¹ For this and other details connected with the early development of radio tracking, see Corliss, The Evolution of STADAN, chapter 2.

² Appendix C of the Naval Laboratory's proposal to the Stewart Committee. Full reference: "A Scientific Satellite Program," NRL Memo Report 487, 5 July 1955, with addendum letter S-7140-262/55, 23 Aug 1955. See also chapter 1, pp. 10-11.

³ See Whipple, "Photographic Meteor Studies. I," Proceedings of the American Philosophical Society, vol. 79, 1938, pp. 499-548; and his "Meteoritic Phenomena and Meteorites," in Clayton S. White and Otis O. Benson, Jr., eds., Physics and Medicine of the Upper Atmosphere: A Study of the Aeropause (Albuquerque: University of New Mexico Press, 1952), pp. 137-170.

⁴ Corliss, op. cit., p. 14.

⁵ Ltr, Homer E. Newell, Jr., to Clyde W. Tombaugh, New Mexico College of Agriculture and Mechanical Arts (NMCAM), 20 June 1956; and undated and untitled typescript identifiable by the handwritten insert, "save for minor changes, this is it," in Hagen's personal file folder.

⁶ Encl (1) of ltr 4100 251/56, Dir/NRL to Chief/Information, Navy Dept., 22 Aug 1956, sub: Press Release and Photographs on Minitrack Transmitter.

⁷ John T. Mengel, "Tracking the Earth Satellite, and Data Transmission by Radio," Proceedings of the IRE, vol. 44, no. 6 (June 1956), p. 755. See also ltr 2030-37 Ser: 1927, Vanguard Technical Officer to David O. Woodbury, Santa Barbara, Cal., 26 Feb 1957.

⁸ See n. 6 and DoD news release 969-56, 17 Sept 1956, sub: Earth Satellite Instruments to be Displayed in New York.

⁹ Mengel, op. cit.

¹⁰ John T. Mengel and Paul Herget, "Tracking Satellites by Radio," Scientific American, vol. 198, no. 1 (January 1958), pp. 23-29.

¹¹ Attachment C, min 7th mtg TPESP, 5 Sept 1956.

¹² See chapter 3.

¹³ NRL Memo Report 487, p. 22; ltr, Hagen to Hugh Odishaw, 9 Aug 1956; NRL Report 4747, p 16; Easton's ms., "Radio Tracking of the Earth Satellite," 12 Apr 1956, pp. 3-10, and accompanying drawings; encl (1) of ltr, Dir/ NRL to Chief/Information, Navy Dept., 13 June 1956, sub: Radio Tracking of Earth Satellite, News Release on; IGY Report 21, Nov 1965, pp. 587f; min 4th mtg TPESP Working Group on Tracking and Computation, p. 3, and min 8th mtg TPESP, p. 8.

¹⁴ Mengel interview; ltr, Chief/Engineers to Dir/NRL, 10 May 1957, sub: Project Vanguard-Army Prime Minitrack Program, a summary of progress; Memo 105 Ser: 9147, Chief/ Naval Research to Chief/Naval Operations, 5 Sept 1957, sub: Project Vanguard Weekly Status Rpt No. 81; attachment 1, memo, NRL to James O. Spriggs, Office/Asst Sec. Def, 17 Sept 1957, sub: Draft of Proposed Memo to the President, submittal of.

¹⁵ Min 4th and 5th mtgs TPESP and attachment 10 to min 7th mtg.

¹⁶ IGY Report 21, p. 569; interview, Whipple, 9 Oct 1967.

¹⁷ E. Nelson Hayes, The "Smithsonian's Satellite-Tracking Program … [Part 1]," Annual Report … Smithsonian Institution … 1961, pp. 286, 298.

¹⁸ IGY Report 21, p. 568.

¹⁹ Min 12th mtg TPESP.

²⁰ IGY Report 21, p. 569; Porter to authors, 21 Mar 1968.

²¹ Ltr, Chief/Naval Research to Chief/R&D, Office/Chief of Staff, Dept/Army, 10 May 1956, sub: Project Vanguard, Passive Tracking Program For; interviews, Hagen, 17 Mar 1967, and Whipple, 9 Oct 1967.

