get away with ejection seats. Maxime Faget, the designer of the Mercury LES, was on the other hand less-than-enthusiastic about this setup. Aside from the possibility of the ejection seats seriously injuring the astronauts, they would also only be usable for about 40 seconds after liftoff, by which point the booster would be attaining Mach 1 speed and ejection would no longer be possible. He was also concerned about the astronauts being launched through the Titan's exhaust plume if they ejected in-flight and later added, "The best thing about Gemini was that they never had to make an escape." The Gemini ejection system was never tested with the Gemini cabin pressurized with pure oxygen, as it was prior to launch. In January 1967, the fatal Apollo 1 fire demonstrated that pressurizing a spacecraft with pure oxygen created an extremely dangerous fire hazard. In a 1997 oral history, astronaut Thomas P. Stafford commented on the Gemini 6 launch abort in December 1965, when he and command pilot Wally Schirra nearly ejected from the spacecraft: Gemini was the first astronaut-carrying spacecraft to include an onboard computer, the Gemini Guidance Computer, to facilitate management and control of mission maneuvers. This computer, sometimes called the Gemini Spacecraft On-Board Computer (OBC), was very similar to the Saturn Launch Vehicle Digital Computer. The Gemini Guidance Computer weighed . Its core memory had 4096 addresses, each containing a 39-bit word composed of three 13-bit "syllables". All numeric data was 26-bit two's-complement integers (sometimes used as fixed-point numbers), either stored in the first two syllables of a word or in the accumulator. Instructions (always with a 4-bit opcode and 9 bits of operand) could go in any syllable. Apollo The Apollo spacecraft was first conceived in 1960 as a three-man craft to follow Project Mercury, with an open-ended mission. It could be used to ferry astronauts to an Earth-orbiting space station, or for flights around or orbiting the Moon, and possibly landing on it. NASA solicited feasibility study designs from several companies in 1960 and 1961, while Faget and the Space Task Group worked on their own design using a conical/blunt-body capsule (Command Module) supported by a cylindrical Service Module providing electrical power and propulsion. NASA reviewed the entrants' designs in May 1961, but when President John F. Kennedy proposed a national effort to land a man on the Moon during the 1960s, NASA decided to reject the