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Computers in Spaceflight: The NASA Experience



1. D. G. Hoag, Apollo Navigation Guidance Computer Systems, Report E-2411 MIT, Cambridge, MA, April 1969, p. 2.

2. A. L. Hopkins, "Electronic Navigator Charts Man's Path to the Moon," Electronics, 109 (January 9, 1967); Ralph Ragan interview, MIT, Cambridge, MA, by Ivan Ertel, April 28, 1966, Johnson Space Center transcript.

3. Hoag, Apollo Navigation Systems, p. 3.

4. Hoag, Apollo Navigation Systems, pp. 3-4

5. P. Hersch, "Engineers Reassessing Electronic Hardware in the Light of Some Near Failures on Apollo 12" IEEE Spec., 23 (January 1970).

6. B. K. Thomas, Jr., "Apollo 8 Proves Value of Onboard Control," Aviation Week, 43 (January 20, 1969).

7. Steve Bales interview, Johnson Space Center, Houston, TX, May 31, 1983; Howard W. Tindall, notes in review of draft chapter, August 1985.

8. John R. Garman interview, Johnson Space Center, Houston, TX, May 25,1983 and June 1, 1983.

9. C. G. Brooks, L. S. Grimwood, and L. S. Swenson, Jr., Chariots or Apollo: A History of Manned Lunar Spacecraft; NASA SP-205 Washington, D.C., 1979, p. 355.

10. Hopkins, "Electronic Navigator," p. 116.

11. Brooks, Grimwood, and Swenson, Chariots for Apollo, pp. 38-39

12. Ragan interview.

13. Hoag, Apollo Navigation Systems, p. 5.

14. Ragan interview.

15. Eldon Hall lecture, "The Apollo Guidance Computer-A Designer's View," Digital Computer Museum, Marlboro, MA, June 10, 1982, transcript at museum's Boston location, p. 4.

16. P. G. Felleman and D. C. Fraser, "Digital Fly-by-Wire: Computers Lead the Way," Astronaut. and Aeronaut., 30 (July-August 1974).

17. H. J. Goett to G. Low, "Recommendations for Apollo On-board Guidance Computer," June 6, 1961, JSC History Office.

18. L. A. Wood to R. Chilton, NASA Space Task Group, "Information of RCA Computers Adaptable to Guidance," June 6, 1961, JSC History Office.

19. R. G. Chilton to multiple addresses, NASA Space Task Group, "Discussions at Goddard of a Possible Joint Development Program for Airborne Computers for OAO and Apollo," memo, June 6, 1961, JSC History Office.

20. R. Alonso to multiple addresses, MIT, "Review of Saturn Computer Discussions," memo, June 27, 1961, JSC History Office.

21. D. W. Gilbert to multiple addresses, JSC, "Guidance Computer for Apollo," memo, July 9, 1963, JSC.

22. Maj. Gen. Samuel C. Phillips, deputy director of the Apollo Program, reported on a meeting to discuss the use of the triple modular redundant Saturn launch vehicle computer in Apollo. S. C. Phillips to multiple addresses, "Saturn V/Apollo Spacecraft Guidance Computer Conference," memo, May 14, 1964, JSC History Office.

23. Hopkins, "Electronic Navigator", p. 110.

24. Ragan interview.

25. E. C. Hall, Reliability History of the Apollo Guidance Computer;. NASA CR-140340 MIT, Cambridge, MA,1972, p. 25.

26. C. D. Brady to multiple addresses, "Integrated Circuit Packages for the AGC," memo, June 19,1964, JSC History Office.

27. D. G. Hoag interview, MIT, Cambridge, MA, by Ivan Ertel, April 29, 1966, Johnson Space Center transcript.

28. Brooks, Grimwood, and Swenson, Chariots for Apollo, p. 187.

29. R. Alonso, H. Blair-Smith, and A. Hopkins, "Logical Description for the Apollo Guidance Computer," MIT, Cambridge, MA, March 1963, p. 1.1.

