Chapter 1
1-1 Introduction
Purpose The purpose of this reference text is to provide information on space systems and their use as they relate to U.S. Army operations. The intended users are U.S. Army commanders, staff officers and Noncommissioned Officers, students attending Army courses of instruction and their instructors. The format and contents are intended to provide the reader a central reference as to the environment of space, the capabilities of U.S. and foreign space systems and how they can impact on U.S. Army operations at strategic, operational and tactical levels.
Scope The scope of this book is intended to provide the reader with a fundamental level of knowledge of space and space systems. It is also intended to be a single reference source. Information on U.S. space systems and those of other nations and organizations is included. Classified information has been excluded to allow wider dissemination and access.
Overview Throughout its history, the U.S. Army has adopted new technology only after it has been proven to be clearly superior and to significantly enhance combat power. The evolution of space capabilities into Army operations has been compared to the incorporation of the airplane into the Army. At first the airplane was only used to provide messenger service in rear areas. Many officers were of the firm opinion that the Army had no need for the airplane because it was not a ground system. Today, it would be unthinkable to go into combat without aircraft, both fixed wing and rotary wing, in support of ground operations.

Space systems are undergoing this same evolutionary process but with less fanfare than aircraft because they are out of sight and, with few exceptions, unmanned. Since the first U.S. artificial satellite was launched in 1958, hundreds of billions of dollars have been invested to develop and place into operation a large number of satellites capable of performing many different functions. New or improved systems are continuing to be developed as technology provides increased capabilities and as users demand more support.

Today, satellites provide essential capabilities in communications, reconnaissance, surveillance, positioning and navigation, weather monitoring and forecasting, environmental monitoring, mapping and geodesy.

In many cases, soldiers have used the capabilities and products of space systems without even being aware they are doing so. For example, many long distance international phone calls are transmitted over satellites without the user's knowledge. Maps are routinely updated with data acquired from satellites. Maps of specific areas have been updated just before and during operations with information provided by satellites. Accurate weather data, especially in enemy controlled areas, is often only obtainable from space systems.

The U.S. Army and its sister services are not the only military organizations with the ability to use space systems in support of their operations. Almost every country has access to communications satellites. Many nations use data from the LANDSAT and SPOT multispectral satellite systems and also MOS­1 and JERS­1 radar satellites. Civil weather satellites transmit images and other data without encrypting the signals so that they can be received by anyone with the appropriate radio receiver and a facsimile machine. The U.S. military must take advantage of all available resources to retain its qualitative advantage. This requires that the Army have soldiers who are familiar with the space environment and the capabilities of space systems to be able to use them to their advantage in the conduct of operational missions.

Recommended Changes This document was prepared by Space Division, HQ TRADOC. Recommended changes should be submitted on DA Form 2028 to: Commander, U.S. Army Training and Doctrine Command, ATTN: ATCD-HS, Fort Monroe, VA 23651-5000