ulating the vacuum of space. Following the completion of these tests in mid-June, the LM and CSM were mated in preparation for transfer to the VAB.

The launch vehicle flight hardware began arriving at KSC in mid-March, and in late May the three stages and the instrument unit were erected on the mobile launcher in the VAB. Tests were conducted on individual systems on each of the stages, and on the overall launch vehicle in readiness for spacecraft erection. The spacecraft was transported to the VAB on June 30, and spacecraft erection was in progress with completion scheduled for July 1. Development Testing

The successful Apollo 9 and Apollo 10 missions mark the completion of all development flight testing required for a lunar landing mission. Ground testing during the first half of 1969 was being done to complete the remaining tests to certify spacecraft hardware for manned space flight, and to resolve performance anomalies which occurred during Apollo 8, 9, and 10 missions.

Command and Service Module.-Development tests for the CSM were conducted, structural tests to qualify the probe and drogue assembly for CSM/LM docking before the Apollo 9 mission were completed, and the command module chute loads test was carried out.

The window frames of the Apollo 9 CSM were modified to eliminate the fogging effect encountered during the flights of Apollo 7 and 8. Results of a ten day thermal-vacuum test showed that the new post cure cycles, used on the Apollo 9 CSM window frames, will preclude fogging.

Lunar Module.-The LM development tests were conducted, and propulsion tests certifying both the ascent engine and the descent engine for Apollo 10 and Apollo 11 missions were completed.

Tests were conducted to determine plume impingement characteristics of the reaction control system on the lunar module structure during the lunar descent phase. As a result of these tests, plume deflectors were installed on the Apollo 11 LM.

Tests to duplicate the pressure drop in the lunar module descent engine regulator manifold during the Apollo 9 mission confirmed the theory that this condition was caused by air introduced during ground servicing of helium. Accordingly, NASA established a new loading procedure to eliminate the introduction of air during this operation.

In preparation for the Apollo 11 mission, a series of LM drop tests was conducted to study the dynamics of the LM and the performance of subsystems at lunar touchdown descent rates.

MANNED SPACE FLIGHT

Launch Vehicle.-Development effort concentrated on investigating and resolving the launch vehicle anomalies which occurred during the Apollo 8 and Apollo 9 missions. The most significant of these was the oscillation of the center engine of the S-II stage on its supporting thrust structure. This is similar to but less severe than the POGO oscillation of all 5 engines experienced on the S-IC-2 stage of Apollo 6.

After a thorough evaluation of the S-II oscillation, engineers proposed to eliminate it by an early center engine cutoff of the Apollo 10 S-II stage (S-II-5). A full duration static test was conducted on the S-II-8 stage at the Mississippi Test Facility (MTF) in April, with an early center engine cutoff simulating the operating condition for the Apollo 10 S-II stage. During this test, the center engine was free of the undesirable oscillations and was not subjected to excessive thermal environment. Based on these favorable test results and a transient loads analysis, an early center engine cutoff was approved for the Apollo 10 S-II stage, and the procedure proved successful on the mission.

Early center engine cutoff has one drawback, however; it reduces the payload capability since the total thrust is reduced during the latter portion of the S-II burn period. An alternate method of damping S-II center engine oscillation, which will not require the early center engine cutoff, uses a pneumatic accumulator in the center engine liquid-oxygen feedline. An accumulator was being installed on the S-II-10 stage for evaluation during static firing in September.

The S-IC-6 and the S-IC-7 were delivered to KSC in February and May, respectively, and the S-IC-8 was delivered in June. The S-IC-9, and S-IC-10 were shipped to MTF for static firing acceptance testing, then returned to Michoud for checkout and preparation for delivery to KSC. Stages S-IC-12 through 15 were in various phases of assembly at the factory during this period.

The S-II-6, S-II-7, and S-II-8 after post static firing checkout and installation of modifications, were delivered to KSC. The S-II-9 and S-II-10 were at MTF for static firing acceptance testing and post firing checkout. Stages S-II-11 through 15 were in various phases of manufacture and assembly.

S-IVB-507 and S-IVB-508 were subjected to test firing checkout and shipped to KSC. S-IVB-509 was removed from storage, subjected to static firing acceptance testing, prepared for shipment to KSC, and placed in storage. S-IVB-510 was shipped to the Sacramento test facility in June for static firing acceptance testing, and

stages S-IVB-511 through 515 were in various phases of fabrication and assembly or modification.

