The engine constantly throttles up and down, not only to counter the drag on the satellite from residual air molecules in near space but also to smooth the flight of the vehicle to minimise the noise in the gravity measurements.
"My gut tells me that the additional flying we may do on this airplane before it goes to the Air and Space Museum should be focused on developing the very best space tourism vehicle, " Rutan said.
This appears to be the mindset of the Air Force regarding its experimental X-37B space plane, the billion-dollar robotic vehicle's orbital flight being extended beyond the 270 days it was initially designed for.