The 1980s will be remembered as, among other things, the decade when the United States lost its commanding position in a number of vital global markets, from autos and steel to semiconductors.

There is a risk that the 1990s will be recalled as the decade when this country lost its leadership in space.

That is the conclusion of a new review of the American space effort issued by the Business-Higher Education Forum, whose members include the leaders of some of the nation's most prestigious businesses and universities.

"The country which first landed a man on the moon has a range of technical capabilities in the complex field of building and launching space systems that is unmatched by any other nation. But the U.S. lead in space is being threatened as the Soviet Union continues its ambitious space science program and Europe and Japan move aggressively to harvest the potential bounty of space," the forum's report says.

Summed up, the report is a plea for a national commitment by government, industry, higher education and the public to maintain U.S. leadership in space, said Marvin L. Goldberger, president of the California Institute of Technology and cochairman of the task force that prepared the report.

Although that commitment was reaffirmed by President Reagan in the aftermath of the Challenger space shuttle disaster, there is plenty of reason to worry about the outcome, said Goldberger.

The forum report concludes that America is at a crossroads in its adventure in the exploration of space's frontier. The same conclusion is offered in a forthcoming book, "The Mars Project, Journeys Beyond the Cold War," by Sen. Spark M. Matsunaga (D-Hawaii).

The competitive risk is very credible, Goldberger says. "About 10 years ago, the scientific community laid out a program for exploration of the solar system. What's happening is, the Soviet Union is doing it. Their technology is not as good as ours. However, they're engaging in cooperative ventures with Western European scientists and improving the quality of their space missions enormously," he says.

Given the makeup of the forum -- representing the cream of the U.S. aerospace, industrial and academic establishment -- some may perhaps dismiss the report as an elegant lobbying campaign for more federal tax dollars for the space effort by some of the prime beneficiaries. And that it is.

It does not attempt to justify the costs of a stronger civilian space effort in terms of the benefits to the public from new kinds of medicines, metalic alloys or other discoveries to be developed in space laboratories.

"I don't think it's realistic to attempt such an analysis," Goldberger says. "We need careful, sustained experiments in the space environment to determine what the potential is." Without that, "you're just reading tea leaves." The forum report argues for a long-term commitment that will assure scientists, students and companies that their investment in space research will not be wasted, he says.

Although the forum report talks about the threat to the U.S. competitive position, it calls for international cooperation, not nationalistic competition, in space.

It highlights the fundamental cleavage in U.S. policy toward space: One side seeks a national program designed to promote a competitive advantage for U.S. scientists and companies, and, most of all, to advance the American military capability in space.

"The other view suggests that space should be used as a diplomatic tool to promote cooperation and synergism among nations. Because these conflicting positions have not been reconciled, the potential benefits of international cooperation have not been fully realized," the forum report says.

The U.S. goal should be international cooperation on the peaceful uses of space, the report concludes.

That is also a central recommendation in Matsunaga's book. The senator, whose book is an outgrowth of his concern about the danger of a U.S.-Soviet nuclear confrontation, argues for a major space project involving the United States, Europe, the Soviets and Japan.

Matsunaga is not talking simply about a new version of U.S.-Soviet detente set to the Star Trek theme.

The fundamental choice for the next stage of space exploration is between an open, cooperative approach and a closed, secretive one, Matsunaga says.

An open environment offers Americans their best chance for commercial success and the realization of the nation's international goals, he says.

"No nation on this planet can match the skill, originality and productive genius of America's diverse network of university research institutions working in alliance with high-tech industry and guided by a cultural commitment to rapid, open commnications," Matsunaga says.

But the benefits would not just be domestic. There are four major players in space, and three of them are democracies. A cooperative space effort could exert a powerful pull on the Soviets toward the orbit of the democracies, the senator argues.

The approach to space that is followed now will set precedents for the journey to Mars and the incredible adventures that surely lie ahead 50 or 100 years from now. If the approach today is secret, rooted in the military priorities of space weaponry, that may dictate the kind of government that will evolve in space in the next century, Matsunaga contends. An open, cooperative approach will set a different course.

It is a big, far-out thought. But it demonstrates the scope of the issues raised by the space challenge. Matsunaga's book, like the forum report, argues that those issues require a much deeper, harder look.