A complex effort unequaled in space communications is being undertaken by Collins Radio Company in designing and building the Communications and Data system to be carried aboard the Apollo spacecraft. Apollo will carry three U. S. astronauts for the first U. S. voyage to the moon.

Communications in terms of human language and electrical language are vital to the success of this mission throughout all phases of the flight, including prelaunch, launch, earth orbit, flight to the moon, return to earth, and recovery.

This effort, while similar to the Collins role in the Mercury program, is many times more complex and advanced. It involves a research and development effort which is the largest in the company's history.

Under the terms of its more than $40 million contract from North American Aviation's Space and Information Systems Division, Collins plans for the Communications and Data system for Apollo include electronics equipment for the following functions:

Voice Communications
During the entire course of the flight mission, it will be necessary for the astronauts and ground personnel to talk to each other. Two types of equipment are used, one for near-earth communications while the spacecraft is in orbit around the earth and one for deep space communications while the spacecraft is en-route to the moon.

Intercommunications
A four-position spacecraft intercommunications system will enable the astronauts to converse with each other within the spacecraft while in their G couches or while moving around inside the spacecraft.

Telemetry Equipment
In order to transmit operational and scientific information back to earth, a complex pulse code modulation (PCM) telemetry transmission system will be used. This system will permit the monitoring of approximately 400 sensors throughout the spacecraft. Radio transmission links will include transmitters for both near earth and deep space transmission.

Television
A "real time" television system will be provided for transmissions of pictures from the spacecraft back to earth. Due to the limited amount of radio frequency power aboard the spacecraft, this television system will be an advancement in the state of the art to permit transmission of an acceptable picture with a minimum amount of power. At present, Collins has two of the nation's top companies in television assisting in the study of this problem to arrive at an optimum system.

In addition to the "real time" television system, a closed loop television system will be provided to permit viewing of external and remote sections of the spacecraft during the flight.

Data Storage
A data storage or tape recorder facility will be provided for those periods when direct communications to the earth will not be possible because of the location of the earth-based communications facilities and during the periods when the spacecraft is behind the moon.

Tracking and Ranging
In order to keep the earth tracking stations fully informed of the spacecraft's exact position during the near earth and lunar transit phase of the mission, equipment will be provided to determine angle, range, and Doppler velocity. This information obtained by the earth stations may be transmitted back to the crew on the spacecraft supplementing on-board navigational systems for crew determination of their position.

Rescue Equipment
While it is planned to bring the spacecraft back to earth at a pre-determined point, there is a possibility of over-shoots and mission aborts in which the spacecraft would be brought down at points other than the planned landing. Rescue voice and beacon equipment are of several varieties and are provided so that ground based, seaborne or air-borne rescue complexes can obtain radio bearings on the spacecraft and communicate by voice with the crew to effect an immediate rescue.

Specific equipment to be supplied for the Apollo program by Collins includes the following:
• HF Single Sideband Transceiver - Voice communication
• VHF AM Transmitter-Receiver - Voice communication
• VHF FM Transmitter - Orbital telemetry transmission
• "S" Band Transmitter-Receiver - Voice, telemetry, television, tracking
• PCM Telemetry System-Telemetry
• Data Storage System - On board re-cording
• Television System - Moon to earth and closed circuit TV
• C Band Transponder Beacon - Tracing
• VHF Pulse Beacon - Rescue direction finding
• Intercommunications System - Astronaut's phone
• Controls and Displays - Astronaut's controls for the entire system
• Discone Antenna and Multiplexer - For all VHF radio equipment
• "S" Band Antenna - For "S" band transmitter-receiver
• Ground Support Equipment- For check-out of entire system

In order to provide the most flexible, reliable, and maintainable equipment, the entire system will be designed an "Integrated Modular Concept." This means that the various black boxes will be built according to a standard set of dimensions and that each black box will have a series of modules for the various electronic circuits. These are centralized in the spacecraft in a standard electronics installation rack and may be easily removed for repair and maintenance.

All vital modules will be carried as spares aboard the spacecraft and by means of an inflight test and maintenance system, the astronaut will be able to locate trouble in the individual module and replace the defective one from the spares carried aboard. This will be a significant factor in increasing the reliability of the equipment. The use of the "Integrated Modular Concept" also permits ease of updating the system.

Another important factor in increasing the reliability of equipment will be in the provision for cooling. Apollo uses a unique liquid cooling system in which the individual space electronics packages (SEP) are mounted on plates which have liquid circulating in them. This is an innovation since in past installations, the cooling has been accomplished largely by cold plates. This "Integrated Modular Concept" was pioneered by Collins several years ago in its application to the CNI systems and later in the mock-ups for specific space application which pointed the way for the present Apollo concept.

As in any space mission, environmental performance of the electronics equipment on board the Apollo craft will be essential toward mission success. Each flight phase of the program will have differing requirements. During the launch phase, vibration, shock, and acoustical noise will be of paramount importance. During the orbit, lunar flight, re-entry, and landing phases, temperature, pressure, and shock will be serious problems.

The two most serious problems are vibration and temperature. The vibration problem will be solved by throughbolt construction which compresses all the modules in the space electronics package and holds them as a rigid structural member, prohibiting excessive build-up of vibrations. Use of foam encapsulation will also assist in solving this problem. It is anticipated that the liquid cooling approach will adequately solve the temperature problems.

As in Project Mercury, reliability of the equipment is a paramount factor.

Realizing that a failure in the communications equipment would jeopardize the safety of the crew and compromise the mission performance, Collins has formed an Apollo reliability team to insure that no aspect is overlooked in this area.

In addition to the equipment to be supplied for the Apollo spacecraft, Collins is responsible for development of the ground support equipment (CSE). This will include a complicated array of bench maintenance racks which will check out each part of the telecommunications system. The ground support equipment will be used during Collins' manufacturing and testing phases of the program as well as at Space & Information Systems Division of North American Aviation, Inc. and at Cape Canaveral and other field sites.

The complexity of this equipment approaches the complexity of the equipment being developed for the spacecraft and is a substantial portion of the Apollo program at Collins.

In addition, a systems test equipment console will check out the complete installation of communications equipment in the Apollo spacecraft at the system level. The system test equipment will be of the semi-automatic type and will provide a complete read-out of the operating parameters of the communications and data system to establish proper performance levels through-out the various phases of the Apollo program.

All three of Collins' major divisions and a team of 10 to 15 subcontractors will be involved in the development of this equipment. The Apollo Project Office is located in Cedar Rapids and is headed by Dr. S. E. Watson. R. J. Pierce is the Technical Director of the program. The Collins Dallas Division will participate in antenna development and in special studies of the ground operational support system. This work is under the direction of A. J. Svien. In Newport Beach, California, the Collins Information Science Center will head a team working in the digital data aspects of the system. This work is headed by R. R. Mosier, Director of Research.

Dr. Watson pointed out that this very complex space program presents a tremendous challenge in management and engineering to accomplish the job successfully. Pierce stated that the scope of the project is so complex that it involves practically every communication discipline now utilized in the art of transporting human and electrical language over radio links. He also stated that it will take a technical effort on the part of Collins and its team of subcontractors far above anything ever attempted in the field of space communications.