"Sputnik fear" is back again, caused not by a Soviet satellite, but a Japanese and west European challenge to U.S. domination of science.

American science still leads the world, according to two dozen leading scientists in various fields who were interviewed. In almost every field, however, the United States faces a strong challenge. Its research in a few fields is now plainly behind the work of other nations, they said, and it is slipping in other fields where this nation still has an edge.

* The number of doctorates granted in science and engineering has dropped about 9 percent since the peak year of 1973, going against the peacetime trend of Ph.D. production in this century.

* The United States has been spending less and less of its economic resources on research over the past decade. American research and development spending plunged 17 percent as a percentage of gross national product between 1968 and 1980, while the Japanese and west Europeans increased their spending dramatically.

* More than one in five doctoral degrees in science and engineering now go to foreign citizens. In some fields, the figures are much higher: In l981, foreigners got 52 percent of all American doctorates in engineering, 38 percent in agriculture and 31 percent in computing.

* Scientists say that some of the most significant cutbacks in federal financing were in the most important areas--fellowships for the best science students, and aid for good laboratory equipment in the universities.

* So few science and math teachers now come out of college that one-third of the nation's high schools students is taught science by completely unqualified teachers, some of whom have never had college math or science courses.

* At some universities, the quality of students going into science has dropped, and non-science students are "simply illiterate" in math and science, as astronomer Geoffrey Burbidge put it.

If American primacy in science slips much more, scientists say, the best American scientists may begin to desert their laboratories and go abroad, just as Britons and other Europeans deserted their labs and came here beginning five decades ago.

For the first time in years, however, scientists say they are optimistic about the future of American science. The Reagan administration increased the budget this year for the National Science Foundation, the major source of federal funds for pure research.

"If you asked me a year ago, I would have said things look very bleak," said Burbidge, director of the Kitt Peak observatory, whose staff was cut last year from 340 to 260.

"The prospects at the moment look good," he said. "But these coming budget increases can't be just a one- or two-year spike. If it's a spike, forget it. That will mean disaster."

Scientists are confident that the United States will continue dominating the annual Nobel Prize awards for a while, but they expressed worry about the erosion of basic research. Mathematician Felix Browder at the University of Chicago said that he, too, he fears that generations of non-scientists are growing up as scientific illiterates, leading to the further decay of science and society.

Donald Kennedy, president of Stanford University, touched on one recurring fear of scientists.

"The genius of American science is the relation between research and training," he said. "Here, research takes place where the apprentices are."

That means that young researchers are able to work independently under the best scientists. In other countries every detail of a young scientist's research is determined by his superiors.

Over the years, Kennedy said he fears, the American system has been greatly damaged. Even with funds for science beginning to rise, the number of students on graduate fellowships is low.

According to the National Science Foundation, 2,550 of the best graduate students were supported annually on fellowship programs about a decade ago. Now, only 1,550 are. Similarly, NSF gave 5,600 training grants to graduate students in 1968, and other agencies had smaller programs.

"Now those are gone," said Terence Porter, head of the NSF fellowship section.

Arthur Schawlow, a laser physicist who has won the Nobel Prize, said another danger is the outdated and dilapidated equipment scientists and students must use in many university laboratories.

He recalled working with obsolete equipment during one budget squeeze at Bell Laboratories. When newer equipment was finally bought, he said, "We were all amazed at how much time and effort had been lost in designing our work to get around the limitations of our machines. It was a major part of our time, and we never realized it."

Lab equipment at some universities is a decade or more behind that in industry, according to Frank Press, president of the National Academy of Sciences. But he said next year's NSF budget will contain some funds for new equipment.

The quality of students also concerns scientists. Researchers at the "elite" universities say their best graduate students are still very good. But below the very top, there is trouble.

The University of Maryland, for example, has a physics department that is regarded as excellent and draws good but not always the very best students in its competition with such schools as Harvard and the California Institute of Technology.

Yet Edward Redish, chairman of the physics department said, "We have a serious problem of inheriting students who are poorly trained . . . at the same time we have reduced budgets. More and more of the class time in physics and engineering is eaten up in remedial courses.

"I have had students in pre-med who couldn't calculate the volume of a cube . . . or do fractions . . . . Even on the graduate level the students are prepared less than I would expect."

The state of American science varies from discipline to discipline. This is how the interviewed scientists assess their fields:

Physics: "For a considerable period after World War II, we set the style for the world," said D. Allan Bromley, a nuclear physicist at Yale. "We certainly no longer do. A number of other countries such as Germany, France, Italy and Japan have given this field high priority."

Leon Ledermann, director of the Fermi National Accelerator Laboratory near Chicago, said the western Europeans have nearly the same population and gross national product as the United States but for some years have spent twice annually on high-energy physics work to discover the most basic elements of matter.

In high-energy physics, Americans have lost their lead to the Europeans, Ledermann said. One sign came this year when European scientists announced the long-awaited and important discovery of the so-called W and Z particles. Proposals to do those experiments at Fermi had been turned down years earlier for lack of money. The discovery of these particles provided important evidence that key theories explaining the basic forces of nature were being borne out.

Computing: Edward Feigenbaum, a Stanford University professor and pioneer in machine intelligence, recently said that the United States will be "betting the future of the entire information processing industry" if it does not counter Japan's 10-year, $850 million crash plan to capture the world lead in the coming "fifth generation" of computers.

Feigenbaum pointed out that until now the United States had dominated the area of "smart" computer programming and led in inventing computer hardware. Its response to Japan has been "discoordinated" and "not very promising," Feigenbaum said.

But recently, a Senate committee passed a measure sponsored by Sen. Edward M. Kennedy (D-Mass.) and others that will put some $25 million into the competition. At the same time, the Advanced Research Projects Agency of the Defense Department has begun a study on how America should respond.

Chemistry and Biology: "We are far ahead of the Europeans and Japanese in molecular biology," said Phillip Sharp, a molecular biologist at MIT and a consultant to Biogen, a biotechnology corporation. "But we are not ahead in applying that research for practical things. The Japanese are very active, even though they do not have a large basic research establishment."

Howard E. Simmons, director of central research and development for E.I. duPont de Nemours & Company, said that in chemistry and biology the "American universities are as strong as they ever have been." But he added that companies fail to take advantage of much that is first-rate in American science.

He attributed industry's increasing hardening of the arteries to many factors, including the rise and eventual dominance of "marketing people" over researchers, of conservatism over risk-taking.

"Top management is more conservative than they used to be . . . , wanting to be able to see a market there" before taking a risk on a product, he said. If they cannot foresee a large market, the product is dropped. By contrast, the Japanese "see an exciting technology and go create a market," he said.