General comments on satellite navigation

1. At different places in this section, I have alluded to alternative ideas for navigation satellites. One, explained in “Navigation by Satellite” in Missiles and Rockets in October 1956, even talks of utilizing the Doppler shift for a navigation satellite. But this paper envisages almanacs and tables of posi­tion and calculations of the distance at closest approach. It implicitly assumes that the orbit would be known and, inevitably because it was written in 1956, does not account for the impact on orbits of Earth’s complex gravitational field, nor for the impact of the ionosphere on the received signal. The paper does envisage the use of computers, but not the sophisticated curve-fitting techniques of Guier and Weiffenbach.

2. “Possible Use of Syncom as a Navigation System—Microwave Loran.” Memo for files, From L. M. Field cc L. A. Hyland (НАС archives 1990-09 box 6 folder 22).

This memo argues that Syncom would make a better navigation satellite than Transit if the station keeping were adequate. It expands on a memo by Donald Williams (see communications section) written on September 1, 1959.