Reagan's new defense weapons - not just a dream

President Reagan's recent television address in which he called upon the United States to ''embark on a program to counter the awesome Soviet missile threat with measures that are defensive'' has been met with much undeserved skepticism and criticism. I believe it is important that some facts be brought to light which might lend more substance to the issue and bring about a more objective assessment of the President's idea.

Among the high-technology alternatives for the President's defensive system are the high-energy laser, particle beams, directed microwave energy, and a more conventional missile system.

The first three of the alternatives form a class of weapons which is termed ''directed-energy weapons.'' Directed-energy weapons gain their lethality from being able to fire their ''bullets'' at the speed of light (186,000 miles a second, which effectively freezes the target in its motion); being able to rapidly redirect their fire; having a range (in space) of thousands of kilometers; and being able to deposit lethal doses of energy (heat) in seconds or even a fraction of a second. No conventional ammunition is required.

The high-energy laser technology is ahead of the particle-beam development, but the microwave energy device lags considerably behind the particle beam. In any case, in assessing the alternatives, it is important that the public realize:

* Contrary to some reports, a particle beam will indeed propagate in space. In fact, the technology is currently available to construct a working particle-beam weapon in space.

* Programs investigating particle-beam weapon technology were sponsored by the Department of Defense as far back as 1958, and are currently gaining momentum.

* The Soviet Union has a significant particle-beam technology program of its own, and its successes have been a motivating factor for the US programs. Some scientists are convinced the Russians lead the US in particle-beam weapons development.

The particle-beam weapon, if successfully deployed, would be the most lethal weapon, capable of selective use, ever conceived. It is a promising candidate to meet President Reagan's dream for an effective ballistic missile defense.

The particle-beam weapon program in the US first began in 1958 under the code name Seesaw. It was funded by the Pentagon's Advanced Research Projects Agency (DARPA) and was highly classified. The concept was to defend the northeastern US against ICBM attack by building the weapon on and under the ground. An elaborate set of tunnels stretching from Washington to New York would be constructed to allow the beam to be generated and propagated to the most appropriate port for firing. The Seesaw concept was abandoned in 1972 as being too expensive and high-risk technology.

Particle-beam research did not stop then, however. The Navy picked up the program with a much more restricted concept for deployment which was far less expensive and more technologically attainable. The program, called Chair Heritage, envisaged that the weapon could be carried aboard a ship and used effectively for fleet defense against nuclear or conventionally armed cruise missiles.

In 1974 the Army began a program with the prime mission of ballistic missile defense, the concept being to deploy the weapon in space using neutral particles (atoms) in the beam. This program, originally called Sipapu, is now carried under the project name of White Horse. In 1976 the Air Force began its program which conceptually involved both atmospheric deployment and space deployment as an anti-satellite weapon.

In 1980 the efforts became more focused when a beam-weapons technology group was established by the Pentagon to coordinate all three programs to avoid duplication and funding competition. DARPA then reentered the funding picture in FY81 and drew up a seven-year program. All signs are that there is a growing interest and earnestness to develop the particle-beam weapon for a variety of possible applications.

The point is this: Millions of dollars have been spent and hundreds of scientists have been engaged in programs over the past 25 years to develop the technology for building particle-beam weapons. And the high-energy laser has received a good deal more attention and money than the particle beam. I am not suggesting that there is complete unanimity in the scientific community on the future prospects for directed-energy weapons. There are many technical problems to be solved before an effective operational particle-beam weapon system can be deployed. (There is a big gap between being able to build a weapon that will successfully operate and one that will be part of an effective and viable weapon system worthy of operational deployment.) To date, though, nothing has been discovered to conclusively rule out the success of such weapons.

This is what President Reagan is suggesting. If we can focus more of our strategic weapons effort on these advanced defensive weapon systems, maybe sometime after the turn of the century technical breakthroughs will have provided us with a formidable defensive network. A lot of prestigious scientific laboratories have been taking the subject very seriously over more years than most people know. I think it is time the news media ''analysts'' and some politicians begin taking it seriously, too.