DESTINATION MOON: A History of the Lunar Orbiter Program
 
 
CHAPTER VII: BUILDING THE SPACECRAFT: PROBLEMS AND RESOLUTIONS
 
Testing Procedures and Program Reviews
 
 
 
[156] One Important feature of the Lunar Orbiter spacecraft was that its design did not rely heavily upon...
 
[157] GRAPHIC
 
[158] redundant subsystems or components. Moreover, although the subsystems were integrated, they were not heavily interdependent and could function more independently of each other than the subsystems could in such spacecraft as Mariner. This design concept reflected Boeing's long standing traditions in aircraft, and it paid off handsomely.
 
The testing philosophy of the Lunar Orbiter was one reason the design proved to be so successful. Several kinds of tests and reviews were used in the program. First was the Preliminary Design Review, conducted by NASA and Boeing. This form of review was always held to check any specific technical area or major subsystem before a final decision was made to freeze the design. When agreement was reached, Langley gave Boeing permission to fix the design, and then both parties met to hold a Critical Design Review. In this review the item, whether a component or a major subsystem, was picked apart or passed as acceptable for fabrication and testing. If approved, the item was procured or fabricated, and after approval Langley tried to hold changes to an absolute minimum. During the fabrication stage, various forms of reviews took place until the item was completed and tested. At the completion point, a formal NASA [159] Acceptance Review was conducted.28
 
The Langley-Boeing testing procedure was aimed at making the first mission a complete operational success. The procedure played a vital part in the program and reflected the positive attitudes throughout the entire Lunar Orbiter Program team.
 
At the beginning of the whole testing sequence, all components of the spacecraft system went through a Flight Acceptance Test (PAT), which exposed them to "nominal"-or expected -vibration, temperature, and vacuum conditions of operational environments. Three sets of each component were then divided into sets A. B. and C for more specific tests. Set A was used for qualification tests simulating overstress conditions. This kind of test was designed to push the component beyond expected endurance limits to determine what punishment it could actually withstand. Set B underwent reliability demonstration tests that simulated two real-time missions at the FAT level. Finally, Set C components made up subsystem assemblies that were tested and then [160] integrated into a complete spacecraft (Spacecraft "C").
 
This first complete spacecraft system, minus the photographic subsystem, was subjected to compatibility tests with the Atlas-Agena launch vehicle; with the tracking and communications network at Goldstone, California; and with the Eastern Test Range tracking and communications facilities at Cape Kennedy.29 The idea to test the spacecraft for compatibility with the DSIF facility at Goldstone had been suggested by JPL; Langley accepted it, and testing proved to be very useful in establishing biases between the Lunar Orbiter communications subsystem and the DSIF receiving station.30 A test film was read out during dryrun exercises there to check the accuracy in the transmitting and receiving equipment.
 
Boeing built a total of eight Lunar Orbiter spacecraft for the program, including Spacecraft C. Following Spacecraft C came Spacecraft 1 and 2. Number 1 underwent qualification tests at spacecraft level while Number 2 was subjected to thermal vacuum tests for a period covering the duration of two missions. The other five Lunar Orbiters (3, 4, 5, 6, and 7) were put through Flight Acceptance Tests...
 
[161] (CHART)
 
LUNAR ORBITER TEST PROGRAM
 
[162] ...and then sent to the Eastern Test Range for their final checkout and launch. The chart below clarifies the sequence:
 
 

Spacecraft Number

C

1

2

3

4

5

6

7

Lunar Orbiter

Ground test

spacecraft

V

I

II

III

IV

Mission

E/5

A/1

B/2

C/3

D/4
 
 
Clifford H. Nelson pointed out to the participants of the XVIII International Astronautical Congress in Belgrade, Yugoslavia, that no serious problems or failures were experienced during all spacecraft-level tests in the program. This testified to the standards and the thoroughness which Boeing and Langley had used in testing at the component and subsystem level, and it also testified to the excellence of the spacecraft's design. Faulty equipment and poor designs had been effectively rooted out during the testing phase of the program when potential problems in subsystem integration had been exposed.31
 
More interesting, however, was the fact that Boeing and Langley had agreed early on testing in a parallel mode rather than in a series mode. Tight schedules and a spartan [163] economy were largely responsible for this. Thus, for example, the three sets of components (A, B, and C), Spacecraft 1 and 2, and the five Flight Spacecraft (3, 4, 5, 6, and 7 ) were tested in periods that substantially overlapped.32 Ira W. Ramsey headed a team of men in the LOPO which was responsible for the entire Lunar Orbiter testing program and for the success of the parallel mode despite its inherent risk.33