²² IGY Report 21, pp. 571f; min 18th mtg TPESP; Hayes, op. cit., p. 289; conf rpt 7340-687, 12 July 1957, third meeting to review and coordinate the joint efforts of NRL, USAF, and SAO on the Moonwatch; ltr, Whipple to Hagen, 20 Dec 1957.

²³ Min 15th and 17th mtgs TPESP.

²⁴ Minutes of staff meeting, Project Vanguard, 9 Dec 1955.

²⁵ Ltr 4130-119 Ser: 2374, Dir/NRL to CO/US AMS, 13 Mar 1956, sub: Calibration Aircraft for Minitrack Stations; memo 6260-349/55, NRL 12 Dec 1955, sub: Aircraft Requirements for Equipment Evaluation, Project Vanguard; master ltr, Mengel to Box 983W c/o IRE, 19 Feb 1957.

²⁶ W. E. Smitherman, "Army Participation in Project Vanguard," IRE Transactions on Military Electronics, vol. MIL-4 , nos. 2-3 (April-July, 1960), p. 326.

²⁷ Mengel and Herget, op. cit. (see no. 10), p. 27.

²⁸ Ibid.

²⁹ See chapter 8, p. 141.

³⁰ NRL ltr 3000-122/56, 15 Aug 1956, Dir/ NRL to Asst Sec/Def (Comptroller), sub: Project Vanguard Tracking Stations, Request for Release of Funds to Department of the Army for Construction of; encl (1) NRL ltr 4130-84 Ser: 2168, 7 Mar 1957; NRL memo 4102-71, 18 Mar 1957, sub: Vanguard Communications; CNO ltr Op-45G Ser: 699P44, 2 Mar 1956, Fourth Endorsement on NRL Washington ltr 2501A-295/56 (1), 10 Feb 1956, Chief/Naval Operations to Asst Sec/Navy (Materiel), sub: Project Vanguard; Proposed Minitrack Site Blossom Point Proving Ground; Dept Navy/BuYds 8: Docks ltr R-421, 12 Apr 1956, Chief/BuYds & Docks to Real Estate Division, Corps Engineers/Depart Army, sub: Diamond Ordnance Fuse Laboratory, Blossom Point Proving Ground … Request for Permit to Use Portion of Land; NRL ltr 4130-291/56 (4130), 3 Apr 1956, Dir/NRL to CO/AFMTC, sub: Project Vanguard: Proposed Minitrack Test Plan for; ONR ltr 108 Ser: 27291, 21 Nov 1956, Chief/Naval Research Asst Ch/Staff, Installations, USAF, sub: Vanguard Minitrack Facilities on Downrange Islands; Office Chief/Engineers ltr, 18 Feb. 1957, sub: Project Vanguard-Army Prime Minitrack Program; NRL ltr 2050-90 Ser: 2741, 18 Mar 1957, Dir/NRL to Chief/Information, Navy Dept, sub: "Minitrack," A Chapter of a New Book, "Little New Moon," by David O. Woodbury; Australian Joint Service Staff ltr 613/ R64, 2 Apr 1957, to NRL; Corliss, The Evolution of STADAN, chapter 2 and Appendix A; conf rpt 4130-60, 8 Feb 1957.

³¹ NRL ltr C-4108-7/55, 12 Jan 1956, Dir/ NRL to Chief, Engineering Intelligence Division, Office Chief/Engineers, sub: Study for Tracking Sites for Project Vanguard; encl (1) to NRL ltr C-106-16/56 of 12 Mar 1956, sub: Preliminary Specifications and Considerations, sub: Minitrack Site Facilities; NRL Report 4767, pp. lf; Smitherman, op. cit. (see n. 26); NEL memo, 24 May 1956, sub: Project Vanguard, NEL Assistance in; NRL ltr C4100-128/56, 5 June 1956, Dir/NRL to Chief, Bureau of Ships, sub: Authorization for NEL Participation in Project Vanguard, Request for; interviews, 19 June 1967, with James J. Fleming and Joseph W. Siry.

