Chariots for Apollo: A History of Manned Lunar Spacecraft|
Before starting Apollo-Saturn IB launches, however, the operations people had to clean up one outstanding matter in New Mexico. NASA had hoped to finish the Little Joe II abort qualification program by the end of 1965, but on 17 December the Flight Readiness Board refused to accept the booster and canceled a launch set for the next day. A month later, at 8:15 on the morning of 20 January 1966, the last Little Joe II headed toward an altitude of 24 kilometers and a downrange distance of 14 kilometers. Then, as designed, the launch vehicle started to tumble; the launch escape system sensed trouble and fired its abort rocket, carrying the command module away from impending disaster. All went well on Mission A-004-the launch, the test conditions, the telemetry, the spacecraft (Block I production model 002), and the postflight analysis. The spacecraft windows picked up too much soot from the tower jettison motor, but the structure remained intact. Little Joe II was honorably-retired, its basic purpose - making sure the launch escape and earth landing systems could protect the astronauts in either emergency or normal operations - accomplished.3
After the last Little Joe flight, the scene shifted to Florida, where a Saturn IB, the first of the uprated vehicles** slated to boost manned flights into earth orbit, was ready. AS-201 did not get a lot of publicity, but Dale Myers and his North American crew considered its spacecraft CSM-009 their "teething" operation:
It . . . proved out our procedures, our checkout techniques, and proved that this equipment [fitted] together. . . . And we got lined up so we [were] able to handle operations both at the Cape and [in Downey]. Although spacecraft 009 had some problems in flight . . . we got what we were looking for from the primary objective, . . . real good data on our heatshield, which we just can't get any testing on in any other way.4
The Saturn IB first stage, assembled by Chrysler and with its eight H-1 engines built by Rocketdyne, had been erected on Complex 34 at Cape Kennedy in August 1965. Command and service module 009 was hoisted atop the booster on 26 December. Between those dates, the new S-IVB stage built by Douglas, with its single Rocketdyne J-2 engine, had been mated to the first stage, checked out, and fitted with an 1,800-kilogram "instrument unit," or guidance ring, made by IBM Federal Systems Division. The top third of the stack - the spacecraft-launch vehicle adapter, the cylindrical service module, the conical command module, and the pylon-shaped launch escape tower - had been North American's responsibility. Once they were stacked together, NASA assumed control. It took two pages to list AS-201's test objectives, but NASA's main aims were to check the compatibility and structural integrity of the spacecraft and launch vehicle and to evaluate the spacecraft's heatshield performance as the vehicle plunged through the atmosphere.5
Spacecraft 009 assembly began in October 1963 and continued throughout 1964, with the inner-shell aluminum-honeycomb pressure vessel taking shape concurrently with the stainless-steel-honeycomb outer shell and its ablative heatshield. By April 1965, 009 had reached the test division at Downey, where it spent the summer. After a review at the factory on 20 October, NASA's Apollo engineers approved the spacecraft for shipment to Cape Kennedy. Three months of servicing and checkout followed before AS-201 was ready for its voyage.
On 20 February 1966, launch technicians at the Cape began a three-day countdown, fully expecting some of the spacecraft's systems to delay the launch. But weather turned out to be the chief problem, causing two postponements. At 5:15 on the afternoon of the 25th, the countdown resumed. Three seconds before ignition - at 9:00 the next morning - a computer signaled that pressure in two helium spheres on the Saturn IB was below the danger line. The count was recycled to 15 minutes before launch and stopped. Discussions waxed hot between Huntsville and Cape engineers. Since no one could be sure how serious the problem really was, the mission was scrubbed at 10:45. Deciding that the drop in pressure was probably caused by either an excessive flow of oxygen in the checkout equipment or leakage in the flight system, Wernher von Braun's Saturn team recommended advancing the ground pressure regulator to maintain a higher pressure in the spheres. Kurt Debus' Cape crew agreed, and the launch was back on the track by 10:57.6
Apollo-Saturn 201 mission, 26 February 1966: launch, recovery (swimmers have attached a flotation collar, a device used in the Gemini and Mercury programs), and two views of the heatshield.
