50 years later, planes are still giving rockets a lift
Last week in space - Dec. 5
In early November, I wrote about an attempt to return a decades-old rocket design to service for launching tiny, cheap satellites. (Last Week in Space - Nov. 8, 2015)
This week, Virgin Galactic (helmed by Sir Richard Branson), announced they'll be using a 747 jet plane to bring satellites to orbit. The plane's name: Cosmic Girl.
Just like the the Strypi rocket in my first post, this combination of plane and rocket is an old, old technology.
In the 1960s, a team of American test pilots flew an experimental plane faster and higher than any other aircraft. They climbed to altitude strapped under a B-52 "mother ship."
Then, at 8.5 miles high, the X-15 lit up its engines and dropped from the B-52. That transition, from flying to falling to flying again, is thrilling.
Ever heard a pilot say, "As we reach our cruising altitude of 32,000 feet." I did, on a flight from Seattle just this Thursday. 32,000 feet works out to 6 miles high. If I could just have convinced the pilot to go 2.5 miles higher, I would've been ready for a launch! (I didn't ask.)
How does this even work? Most of a rocket's energy is spent building up speed and getting out of the atmosphere. Sitting in the Seattle airport, I was subject to 1.219 kilograms per cubic meter of pressure. That pressure wouldn't change too much inside my plane, aircraft are pressurized to keep whiny humans comfortable. But outside the plane, the pressure dropped to 0.43 kilograms per cubic meter.
Even just at my passenger altitude, a rocket would contend with just a third of the air pressure. Climb up to the 8.5 miles high where X-15's launched, and you're down to just 0.24 kilograms per cubic meter.
After dropping from the place, the pilots would climb on rocket power. They had a long way to go.
X-15 test pilot Joseph Walker climbed the highest. In 1963, a year after John Glenn orbited earth, Walker took an X-15 plane up to 67 miles high.
By the time the program ended in December 1968, the X-15 program had laid the groundwork for a new generation of aircraft like the SR-71 Blackbird and spacecraft like the shuttle. An X-15 flight still holds the record for the highest speed reached by a manned, powered aircraft.
Joseph Walker's story, though, ends on a bittersweet note. Sixty-seven miles is more than enough to earn your astronaut wings. Walker, though, didn't receive his until NASA awarded them to three X-15 who were missed during the original program in 2005. His wings were awarded posthumously. Walker was killed in an flight accident in 1966.
Walker’s contributions to exploration will live on, though, as a new team looks to the spaceflight’s past for its future.
PS: This isn't how Virgin Galactic thought they'd be launching satellites. For the rest of the story, read Chris Gebhardt and Nate Moeller at NASASpaceFlight.
PPS: There’s a great documentary on X-15′s on YouTube. I highly recommend it.