There are other defensive architectures that we are studying. In particular we are looking at defenses that are based on the ground and whose defensive components, be they sensors or directed energy weapons or interceptors, are popped up and make ABM intercepts in space, but are terrestrially based. We have studied these defenses less. We believe they are-they are promising also and we continue to study them.

In particular, we believe they are highly survivable and even though their performance levels are lower, we believe their cost could also be lower and, therefore, they themselves, could be quite cost effective.

Finally, we are also paying considerable attention to the question of defense of our allies to the theater range missiles that threaten them. We are looking at specific configurations that are capable of supporting that notion.

Senator BINGAMAN. You do agree that first category you are looking at the most is by far the least survivable?

Mr. GARDNER. We do not believe it is by far the least survivable, no, sir. We believe we will be capable of defining these systems in such a way that they will be adequately survivable.

We also believe that that technical problem will be more difficult in this case. Although difficult, we think it is achievable.

Senator NUNN. In your architecture can you visualize at this date, and I know it is a long term question, can you visualize two countries having that kind of survivable defense up there in space? Mr. GARDNER. Yes, sir, we can.

Senator NUNN. Both of them would be survivable?

Mr. GARDNER. Yes, sir, we can.

Senator NUNN. How far have you gone on that model?

Mr. GARDNER. We are just beginning to understand that, in all honesty. I think General Abrahamson will speak to that question.

General ABRAHAMSON. I will talk about some specific survivability contexts that can be deployed for systems in space, satellites, but are very difficult to be deployed for missiles traveling through space or coming from the upper atmosphere.

The key here is that we really must find the place where the fundamental advantage is with the defense or the place you deploy the system. That is not an easy search.

Unlike all too many who have already concluded, based on their concept of what satellites look like today, and what satellites might be limited to in the future, I just do not accept the idea that that is inherently not survivable.

Mr. GARDNER. Let me conclude my discussion with a brief summary of some of the first broad characteristics of a defense configured in this way and then speak briefly to some of the more detailed examples of such a defense system configuration.

The next chart summarizes in conceptual terms, the way in which such a defense would operate. The attacker is coming from here, is coming into the North American Continent here, and the defenses are configured with a number of basic components summarized in this chart.

[Chart deleted.]

First, there are two classes of defensive weapons in this architecture. One identified here as a space-based kinetic kill vehicle and the other one as a ground-based directed energy weapon operating with a two-mirror relay. Those are the two defensive weapons that are capable of operating in this defense in order to make intercept in the boost and postboost phases.

The kinetic kill vehicles are capable of making intercept in the midcourse phase, those that are located in orbit separate from the ones that happen to be over the Soviet Union at the time attack

occurs.

In addition to these two space-based defensive components, there are also interceptors based on the ground in the vicinity of the location that would be under attack and these include both a longrange interceptor capable of making exoatmospheric and high endoatmospheric intercept as well as a low altitude interceptor operating within the atmosphere.

So, there are four weapons in this system. These weapons are supported by several sensors. One of the key sensors is a space surveillance and tracking system [SSTS] located in medium Earth orbit that is capable of doing surveillance against all objects that come into space as well as doing surveillance of rockets against the harder Earth.

It provides attacking information for intercept against the boost, postboost, and midcourse phases.

There are also two other sensors in this system, one is an airborne sensor system that contains optical sensors similar to this optical sensor program, providing surveillance of the residual of threatening objects that have not been destroyed as a result of previous defense action.

We envision this airborne sensor system as being on a platform orbiting at high altitude, 50,000 or 60,000 feet, and deployed around the periphery of the defended region.

Finally, there is a ground-based radar that works in conjunction with this airborne optical sensor system to support these later phases of the defensive system.

Senator BINGAMAN. The underlying assumption here is that the Soviets would launch a missile attack without first taking out any of our space-based assets; is that right?

Mr. GARDNER. That is not correct. In fact, the next chart allows me to speak directly to the question.

This identifies the concept against which we are operating. We have at least an example of a design that is consistent with this concept in which we have gone through and configured the defense system and another to a considerable level of detail.

[Deleted.]

So, the defensive system has been configured to handle just that kind of circumstance.

What we have shown here and what this summarizes is some of the numerical quantities and general design characteristics necessary to handle that size threat. [Deleted.]

So, this is an example of a very aggressive defense system configuration that we believe is capable of performing to a very high level of effectiveness in the face of a very large attack.

Senator BINGAMAN. Is it fair to say you are assuming no attack on our space-based vehicles by any of their space-based vehicles in this example?

Mr. GARDNER. No. We are assuming that there would also be a potential attack [deleted] that could directly threaten our weapons. We have not yet done calculations on an attack on their part of space-based components specifically configured against this defense except in the following sense.

[Deleted.]

Senator NUNN. You are assuming [deleted] on both sides, or something like that?

Mr. GARDNER. [Deleted.]

Senator BINGAMAN. [Deleted.]

Mr. GARDNER. [Deleted.]

Let me conclude this discussion with some brief observations on what we have found about this process.

