Virgin Orbit, a satellite launch company whose fortunes have sunk since one of its rockets failed to reach orbit in January, filed for bankruptcy protection in the United States on Tuesday. The company, founded by Richard Branson, had an unusual way of getting satellites into space: A converted Boeing 747 aircraft would carry aloft a satellite-packed rocket under its wing. When aloft, the rocket would detach and fire its engines, climbing upward into orbit before releasing the satellites. England, failed after the rocket fell short of reaching orbit, and the nine satellites on board were lost. The company, based in California, was attempting the first launch of satellites from Britain, and the mission was a high-profile event strongly supported by the country’s space community. Afterward, Virgin Orbit said it would return and try again, but financing began to dry up, and the company’s stock price started to slide. Last week, Virgin Orbit said it was laying off 675 employees, or about 85 percent of its work force, citing its “inability to secure meaningful funding.” Dan Hart, the company’s chief executive, said Virgin Orbit would seek a purchaser. “We believe that the cutting-edge launch technology that this team has created will have wide appeal to buyers as we continue in the process to sell the company,” he said in a statement. Virgin Orbit’s launch format is considered more flexible and cheaper than vertical rocket launchers because it can operate from airstrips around the world. For that reason, some analysts have said, it may remain of interest to governments including the United States. Until this year, Virgin Orbit’s previous launches had been from the Mojave Desert in California, and four out of five were successful. But its method so far has failed to establish itself as reliable, and the underwing rocket had less capacity than more conventional systems used by companies like Elon Musk’s SpaceX. The failed launch in Cornwall wound up being a poor advertisement for prospective customers and investors. for the District of Delaware, Virgin Orbit listed about $243 million in assets and $153 million in debts. Virgin Orbit, which went public in late 2021 via a merger with a so-called blank check company, was worth some $3.5 billion in market value at its peak. Stanley Reed contributed reporting.