The NASA tracking and data acquisition networks continued to carry a substantial workload. They supported more than 50 NASA-launched missions, 11 of which occurred during this period. The major ones included Apollo 11 and 12, Orbiting Solar Observatory (OSO) 6, Applications Technology Satellite (ATS) 5, and ESRO-1B, a cooperative project of NASA and the European space research organization.

Apollo 11 was the highlight of the reporting period, and the many years spent in constructing and equipping the Manned Space Flight Network to support the lunar landing mission proved worthwhile during this flight. In addition to providing the accurate tracking and communications support necessary to insure astronaut safety, the network enabled hundreds of millions of persons to share, via live television, in that historic venture.

Also during the period, the Deep Space Network supported the encounter phases of Mars by the highly successful Mariner 6 and 7 missions, launched February 25 and March 27, 1969, respectively. The preliminary analysis of the scientific data acquired from the twin spacecraft has significantly enhanced man's understanding of the atmosphere and surface of Mars.

MANNED SPACE FLIGHT NETWORK

On July 16, the manned space flight network began in-flight support of the Apollo 11 mission. The experience gained supporting the Mercury, Gemini, and previous Apollo missions resulted in a flawless performance by the network facilities and operating personnel. Voice communications were excellent; few persons will

ever forget the clarity of Astronaut Armstrong's voice as he said, "Houston, Tranquility Base here. The Eagle has landed."

With successful completion of the Nation's objective of landing a man on the moon and returning him safely to earth, the Apollo schedule was revised to a lower launch rate, and the network configuration was reviewed to see if selected reductions in facilities could be achieved without comprising the astronauts' safety. The demonstrated capability of the Apollo launch vehicle and spacecraft to adhere to planned mission timing resulted in a decrease in the previously required support flexibility, and significant changes in the network configuration were possible for the Apollo 12 mission (fig. 6-1). NASA found that only one of the national range tracking ships would be required for Apollo 12 and subsequent missions, and that the requirements for Apollo aircraft could similarly be reduced from eight to four. The reduced geographical coverage requirements also permitted the withdrawal of two 30foot-diameter antenna land stations, those on Grand Bahama Island and Antigua, from the support of Apollo.

The success of the Apollo 12 mission highlighted the vital role of the network in support of the manned lunar landing program. As

Astronauts Pete Conrad and Alan Bean began their descent to the lunar surface, the network transmitted and received real-time flight control data between the Lunar Module (LM) spacecraft and the Mission Control Center, Houston, Tex. An extremely important portion of these data was a correction to the descent trajectory. The data were fed into the onboard guidance system and corrected the descent trajectory in real-time as the spacecraft headed for the lunar surface. The correction enabled the LM to make a "pinpoint" landing in the Ocean of Storms, within about 600 feet of the Surveyor 3 spacecraft.

The network was continuing its support of the Apollo 12 mission by monitoring the Apollo Lunar Surface Experiment Packages (ALSEP) left on the moon's surface. The future lunar landing missions will also carry ALSEP's and will increase significantly the workload on the network.

The network facilities also supported NASA unmanned flight projects and certain missions of other Government agencies (the latter support usually comes during the launch phase of DOD projects such as the Minuteman III and Poseidon vehicle tests.)

NASA COMMUNICATIONS SYSTEM

The NASA Communications System (NASCOM) is a worldwide network of operational lines and facilities which interconnect the mission control centers, launch areas, test sites, and the foreign and domestic tracking stations. It consists of circuits leased from the domestic and international common carriers which include land lines, underseas cable, high frequency radio, and communications satellites. (Fig. 6-2.) The NASCOM provides communications service in support of all NASA flight programs, as well as programs of other agencies as mutually agreed.

During the reporting period, the communications satellite service costs were reduced significantly because of the reconfiguration of the Manned Space Fight Network. As noted earlier, the demonstrated capability of the Apollo spacecraft and the Saturn V launch vehicle permitted the release of all but one instrumentation ship. With the elimination of the Indian and Pacific Ocean ships, communications satellite service and back-up high frequency radio service to these areas were discontinued. Further, the revised Apollo launch schedule permitted the satellite service to the Atlantic Ocean ship to be reduced from full-time to part-time service.

The satellite network continued to support a wide variety of scientific and applications flight programs. In addition to the NASA programs, the network supports the space efforts of other Government agencies, private industry, and foreign governments as well.

The support is provided through the electronic facilities of the Space Tracking and Data Acquisition Network (STADAN), operated under the management of the Goddard Space Flight Center. At the end of the reporting period the STADAN consisted of facilities at 10 U.S. and foreign locations (fig. 6-3) and a centralized control center at the Goddard Center, Greenbelt, Md. The station locations are as follows:

United States

Fairbanks, Alaska

Goldstone, Calif.
Fort Myers, Fla.
Rosman, N.C.

Foreign Countries
Canberra, Australia
Santiago, Chile

Quito, Ecuador

Winkfield, England

Tananarive, Madagascar

Johannesburg, South Africa

This list respresents a decrease of three stations from the preceding report period. Changing flight program requirements and substantial budget reductions resulted in station closures at Toowoomba, Australia; St. John's, Newfoundland; and Lima, Peru.

The NASA STADAN stations are supplemented by Baker-Nunn and geodetic camera stations operated by the Smithsonian Astrophysical Observatory. This optical support is financed by a research grant from NASA to the Smithsonian Institution.

The network supported six spacecraft launched during the period and more than 40 satellites launched earlier. The six launches included ATS-5; OSO-6; ESRO-1B, a cooperative project of NASA and the European Space Research Organization; and INTELSAT III F-5, a communications satellite of the ComSat Corp. Also during the period, the network completed its support of the Biosatellite 3 flight. By maintaining constant contact with the spacecraft, the network was able to terminate the mission early when problems arose with the onboard primate. Although the mission was aborted short of its scheduled flight of 1 month, the results obtained were quite important.

Emergency support was required from the network for the Applications Technology Satellite, ATS-5. Shortly after its August 12