I again would like to caution you that these are conclusions that we have reached at the early portion of our study. We have a lot of work yet to do. Nevertheless, we believe that we are beginning to understand some of these issues better.

For example, we believe that defenses that are capable of intercept in the boost phase are very important. This is especially the case against very large threats under the assumption that offensive arms control is not successful and the defensive system has to be capable of handling very large threats measured in the tens of thousands.

We believe that the ground-based terminal and midcourse defense can operate, but it requires we solve the problem of midcourse discrimination. The midcourse region of the flight of an ICBM is a region in which a large amount of time is spent, with the threat coasting through space at high velocity.

The defense performance is greatly increased if it is capable of efficiently attacking in that region. In order to be able to do so, we

have to be capable of solving this midcourse discrimination problem. We believe we have promising concepts to do that.

SYSTEM ARCHITECTURE STUDIES
KEY OBSERVATIONS

• BOOST PHASE LAYER NEEDED FOR LARGE THREATS

GROUND-BASED TERMINAL AND MIDCOURSE DEFENSES
CAN PROVIDE SUBSTANTIAL DEFENSE CAPABILITY WITH
MIDCOURSE DISCRIMINATION

• BOOST, POST-BOOST AND MIDCOURSE DEFENSES
COMPLEMENT EACH OTHER

• TERMINAL DEFENSE CAN:

REDUCE OVERALL LEAKAGE

- DEFEND AGAINST DEPRESSED TRAJECTORY SLBMS

As we have looked at these defenses, we have found that boost, postboost and midcourse defenses complement each other. That is in those cases where the boost-phase defenses operate better, it relieves some of the stress on midcourse defenses and in fact makes the discrimination problem, we think, somewhat simpler.

There are important synergisms that we believe can be exploited here.

Finally, the terminal defense systems are the last phase of the defenses to operate. They generally are the ones that we understand the best technically and they are important for two significant reasons.

They are the things that establish and reduce the overall leakage of the system, we believe, to potentially very low levels. Especially they have to be capable of offering defense against the first trajectory ICBM.

In this respect, these defenses look similar to theater defense of tactical ballistic missiles that threaten our allies. We believe there is a goodly amount of synergism between terminal defenses that operate in our own favor and terminal defenses that operate in support of our allies against shorter range missiles that threaten them.

Senator NUNN. What assumption do you make here about how much of this information has been shared with the Soviet Union? General ABRAHAMSON. Of the specifics or what?

Senator NUNN. The whole question. You have made a very, very big assumption about their countermeasure not being effective against our defenses and they not being able to knock down our defenses.

Obviously, if you are sharing data, sharing technology and you are jointly working on the countermeasures, it would be much more forthcoming.

Have you assumed they know all the essential details of our system in projecting their own countermeasures, or have you assumed they do not know how our system really operates?

General ABRAHAMSON. Obviously, we are assuming from a military viewpoint that there are parts of the program that have to be intact, absolutely effective clearly.

Now, the question on sharing. There are lots of different kinds and ways in which you can share. It might be worthwhile to talk about one and it is here now. I am not suggesting this is the way one would share.

Senator NUNN. You are assuming that we are able to keep our key technology secret in this?

General ABRAHAMSON. Yes.

Chairman GOLDWATER. Thank you very much.

Senator WARNER. I am told that Mr. Gardner in his presentation did not put quite the emphasis as he did with me in previous discussions on the significance of the layered defense.

Could you amplify on that?

Mr. GARDNER. Let me briefly summarize the point. As we have looked at and attempted to understand the ways in which directed energy weapons operate in these defenses, we have found that they have some real strengths that we address now and our understanding of those strengths can probably best be summarized by appreciating the degree to which those directed energy weapon concepts can have very high defensive firepower.

Because the defense systems operate with directed energy weapons at the speed of light, what happens is that the amount of time required for a directed energy system to operate and destroy a missile is very short, on the order of one second or less.

We are looking for directed energy weapon concepts that can destroy a target within a quarter of a second or so and we are looking for sensor systems that can recognize that that weapon has been destroyed and slew to another weapon in three-quarters of a second maximum.

So, the total time that will be required for a directed energy weapon to destroy a target is very short, on the order of a second. Now, since a ballistic missile flies during its vulnerable boost and postboost phase for tens of seconds in the most extreme case and hundreds of seconds in the case of existing ballistic missile systems that threaten us now from the Soviet Union, not only the ones they have now, but the ones that are in their R&D chain, it means that the defensive system, utilizing directed energy weapons, can have a very large number of potential layers operating in this boost phase. The exact number, of course, depends on the configuration of defense and configuration of the attack, but the number can potentially be very large.

We look at that as a significant advantage that this emerging technology provides us. We have to find ways to exploit this advantage even more aggressively than we have already.

Senator WARNER. In other words, the seven layers provide seven engagement processes?

Mr. GARDNER. Yes, sir.

Senator WARNER. General Abrahamson, I understand you have a chart presentation. Then we will turn to questions.