FIRST PHASE OF LUNAR EXPLORATION COMPLETED:

Mission to Fra Mauro

Whether any Americans were going to Mars in this century or not, the crew of Apollo 13 - Jim Lovell, Ken Mattingly, and Fred Haise - were going to the moon, and they were too busy preparing for that mission to worry about anything more spectacular. Their Saturn V was trundled out to launch complex 39A on December 15, 1969, anticipating launch on March 12, 1970.78 On January 8, however, Headquarters announced that Apollo 13 had been rescheduled for April 11 to allow more detailed analysis of specific plans.79

The target for Apollo 13 was a spot some 180 kilometers (112 miles) east of Apollo 12's landing site, just north of the crater Fra Mauro. The mission's primary task was to sample the geologic unit called the Fra Mauro Formation, which covers a large area around the Imbrium basin. The Fra Mauro Formation was generally believed to consist of material ejected when Imbrium, one of the largest impact basins on the moon, was formed. Scientists hoped that samples would allow them to date the "Imbrian event," which would establish the time relationships of related and adjacent features. Finally, they expected that the Fra Mauro site would provide samples that came from deep within the moon, excavated by the Imbrian event.80 The mission would also emplace a second set of lunar surface instruments, differing from those flown on Apollo 12; a heat-flow experiment and a charged-particle environment detector were substituted for the solar wind spectrometer, the magnetometer, and the suprathermal ion detector. A second calibration of the lunar seismometers was to be accomplished by crashing the Saturn V's third stage at a preselected location on the moon.81

Preparations for the launch proceeded without major problems through February and March. Three days before launch, Jack Swigert took Ken Mattingly's place as command module pilot, after the prime crew had been exposed to German measles and Mattingly was found to have no immunity. Apollo 13 lifted off on schedule at 2:13 p.m. Eastern Standard Time on April 11, and for two days operations were routine; Capcom remarked at one point that flight controllers were bored to tears. A few hours later, however, an oxygen tank in the service module ruptured, depriving the spacecraft of most of its electrical power and oxygen, and the mission had to be aborted. Only a heroic effort of real-time improvisation by mission operations teams saved the crew.82

Almost lost in the drama of the mission was the one piece of scientific information that Apollo 13 was able to provide. Shortly after command module pilot Jack Swigert had extracted the lunar module from atop the S-IVB stage, ground controllers fired the auxiliary propulsion system on the big rocket, putting it on a course to crash into the moon. Three days later the 30,700-pound (13,925 kilogram) hulk struck the lunar surface at 5,600 miles per hour (2.5 kilometers per second) some 74 miles (119 kilometers) west-northwest of the Apollo 12 landing site, releasing energy estimated as equivalent to the explosion of 7.7 tons (7,000 kilograms) of TNT. Half a minute later the passive seismometer left by Apollo 12 recorded the onset of vibrations that persisted for more than four hours. Another instrument, the lunar ionosphere detector, sensed a gas cloud that arrived a few seconds before the seismic signal and lasted for more than a minute. Seismologists were baffled by the moon's response to shock, but welcomed the new means of generating data.83

In the year that it took to discover and correct the cause of the Apollo 13 failure, the scope of the remaining missions was altered. Apollo 14 would visit the site intended for exploration by Apollo 13, but it would go there as the last of the intermediate exploration missions. The flights that remained would stretch the capabilities of the Apollo systems virtually to their limits, providing longer visits to the lunar surface and increased mobility for the astronauts. Unfortunately for lunar science, two missions were to be cut from an already minimal program.

78. Mueller to Administrator, "Manned Space Flight Weekly Report," Dec. 15, 1969; Dale D. Myers to Administrator, "Manned Space Flight Weekly Report," Jan. 19, 1970.

79. NASA Release 70-5, Jan. 8, 1970.

80. Calio to Mgr., Apollo Spacecraft Program, "Recommendations for Science Sites for Apollo Missions 13- 20," Oct. 20, 1969.

81. MSC, "Apollo 13 Mission Report," MSC-02680, Sept. 1970, p. 12-2 and App. A, p. A-2.

82. The best account of Apollo 13 is that of Henry S. F. Cooper, 13: The Flight That Failed (New York: Dial Press, 1973), a taut narrative that captures the flavor of the entire mission. For a first-person account by a participant, see mission commander James A. Lovell's chapter, "Houston, We've Had A Problem," in Apollo Expeditions to the Moon, Edgar M. Cortright, ed., NASA SP-350 (Washington, 1975). A brief summary of the mission and the investigation is given in Benson and Faherty, Moonport, pp. 489-94. Headquarters' Public Affairs Office prepared a 25-page booklet on the flight, "Houston, we've got a problem," NASA EP- 76 (Washington, 1970). A concise summary of the constraints faced by flight controllers and the rationale for the real-time decisions made during Apollo 13 was presented by Glynn S. Lunney, one of 13's flight directors, as AIAA Paper No. 70-1260, "Discussion of Several Problem Areas During the Apollo 13 Operation," at the AIAA 7th Annual Meeting and Technical Display, Houston, Oct. 19-22, 1970. The Report of the Apollo 13 Review Board, a summary volume and eight technical appendices, was released two months after the accident. It contains full technical details of the causes of the accident as deduced from inflight telemetry, the history of the faulty tank, and tests performed to support the investigation. Board chairman Edgar M. Cortright presented the board's findings to the House space committee on June 16, 1970; see House, The Apollo 13 Accident, hearings before the Committee on Science and Astronautics, 91/2, June 16, 1970.

83. Apollo 13 Mission Report, pp. 11-9 to 11-10.