A West German physicist and an American biomedical engineer were named yesterday as the first non-astronauts to make a flight aboard the space shuttle.

The National Aeronautics and Space Administration selected Ulf Merbold, 41, and Byron K. Lichtenberg, 34, to occupy the last two positions in the six-member crew on the ninth shuttle mission scheduled for Sept. 30, 1983.

Merbold and Lichtenberg are to work in the Spacelab workshop that will be installed for the first time in the shuttle's cargo bay for that flight. They plan to operate and maintain 38 scientific instrument packages.

"My feelings about being the first European to fly on an American spacecraft are quite mixed," Merbold said at a news conference at the Marshall Space Flight Center in Huntsville, Ala., where he and Lichtenberg have been training in competition with a Dutch physicist and another American physicist.

"We have spent almost five years here as a team and it is a sad thing now to split up into two groups, one to go into space and the other to remain here on the ground," he said.

Spacelab has been a U.S.-European project for 10 years.

The Spacelab workshop was developed and built by the European Space Agency for $1 billion, and many instruments to be flown on Spacelab will be supplied by European scientists. Part of the agreement between ESA and NASA calls for one European scientist to be on all shuttle missions that carry the Spacelab workshop.

Merbold, trained at Stuttgart University, competed for his Spacelab seat on the shuttle with Wubbo Ockels, 36, a Dutch physicist who holds a doctorate from the University of Groningen.

Lichtenberg, who holds a Ph.D. from the Massachusetts Institute of Technology, competed with Michael L. Lampton, 41, holder of a doctorate in physics from the California Institute of Technology.

The winners were picked in a secret ballot by a panel of 36 American and European scientists.