When they talk frankly - and privately - responsible high-level officials are doubtful that a SALT II agreement can be reached this year. They add up the score and the total is gloomsville, insofar as hopes for an agreement that could reach the Senate with a chance for ratification after the prolonged debate on the Panama Canal treaties.

Certain reasons are obvious enough. One is the constantly increasing Soviet-Cuban attack on Somalia with the aim of assuring the communist hold on the Horn of Africa. This is Soviet expansionism threatening the vital lifeline of the West of the oil of the Middle East.

There are, however, other and perhaps equally compelling reasons for doubts about a new arms-control treaty that are still the secret worry of U.S. negotiators. They concern the traffic of the two superpowers in outer space.

The Soviets have developed a killer satellite. Not only have they done all the research and development but they have conducted five successful tests. These tests have been directed at their own satellites since to shoot down one of ours would be a violation of SALT I. The killer-satellite capacity does not itself violate the agreement signed by Richard Nixon in 1972.

To see this diagrammed by one of the most brilliant men in the nuclear field is to feel that the games children play have been elevated to the nuclear age. The U.S. satellite, a surveillance satellite, say, moves around the globe at a level four or five hundred miles above the earth. It is pursued by the speedier killer satellite.

When the latter impacts, its high explosive charge blows up both satellites. Presumably this would be a non-nuclear explosive, and there would be no such dramatic incident as occurred over northern Canada when a nuclear-powered satellite disintegrated and dangerously hot fragments fell to earth.

In our own military there are those who would like to start immediately a crash program for the killer satellite. But is this the answer? Would it not merely carry the tensions and the enhanced threat of war into the stars? And the corollary question is whether the Soviets can be negotiated out of the use of such a threatening weapon.

Another facet of the stalled negotiations gives a credibility to the wilder fantasies of Star Wars. Although this is still in dispute, negotiators accuse the Soviets of encrypting their satellies in such a way that we cannot read the messages they are sending out. This puts a heavy burden on the right of surveillance granted under SALT I.

To encrypt means to code. The Soviets have practiced encryption by computer in such a way that it would take the United States six months to decode what is going out over their satellites. There are those in the negotiating process who say this is no violation. Nevertheless it is still an important part of the dialogue between Washington and Moscow.

Meanwhile, as television commentators would put it, Paul C. Warnke, director of the Arms Control and Disarmament Agency and the United States' chief day-to-day negotiator, is in Geneva sitting across the table from his Soviet vis-a-vis. Warnke is skilled at this thankless job, thankless, in part, because enemies of any agreement with the Soviet Union attacked him to discredit him even before the game had begun.

But it is a slow process. The Soviets with no real power of decision at the negotiating table must cable everything back to Moscow for a response often slow in coming.

More important is the present balance in the negotiating scales. One of the pivotal figures in the negotiating process put it this way:

We have made all the concessions we can possibly make. It is now to be determined whether the other side can move. We do not know.

One doubt is whether the aging men who make up the ruling body in the Kremlin have the capacity to act. Related to this is whether their possible successors, younger men, would want to act. The Soviet Union is moving rapidly forward in weapons development with no need to choose in a totalitarian state between guns and butter.

As the weeks and months pass, the onset of the congressional election draws nearer. That is one reason the pessimists say it is probably too late to conclude another SALT agreement. With the die-hard opposition already engendered, no administration would throw such a controversy into the Senate on the eve of an election.

The philosophic view is that an agreement signed even as late as September or October can go over to the next session of Congress. If that seems a slight hope, at least it is a hope.