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Aviation History
1961
1961 - 0680.PDF
690 FLIGHT, 25 May 1961 Missiles and Space flight... needed on the Redstone-boosted nights to cause re-entry, one of theobjectives of these flights is to exercise the retro-rocket system for "in space" qualification. This phase of the flight begins with theestablishment of the proper retrorocket firing attitude and ends with the successful delivery of the spacecraft aboard the recoveryship. IF ... . . . the automatic attitude control system does not orient the space-craft to the proper retrorocket firing attitude, the astronaut in the cock- pit can assume attitude control through one of two alternate controlsystems. . . . the automatic timer in the cockpit does not fire the retrorockets,they can be fired by ground command from the Mercury Control Center; or they can be fired by the astronaut in the cockpit. . . . the automatic system fails to initiate jettisoning of the spentretrorocket pack, the pilot can initiate the sequence from the cockpit. . . . the automatic system does not retract the periscope before re-entry into the atmosphere, the pilot can retract it manually. Since each Mercury manned-mission profile is to be flownunmanned before man can fly the same profile, all systems must be designed, manufactured, and installed in the spacecraft to operateon a completely automated basis. Many of the primary flight actions and systems can be activated or controlled from the ground. How-ever, it has not been possible to provide for ground control over all spacecraft systems. The introduction of the astronaut—the humanobservation and judgment factor—serves to enhance operational reliability to a great degree. For example, automated electronicequipment which controls the initiation of the landing and recovery aids is duplicated. These systems are installed in parallel so thatfailure of one system should automatically cause a switchover to the alternate system. IF ... . . . these parallel systems fail to deploy the 6ft-diameter drogueparachute at about 21,000ft, the astronaut in the cockpit can deploy the chute manually. At this point, small strips of aluminum (radar chaff)are dispersed to provide a target for radar location. . . . the antenna canister, to which the drogue parachute is attached,is not jettisoned automatically to deploy the main 63ft ringsail-type landing parachute, the pilot can manually jettison the canister anddeploy the main chute. ... the main landing parachute does not deploy or open properly, atabout 10,000ft, a reserve landing parachute is available and can be deployed by the astronaut in the cockpit. Recovery from the Sea When the main landing parachute is deployed, a SOFAR under-water bomb is deployed over the side to provide an audible sound landing-point indication, and an ultra-high frequency Sarahradio beacon begins transmitting, A can of sea-marker dye is deployed with the reserve parachute and remains attached to thespacecraft by a lanyard regardless of when the reserve chute is 5 deployed. *On landing, an impact switch jettisons the landing parachute andinitiates the remaining location and recovery aids. These include release of sea-marker dye with the reserve parachute if it has notpreviously been deployed, triggering a high-intensity flashing light, extension of a 16ft whip antenna and the initiation of the operationof a high-frequency radio beacon. IF ... . . . the automatic equipment fails to release the main parachute andjettison the reserve parachute, the astronaut can initiate the systems manually. ... the ultra-high frequency Sarah radio beacon fails, the high-frequency radio beacon automatically becomes the primary radio- location aid. . . . both the UHF Sarah beacon and the HF recovery beacons fail tooperate, the astronaut's UHF and HF radio transmitters become pri- mary radio location aids. ... all the radio beacon location aids fail, the high-intensity flashinglight and sea-marker dye become valuable aids to visual location by searching aircraft and ships. ... the spacecraft should spring a leak after landing, or if the life-support system should become fouled after landing, the astronaut can escape either through the upper neck of the spacecraft or through theside hatch. ... it becomes necessary to terminate, or if the flight terminates early,inadvertently, elements of the Mercury recovery forces are deployed along the intended flight-path to make the recovery.... it is necessary to abort the mission, either off-the-pad or immedi- ately after engine ignition and lift-off, emergency rescue and recoverycrew and equipment have been stationed near the launch area. The foregoing is not a complete study of all redundant Mercury systems or of all the vexing "ifs" which must be considered in the conduct of Mercury flight tests. It is intended, rather, as a primer for the layman interested in acquiring a basic understanding of contingency planning in the Mercury mission. During his speech in Ottawa on May 17 President Kennedy sug- gested a "NATO sea- borne missile force." This model, here being inspected by Vice-Ad- miral John Hayward, US Navy, and Milton Rosen, of NASA, shows an Atlas-Centaur launch installation built on a drydock ship. The model was brought before the House of Representa- tives Space Committee on May IS HIGH OR LOW ORBITS? The relative merits for communications purposes of "synchro-nous" satellites orbiting at 19,300 n.m. with a period of 24hr, and satellites at lower altitudes, were thoroughly discussed in Londonon May 12 at the symposium on communications satellites organ- ized by the British Interplanetary Society. Eight listed papers byBritish and American authors were presented, and a brief contribu- tion was given in addition by Mr Ronald Smelt, chief scientist.Lockheed Aircraft Corporation. In Some Practical Problems of Satellite Communication, DrJ. R. Pierce of Bell Telephone Laboratories, Murray Hill, New Jersey, made the point that the most useful and most economicallyattractive service that satellite communication could provide was that of linking together the existing, highly developed communica-tion systems of various continents. The speaker maintained that, because of the time delay in transmission, it was clear that 24-hour"stationary" satellites "can never give us quite as good a telephone circuit as those we now have via cable." It had been proposed thatnon-steerable ground antennas might suffice for stationary satellites. but this appeared impracticable. Satellite life was a critical problem, Dr Pierce pointed out. andmost active space payloads depended on solar cells. Although these cells could be protected against the electrons of the outer Van Allenbelt, it appeared impossible to protect them from the protons in the inner belt; this radiation was most intense at about 2,000 miles andextended out to perhaps 5,000 miles. The choice between various possible satellite systems, the speakersaid, must depend on the established state of the art. Echo had established the capabilities of a passive satellite, and, assumingequally favourable results following the experimental launching of a simple active type, "a practical and economical communicationssystem making use of many low-altitude satellites in random orbit need not be many years distant. This is what we are now workingtoward at the Bell Laboratories." In The Synchronous Communication Satellite, Mr R. P. Havilandof the General Electric Company's Missile and Space Vehicle Department stated that the synchronous satellite appeared to beless desirable than lower-altitude satellites for a telephone or telegraph relay service, but appeared to be superior for directworld-wide television and radio transmission. The importance of reliability was emphasized by Mr Smelt inhis account of Lockheed work and thinking on satellite systems, A reliability of some 50 per cent had been obtained in she firstthree or four Discoverer launches; this had increased to 60 per cent over the first ten; and in the last few firings in the series wepercentage of successes had risen to 80. Concerning the rossible types of communications satellites, the Lockheed compareached the conclusion that, were it not for the reliability p- the synchronous satellite would be preferable. Tracking was an important and difficult part of anysystem, Mr Smelt emphasized. It was bad enough coping wi- or four satellites at the same time, let alone the 50 which h,mentioned by another speaker at the symposium. "We ha , lost these satellites for seven or eight orbits," the speaker"We had to go back and put more terms in the equations." s had itellne i beel1otten
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