30. Hopkins, "Electronic Navigator," p. 110.

31. Hall, Reliability History; p. 9.

32. Alonso, Blair-Smith, and Hopkins, "Logical Description," p. 1.1.

33. Alonso, Blair-Smith, and Hopkins, "Logical Description," p. vii.

34. Ragan interview.

35. Ragan interview.

36. Hall, Reliability History, p. 5.

37. Hopkins, "Guidance Computer Design," Spacecraft Navigation, Guidance, and Control MIT, Cambridge, MA, 1965, pp. 13-15.

38. Hopkins, "Electronic Navigator," p. 112.

39. R. H. Battin and F. H. Martin, "Computer Controlled Steering of the Apollo Spacecraft," J. Spacecr. Rockets, 5, 402 (1968); A. Drake and B. 1. Savage, AGC4 Basic Training Manual MIT, Cambridge, MA, 1967, pp. 1.1-1.2.

40. F. Bedford, S. P. Cockrell, and R. T. Savely, Apollo Experience Report: Onboard Navigational and Alignment Software, MSC-04238, Houston, TX, 1971, p. 2; Hopkins, "Electronic Navigator," p. 113.

41. Drake and Savage, AGC4, p. 1.3.

42. Hopkins, "Electronic Navigator," p. 118.

43. Hall, Reliability History, p. 10; Raytheon Corporation, Apollo Guidance Computer Program Block 1 (100) and Block 2-Final Report (July 25, 1969-December 31,1969), p. 2.17.

44. Hall lecture, p. 5.

45. R. Alonso and A. Hopkins, The Apollo Guidance Computer, NASA CR-118183, MIT, Cambridge, MA, p. 8.

46. E. M. Copps, Recovery from Transient Failures of the Apollo Guidance Computer, NASA CR-92255, MIT, Cambridge, MA, 1968, p. 2.

47. Drake and Savage, AGC4, p. 1.13.

48. H. Kreide and D. W. Lambert, "Computation: Aerospace Computers in Aircraft, Missiles, and Spacecraft," Space/Aeronaut., 42 77 (1964).

49. Alonso and Hopkins, Apollo Computer, p. 12.

50. L. J. Carey and W. A. Sturm, "Space Software at the Crossroads," Space/Aeronaut. 63 (December 1968); Kreide and Lambert, "Computation," pp. 97-98.

51. A. Hopkins, "Design Concepts of the Apollo Guidance Computer," Mimeograph, MIT Instrumentation Lab, Cambridge, MA, June 1963, p. 2.1.

52. Alonso, Blair-Smith, and Hopkins, "Logical Description," p. 1.3; Stan Mann interview, Johnson Space Center, Houston, TX, June 6, 1983.

53. E. C. Hall, MIT's Role in Project Apollo: Computer Subsystem, Charles Stark Draper Laboratory, Cambridge, MA, 1972, vol. 3, p. 3.

54. Alonso, Blair-Smith, and Hopkins, "Logical Description," p. 4.2; Hopkins, "Design Concepts," June 1963, p. 2.5; P. Kuttner, "The Rope Memory-A Permanent Storage Device," Proc. AFIPS, 49 (November 1963).

55. Hopkins, "Electronic Navigator," p. 114.

56. Raytheon Corporation, Final Report, p. 2.29.

57. Drake and Savage, AGC4, p. 1.6.

58. John R. Garman interview, Johnson Space Center, Houston, TX, May 25, 1983 and June 1,1983.

59. Raytheon Corporation, Final Report, p. 4.5.

60. A. Laats and J. E. Miller, Aollo Guidance and Control System Flight Experience, NASA CR- 101823, MIT, Cambridge, MA, 1969, p. l.

