cerebus@bucsf.bu.edu (Tim Miller) (10/18/89)
From: cerebus@bucsf.bu.edu (Tim Miller) On the subject of SDI, there is one thing that bothers me. Why is it that 90% of the media's attention is focused on the use of lasers ar beam weapons instead of (IMHO, more feasable) 'kinetic energy' (KE) weapons? I have also seen this tendancy toward ignoring KE weapons in the scientists that are researching the weapons as well as those that are criticizing the initiative. Research _is_ being done in KE weapons, but _my_ impression of the work is that it is taking a back seat to beam weapon research. Is there something so attractive about a laser weapons system that scientists and laymen alike ignore the possiblility of the so-called 'smart rocks' and 'orbiting machine-guns' (sattelite linear accelerators throwing plastic pellets at about 7-10 miles per sec)? Beam weapons are a problem. The eat power; they break down easily (ask the guys with the NOVA laser-- it fires once, maybe twice a day); and are expensive to repair and maintain. Does this sound like a good defense system? On the other hand, a smart rock only has to be launched, preferrably in bursts, like a shotgun blast; yeilding a much better chance of striking the target (and the rock need only graze the missile; I read that it had been calculated that even a grazing impact at 10 mps [an average orbital collision velocity] is like setting off a hand grenade strapped to the stressed aluminum skin of an ICBM). Smart rocks could operate as a first line, taking out ICBMs at the end of their boost phase; linear accelerators could operate as a second line, pinpointing and shotgunning individual warheads. Even light plastic pellets 1cm in diameter gouge out craters in blocks of aluminum that are inches deep in tests carried out at 4mps-- much slower than what would be implemented. Ask anyone who hunts any kind of bird; they'll tell you that a shotgun is a better weapon for a flying target than _any_ rifle, no matter how good your aim. So why does the design philosophy of SDI seem to lean toward beam weapons at the near exclusion of all else? Timothy J. Miller cerebus@bucsf.bu.edu
jon@cs.washington.edu (Jon Jacky) (10/25/89)
From: jon@cs.washington.edu (Jon Jacky) > (Tim Miller asks) why does the design philosophy of SDI seem to lean toward > beam weapons at the near exclusion of all else? It doesn't. The SDIO calls beam weapons "directed energy weapons" (DEW). I recall reading that DEW work never took a majority of SDI funding, in fact in their heyday early in the program I think they were only getting about 20 percent. Kinetic Energy Weapons (KEW) --- "smart rocks" and all the rest --- always got a lot and in recent years have dominated SDI funding. Other SDI funding categories are SATKA (Surveillance, Acquisition, Tracking and Kill Assessmen,), Battle Management and Communications and a few others, which also get a lot. > Beam weapons are a problem That is the consensus view. In summer 1987 the American Physical Society produced a long report that was very critical of DEW. Some DEW proponents disputed some of its conclusions bitterly but it seems to have held up. A summary of the report and a lot of the debate that followed were printed in one of the big physics journals. Since then, DEW funding has been deemphasized. In a recent article in AVIATION WEEK the current SDIO chief, Monahan, said progress on DEW had been less than hoped. Hardly anyone thinks beam weapons are a realistic prospect in the forseeable future. > Research is being done in KE weapons, but _my_ impression of the work is > that it is taking a back seat to beam weapon research. Not so. KEW are getting much more money and attention. Early in 1988 the SDI described something called a Phase I architecture, which was supposed to be a plausible deployment plan. It was all KEW. The main components were two weapons called HEDI and ERIS, which are both *ground-based* KEW interceptors. HEDI and ERIS are essentially 1960's-vintage Safeguard and Sprint ABM boosters topped with new KEW upper stages, which are supposed to destroy incoming missiles by smashing into them, rather than with nearby (or not-so-nearby) nuclear explosions as the 1960's ABM's were supposed to do. Later in Phase I there were plans to deploy orbiting KEW as well, fairly large things grouped together in orbiting "garages". There was some talk of adding some DEW at some remote future time, but these were not really part of Phase I. None of this gear actually exists yet, though its in various stages of R&D. The SDIO estimated Phase I deployment would cost around $100 billion. Congrs' Office of Technology Assessment (OTA) estimateded $200 billion. In other words, forget it. Before he resigned last year, SDIO head General Abrahamson enthused about a new KEW scheme, "brilliant pebbles" (after "smart rocks"). The "Brilliant Pebbles" concept puts 100,000 or so small (~100 pound) satellites in orbit, each with its own rocket motor, sensors and guidance computer. Each one is supposed to detect disallowed enemy launches, then smash into any disallowed missiles with little or no control or direction from the ground. Abrahamson claimed such a system could be deployed for about $25 billion, which is within the realm of political possibility. Since this spring there has been a great deal of excitement about Brilliant Pebbles, and SDIO chief Monahan appointed several different expert panels to study the idea and report back whether the Phase I plan should be altered or replaced, or alternatively if Pebbles are not such a great idea after all, should be retained in more or less its original form. The panels are supposed to report back this November. > I have also seen this tendency toward ignoring KE weapons in the scientists > ... that are criticizing the