Asserting that the Soviet Union is making major advances in military space technology, Secretary of Defense Harold Brown yesterday proposed a near-doubling of U.S. expenditures for outer space weaponry.

"We certainly have no desire to engage in a space weapons race," said Brown in his annual report presented to the House Armed Services Committee. "However, the Sovices with their present capability are leaving us with little choice."

Brown said the Pentagon plans to increase spending for military sapce programs from $41.6 million to $73 million between fiscal 1978 and 1979 - a pidding sum by normal magnitudes of defense spending. The entire military spending bill being proposed for fiscal 1979 is $126 billion.

However, Brown indicated that U.S. military space spending could increase sharply in the next few years to match Soviet initiatives in space.

"Because of our growing dependence on space systems," sid Brown, "we can hardly permit them the [Soviet Union] to have a dominant position in the ASAT [anti-satellite] realm."

Brown on Oct. 4 credited the Soviets with having an operational space weapon that could attack "some" U.S. satellites, presumably the low-flying reconnaissance satellites, not the communications satellites that hover 22,400 miles above the earth.

Yesterday, Brown contended that the Soviets are "not only improving their orbital ASAT interceptor," but are doing related work.

"We might have to take steps to deter attacks on our satellites to deal with attacks should they occur, and to have the capability to destroy Soviet satellites if necessary," Brown said.

Brown's warning about a military space race stood out from an otherwise low-key, 75-page report to Congress in the state of the nation's defense.

Although the United States has some catching up to do in defense, there is no need for crash programs or panic, Brown said. President Carter has said the fiscal 1979 defense budget, totaling $126 billion, will be followed by successively higher ones, rising at the rate of 3 percent annually in constant dollars.

In looking at military developments around the world, Brown said, building up U.S. conventional forces for NATO is the prime need, and that China is slowly approaching full membership in the nuclear club, with unclear-powered missile submarines a likely next step.

He argued for keeping U.S. options open on questionable new weaponry, including the MX intercontinental land missile and Navy aircraft carriers, but defended going full speed ahead with the cruise missile.

However, just as the investment in the cruise missile is shooting up in this and subsequent years under the Carter administratiion's proposed budgets, so could the investment in space weapons.

In recent written guidance for military plans for the five-year period fiscal 1980 through 1984, Brown told military leader to "continue to increase" the investment in military space programs.

He noted in his consolidated guidance that U.S. "ability to directly attack hostile space systems, if required, is non-existent". An attack on an American satellite deep in space might go undetected, he added.

Brown said yesterday that $36.1 million is earmarked in the Pentagon's fiscal 1979 budget to keep a better watch on deep space.

As for attacking a Soviet satellite, the Air Force in September awarded a $58.7 million contract to the Vought Corp. of Dallas to develop a flying test model of a satellite killer.

Unlike the comparatively slow Soviet satellite killer Brown discussed yesterday, which would have to fly on an intercept route and then blow itself up to destroy the target satellite with flying shrapnel, the U.S. satellite killer would zoom into space aboard a rocket.

Once in space, the satellite killer, the size of a tomato can, would leave its booster rocket and crash into the target satellite by homing in on its heat. The collision at thousands of miles an hour would do the destroying.

Indicating that this Vought program is only one of many satellite killer devices to be developed, Brown said in discussing satellite weaponry yesterday: "In the absence of negotiated controls, our program seeks a balance of operational capabilities for the 1980s."

The United States worked in the 1950s on an anti-satellite system called Saint, for Satellite Intercept, and in the 1960s deployed on Kwajalein Island in the Pacific a battery of anti-satellite rockets. They were abandoned since, like shotguns in a duck blind, they would only be effective if the target satellite flew within range.

Brown, in his wide-ranging report, discussed these other subjects:

China. "The strategic nuclear programs have continued to develop at a slow pace." Although China has short-and medium-range nuclear-tipped missiles, "a few" intercontinental range missiles "could be deployed by 1980 . . . We believe that work continues on the development of a unclear powered submarine and the missiles to go with it . . ." The Soviets allocate "up to or about 20 percent" of their defense budget to China and the Far East.

Soviet civil defense. "Overall, there has been no significant reductio in the vulnerability of Soviet industry to nuclear atack."

Soviet Backfire bomber. "We believe that the primary purpose of the Backfire is to perform peripheral attack, theater and naval missions - although it has some intercontinental capability and can reach portions of the United States on one-way, high-altitude unrefueled missions." (How to classify Backfire has been a sticking point in arms-control negotiations.)

Soviet cruise missiles. "Both the Bear and Backfire (Soviet bombers) can carry air-launched cruise missiles with ranges of about 600 kilometers. There is no curent evidence" that the Soviet have an air-launched cruise missile "comparable" to the U.S. weapon, but they could build one "within the next five to 10 years."

New Soviet missile submarine. "A new submarine, the Delta III, is now undergoing sea trials."

Antisubmarine-warfare. Neither Soviet killer submarines nor other antisubmarine-warfare systems "represent a serious threat" to the U.S. fleet of Polair-Poseidon missile submarines.

Future Navy fleet. "A 600-ship active Navy," a prime goal of U.S. Navy leaders, "is not feasible in the next decade."

Brown's assessment of how the United States and Soviet Union compare military threaded through his report, with these comments reflecting his theme:

"The situation is one of standoff or stalemate" in strategic nuclear weapons. "While there is work ahead of us, there are no grounds for panic or crash effort . . . Although both of us are heavyweights, I am confident that we remain the more agile of the two.

"Perhaps the analogy of the hare and the tortoise is more appropriate as a description of the Soviet-American competition in the past. Certainly we pulled ahead in the late 1950s or early 1960s, and then substantially reduced our basic effort while the Soviets continued to expand theirs at a steady pace. Now we must increase our investment if we are to stay abreast . . .

"That we have the prudence and patience to run at whatever pace the Soviets may choose remains to be seen. All I can say to you is that the fiscal 1979 budget and projected programs recommend what this administration regard as the ritht re men for a long-distance runner."