Stratolaunch's rocket carrier plane, the largest aircraft ever built, takes off from the Mojave Air and Space Port in Mojave, California during its first test flight on April 13, 2019.

The company that operates the world's largest airplane has a new owner — but we don't know who it is.

Stratolaunch Systems , the satellite-launching venture established by billionaire Microsoft co-founder and longtime space enthusiast Paul Allen in 2011, has changed hands, the company announced earlier this month.

"Stratolaunch LLC has transitioned ownership and is continuing regular operations," Stratolaunch representatives wrote in an Oct. 11 statement . That statement did not identify the new owner, and we remain in the dark today.

Related: Stratolaunch Test Photos: The World's Largest Plane in Action

California-based company Scaled Composites built for Stratolaunch a huge plane with a 385-foot (117 meters) wingspan. This dual-fuselage aircraft, known as Roc, is designed to carry a satellite-toting rocket high in the sky. After being dropped at altitude, the rocket will fire up, carrying its payload to space.

This air-launch strategy is not new; it's currently employed by Northrop Grumman's Pegasus rockets and Virgin Galactic's six-passenger SpaceShipTwo suborbital vehicle, for example.

Stratolaunch had been owned by Allen's holding company, Vulcan. But after Allen died in October 2018, his sister Jody — the co-founder and chair of Vulcan, and the executor and trustee of her brother's estate — decided to set an exit strategy, Reuters reported earlier this year .

Stratolaunch soon scaled back its operations significantly and laid off a large portion of its workforce, Geekwire reported . And in June, CNBC reported that Vulcan was seeking to sell Roc , for $400 million.

Roc has just one flight under its belt, a 2.5-hour-long test jaunt that took place this past April over California's Mojave Desert. It's unclear when the huge plane will lift off again; we'll just have to wait for more news.

"Our near-term launch vehicle development strategy focuses on providing customizable, reusable, and affordable rocket-powered testbed vehicles and associated flight services," Vulcan representatives added in the Oct. 11 statement. "As we continue on our mission, Stratolaunch will bring the carrier aircraft test and operations program fully in-house. We thank Vulcan Inc and Scaled Composites for turning an ambitious idea into a flight-proven aircraft."