initiative Not really. The 1988 study by the OTA was mostly a critique of KEW (and software, which is not specific to DEW). That report concluded that the whole $200 billion Phase I system might stop between a few and a small fraction of an enemy missile attack. > Why is it that 90% of the media's attention is focused on the use of > lasers or beam weapons? I wouldn't say it was 90%, although they are still reported out of proportion to their actual importance to the program. They were more important at the very start of the program and perhaps the impression just stuck. Initially there was a great deal of excitement over the X-ray laser invented at Lawrence Livermore Labs around 1982, which Edward Teller and his protege Lowell Wood were claiming (many have reported) would be able to take out the whole Soviet missile force, and which was ready (it is said they claimed) for engineering development. These early claims about the X-ray laser are often reported to have played a big role in pursuading Reagan to start the SDI program. The X-ray laser turned out not to be suitable for near-term development as a practical weapon, and in recent years Wood and Teller don't talk about it anymore, but have become just as enthusiastic boosters for "Brilliant Pebbles." A few media sources have fairly thorough coverage of SDI, in particular THE NEW YORK TIMES is the best. THE WALL STREET JOURNAL occasionally reviews SDI. TECHNOLOGY REVIEW occasionally has a good review and of course AVIATION WEEK reports about a lot of different SDI projects, although it doesn't really provide much in the way of overview. I don't see the WASHINGTON POST much but its probably okay. As for the rest, they are spotty; the occasional SDI story appears but things are not necessarily covered in proportion to their cost or importance. And also, beam weapons just seem to exert a grip on the popular imagination that nothing else can match! - Jon Jacky, University of Washington, jon@gaffer.rad.washington.edu
henry@zoo.toronto.edu (Henry Spencer) (10/27/89)
From: henry@zoo.toronto.edu (Henry Spencer) >From: jon@cs.washington.edu (Jon Jacky) >... The "Brilliant >Pebbles" concept puts 100,000 or so small (~100 pound) satellites in orbit... Correction: not 100 pounds, more like 100 *grams*. ("Pebbles", not "rocks".) Putting up 100,000 100-pound satellites would require the entire launch capacity of the *Soviet Union* for most of a decade. (US launch capacity is a joke by comparison.) One of the major selling points of B.P. is getting the weight of the individual interceptors down to the point where one can afford to launch massive numbers of them. Many of SDI's problems diminish greatly if interceptors are plentiful and need not be carefully conserved. Henry Spencer at U of Toronto Zoology uunet!attcan!utzoo!henry henry@zoo.toronto.edu
jon@cs.washington.edu (Jon Jacky) (10/30/89)
From: jon@cs.washington.edu (Jon Jacky) > Henry Spencer (henry@utzoo.toronto.edu) writes of the "Brilliant Pebbles" > scheme to orbit up to 100,000 100-pound antimissile satellites, > "Correction, not 100 pounds, more like 100 *grams* ("pebbles", not "rocks")" In the "Brilliant Pebbles" plan currently being studied by the SDIO, the pebbles are 100 *pounds*, not grams. Or at least that's how they were described in the flurry of news stories that appeared last spring. A NEW YORK TIMES story ("What's next for `Star Wars'? `Brilliant Pebbles'", William J. Broad, Tuesday April 25 1989, p. 19) includes an artist's conception of a "pebble", which the caption explains is about three feet long and weighs 100 pounds. The picture shows a torpedo-like object, which is mostly a tank of rocket fuel, with the sensor and "brilliant" computer stuck on the front. The picture is captioned, "Source: Strategic Defense Initiative." I think I recall seeing a photo of a model of that thing in AVIATION WEEK about the same time. Perhaps Henry is thinking of an earlier pebbles incarnation. At the SDI "fifth birthday party" in March 1988, Livermore weapons scientist (of X-ray laser fame) Lowell Wood rhapsodized about a pebbles scheme in which the satellites wieghed (or "massed") about 1.5 to 2.5 kilograms. However, when the pebbles scheme surfaced again, in former SDIO director James Abrahamson's "End of Tour" memo, they had become a lot bigger, and there were a lot fewer of them (from "100,000" in Wood's scheme to "thousands" in Abrahamson's memo). Then there is the version in the NEW YORK TIMES story, which probably represents someone's engineering judgment about what it would actually take to implement the proposed pebbles functionality with technology that is likely to appear in the next five or ten years. With "pebbles" as with other SDI schemes, it is quite difficult to distinguish the actual projects that the SDIO is devoting significant money and effort to from the many concepts, ideas and notions that are floated about, which are hardly more than people speculating out loud. It is not unusual for different versions of a scheme referred to by a single name to differ by several orders of magnitude in important technical characteristics. > (Henry notes that the launch requirements for orbiting large numbers of > the larger-version pebbles are prodigious) Indeed, that is a problem. > Many of SDI's problems diminish greatly if interceptors are plentiful and > need not be conserved But others do not, and additional problems are implied by filling low earth orbit with huge numbers of very highly automated rocket-smashing machines. The October, 1989 issue of TECHNOLOGY REVIEW and the current (I think November) issue of BULLETIN OF THE ATOMIC SCIENTISTS both contain articles critical of "brilliant pebbles", which include histories of the program. - Jon Jacky, University of Washington, jon@gaffer.rad.washington.edu