First Men on Moon

This series has eight easy 5-minute installments. This first installment: Launch.

Introduction
What stories in history are as important to human progress as this one? This story of the achievement is from NASA’s official report. Despite the dry writing style of this government report, the sheer drama of this story comes through.

This selection is from the Pilots section of the Apollo 11 Mission Report by NASA Mission Evaluation Team and by The Astronauts: Neil Armstrong, Edwin “Buzz” Aldrin, and Michael Collins published in 1971.  For works benefiting from the latest research see the “More information” section at the bottom of these pages.

NASA Mission Evaluation Team was responsible for pulling together all of the participants’ reports into one comprehensive report.

The Astronauts: Neil Armstrong, Edwin “Buzz” Aldrin, and Michael Collins were the crew of the Apollo 11 spacecraft.

Time: July 16, 1969
Place: Cape Canaveral

Prelaunch Activities

All prelaunch systems operations and checks were completed on time and without difficulty. The configuration of the environmental control system included operation of the secondary glycol loop and provided comfortable cockpit temperature conditions.

Launch

Lift-off occurred precisely on time with ignition accompanied by a low rumbling noise and moderate vibration that increased significantly at the moment of holddown release. The vibration magnitudes decreased appreciably at the time tower clearance was verified. The yaw, pitch, and roll guidance-program sequences occurred as expected. No unusual sounds or vibrations were noted during passage through the region of maximum dynamic pressure, and the angle of attack remained near zero. The S-IC/S-11 staging sequence occurred smoothly and at the expected time.

The entire S-11 stage flight was remarkably smooth and quiet, and the launch escape tower and boost protective cover were jettisoned normally. The mixture-ratio shift of the J2 engine in the S-11 stage was accompanied by a noticeable acceleration decrease. The S-11/S-IVB staging sequence occurred smoothly and approximately at the predicted time. The S-IVB insertion trajectory was completed without incident, and the automatic guidance shutdown yielded an insertion-orbit ephemeris, from the command module computer, of 102.1 by 103.9 miles. Communications between the crewmembers and the Manned Space Flight Network were excellent throughout all launch stages.

Earth Orbit Coast and Translunar Injection

The insertion checklist was completed, and a series of spacecraft systems checks disclosed no abnormalities. All tests of the navigation equipment, including alinements and drift checks, were satisfactory. The service module reaction control thrusters were fired in the minimum-impulse mode and were verified by telemetry.

No abnormalities were noted during preparation for translunar injection. Initiation of translunar injection was accompanied by the proper onboard indications, and the S-IVB propellant tanks were repressurized on schedule.

The S-IVB stage reignited on time at 2:44:16 without ignition or guidance transients. An apparent 0.5° to 1.5° pitch-attitude error on the attitude indicators was not confirmed by the command module computer, which indicated that the attitude and the attitude rate duplicated the reference trajectory precisely. (See “Guidance , Navigation, and Control” in section 8.) The guided cut-off yielded a velocity very close to that expected, as indicated by the onboard computer. The entry monitor system further confirmed that the forward velocity error for the translunar injection maneuver was within 3.3 ft/sec.

Transposition and Docking

The digital autopilot was used for the transposition maneuver scheduled to begin 20 seconds after spacecraft separation from the S-IVB. The time delay was to allow the command and service modules to drift approximately 70 feet prior to thrusting back toward the S-IVB. The separation and the beginning of transposition were on time. To assure a pitchup maneuver for better visibility through the hatch window, pitch axis control was retained in a manual mode until after a pitchup rate of approximately 1 deg/sec was attained. Control was then given to the digital autopilot to continue the combined pitch/roll maneuver. However, the autopilot stopped pitching up at this point, and it was necessary to reestablish manual control. (See “Guidance, Navigation, and Control” in section 8 for more discussion of the autopilot.) This control cycle was repeated several times before the autopilot continued the transposition maneuver. Consequently, additional time and reaction control fuel (18 pounds above the preflight nominal) were required, and the spacecraft reached a maximum separation distance of at least 100 feet from the S-IVB.

The subsequent closing maneuvers were made normally under digital autopilot control by using a 2-deg/sec rate and 0.5° deadband control mode. Contact was made at an estimated 0.1 ft/sec, without side velocity, but with a small roll misalinement. Subsequent tunnel inspection revealed a roll index angle of 2.0° and a contact mark on the drogue 4 inches long. Lunar module extraction was normal.

Translunar Coast

The S-IVB was targeted to achieve a translunar injection cut-off velocity 6.5 ft/sec in excess of that required to place the spacecraft on the desi red free-return trajectory. This overspeed was then cancelled by a service propulsion correction of 20 ft/sec at 23 minutes after spacecraft ejection.

Two periods of cislunar midcourse navigation, using the command module computer program (P23), were planned and executed. The first determination, at 6 hours , was primarily to establish the apparent horizon altitude for optical marks in the computer. The first determination was begun at a distance of approximately 30 000 miles; while the second determination, at 24 hours, was designed to establish the optical bias errors accurately. Excess time and fuel were expended during the first period because of difficulty in locating the substellar point of each star. Ground-supplied gimbal angles were used rather than those from the onboard computer. This technique was devised because computer solutions are unconstrained about the optics shaft axis; therefore, the computer is unable to predict if the lunar module structure might block the line of sight to the star. The ground-supplied angles prevented the lunar module structure from occulting the star, but were not accurate in locating the precise substellar point, as evidenced by the fact that the sextant reticle pattern was not parallel to the horizon. Additional maneuvers were required to achieve a parallel reticle pattern near the point of horizon-star superposition.

The second period of navigation measurements was less difficult, largely because the earth appeared much smaller, and trim maneuvers to the substellar point could be made much more quickly and economically.

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