61. Raytheon Corporation, Final Report, p. 2.56.

62. Ragan interview.

63. R. C. Seamans, Jr., to multiple addresses, "Raytheon Negotiations on Apollo Guidance Computer," memo, November 9, 1962, JSC History Office.

64. J. F. Shea to multiple addresses, Johnson Space Center, "Integrated Circuit Packages for the Block II Apollo Guidance Computer (AGC)," memo, September 9, 1964, JSC History Office.

65. Hall, Reliability History, p. 43.

66. C. W. Frasier to multiple addresses, Johnson Space Center, "Block II Computer Design Deficiency," memo, August 10, 1965, JSC History Office.

67. I. V. Ertel, The Apollo Spacecraft, GPO, Washington, D.C., 1969, pp. 31-32.

68. Hall, Reliability History, pp. 15-16,19.

69. Raytheon Corporation, Final Report, p. 3.12.

70. Felleman and Fraser, "Digital Fly-By-Wire," p. 30.

71. W.M. Keese, et al, Management Procedures in Computer Programming for Apollo-Interim Report, Bellcomm. Inc., Washington, D.C., November 30, 1964.

72. Garman interview.

73. Hopkins, "Design Concepts," June 1963, p. 3.11.

74. Frank Hughes interview, Johnson Space Center, Houston, TX, June 2, 1983.

75. Ertel, Apollo Spacecraft, p. 288.

76. Mann interview.

77. Guidance Software Validation Commission, Apollo Guidance Software Development and Verification Plan, Manned Spacecraft Center, Houston, TX, October 4, 1957, p. 2.1.

78. Ed Lineberry interview, Johnson Space Center, Houston, TX, June 2, 1983.

79. Dick Parten interview, Johnson Space Center, Houston, TX, June 3, 1983 and June 16, 1983.

80. M. D. Richter to multiple addresses, MIT, "Summary of AGC Program Processing Procedures," memo, August 13, 1965, JSC History Office.

81. Garman interview.

82. RASPO to MIT memo, JSC History Office Archives, October 22,1963.

83. Hopkins, "Guidance Computer Design," p. 48.

84. Mann interview.

85. C. A. Muntz, Users Guide to the Block 2 AGC/LGC Interpreter, NASACR-1268l5, MIT, Cambridge, MA, April 1965.

86. Hopkins, "Electronic Navigator," p. 117.

87. Battin and Martin, "Computer Controlled Steering," p. 403.

88. Hopkins, "Electronic Navigator," p. 117.

89. Copps, Recovery From Transient Failures, p. 3.

90. D. J. Bowler, Apollo Guidance Computer Improvement Study-Apollo Guidance, Navigation, and Control, NASA CR-114898, MIT, Cambridge, MA, 1970, p.2.

91. George W. Cherry to multiple addresses, "Exegesis of the 1201 and 1202 Alarms Which Occurred During the [Mission G] Lunar Landing," memo no. 370-69, MIT Instrumentation Lab, Cambridge, MA, August 4, 1969, JSC History Office.

92. Hopkins, "Electronic Navigator," p. 117; T. Lawton and C.A. Muntz, Organization of Computation and Control of the Apollo Guidance Computer, MIT Instrumentation Lab., Cambridge, MA, E-1758, 1965, p. 15.

93. Drake and Savage, AGC4, p. 1.21.

94. Garman interview.

95. Hopkins, "Design Concepts," June 1963, pp. 2.8-2.9; Lawton and Muntz, Computation and Control, p.15.

96. Gatman interview.

97. Raytheon Corporation, Final Report, p. 2.32.

98. Howard "Bill Tidall to multiple addresses, "Spacecraft Computer Program Names," memo, May 23, 1967, JSC History Office.