At 11:12 a.m. 26 February, AS-201's first stage ignited and drove the combined vehicles up to 57 kilometers where, after separation, the S-IVB took over, propelling the payload up to 425 kilometers. The second stage then dropped off, and the spacecraft coasted in an arc, reaching a peak altitude of 488 kilometers. At the zenith, the service module engine fired for 184 seconds, hurtling the command module into a steep descent. After a 10-second cutoff, the rocket engine fired again, for 10 seconds, to prove it could restart. The two modules then separated. The command module, traveling at 8,300 meters per second, turned blunt end forward to meet the friction caused by the growing density of the atmosphere.7
Both booster and spacecraft performed adequately. From liftoff in Florida to touchdown in the South Atlantic, the mission lasted only 37 minutes. The spacecraft was recovered by the U.S.S. Boxer two and a half hours after splashdown. AS-201 proved that the spacecraft was structurally sound and, most important, that the heatshield could survive an atmospheric reentry.
There were several malfunctions, mostly minor. Three were serious. First, after the service propulsion system fired, it operated correctly for only 80 seconds. Then the pressure fell 30 percent because of helium ingestion into the oxidizer chamber. Second, a fault in the electrical power system caused a loss of steering control, resulting in a rolling reentry. And, third, flight measurements during reentry were distorted because of a short circuit. Although Mueller agreed that the mission objectives had been met, these three problems would have to be corrected.8
The service module engine received instant attention. North American's Robert E. Field and Aerojet-General's Dan David (the engine's Apollo manager) ordered an analysis of what had gone wrong. The engine had operated well enough to finish the mission, but Field and David had to be sure that the Block II engine (undergoing ground testing) would not run into a similar situation during a lunar mission. They learned that a leak in an oxidizer line had permitted helium to mix with the oxidizer, causing the drop in temperature and pressure.
For all of Houston's insistence on redundancy, this was one major system that had no backup. And it was a vital system. Because of the lunar-orbit rendezvous decision, it had a variety of jobs: midcourse corrections on the way to the moon, lunar-orbit insertion, and transearth injection (placing the spacecraft on the homeward path) on the return voyage. Weight penalties forbade a second propulsion system; the service module engine had to carry its own built-in reliability.9
To allow time for studying and solving propulsion system problems and to prevent program delays, NASA managers shuffled the launch sequence. Since AS-203 was not scheduled to carry a payload, it would be flown before AS-202. Billed as a launch vehicle development flight, the third Saturn IB was to place its S-IVB stage in orbit for study of liquid-hydrogen behavior in a weightless environment.** On 5 July 1966, AS-203 was launched from Kennedy to insert the 26,500-kilogram second stage into orbit. Ground observers monitored the S-IVB by television during its first four circuits, watching the 8,600 kilograms of liquid hydrogen remaining in its tanks. Despite some turbulence, the S-IVB appeared capable of boosting the astronauts on a flight path to the moon.10
Mission AS-202 was twice as complicated as AS-201. It would last 90 minutes, reach an altitude of 100 kilometers, and travel two-thirds of the way around the world. Launched on 25 August, AS-202 had a host of objectives, but the focal interest was service module engine firings. With clockwork precision, the motor fired four times, for a total operating time of 200 seconds. After a steeper reentry than expected, the command module was plucked from the Pacific Ocean near Wake Island by the recovery forces ten hours after liftoff and placed aboard the U.S.S. Hornet. On the carrier, specialists found that the heatshield and capsule had come through reentry admirably.11
** The Saturn IB first stage differed from that of the Saturn I in that its eight engines had been uprated from 5.8 million to a total of 7.1 million newtons (from 1.3 million to 1.6 million pounds of thrust).
** Langley Research Center made another study of liquid-hydrogen behavior under zero gravity during 1966. On 7 June, Wallops Island crews launched a two-stage Wasp (Weightless Analysis Sounding Probe), carrying a 680-kilogram scale model of an S-II fuel tank. For seven minutes of weightless flight, television cameras mounted on a transparent tank transmitted data back to Wallops that added to the confidence of Houston engineers in launching AS-203 the following month.
