Boeing will invest $20 million in Richard Branson’s Virgin Galactic to help it develop technologies that would allow for high-speed transportation to ferry passengers across the globe faster than the speed of sound, and possibly through space.

The investment is a relatively modest amount for the aviation behemoth. But it represents what the companies called a “first step” in an unusual corporate partnership that they hope will dramatically cut travel time.

Virgin Galactic, the self-proclaimed “world’s first commercial spaceline,” is working to ferry paying passengers to the edge of space and back by next year. The company has already reached space twice, once in late 2018 and then again earlier this year. But Branson’s goal has long been to develop a powerful jet capable of crisscrossing the globe at very high speeds, and even leaving the atmosphere.

The companies said one of their main goals was to see if they could develop a vehicle capable of hypersonic speed that would travel at five times the speed of sound.

In a statement to The Post, Branson said the deal marked “the beginning of an important collaboration for the future of air and space travel, which are the natural next steps for us. Virgin Galactic and Boeing share a vision of opening access to the world and space, to more people in safe and environmentally responsible ways.”

In an interview, George Whitesides, Virgin Galactic’s CEO, said the goal was to leverage Boeing’s aviation expertise as Virgin Galactic works on new propulsion systems and materials to build a new-generation transportation system that would be economically viable.

It is too early to say, however, what the design would be — whether it would be a vehicle capable of getting to space and reentering, or a supersonic jet that would stay in the upper atmosphere.

The companies said they were well aware that travel going faster than the speed of sound has proven commercially difficult and that finding a viable market for it, even if the technical challenges are overcome, has been tried before. Boeing won a government competition to build a supersonic transport in the 1960s but abandoned the project in 1971 when Congress eliminated funding.

The Concorde, a creation of a British-French consortium, whisked passengers at twice the speed of sound on intercontinental flights for 27 years. But it proved an expensive option for passengers and was taken out of service in 2003. No one has found a model that works commercially since.

The announcement of Boeing’s investment comes as the company is still reeling from two fatal crashes involving its 737 Max airplanes and has faced repeated delays in building a spacecraft for NASA that would fly astronauts to the International Space Station.

Still, Brian Schettler, senior managing director of Boeing HorizonX Ventures, which invests in start-ups and new technologies, said that the partnership between Virgin Galactic, which Branson founded with the goal of ferrying tourists to space, and Boeing, which has been a key player since the dawn of the Space Age, would help commercialize space.

Virgin Galactic soon plans to start flying customers who are paying as much as $250,000 for tourist jaunts to space out of Spaceport America in New Mexico. It is also in talks to build spaceports in other countries such as Italy, the United Kingdom, Australia, the United Arab Emirates and some unnamed Asian countries, Whitesides said. The long-term goal is to set up hubs around the world for its high-speed travel network.

The investment comes as Virgin Galactic recently announced it was going public by merging with Social Capital Hedosophia, a New York investment firm. Boeing’s investment would be in return for shares in Virgin Galactic, so the deal is contingent on the closing of the merger, which is expected by the end of the year.