Missle Defense & 1980s SDI

The current idea is to “shoot a bullet with a bullet”. What happened to the older idea of using lasers to shoot down incoming missiles? In other words, why did SDI (“Star Wars”) fail? Was it because the targeting was not accurate/fast enough? Or the lasers were not powerful enough?

Also, would a laser based shield necessarily be space-based or could such a defense be ground-based?

I recently read an article in Time (yea, I know…) that indicated there were four methods under consideration:

  1. Ground-based missile (apparently the cheapest since some research has already been done)
  2. Sea-based missile (an extension of AEGIS)
  3. Air-based laser (747’s with a huge laser in the nose)
  4. Satelite-based laser (classic SDI)

Seeing as how financial considerations are more important on this go-around, I expect that’s why option number 1 is the one being pursued more than the others.

Not meaning to hijack but… I think the more interesting question is why we think it would be successful this time around when during the 80’s everyone in the know was fully aware SDI wouldn’t work–it was a ploy to either get the Soviets to strain their resources or use as a strategic bargaining point. Has the technology improved so much that the system would be feasible now?

I think it’s wishful thinking, and always was.

I was aghast when I heard Reagan’s March 23, 1983 sppech proposing SDI. “This man must know something I don’t,” I thought. So, apparently, did a lot of other people, including members of his administration. I now know what he knew at the time – chiefly Edward Teller’s “Excalibur” laser system (atomic bomb-pumped X-ray lasers).

In truth, there never was a well-defined SDI plan – there were a lot of proposed systems, all with their pros and cons. It made for interesting and slippery debates between the pro- and anti-SDI camps, because you could criticize or promote one aspect of one system and have your opponent retailate by talking about a completely different system.

As far as I can see (and I’m not an arms control expert, but I’ve got a doctorate in Laser Physics) none of these systems was practical. And no matter what anyone says, I don’t believe that the Soviets were spooked by our “technological end run” – some of the most incisive criticisms of the system came from the Russians. (So did the revolutionary quadrupole magnet that some proposed using for neutral particle beams.) To believe that the Russian leaders didn’t believe their own experts is to attribute an astonishing degree of stupidity to them. It’s not a good idea to assume your opponent is stupid. I have yet to see a scrap of evidence that fear of SDI is one of the things that caused the fall of the Soviet Empire by making them spend themselves into bankruptcy, but this seems to be the advancing mythology.
Although there were some impressive gains for laser-based systems, I don’t think they were impressive enough to show that we had a viable system in hand. When MIRACL (the Mid Infra Red Advanced Chemical Laser) blew a strapped-down booster full of water into oblivion in one shot, it was impressive. Some critics said that stressing the tank was not necessary, but it DID simulate the strain on an in-flight booster. I wondered myself how far away the laser was – the news reports didn’t say, and for all I knew it was just off-camera. It turns out to have been a kilometer away, which is impressive, but a tiny fraction of the distance away a space-based laser would have been from its targets, Laser beams, despite what you may have heard, DO expand with distance. Once you’re more than a confocal parameter away the beam area spreads out with the square of the distance, so distance is a BIG factor.

Then there’s the issue of directing the beam. Proponents of SDI say that ablative coatings won’t help your missile – the beam’s blast effects will still damage the surface. Making the missile shiny won’t help either, as small defects will be damaged by the laser beam. So what is that beam going to do to your directing mirror, which is so much closer, subject to a smaller (and therefore more intense) laser beam, and is going to hit “hit” several times in rapid succession? We’ve had our lab lasers destroy themselves in just this way.

Then there’s the problem of supplying power to the laser – Chemical Lasers would themselves have to be big tanks of gas. Nuclear lasers violate treaties, and are untrustworthy to boot.

I suspect that “Smart Rocks” (which somewhere along the line became “Brillliant Pebbles”) won out because they avoided these problems. They were a workable relatively low-tech solution to the problem.

This is probably on the fast track to GD, but here’s my $0.02.

mrblue92 wrote:

Comparisons to '80s era SDI against the USSR who had a sizeable nuclear arsenal aren’t really applicable today.