3. Mueller to Admin., NASA, "Apollo Spacecraft Flight Abort Test, Mission A-004," 1 Dec. 1965, with enc., and "Apollo Spacecraft Intermediate Altitude Abort Test Mission A-004, Postlaunch Report No. 1," 26 Jan. 1966, with enc.; MSC, "Postlaunch Report for Apollo Mission A-004 (Spacecraft 002)," MSC-A-R-66-3, 15 April 1966; Milton A. Silveira, MSC, to Pinkney McGathy, "Program close out Little Joe II," 29 Oct. 1965; General Dynamics, Convair Div.,"Little Joe II Test Launch Vehicle, NASA Project Apollo: Final Report," 1, GDC-66-042, May 1966, pp. 1-18, 1-19, 8-1.
4. House Committee on Science anti Astronautics, Subcommittee on NASA Oversight, Apollo Program Pace and Progress: Staff Study, 90th Cong., 1st sess., 1967, pp. 705-06.
5. NASA, "NASA to Launch First Unmanned Apollo/Saturn," news release 66-22, 1 Feb. 1966, and "Project: Apollo Saturn 201," press kit, news release 66-32, 9 Feb. 1966; Mueller to Admin., NASA, "Apollo Saturn Flight Mission AS-201," 15 Feb. 1966, with enc.; MSC, "Post-launch Report for Mission AS-201 (Apollo Spacecraft 009)," MSC-A-R-66-4, 6 May 1966, pp. 2-1, 3-1, 3-2.
6. MSC, "Postlaunch Report for AS-201," pp. 12-4 through 12-6; Melvyn Savage to Dir., Apollo Prog., "A/S 201 Hold," 3 March 1966.
7. MSC, "Postlaunch Report for AS-201," pp. 2-4, 5-6.
8. Ibid., p. 11-1; Owen E. Maynard TWX to James E. Webb and Gilruth, "MSC Flight Status (3-Day) Report for Apollo Spacecraft Mission AS-201 (SC-009)," 1 March 1966; NASA. "First Apollo Saturn Flight Objectives Achieved," news release 66-51, 7 March 1966; Mueller to Admin., NASA, "Apollo Saturn Flight Mission AS-201, Post Launch Report No. 1," 8 March 1966, with enc.
9. Aerojet-General, "Dan David, Manager, Apollo Program, Space Systems Division, Liquid Rocket Operations, Aerojet-General Corporation," biography, April 1964; Cecil R. Gibson, Neil A. Townsend, and James A. Wood, "History of the Apollo Service Propulsion Sub-system," January 1970.
10. NASA, "Saturn IB Launch Schedule Is Revised," news release 66-78, 4 April 1966; "Apollo Saturn Set June 30 at Cape Kennedy," news release 66-142, 4 June 1966; and "Project: Saturn Apollo Uprated Saturn (Second Mission)," press kit, news release 66-157, 21 June 1966. Mueller to Admin., NASA, "Apollo-Saturn Flight, Mission AS-203," 22 June 1966, with enc., and "Apollo-Saturn Flight Mission AS-203, Post Launch Report No. 1," 15 July 1966, with enc.; NASA, "WASP Launch Tests Hydrogen Fuel Sloshing," news release 66-147, 7 June 1966.
11. Mueller to Admin., NASA, "Apollo Saturn Flight, Mission AS-202," 19 Aug. 1966, with enc., and "Apollo Saturn Flight Mission AS-202, Post Launch Report No. 1," 1 Sept. 1966, with enc.; Clarence A. Syvertson, ARC, to MSC, Attn.: Gilruth, "Preliminary examination of Apollo Command Module on Flight Mission AS-202," 22 Sept. 1966, with enc., Glen Goodwin to Dir., Ames Research Center, "Preliminary Report on Apollo Spacecraft Flight AS-202 Recovery Operation," 20 Sept. 1966; MSC, "Postlaunch Report for Mission AS-202 (Apollo Spacecraft 011)," MSC-A-R-66-5, 12 Oct. 1966.