The Soviet Union scored a new space triumph yesterday linking two manned spacecraft with an orbiting space station for the first time.

Tass, the Soviet news agency, announced that Soyuz 27 cosmonauts Lt. Col. Vladimir Janibekov and Oleg Makarov successfully docked with the Salyut 6 space station at 9:06 a.m. EST, and joined two Soyuz 26 cosmonauts who had been aboard the spacelab since Dec. 11.

While Tass said Janibekov and Makarov would return to earth in five days, Western experts predicted that other cosmonauts would be sent to take their place as part of a Soviet effort to keep the Salyut 6 space station continously manned - perhaps for as long as a year.

"I fully believe they will try to keep the Salyut manned," declared former American astronaut Eugene Cernan, who worked closely with Russian cosmonauts in preparing for the 1975 joint U.S.-Soviet space mission.

"The Russians have put themselves, in a very archaic way, into the shuttle era," Cernan said. "As long as the Salyut can function as a viable vehicle, they can shuttle crews back and forth like changing the watch."

U.S. experts emphasized, however, that shuttling cosmonauts to-and-from a Salyut space station aboard relatively primitive Soyuz capsules could not be compared as a technological feat to the initial flight of the American space shuttle now scheduled for early 1979.

"The U.S. shuttle vehicle is aeons of time ahead of the Soyuz," Cernan said. "The Russians can just roll those Soyuz capsules off the production line. They have stepped into the shuttle world with old hardware."

Nevertheless, Cernan echoed the sentiments of a number of U.S. space enthusiasts whose suffer in silence as the Soviet Union's space program, which is far more active, registers new firsts.

"You have to congratulate them," he said. "The fact is, they're there - and we're not."

Tass called today's linkup "a major accomplishment of Soviet science and technology."

The Salyut 6, which was launched Sept. 29, is the first Soviet orbiting station to have two docking ports - one at either end.

The Soviets have had trouble with dockings in the past, and in October, Soyuz 25 failed in the first Soviet effort to put men aboard Salyut 6.

After Soyuz 26 successfully docked with Salyut in December, flight engineer Georgy Grechko took a walk in space Dec. 20 to determine whether the abortive October attempt had damaged the docking unit.

For reasons that have never been explained, Grechko conducted the examination at night with a flashlight. He reported the docking unit in good working order, clearing the way for yesterday's Soyuz 27 linkup.

During yesterday's docking, the Soyuz 26 cosmonauts took the precaution of leaving the Salyut and sealing themselves off in their space capsule.

"This is quite understandable since it will be the first time that another spacecraft has approached a manned space station," Radio Moscow declared.

Three hours after the docking, the Soyuz 26 cosmonauts returned to the space laboratory towelcome their newly arrived colleagues.

Moscow television last night showed the two Soyuz 26 cosmonauts, Grechko and Yuri Romanenko, slowly opening a hatch to pull the newcomers into the Salyut.

"Now we will see our dear friends," Romanenko said.

A moment later, Janibekov and Makarov were hauled aboard, bearing letters for the Soyuz 26 cosmonauts from their families and copies of the newspaper Pravda, which has recorded their activities while in orbit.

The four all exchanged a weightless version of a Russian bear hug, then drank a toast of cherry juice squeezed from small tubes.