S-IU-507 was checked out, retrofitted, retested, and delivered to KSC in May. Assembly checkout of the S-IU-508 in March and April was followed by retrofitting and retesting. Component assembly of the S-IU-509 was completed in May, and checkout was in progress. Stages S-IU-510 through 512 were in various stages of fabrication and assembly.

Extravehicular Mobility Unit.-Thermal vacuum tests were completed with the Apollo 9 crew and the Apollo 11 crew, using the extravehicular mobility unit (EMU). (Fig. 1-12) The EMU consists of the extravehicular suit, oxygen supply, and all other equipment needed to provide life support for a four-hour mission outside the lunar module without replenishing expendables. The equipment operated properly, and the crew was able to function. satisfactorily for simulated mission conditions. Tests to qualify improved arm bearings were completed in May. The bearings were incorporated in the extravehicular suit for the Apollo 11 crew to provide increased mobility.

ALSEP EASEP.-Qualification testing of the Early Apollo Scientific Experiment Payload (EASEP) was completed in April. EASEP, for Apollo 11, is a modification of the Apollo Lunar Surface Experiments Package, the full lunar experiment package for Apollo 12 and subsequent Apollo missions. Since so little is known of the endurance and mobility of man in the lunar environment, a primary objective of the Apollo 11 lunar walk will be to evaluate the capabilities and limitations of the astronauts. For this reason EASEP was developed. During an EVA demonstration, the Apollo 12 astronauts deployed the EASEP successfully. In June, the scientific investigators and the Apollo 11 astronauts conducted a successful simulation of the EASEP activities, ranging from the data plans and procedures to the use of facilities. ALSEP I was delivered to KSC and installed in the Apollo 12 spacecraft in June.

Lunar Exploration

Each success of the early Apollo missions increased the probability that a lunar landing can be achieved with significantly fewer than 15 Saturn V space vehicles. The number 15 had been established early in the program to provide reasonable assurance that the program objective of a lunar landing would be achieved. Achievement of the lunar landing as early as Apollo 11 would provide the opportunity for exploiting the investment and the

capability of the Apollo Program for continued lunar exploration. The remaining Saturn V vehicles and associated spacecraft are well into production and are being delivered to support the planned requirements to achieve the first lunar landing. With an early landing, this hardware could provide the basic system for a significant lunar exploration program.

Recognition of such an opportunity led to comprehensive studies, starting in early 1969, to define this lunar exploration phase of

Apollo and to plan for an orderly transition, including phasing down specific contractual efforts following the successful first lunar landing. Once this national goal has been achieved, NASA's aim is to conduct the lunar exploration phase at the rate of approximately three launches per year.

Through exploring the moon, NASA hopes to increase the scientific knowledge required to improve understanding of the solar system and its origin, including clues to the origin of life; and to evaluate potential exploration of the moon for its natural resources and as a base for lunar and other planetary exploration. The Agency also hopes to gain experience in space operations, such as in logistics support for man on a distant planet; and to develop a greater capability for exploration.

Space Suit

Astronaut mobility is a key element in effective manned lunar surface exploration and will ultimately be achieved by using Lunar Rovers. In the near term, however, significant gains can be made by improvements in the space suit. Changes in the current space suit were incorporated to make it easier for the astronaut to move about on the lunar surface. The suit will provide greater comfort, reduce fatigue, and have the durability to resist the abrasion and wear inherent in longer periods of extravehicular activity.

Portable Life Support System (PLSS)

Improvements in the current Portable Life Support System to increase its ability to support life while the astronauts remain outside the Lunar Module for longer periods are being studied.

Lunar Module Improvements

LM modifications being considered include enlarging the descent propellant tanks to improve LM flexibility in reaching selected sites, and adding water and oxygen tanks, batteries, and crew provisions to increase LM staytime capability from 36 hours to approximately 3 days. The latter would also improve habitability. Lunar Orbital Science

The CSM has a potential for obtaining valuable scientific data while in lunar orbit. Also, the Service Module has an empty bay which can be used to carry the instruments needed for acquiring this scientific data from the lunar surface. A variety of scientific