As mentioned before, scramjet-powered aircraft don’t carry oxygen onboard. That means that they can’t lift off like conventional spacecraft. The X-43A requires a booster rocket to get it up to a hypersonic speed, at which point it is released and sent flying on its own. This rocket boost is necessary for the scramjet engine to work.
Here’s a rundown of how the X-43A test flights work:
- The X-43A is attached to a Pegasus booster rocket.
- The X-43A and booster rocket are carried up to about 20,000 feet (6,000 m) by a customized, B-52 aircraft.
- The B-52 releases the launch vehicle.
- The booster rocket accelerates to a speed of approximately Mach 5 and flies to an altitude of about 100,000 feet (30,500 m).
- The X-43A separates from the booster rocket and flies under its own power and preprogrammed control.
- The X-43A flies over the ocean for a few minutes before splashing down.
NASA officials say that the scramjet engine would be a major step forward for NASA and would arguably provide a safer, more flexible, less expensive way to get people and cargo to space.