Physics 5 / History 177                                           Fall1997/ Spring 1998

The Nuclear Age: Its Physics and History

Profs. Gary R. Goldstein and Martin J. Sherwin


Strategic Defense Initiative and ABM

How to defend against nuclear weapons - the Triad, cruise missiles, tactical weapons and sabotage.

I. ABM and SALT I

  1. Nuclear missile defense against incoming RV's
    1. Defending silos to preserve retaliatory ability (Safeguard)
    2. Defending population centers (Galosh)
    3. Countermeasures
      1. Decoys to confuse tracking and targetting
      2. Proliferating to overcome defense (cost?)
    4. Treaty forbade new development and testing in space - limited deployment to 2/country
      1. Costly
      2. Ineffective for cities since 100% coverage needed
  2. System requirements
    1. Detection of launches via satellite long range radar or early warning system
    2. Tracking via shorter range satellite based radar or ground based radars that look at horizon
    3. Projecting trajectories with computers on-line
    4. Coordinating ABM launches and targetting with more short range radar
    5. Medium and short range nuclear missiles (nuclear for explosion within 2 or 3 Km to "kill" target with gamma's)

II. SDI or Star Wars (over $40 billion so far)

  1. System requirements are the same, but technology advanced "to meet the challenge"
    1. microelectronics and third generation nuclear weapons
    2. satellite basing and high power directed energy weapons in development - booster phase interception
      1. lasers
      2. kinetic kill weapons
    3. fast burn solid fuel interceptors
  2. Problems - see transparencies
    1. Proliferation
    2. Decoys
    3. Fast burn boosters
    4. Untested software
    5. Cost of placing hardware in orbit (heavy duty rockets or atomic powered rockets - atmospheric test ban?)
    6. Complexity
    7. EMP vulnerability
    8. Space mines, debris, ASAT
    9. Destabilizing
      1. First Strike threat
      2. "Enhanced deterrence"
    10. No protection against short range or tactical weapons, cruise missiles or sabotage

III. G[lobal] P[rotection] A[gainst] L[imited] S[trikes]

  1. Limited goals still require full earth coverage by KEW's or "Brilliant pebbles" (with relative computer autonomy) and two layered
    1. Expensive to deploy on satellites - up to 5000
    2. Complexity not an order of magnitude less
    3. ASAT, space mines, still problems
    4. Detection and acquisition as extensive as old SDI
  2. Problems
    1. Short range attacks on neighboring countries escape detection
    2. Autonomy leads to fratricide
    3. Encourages rapid deployment and preemptive strikes
    4. EMP
    5. Sabotage
    6. Pressure triggers of enemy missiles

IV. A laser calculation - how energetic and how many lasers would need to be in orbit to have a chance of stopping a full contingent of MIRVed ICBMs?

  1. ~20KJ/cm2 to fracture ICBM booster
  2. Diffraction limited lasers (100 MW for HF laser, enormous power for N.Bomb)
  3. Encounter time makes up for power shortfall, but limits effectiveness of any single laser
  4. t(accessable)/t(encounter) = no. of shots for 1 laser
  5. no.of targets/no. of shots per laser = no. of lasers
  6. 1/5% coverage factor -> no. of laser platforms in orbit

V. New BMD (92) or NMD (94), THAAD and Navy Wide Area Defense (97-...)

  1. Large scale - strategic capable
  2. Theater weapons - the myth of the Patriot Missile
  3. "Demarcation" negotiations (Sep.97) and reactivation of ABM Treaty
    1. TMD vs. Strategic MD
      1. 6 US systems, 4 true Theater Defenses
      2. THAAD and Navy Area Wide Defense (~2000)
      3. 2.6 Km/s and 4.5 Km/s for interceptors
      4. Intercept targets of 5 Km/s (intermediate) or 7 Km/s (Long range)
      5. Large "footprint" (Testing continues at Kwajalein Test Range Facility)
    2. SBIS-Low (sattelite based infrared sensors in low orbit) or "brilliant eyes" - violation of ABM treaty by being nationwide (not area) detection and tracking system
    3. NMD (Clinton's 3+3 plan) 20 interceptors in 2000 and 100 in 2003 - violation by being national defense rather than area defense
  4. START II in jeopardy (ABM violations and NATO expansion) in Russia