While the three armed services have separate and distinct roles, there are three things each must do. We call these megamissions. While two of these magamissions have future implications, they all require actions that must be done "today".
Megamission One: "Today"
Carry out the assignments given by the President and Congress.
Megamission Two: "Tomorrow"
Procure today the weapons systems needed to accomplish Megamission One tomorrow.
Megamission Three: "Day After Tomorrow"
Today identify and stimulate development of the technologies needed to accomplish Megamission Two tomorrow.
We have deliberately avoided precision in specifying the time scales involved, since those will change with specific weapons systems and missions.
Megamissions One and Two are uncontroversial. We dont believe Megamission Three is controversial either. It is sometimes left out in making plans because its the easiest to ignore, but of the three Megamissions it has a claim to be the most important of the lot. Its also the most difficult.
In 1920 the U.S. Army neglected Megamission Three: Those in control of military planning failed to recognize the growing importance of airpower in future conflicts. A few forward thinkers dissented; to them it was obvious that by 1940 airpower would be decisive. Their vision was proved correct when German air support overcame the French artillery defenses of the river lines long enough to allow armor to cross. France fell within 45 days of a breakthrough that simply could not have been achieved without airpower. From that time on air supremacy was an important, and usually decisive, element of military victory.
Spacepower today is similar to airpower in 1920: within 20 years space supremacy will be a decisive element of military victory on land or sea. The power that has access to space and can deny access to its enemy will have an advantage at least as great as air supremacy or sea supremacy.
Moreover, space supremacy can probably be converted to air and sea supremacy. As an example for discussion, consider the system this author has described under the name "THOR". Thor consists of orbiting steel rods perhaps 20 feet long by one foot in diameter. They contain minimal terminal guidance capability, and a means of locating themselves and their targets through GPS. They can strike fixed targets with CEP approaching 25 feet. Few elements of air and naval power are invulnerable to bombardment by kinetic energy weapons from space. No ship can withstand the impact of 20 feet of steel rod at velocities greater than 12,000 feet per second. Airfields wont fare much better.
The major cost of Thor and other more likely space bombardment systems is the launch cost. Thor also requires intact GPS and space observation systems. Costs of both are driven largely by launch costs. A great many potentially decisive weapons come to mind given low cost access to space.
Low cost access to space is a matter of technological development, not of breakthroughs. It takes about the same amount of fuel to fly a pound from Los Angeles to Australia as it does to put that pound in Low Earth Orbit (LEO). There is no intrinsic reason why space lift costs should exceed airlift costs by more than a small multiple, if at all. The United States is not the only nation capable of developing systems capable of routine economical access to (LEO), nor is there any reason to suppose that every nation that develops that capability will be devoted to peace. Space supremacy can be used as a powerful instrument of international blackmail.
In summary: spacepower will be as decisive in 20 years as airpower was in 1940, and development of key space technologies is as important for our future as development of aircraft technologies was in 1920. A vital element of future spacepower will be capability for routine and economical access to space.
Summary and Conclusion
THOR: Thor Odinson was the Norse God of Thunder. One of his missions was vengeance against those who harmed the Aesir, as well as recovery of any property stolen from them. The first practical Intermediate Range Ballistic Missile (IRBM) deployed by the United States was code named "Thor". That missile has long been retired from the inventory.
In 1964 Dr. Jerry Pournelle described a potential weapons system concept consisting of a guided orbiting element with terminal guidance. In 1975 he published a new and more complete description of the system that could have been deployed in the mid-1980's. The completion of the GPS (Global Positioning System) satellite system eliminated one of the largest expense requirements for deploying Thor.
The basic weapon system consists of an orbiting element some 20 to 40 feet long. It requires a GPS receiver to locate itself; a means of taking it out of orbit; an atmospheric guidance system, such as a means of changing its center of gravity (moving weights, small fins, etc.), and a communication system to give it a target and activate the system. No warhead is wanted or needed. Thor will impact a target area at about 12,000 feet per second; that is sufficient kinetic energy to destroy most hard targets, with minimum collateral damage and of course no fall-out. Achievable accuracy has been estimated at ten to twenty feet CEP.
CEP: Circular Error of Probability, sometimes called circular probable error. The radius of a circle inside which 50% of the missiles will fall. Published estimates of Minuteman accuracy at intercontinental range were about three hundred feet for a pure ballistic flight and no terminal guidance.
Intact Space Assets: Recent US Army war games startled game planners when the "Pink" player opened hostilities by sweeping US satellites from space. High altitude nuclear detonations removed a number of our satellites through ElectroMagnetic Pulse (EMP). The GPS satellites fly through the Van Allen Belt and thus are radiation hardened, but they too are vulnerable to other kinds of attack. Without intact space assets much of the US high technology capability vanishes in the first hours of the war.
Space lift costs: these are discussed in other papers. While the energy equivalence of air travel and rocket flight to orbit are not exact, they're close enough for first approximations. Airlines typically operate at a small multiple of fuel costs. There is no reason why spacecraft cannot do so as well. See my SSX papers in this series.
This Megamission is the easiest to ignore, but you ignore it at your peril.
See Stefan T. Possony and J. E. Pournelle, The Strategy of Technology: Winning the Decisive War, University Press of Cambridge, Mass., 1970; copies made for use by USAF Air War College by permission of the authors. Portions reprinted in articles by the authors and F. X. Kane. This book is now available as shareware on this web site.
Most important of the lot:
"A gigantic technological race is in progress. . . There are no battles in this strategy; each side is merely trying to outdo in performance the equipment of the other. It has been termed logistic strategy. Its tactics are industrial, technical, and financial. It is a form of indirect attrition; instead of destroying enemy resources, its object is to make them obsolete, thereby forcing on him enormous expenditure. . . .
A silent and apparently peaceful war is therefore in progress, but it could well be a war which of itself could be decisive." General dArmee Andre Beaufre, quoted in Possony &; Pournelle op. cit.
Note that this is a fair description of both the progress and end of the Cold War.
The exact mechanism of terminal guidance isnt important. You can change the center of gravity or use aerodynamic mechanisms.
See "Stability and National Security", a policy planning study prepared under contract to Headquarters, United States Air Force, Directorate of Doctrines, Concepts, and Objectives (AFXDOC), Pepperdine Research Institute, J. E. Pournelle Principal Investigator; USAF Contract F44620-67-C-0101, 1968.
Note that other technologies were also important: communications and electronics were vital elements in both the Battle of Britain and the Battle of the North Atlantic; either of those battles could have been decisive if lost. We do not here imply that access to space is the only important space technology USAF must assure, merely that it is one of the decisive elements most easily identified.