Richard Branson is finally getting his trip to space on Sunday.

It has been a very long wait for Mr. Branson, the irreverent, 70-year-old British billionaire who leads a galaxy of Virgin companies. In 2004, he founded Virgin Galactic to provide adventurous tourists with rides on rocket-powered planes to the edge of space and back.

At the time, he thought commercial service would begin in two to three years. Instead, close to 17 years have passed. Virgin Galactic says it still has three more test flights to conduct, including the one on Sunday, before it can be ready for paying passengers.

For this flight, Mr. Branson will be a member of the crew. His task is to evaluate the cabin experience for future customers.

The flight is scheduled to take off on Sunday morning from Spaceport America in New Mexico, about 180 miles south of Albuquerque.

Virgin will broadcast coverage of the flight beginning at 9 a.m. Eastern time, with Stephen Colbert hosting the livestream. The singer Khalid is scheduled to perform a new song after the crew lands, and Elon Musk, the founder of SpaceX, suggested he may make an appearance.

The rocket plane, a type called SpaceShipTwo, is about the size of an executive jet. In addition to the two pilots, there will be four people in the cabin. This particular SpaceShipTwo is named V.S.S. Unity.

To get off the ground, Unity is carried by a larger plane to an altitude of about 50,000 feet. There, Unity will be released, and the rocket plane’s motor will ignite. The acceleration will make people on board feel a force up to 3.5 times their normal weight on the way to an altitude of more than 50 miles.

At the top of the arc, those on board will be able to get out of their seats and experience about four minutes of apparent weightlessness. Of course, they will not have actually escaped gravity. Fifty miles up, Earth’s downward gravitational pull is essentially just as strong as it is on the ground; rather, the passengers will be falling at the same pace as the plane around them.

The two tail booms at the back of the space plane rotate up to a “feathered” configuration that creates more drag and stability, allowing the plane to re-enter Earth’s atmosphere more gently. This configuration makes SpaceShipTwo more like a badminton shuttlecock, which always falls with the pointy side oriented down, than a plane.

Still, the forces felt by the passengers on the way down will be greater than on the way up, reaching six times the force of gravity.

Once the plane is back in the atmosphere, the tail booms rotate back down, and the plane will glide to a landing. The whole flight may take less than two hours.

The pilots are David Mackay and Michael Masucci.

In addition to Mr. Branson, three Virgin Galactic employees will evaluate how the experience will be for future paying customers. They are Beth Moses, the chief astronaut instructor; Colin Bennett, lead operations engineer; and Sirisha Bandla, vice president of government affairs and research operations. Ms. Bandla will also conduct a science experiment provided by the University of Florida.