Strategic missile defense wouldn’t be aimed at an opponent with a reasonable number of nuke-packing ballistic missiles. It’s aimed at the countries that have just a few nukes and ICBMs to go with them.

Say you’ve got Country X that’s built a few nukes and went out and bought some missile technology and put together a half dozen ICBMs but otherwise is a feeble conventional military threat. Say Country X has got a beef with the US. The US doesn’t really want to be in situation where Country X is able say, “Pull back your forward deployed troops or carrier task force, or we’ll nuke it or a city of our choice.”

Of all the options being investigated, it seems to me that a sea-based missile system is the most strategically desirable and the most technically feasible. Given a good radar system and a fast missile, it should be possible to intercept ICBMs in boost phase when they’re fat and slow and unable to take evasive courses. Interception in space or on descent is much more problematic and has to deal with decoys, MIRVs and the like.

A sea-based system may not even require the US to abrogate the ABM treaty. Nobody got raised much of a ruckus over the Patriot and it was capable of shooting down theater missile threats. Upgrade the ‘Aegis’ platform with new radar and a fast, long-ranged missile and call it ‘Aegis II’ and let its capabilities be known. Countries that possess a miniscule nuclear missile arsenal will have to think twice about nuclear blackmail with an Aegis II cruiser parked offshore.

The airborne laser system could also be used against missiles in boost phase but has some big practical drawbacks. The reach of the system is limited by the planes range. To get the system to the trouble spot would likely require overflight and basing permission from other countries and that can’t necessarily be counted on in a crisis. Planes can’t stay on station for extended periods as ships can.

Andrew Warinner

The number of missiles isn’t the problem… the OP was referring to laser based systems, and as Cal points out, the technological difficulties are still there.

I won’t claim to know for certain that the ploy was successful, but I’m sure you realize there is frequently a disconnect between the people who make the decisions and the people who understand the technology. You may be right, but the sources I’ve read indicate the Soviet political leadership was seriously frightened by SDI, so much so that Reagan’s refusal to give it up crashed the Strategic Arms Reduction Talks (START) in '86. I’m curious to hear from the experts…

It’s either admit that SDI caused the fall or admit that the Communist system is inhertantly faulty, something liberials (progressives?) don’t like to here. They are caught between a rock and a hard place on this one. But that’s just my humble O :wink:

Also the ABM treaty (IIRC) was signed be reps of the US and USSR - problem is that the USSR: 1 violated that treaty ( I believe they did but can’t remember, maybe someone can help me out) 2 DOES NOT EXIST ANYMORE

even if 1 is not true (or can’t be proved) 2 spells out to me null and void

I think option #2 is no good, too. Russia and the other former Soviet nuclear powers are the succesors-in-interest to the ABM Treaty. I’m no lawyer, but I think that the treaty still holds full weight. I seem to recall that Shrub has already noted that it would require the Senate to abrogate the terms of the treaty, indicative of a formal withdrawal from the treaty’s terms.

Anyway, there are some excellent reasons why the missile v. missile option is being pursued over the laser option.

First, most military lasers are hypergolic lasers; they use the energy of a chemical reaction to create the beam. That massive energy output is nowhere close to 100% efficient, which means that the chemical reaction chamber must vent. The vented exhaust in creates a huge problem because it throws off the equilibrium of the firing platform, and it has to happen while it is firing, or the reaction chamber will explode. I don’t know much about Teller’s directed energy nukes, but I’m willing to bet that there are similar potential problems. Remember, throwing off a laser beam by as little as a millimeter at the source can translate to a miss at 120 kilometers. Even if hypergolic venting problems are solved, lasers are completely unforgiving, at the whim of any random vibration.

Second, in the late 1960’s, we already had a missile-based ABM system in the works. It was a nuclear anti-ballistic missile system, but it still had to get close to the target, and it was showing good results shortly before the ABM treaty was signed. Therefore, creating a missile v. missile system is a matter of refinement rather than ground-up invention. A nuke anti-missile still needs to get within a few kilometers, a Patriot-style AA missile needs to get to within a few meters, a solid hit needs to get within a few centimeters. Technology in miniaturization and accuracy has increased exponentially, so meeting the parameters probably seems possible to some people.

