|Image credit: NASA|
Mueller took drastic action. When he joined NASA, the Apollo flight-test plan was based on the philosophy of incremental testing, which meant that untried rocket stages would launch only dummy stages and dummy spacecraft. On 29 October 1963, Mueller informed his senior managers that Apollo test flights would henceforth use complete systems. Mueller's directive meant that, when the Saturn V S-IC first stage flew for the first time, it would be as part of a complete 363-foot-tall three-stage Saturn V. The new "all-up" approach would, it was hoped, slash the number of test flights needed before the Saturn V could launch astronauts to the moon.
|George Mueller. Image credit: NASA|
Eighteen months after Mueller's announcement, E. Harris and J. Brom, engineers with The RAND Corporation think tank, proposed one such back-up plan. Their brief report, originally classified "Secret," looked at how NASA might accomplish a manned moon landing by 1970 if the Saturn V could not be certified as safe enough to launch astronauts.
Harris and Brom's backup plan would see the Apollo Saturn V lift off without astronauts on board. It would expend its S-IC first stage and S-II second stage in turn, then its S-IVB third stage would place itself plus unmanned Apollo Command and Service Module (CSM) and Lunar Module (LM) spacecraft into parking orbit about the Earth. Because it would carry no crew, the CSM would need no Launch Escape System (LES) tower on its nose.
The astronauts would reach Earth orbit separately in a ferry CSM launched atop a two-stage Saturn IB rocket. The ferry CSM would carry a special drogue docking unit on its nose for linking up with the unmanned CSM's nose-mounted probe docking unit. The special drogue, the only new system required for RAND's backup plan, would need about one year and "perhaps several million dollars" to develop.
|The top of the Apollo 13 Lunar Module Aquarius. The red arrow points to the concave drogue docking unit. Image credit: NASA|
The RAND engineers declined to recommend whether the unmanned Saturn V or the manned Saturn IB should be launched first. They noted that liquid hydrogen fuel in the Saturn V's S-IVB stage would boil and escape at a rate of 700 pounds per hour; the stage would thus need to be restarted within 4.5 hours of reaching parking orbit if it were to retain enough propellants for Trans-Lunar Injection. They noted that deletion of the 2900-pound LES would make the unmanned Saturn V that much lighter, so its S-IVB stage could be loaded with an extra 2900 pounds of liquid hydrogen; that is, enough to permit it to loiter in low-Earth orbit for nearly 10 hours. Extending the loiter time further would demand a complex and costly S-IVB stage redesign.
Launching the crew first would avoid the S-IVB stage loiter-time constraint. Harris and Brom noted that, though the Apollo lunar mission was scheduled to last only from seven to 10 days, NASA planned a 14-day Earth-orbital Gemini mission by the end of 1965 to certify that astronauts could withstand long space flights. Assuming that the Gemini flight confirmed that humans could endure 14 days in weightlessness, then the ferry CSM crew could in theory wait for from four to seven days for the unmanned Saturn V to join them in Earth orbit. Harris and Brom recommended that, if the unmanned Saturn V became delayed so that the astronauts waiting in orbit could not accomplish a lunar mission and return to Earth within 14 days of first reaching space, then they should carry out an unspecified backup Earth-orbital mission in the ferry CSM so that their flight would not be wasted.
NASA officials did not take up the Harris and Brom proposal, though for a time in 1968 they might have wished that they had. The first unmanned Saturn V test flight, Apollo 4, lifted off on 9 November 1967. In keeping with Mueller's 1963 directive, it included complete S-IC, S-II, and S-IVB stages, plus a CSM with LES. Because LM development had hit snags, a dummy LM rode inside its SLA. The eight-hour Earth-orbital mission was an unqualified success.
|Troubled flight: Apollo 6 unmanned Saturn V test, 4 April 1968. Image credit: NASA|
The pogo oscillations might have injured astronauts; the S-IVB failure would certainly have scrubbed their flight to the moon. Post-flight analysis showed, however, that the pogo and engine failures had relatively simple fixes. After intense internal debate, NASA decided in October 1968 that the third Saturn V should launch Apollo 8 astronauts Frank Borman, James Lovell, and William Anders to the moon. The giant rocket performed flawlessly, placing the Apollo 8 CSM on course for lunar orbit on 21 December 1968.
"Apollo Launch-Vehicle Man-Rating: Some Considerations and an Alternative Contingency Plan (U)," Memorandum RM-4489-NASA, E. D. Harris and J. R. Brom, The RAND Corporation, May 1965
The Apollo Spacecraft: A Chronology, Volume II, NASA SP-4009, Mary Louise Morse & Jean Kernahan Bays, NASA Scientific and Technical Information Office, 1973, pp. 104-106
Stages to Saturn: A Technological History of the Apollo/Saturn Launch Vehicles, NASA SP-4206, Roger Bilstein, NASA, 1980, pp. 347-363
Apollo: The Race to the Moon, Charles Murray & Catherine Bly Cox, Simon & Schuster, 1989, pp. 153-162
What If Apollo Astronauts Became Marooned in Lunar Orbit? (1968)
What If an Apollo Lunar Module Ran Low on Fuel and Aborted Its Moon Landing? (1966)
What If An Apollo Saturn Rocket Exploded on the Launch Pad? (1965)