA) Atlas V rockets. SpaceX has provided launch services for the most recent two, OTV-6 flew on a Falcon 9.