99. Ertel, Apollo Spacecraft, p. 238.

100. Copps, Recovery From Transient Failures, p. 4; Hall, Reliability History, pp. 7-8.

101. Copps, Recovery From Transient Failures, pp. l, 5; Cherry, "Exegesis of the 1201 and 1202 Alarms."

102. Copps, Recovery From Transient Failures, p. 3.

103. Hopkins, "Design Concepts," p. 2.11.

104. Hopkins, "Design Concepts," p. 2.11.

105. Hall, Reliability History, p. 31.

106. Cherry, "Exegesis of the 1201 and 1202 Alarms."

107. Garman interview.

108. Cherry, "Exegesis of the 1201 and 1202 Alarms."

109. T. Lawton and C. A. Muntz, Verification Plan for AGC/LGC, MIT, Cambridge, MA, E-1786, 1964, p. 5.

110. Lawton and Muntz, Verification Plan, p. 5; MIT, Guidance System Operations Plan for Manned CM Earth Orbital and Lunar Missions Using Program COLLOSSUS, Sec. 5, NASA CR-97515, MIT, Cambridge, MA, n.d., p. 6.2.

111. Mann interview.

112. Carey and Sturm, "Space Software," p. 63.

113. Mann interview.

114. Lawton and Muntz, Verification Plan, p. 14.

115. Guidance Software Control Panel File, JSC History Office Archives, May 13, 1966.

116. Bowler, Improvement Study, p. 2.

117. Hoag interview.

118. Tindall to multiple addresses, "Apollo Spacecraft Computer Program Development Newsletter," memo, May 31, 1966, JSC History Office.

119. Tindall, "Program Development Newsletter."

120. See Madeline S. Johnson, MIT's Role in Project Apollo: The Software Effort, Charles Stark Draper Laboratory, Cambridge, MA, 1971, vol. 2, pp. 21-22 for a chart showing the "manloading" at MIT during the Apollo effort.

121. Mann interview.

122. Tindall to multiple addresses, "Apollo Spacecraft Computer Programs-Or, A Bucket of Worms," memo, June 13, 1966, JSC History Office.

123. Tindall to multiple addresses, "Another Apollo Spacecraft Computer Status Report," memo, July 1, 1966, JSC History Office.

124. Tindall to multiple addresses, "Spacecraft Computer Programming Development Improvements to be Utilized by MIT," memo, 67-FM-1-T:85, October 18, 1967.

125. Tindall, "Program Development Newsletter."

126. Tindall to multiple addresses, untitled memos, May 13, 1966 and May 14, 1966, JSC History Office.

127. Tindall, "Apollo Spacecraft Computer ProgramsóOr, A Bucket of Worms."

128. Tindall, "Apollo Spacecraft Computer ProgramsóOr, A Bucket of Worms."

129. Tindall to multiple addresses, "AS-204 Computer Program Status," memo, July 21,1966, JSC History Office.

130. Tindall to multiple addresses, "Spacecraft Computer Program Status for AS-501," memo, September 20, 1966, JSC History Office.

131. Tindall, "Apollo Spacecraft Computer ProgramsóOr, A Bucket of Worms."

132. Ray Morth, "De-orbit Burn Program," (Flight 204), memo no: 35, January 23, 1967, MIT, Cambridge, MA, JSC History Office.

133. Hughes interview; Tindall concurs. He wrote in a memo for distribution on April 28,1967 that "it is almost certain that deficiencies will exist in the program we will ultimately fly." He then proceeded to improve the software during the delay in the Apollo program caused by the fire.

134. Tindall to multiple addresses, "In Which is Described the Apollo Spacecraft Computer Programs Currently Being Developed," memo, March 24, 1967, JSC History Office.

135. Tindall to multiple addresses, "Spacecraft Computer Program Status, memo, October 17,1967, JSC History Office.

136. Tindall to multiple addresses, "A New Spacecraft Computer Program Development Working Philosophy is Taking Shape," memo, 67-TM-1-39, May 17,19.

