Free Astronomy Magazine January-February 2015

ASTRONAUTICS in the air and plunged to the ground. The first assumptions on the causes of the di- saster immediately fo- cused on the new type of fuel, but as soon as the technicians of the National Transporta- tion Safety Board (the independent federal agency in charge of in- vestigating the disas- ter) started to gather the remains of the spaceplane scattered over an area of 8 km 2 in the Mojave Desert (nearly 200 Km north of Los Angeles), it be- came evident that the propellant could not have been the cause, since both the engine and the new fuel tank showed no sign of being compromised. Within 24 hours the in- vestigators’ attention shifted to another possible cause, revealed by one of the six cameras installed onboard the aircraft; the one in the cockpit. The images show that the lock-unlock lever of the feathering mechanism activated too early, at a speed of Mach 1.0 rather than at the recommend- ed speed of Mach 1.4. Such mechanism con- trolling the spaceplane feathering mode consists in the partial upward rotation of the tail section to provide greater surface area and thus increased atmospheric drag in thin air, and serves to slow down the aircraft during its glided descent. From what has been gathered so far (the results of the of- ficial investigation will be known in about a year), the 39 year old pilot Michael Alsbury, who died in the accident, executed the first phase of the two-steps process, but the second phase required to complete it, for unknown reasons, seems to have engaged without being com- manded. Aside from this, it is rather odd that an aircraft whose structural compo- nents are 100 percent carbon composite, ca- pable of withstand- ing the aerodynamic forces of Mach 1.4, could collapse at Mach 1.0, but evident- ly the atmospheric density (lesser at the altitude where Mach 1.4 is reach-ed) is a critical factor. Consid- ering that SpaceShip- T he first rescu- ers arrived in the Mojave Des- ert area where the wreckage of the spaceplane fell. In the video below, various scenes of the sur- vey by the inves- tigators of the National Trans- portation Safety Board, with their acting director Christopher Hart (recognizable with sunglasses). [NTSB]