Project Mercury: "Flight of Sigma 7" 1962 NASA Wally Schirra; 3rd Manned Orbital Misson

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• published: 02 Jan 2018
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Project Mercury playlist: https://www.youtube.com/playlist?list=PL_hX5wLdhf_JhjIwLJjL8MHIhHVJyMm0b more at http://scitech.quickfound.net/ Flight of Mercury-Atlas 8, carrying astronaut Walter Schirra on the 3rd orbital manned Mercury mission. The spacecraft: Sigma 7. Reupload of a previously uploaded film, in one piece instead of multiple parts, and with improved video & sound. Originally a public domain film from NASA, slightly cropped to remove uneven edges, with the aspect ratio corrected, and one-pass brightness-contrast-color correction & mild video noise reduction applied. The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original). from "This New Ocean: A History of Project Mercury" 1966 http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19990026158_1999028570.pdf At 7 : 15 a.m., the engines of Atlas 113-D roared and the big booster rose from the pad to rocket Schirra and Sigma 7 on their journey through space. "I have the lift-off," Schirra shouted into his microphone to Slayton in the Mercury Control Center, "and she feels real nice." Ten seconds above the pad, however, No. 113-D telemetered signals showing an unexpected clockwise roll. Both primary and secondary sensors inside the launch vehicle, monitoring such movements to determine the seriousness of the situation, registered a rifling roll only 20 percent short of an abort condition. Then, to the relief of the capsule and booster monitors in the control center, the threatening twist suddenly smoothed out. Schirra began transmitting the status of his supplies and systems' operation. After a little more than a minute, he realized that he seemed to be talking to himself. Glancing around the cockpit, he noted that evidently the noise associated with max q had incorrectly operated the sound-activated radio microphone, and so he pushed the button to talk to Slayton. Surely something should be done to obviate this problem, he thought, because he needed to keep his hand on the abort handle, or "chicken switch," rather than having to press the "talk" button manually. Schirra listened for booster engine cutoff; it came two seconds earlier than programmed. He saw a flash of light and smoke reflected from the booster engines at the time the aft section parted from the sustainer. Seconds later the escape tower jerked away from the top of Sigma 7, its rocket blast spreading a spotty film on the window. Sustainer engine acceleration seemed slow, Schirra mused, but since his escape tower had "really said 'sayonara,' " he could only wait and see if the sustainer would burn long enough to accelerate him into orbit. Acceleration seemed to drive on and on, the pilot said, and finally the sustainer engine cut off, about 10 seconds late. Data registered on the control panels at the Cape indicated a 15-foot-per-second overspeed that would send Schirra higher--176 miles--and faster--17,557 miles per hour--than any other astronaut had gone or would go during Project Mercury... Schirra said that the fly-by-wire system that had been redesigned to use only the low thrusters, if desired, served well to adjust his attitude to track the spent sustainer. The thrusters responded crisply and cut off without residual reactions. Tracking the booster seemed even easier than following a target in an aircraft on an air-to-air gunnery problem. Schirra nevertheless knew that he had neither the attitude control and maneuvering thrust nor the computational ability to perform a rendezvous. There were simply too many conditions to be judged if he were to solve the orbital mechanics task so shortly after launching. Schirra later expressed the opinion that rendezvous with another vehicle in §pace appeared to be possible, but that he believed a pilot would have to have very precise attitude data to effect a coupling. He confirmed what students of celestial mechanics already knew, while providing them with a feel for the problems of perceiving relative motion. Differences in velocity of only 20 to 30 feet per second between two objects in space could be disastrous, he said... Eight hours and 52 minutes after Sigma 7 lifted off from the Cape, the first retrorocket fired. When Schirra punched the button for this action, the tiny instant of time before the firing "seemed agonizingly long." As each retrorocket fired crisply at five-second intervals, Schirra was pleasantly amazed that the spacecraft appeared to hold as steady as a rock. Quickly he checked this impression with a glance out of the window; the star pattern he could see did not even appear to quiver. After retrofire he checked the automatic fuel gauge and found the needle hovering between 52 and 53 percent...