137. Ertel, Apollo Spacecraft, p. 250.

138. Ertel, Apollo Spacecraft, pp. 203 204.

139. John P. Mayer to multiple addresses, "Notes on Meeting of the Apollo Guidance Software Task Force in Washington on February 9, 1968," memo no. 68-RM-10, February 13, 1968.

140. Apollo Guidance Software Task Force, "Final Report," memo, September 23, 1968, JSC History Office, p. 4.

141. Apollo Guidance Software Task Force, "Final Report," p. 7; Ertel, Apollo Spacecraft, p. 250.

142. Ertel, Apollo Spacecraft, p. 288.

143. Mann interview

144. W. J. North and C. H. Woodling, "Apollo Crew Procedures, Simulation, and Flight Planning," Astronaut. and Aeronaut. 58 (March 1970).

145. Howard W. Tindall, in his review of the draft of this chapter, noted that the crew insisted on flexibility and control from the start of the program, so in a way they set the level of computer-related activity for themselves.

146. Raytheon Corporation, Final Report, p. 2.9.

147. J. M. Dahlen, Apollo Guidance Navigation and Control. Guidance and Navigation System Operations Plan, Apollo Mission 202, NASA CR-65770, MIT, Cambridge, MA, 1966, p. 3.19; Laats and Miller, Apollo Guidance Flight Experience, p. 6.

148. Hopkins, "Design Concepts," June 1963, p. 2.3.

149. Hall lecture, p. 8.

150. Copps, Recovery From Transient Failures, p. 2.

151. Hopkins, " Electronic Navigator, " p. 116.

152. Hopkins, "Electronic Navigator," p. 117.

153. Copps, Recovery From Transient Failures, p. 2.

154. Garman interview

155. Gene Cernan, telephone interview from Houston, November 7, 1983.

156. Vance Brand interview, Johnson Space Center, Houston, TX, June 2, 1983; John Young interview, telephone from Houston, TX, March 2, 1984.

157. Ragan interview.

158. Cernan interview.

159. Mann interview.

160. P. M. Kurten, Apollo Experience Report: Guidance and Control Systems-Lunar Module Abort Guidance System, NASA TN -D-7990, Johnson Space Center, Houston, TX, 1975, p. 4.

161. TRW, news release, July 1,1969, JSC History Office Archives.

162. TRW, news release, July 1,1969.

163. Kurten, Abort Guidance System, p. 1; B. Miller, "Abort Backup for LEM Near Production," TRW Executive Clips, 1 (January 15, 1966).

164. Kurten, Abort Guidance System, p. 5.

165. Kurten, Abort Guidance System, p. 6.

166. B. Miller, "Abort Backup," p. 4.

167. J.J. Seidman, "LEM/AGS Marco 4418", mimeograph, September 1966, JSC History Office, p. l.

168. Kurten, Abort Guidance System, p. 7; B. Miller, "Abort Backup," p. 4; TRW, news release, July 1, 1969.

169. B. Miller, "Abort Backup," p. 3.

170. Jonas Beraru, "The TRW Systems MARCO 4418-A Man Rated Computer," (TRW, 1979), p. 26.

171. TRW, news release, July 1, 1969.

172. Kurten, Abort Guidance System, pp. 8-9.

173. Kurten, Abort Guidance System, p. 42.

174. Tindall, notes in review of the draft of this chapter, August, 1985.

175. Kurten, Abort Guidance System, p. 38.

176. Kurten, Abort Guidance System, pp. 22-23.

177. TRW, news release, July l, 1969.

178. Young interview.

179. Young interview.

180. Apollo Guidance Software Task Force, Final Report, pp. 5-6; R. R. Regelbrugge, Apollo Experience Report: Apollo Spacecraft and Ground Software Development for Rendezvous, MSC-02676, 1970, p 5. S. A. Sjoberg, "Objectives for Software Controlled Aerospace Systems in the Next Decade," memo for distribution, Manned Spacecraft Center, July 14, 1970, p. 2.

181. Bowler, Improvement Study.