8. Letter From the Special Advisor to the President for Science and Technology (Press) to Secretary of Defense Brown1

Dear Harold:

Attached is a report prepared by the Office of Science and Technology Policy Space Advisory Group on the anti-satellite issue. Their [Page 27] recommendations are that the US acquire an electronic as well as a non-nuclear interference capability. In light of current discussions, you will likely find the report of interest. This group also has completed its review on space based radars that you requested.2 I will forward this report to you separately.

Yours sincerely,

Frank Press3


Memorandum From the Chair of the Advisory Group on Space Systems (Buchsbaum) to the Special Advisor to the President for Science and Technology (Press)4


  • US Anti-Satellite Capability

The growing Soviet use of satellites for military functions has heightened the need to revise US policy with respect to a US anti-satellite capability. The Group believes that the Soviets should not be allowed a one-sided sanctuary in space for critical space systems that directly support their military forces. [4 lines not declassified] These systems would be appropriate targets for attack under some conditions. The number and types of such space systems are expected to grow.

The Group believes it is undesirable for the US to remain incapable of interfering with Soviet militarily-related space-systems, particularly those space systems which would constitute a direct threat to Allied forces during a conflict. These satellites are limited in number and at low altitudes. [5½ lines not declassified]

[2½ lines not declassified] However, we believe that the most effective way to assure the survival of valuable US space assets in time of crisis is, first, to reduce through appropriate technical measures the electronic and even the physical vulnerability of US satellites and, second, to have substantial alternative mission capabilities for the con[Page 28]duct of war. Approaches for achieving greater survivability were addressed in NSDM 333.5 The Group believes that expeditious implementation of enhanced survivability measures for critical space assets should be given high priority.

There are two broad alternatives for an anti-satellite capability: (1) physical destruction or damage, and (2) electronic interference.

[4 lines not declassified] However, such a capability is likely to be perceived as more provocative than electronic interference for two reasons: (1) its effect is irreversible and unambiguous and (2) the political consequences of its use are likely to be more severe. Moreover, such a physical destruction system is likely to be more expensive than an electronic interference system.

Physical damage by radiation such as laser, microwave, or possibly particle radiation has characteristics somewhat intermediate between explosive kill and electronic interference. Its effects would not be reversible, but could be ambiguous and the political consequences less severe than in the case of explosive kill.

The Group recommends that first priority be given to developing an early capability for electronic interference. Different satellites have vulnerabilities to different electronic warfare techniques. The generic techniques which may in principle be employed include noise jamming, deception, command link capture, uplink jamming, delayed repeater jamming, and RF burnout of electronic components. Not all of these techniques can be employed effectively against all satellites. Some of these techniques would be realized most effectively with co-orbital jamming satellites, while others could be best achieved from ground-based jammers. Specifically, some types of radar, ELINT, and navigation satellites could be negated by another satellite nearby which emits a noise barrage or rebroadcasts their signals with small random time delays.

Since the operation of many satellite systems is dependent on the frequent receipt of commands from ground stations, command link capture or jamming represents a particular vulnerability of satellite systems. The possibility of interfering with this link depends strongly on the altitude of the satellite. The command link of a low altitude satellite, such as a photo-reconnaissance satellite, is normally only turned on to receive when the satellite is over the Soviet ground station and is out of view of possible jamming sites. As a result, it is more difficult to interfere with low altitude satellites than it is to interfere with satellites in synchronous operational orbit which are always in view.

[Page 29]

The Group cautions, however, that the operational problems associated with electronic interference must be carefully controlled. US testing of such a capability can compromise its effectiveness and would be provocative if exercised against Soviet systems.

[1 paragraph (11 lines) not declassified]

In general the nature of the US development program should be influenced by potential arms control agreements as well as military requirement. However, in this case it may not be easy to negotiate a useful and verifiable agreement limiting anti-satellite activities. It is not clear what kind of agreement would be in the US interests. Given the nature of present assets, it would seem that an agreement that would limit both the US and the Soviet Union to low-altitude ASAT capability would be desirable. Such an agreement may be difficult to reach at present. In contrast to the Soviets, we have no low altitude intercept capability while their high altitude space assets are more limited than ours. In addition, because of the limited number of targets, there is no real distinction between an effectively deployed ASAT system and one that is still in the test stage of development. Further, the Group does not believe that it is practical to obtain a verifiable and useful agreement limiting electronic interference. These various factors must be clearly and fully understood before entering into negotiations on ASAT limitations.

[1 paragraph (5½ lines) not declassified]

This target list places enormous technical and operational demands on a US system. The size and composition of the targets and the time requirements imply a substantial system deployment including non-conus basing, in the southern hemisphere. While the Group is not in a position to present a definitive target list, we believe a more modest system aimed at the critical military threat is appropriate. [2½ lines not declassified]

The size of this target set and the time requirements must, of course, be reassessed as the composition of the Soviet satellite fleet evolves.

A system aimed only at low-orbit interception is also suggested by the fact that a demonstration of a high-altitude capability by the US would encourage the early development of a similar capability by the USSR. This would negate the current US superiority of high altitude. In summary, proceeding with development of a low-orbit intercept system is appropriate. The decision to undertake flight testing at a suitable time in the development cycle should consider the status of arms control negotiations or agreements. At present, it would be premature to develop or demonstrate a high altitude intercept capability.

  1. Source: Washington National Records Center, OSD Files: FRC 330–80–0017, Box 56, 471.96 (Aug–10 Nov) 1977. Secret. A stamped notation at the top of the page reads: “SEC DEF HAS SEEN.” In the upper right-hand corner, Brown wrote “9/10. AF should also get a copy. HB.”
  2. Not found.
  3. Press signed “Frank” above this typed signature.
  4. Secret. The date is handwritten.
  5. See footnote 15, Document 6.