(Editor’s Note: With the conclusion of the seven scheduled Surveyor flights, Hughes News asked Program Manager Bob Sears to assess the significant contributions of the program to engineering technology and their possible applications in the future. Herewith, his answers).
Design Concepts’ Basic Soundness Held Prime Gain
The many outstanding contributions of Surveyor to the nation’s space program can be divided into two principal categories. First, the scientific findings of the character of the moon and secondly, the engineering technology required to send a spacecraft a quarter of a million miles and land it accurately and softly on the unknown lunar surface.
The basic soundness of the system design concepts developed early in this decade must be cited as the principal contributor to the success. Among these concepts are:
- A commandable-type spacecraft which responds to ground commands rather than the onboard spacecraft computing system has been proven. This feature could never be accomplished without an RF system performing flawlessly for the command and communication links. During the transit period, more than 5000 commands were sent and successfully executed by the spacecraft.
- This feature also provided flexibility by using the ground intelligence to correct problems. For example, it was possible to reprogram the terminal descent, which saved the Surveyor V mission, and to effect the first lunar repair when on Surveyor VII the surface sampler maneuvered the alpha-scattering instrument to the surface when it failed to deploy.
- The completely automatic terminal descent was another key feature. The closed loop functioning of the radars, flight control system, and propulsion was proved out both on earth with our T-2 Holloman tests and on the five successful lunar touchdowns. These features have direct applications to other type spacecrafts, such as those going to the nearby planets, Mars and Venus.
- This combination of a retro solid-propellant engine and throttling vernier engines for propulsion has been proven. On the five flights the command usage of the vernier to execute pinpoint mid-course corrections, provide stabilization during retro firing, and then continuously throttle for final flare-out has been amply demonstrated.
- Another feature was the ability to perform these many complex functions at minimum weight. For example, the basic structure weight is only 65 pounds, which is remarkable when one considers that the Surveyor at the time of touchdown is over 600 pounds. Minimum weight was also accomplished by Hughes techniques of electronic packaging and by small gage harness wires and connectors.
- Another feature is the temperature control for the spacecraft. A minimum of active electrical heating was required. Instead, super insulation, thermal switches, and unique paint patterns were used. Temperature control through the rigors of space and lunar environment was provided by the more reliable passive method.
- The above represents only a few of the design features which were keystone in the Surveyor success. It is also fitting to cite the ground test program as a vital factor. By long and exhausting environmental tests simulating all of the conditions during flight and after landing, the spacecraft was in a sense burned in and thus qualified for its flight mission.
All of the above has been of tremendous benefit to our space planners’ understanding for accomplishing extraterrestrial missions.
So much has been written on Surveyor findings on the moon that it is probably inappropriate for further comment here. Fundamentally, it has been learned that the lunar surface is benign in terms of executing manned landings, providing that a proper moonport has been selected.
Additionally, the program has yielded a wealth of scientific data which can be studied for years for clues on the origin of the universe. When man lands on the moon he will find his Surveyor predecessor already resting in position to welcome him.