### Navigation (Global Positioning)

The military mission of navigation is as old as history itself, and space based navigation is nothing more than the latest method to answer the question, Where Am I? Again, like tactical communications, the Navy pioneered the use of satellites to determine locations on earth, with its Transit system, which became our country's first operational military space system. The Navy's prime requirement was to provide position data to its ships and submarines. The first Transit launch was in 1960, was fully operational by 1964, and was widely used by both the Navy and commercial shipping. It gave location in two dimensions (longitude and latitude) with an accuracy of 200 feet. The only drawback to this system was that it did not give altitude or velocity which made it not very useful for high speed aircraft. In 1964, both the Navy and the Air Force began studies investigating how to upgrade and improve the system to give three dimensional coordinates with velocity and time. The Navy program was called Timation, for Time Navigation, and envisioned a constellation of 21 to 27 satellites in a medium altitude orbit (8 hour orbit) with improved atomic clocks. In fact, the Navy launched two Timation satellites in the late 1960s to test the improved features of their system. The Air Force version was 612B with a proposed constellation of 20 satellites at a geosynchronous orbit. The ability of this system was ground tested at White Sands Proving Ground during the early 1970s, and showed position accuracy of 50 feet. However in 1973, DoD directed that a joint program office for space based navigation be formed with the Air Force as the lead military service. Colonel Bradford Parkinson (USAF) was selected as the first program manager with the given charter to develop a joint initial concept and gain DoD's approval to field the system. What evolved was a system that used the best of both, using the signal structure and frequencies of 612B and the medium altitude orbits and number of satellites similar to those of Timation.

Originally the constellation was to have 21 satellites in three orbital planes, but this was later expanded to 24 in six planes of orbit. This would be the largest single constellation of spacecraft controlled by the military. GPS start was authorized in December 1973, and was acquired in three phases. The first phase, validation of the GPS concept, occurred in the 70s. This included building Block I navigation satellites along with a prototype control segment. The first four Block I satellites were launched in 1978, four years after initiation of the program. This permitted full scale testing from Yuma Proving Grounds in Arizona using aircraft, helicopters, tanks, jeeps, and with ships at sea. The Defense Department authorized full scale development in 1979. Navstar GPS would not realize its full potential for another 10 years and would include a war.

### Space Infrastructure and Organization

A complete space system consists of five different segments to be fully functional. They are:

1. a space segment (the satellite you want to orbit, or interplanetary probe you launch for exploration)
2. a ground segment (the place where you talk to satellites - this can be either a common user or mission unique system)
3. a communications segment (the means for talking between the space and ground segments)
4. a launch segment (the rocket to put your satellite into orbit, or beyond)
5. a user segment (the people who want the data gathered by your satellite - in the space business, this segment is considered the most important since they control the money)

By 1970, many of these segments were completely operational for military systems, with many undergoing upgrades to improve their performances. Many military space missions (the space segment) were established in the 1960s such as reconnaissance (Corona), navigation (Transit), weather (DMSP), nuclear detection (Vela), and communications (IDCSP). Other missions had begun concept or developmental testing such as early warning (MIDAS). Many more systems became operational or had began development in the 1970s such as early warning / nuclear detection (DSP), strategic communications (DSCS II), tactical communications (FltSatCom), and navigation (GPS). Two crucial segments, the ground and communications, underwent vast improvements in the 1970s to increase their capabilities. The military ground segment was called the Air Force Satellite Control Facility or AFSCF. It consisted of a centralized command and control center (the Satellite Test Center or STC) located at Sunnyvale AFS, California and seven Remote Tracking Stations or RTSs, located through the world. It was the communications segment that connected this dispersed group of RTSs with the STC, first by land lines, radio stations, and submarine cables in the 1960s, leading to communications among this group of facilities by satellites (DSCS II) by the end of the 1970s. By the beginnings of the 1970s, Cape Canaveral AB in Florida was the main launch site for military satellites going into geosynchronous or equatorial orbit, while Vandenberg AFB in California became the launch site for satellites going into polar orbit. Both sites in Florida and California could handle most types of launch vehicles including Thor, Atlas, Deltas, and Titans with numerous combinations of upper stages.

The irony of this whole situation was that since the prime function of the Air Force was to fly and fight with aircraft or strategic nuclear war with bombers and ICBMs, the new mission of space was left to the research, development and acquisition community of the USAF. Therefore from 1959 with the first launch of Discoverer I from Vandenberg AFB to the activation of Air Force Space Command in 1982, Los Angeles Air Force Base, first known in the 1960s as Space Systems Division then Space and Missiles Systems Organization (SAMSO) in the 1970s, had become a defacto operational command for military space systems. As Dave Spires in his book BEYOND HORIZONS says, "...organizational developments enhanced the control of a research and development command over space systems that were becoming increasingly operational."

Nicholas M. Short, Sr. email: nmshort@ptd.net
Jim Rosalanka (jrosolanka@worldnet.att.net)