I suppose the bottom line might be summed up like this: we know to aim rockets on the fly; we don’t know how to make a moving–and maybe not even a stationary–firing platform stable enough for lasers.

By happy coincidence, this was discussed just a few days ago:
Soviet Union Legal Question

It may spell out null and void to you, but to the US and Russian governments, the matter’s not quite so simple.


k2dave: To tell the truth, even though I’m a liberal type, it doesn’t bother me to say that the Soviet system was flawed.But I think you’re wrong to limit things to those two alternatives. History isn’t as inevitable as some people think. The North could have lost the Civil War if one or two things had been different, no matter how many factories and railroads they had.

Mrblue92: Yes, the Soviets backed out in Reykyevik, but they had lots to be afraid of in Reagan’s pursuit of SDI, even if there wasn’t a chance in heaven of creating a plausible, workable Star Shield. He was essentially suggesting militarizing space, possible putting nuclear sources (and, for all they knew, bombs) in orbit. The Excaliber system, as publicly pushed, would require the US to have subs patrolling near the Soviet coastline, armed with “pop-up” “third generation” nuclear devices that were supposed to pump x-ray lasers, but could certainly wreak other sorts of havoc. If he were to start depolying such things it wouldn’t matter if SDI worked at all as advertised – it would still be a scary prospect.

I’m still not at all convinced that this brought about the Fall of the Soviet Empire. That’s not cross-grainedness on my part, or affiliation to Leftist Ideals. I mean I literally haven’t seen anyone make a plausible case that the fear of Reagan’s programs forced the Russians to spend themselves into oblivion.

Point taken. I personally suspect it might have helped, combined with other, less visible factors, but I could be wrong.

I was re-reading a bit on Reykjavik last night–you might find this interesting… It seems that the bigger problem there was that neither Reagan or Gorby had a complete understanding of the ABM Treaty. Apparently Gorby wanted to allow SDI so long as the ABM Treaty was adhered to and SDI remained a “laboratory” project. Reagan got hung up on the word “laboratory”. Neither party realized the treaty allowed field testing so long as the system wasn’t deployable. Had it not been for this, the two might have agreed to get rid of the vast majority of nuclear stockpiles. (Of course trying to ratify such an agreement would have been an interesting proposition given the historical level of mistrust.)

(War and Peace in the Nuclear Age - John Newhouse)

k2dave wrote:

As I remember, the Reagan Administration got excited about the USSR building a large radar system at Krasnoyarsk.

Under the terms of the ABM treaty, both sides promised not to build “two large phased-array ABM radars comparable in potential to corresponding ABM radars” and “not to deploy in the future radars for early warning of strategic ballistic missile attack except at locations along the periphery of its national territory and oriented outward.”

The Krasnoyarsk radar was a large phased array radar and it wasn’t located on periphery of the USSR or directed outward.

The Reagan Administration choose to interpret this as a violation of the ABM Treaty, which it obviously was, but it is open to question whether the radar was to provide tracking and targeting data to the Moscow ABM system, thus being a substantive violation of the ABM treaty, turning it into an regional ABM system (as Reagan claimed) or just an early warning radar that was in technical violation of the ABM treaty (as the Soviets claimed).

Andrew Warinner

The current state of the art: Modern targetting systems are able to distinguish between a warhead and decoys with high accuracy… Provided that the warhead has a radio transponder on board broadcasting “I am the real warhead”. This is what proponents of the missile defense system call a “success”.

Our choices are to drop the program and be vulnerable to missiles, or to pump billions of dollars into the program, and still be vulnerable to missiles.

Chronos wrote:

Only if you’re trying to shoot 'em down in reentry.

I don’t think those are the only choices nor is it an accurate assessment of the threat missile defense is meant to counter.

Andrew Warinner

One out of three is high accuracy? Would that I were allowed to pay my taxes with such accuracy!

(By the way, I recognize that one of the two failures was in the propulsion system. For those of you who find that an important distinction, please contact me as I have a highly reliable car I’ll sell cheap.)