³² "Specification for Minitrack Ground Station Units," 28 May 1956; NRL ltr C-4130-57/56 (4130) 100317, 19 July 1956, Dir/NRL to Chief/Naval Operations (Contracts Div.), sub: Minitrack Ground Station Units, Selection of Contractor for; Contract Nonr-2190 (00), 1 Aug 1956, between Office of Naval Research and Bendix Radio Div. of Bendix Aviation

³³ NRL ltr 4130-34/56 (4130) of 9 May 1956, Corp., Baltimore, Md. Dir/NRL to CO/AFMTC, sub: Project Vanguard: Minitrack Antenna Mounts; CSR 5330-500/56, 13 June 1956; CSR 5330-574/56, July 1956; ONR ltr 610 Ser: 17999, 25 Jan 1957, Chief/Naval Operations to Technical Appliance Corp., sub: Contract Nonr-2268 (00) .

³⁴ "Melpar, Inc." contract file; encl (1) of NRL ltr 4100-259/56, 7 Sept 1956, Dir/NRL to Chief/Information, Navy Dept, sub: AN/DPN (48) Radar Beacon (article for Melpar Company publication).

³⁵ ONR ltr 601 Ser: 17854, 6 Aug 1956, Bennett to Dir/NRL.

³⁶ Interviews: Herget, by phone, 18 July 1967; Mengel, 17 Mar 1967; Siry and Fleming, 19 June 1967.

³⁷ NRL ltr 4100-161/56 (110044), 26 June 1956, Dir/NRL to Supt, U.S. Naval Observatory, sub: Assistant in Project Vanguard, Request for; Dept/Navy, U.S. Naval Observatory, ltr Ser: 1078, 29 June 1956, Supt/Naval Observatory to Dir/NRL; Encl (1) to NRL ltr 4100-189/56, 17 July 1956, sub: Vanguard Project Directive, Working Group on Orbits, Establishment of.

³⁸ NRL ltr C-7100-149/55, 14 Oct 1955, Dir/ NRL to Dr. C. C. Hurd, IBM, 590 Madison Avenue, New York City 22, sub: Computer Needs for Project Vanguard.

³⁹ Ibid.

⁴⁰ ONR ltr 610J, 9 Mar 1956; NRL ltr C-4100-112/56, 8 May 1956, Dir/NRL to Chief/Naval Research, sub: Contractor for Satellite Orbit Computational Facilities for Project Vanguard, Selection of; Nonr-2169 (00), Contract between Government and IBM, dated 22 June 1956; NRL news release, 5 July 1956, sub: IBM to Provide Computing Facility for Project Vanguard; IBM ltr, 15 Apr 1957, sub: Project Vanguard Progress Rpt 9; news release (source not indicated), slugged "For Release: June 30, 1957 at 8 p.m.," and dated Washington, June 30, 1957; IBM ltr, 30 Aug 1957, to NRL, sub: Project Vanguard Progress Rpt 13.

⁴¹ NRL Report 5113, p. 17; memo, Hagen to Codes 1510 and 1810, 4 June 1956, sub: Dr. Peter Musen, Information Covering; and A. Robin Mowlem, mathematician in charge of programming, IBM Computing Center, "How the Computer Calculates Orbits," [undated IBM information release].

⁴² Mazur, Fleming, and Siry interviews; NRL memo 4150-85/56 (4150), 6 June 1956, sub: Justification for Use of AN/FPS-16; minutes of Technical Board meeting 6-57, 5 Feb 1957; memo 5130-17: ABB, 1 Mar 1957, sub: Conference Rpt, Data Transmission Link between IBM 704/sic/Computer and Third-Stage Firing Console …; CSR 5230-158, 10 Apr 1957, sub: "Ground Backup Guidance Plan Discussed"; NRL Report 5113, p. 17.

⁴³ NRL Technical Information Division release, 9 July 1957, "Navy Will Use 'Electric Brain' to Study Flight of Vanguard Launching Vehicles"; Mengel and Herget, op. cit. (see n. 10), pp. 27f; NRL Report 4880, p. 23; NRL Report 5113, p. 17; Fleming-Siry interview.