CEO Elon Musk’s Space Exploration Technologies Corp. is expected to give federal authorities by early December a preliminary investigative report pinpointing fueling procedures as the most likely cause of a September unmanned rocket explosion. After SpaceX's Falcon 9 rocket exploded while being fueled by a test fire, the company said it would be launching again soon. Musk also said that the company has identified the cause of the September explosion, and the Falcon 9 could be fixed and flying by mid-December.
SpaceX Finally Discovers Cause Of Falcon 9 Rocket Explosion
As reported by Popular Science, the Falcon 9 rocket flies by combusting liquid kerosene with oxygen. Because there's no oxygen in space, the rocket needs to bring its own. To pack in as much fuel as possible, most rockets cool oxygen gas until it's liquefied; SpaceX takes it one step further by cooling it even more, possibly to increase the density and thus how much fuel the rocket can carry. “It was a really surprising problem. It’s never been encountered before in the history of rocketry,” said Musk in an interview.
Speaking on CNBC, Musk said “it basically involves liquid helium, advanced carbon fiber composites, and solid oxygen. Oxygen so cold that it actually enters solid phase.” The problem has to do with some super-cold oxygen reacting with the carbon fiber composites within the fuel tank. Musk gave some hints during a speech he gave to the National Reconnaissance Office. He argued that the supercooled liquid oxygen that SpaceX uses as propellant actually became so cold that it turned into a solid.
'Oxygen So Cold That it Actually Enters Solid Phase'
Solid oxygen forms at normal atmospheric pressure at a temperature below 54.36 K (−218.79 °C, −361.82 °F). Solid oxygen O2, like liquid oxygen, is a clear substance with a light sky-blue color caused by absorption in the red part of the visible light spectrum. The density of solid oxygen ranges from 21 cm3/mol in the α-phase, to 23.5 cm3/mol in the γ-phase.
Oxygen molecules have attracted attention because of the relationship between the molecular magnetization and crystal structures, electronic structures, and superconductivity. Oxygen is the only simple diatomic molecule to carry a magnetic moment. This makes solid oxygen particularly interesting, as it is considered a 'spin-controlled' crystal that displays antiferromagnetic magnetic order in the low-temperature phases.
This solid oxygen may that formed could have ignited with the carbon and have had a bad reaction with another piece of hardware — one of the vehicle’s liquid helium pressure vessels. Three of these vessels sit inside the upper oxygen tank that holds the supercooled liquid oxygen propellant. They’re responsible for filling and pressurizing the empty space that’s left when the propellant leaves the tank. The vessels are also over wrapped with a carbon fiber composite material, according to The Verge.