Astrophysicist/writer/inventor Martin O. Harwit -- who made airplane models as a boy and pioneered the study of cosmic infrared radiation as a man -- will become director of the National Air and Space Museum Aug. 17, Smithsonian Secretary Robert McCormick Adams announced yesterday.

Harwit, 56, is a professor of astronomy at Cornell University and codirector of its project on the history and philosophy of science and technology.

He said he was pleased about his new job because "though most people think of the Air and Space Museum for its tremendous ability to display astronautics and space flight, it's also a prime institution for historical research on aviation and space science."

He said he doesn't believe in flying saucers or unknown alien landings, but he does believe that in the next 50 years, "there will be greater uses for outer space -- for better, or possibly worse."

A massive attempt by the United States to colonize Mars, suggested by the National Committee on Space, will be the subject of national debate soon, he said. "Whether we should devote considerable national resources to this adventure will take lots of thought."

In the museum, he hopes for more exchanges with other countries and, "as an astrophysicist, I think it would be fun to have an exhibit that considers problems and hazards associated with travel beyond the solar system. We can now make reasonable assessments on the problem from one star to the next, even one solar system to another. We can speculate on technology to overcome the problems of human physiology in space -- the effects of gravity on the loss of bone calcium and cosmic radiation bombardment."

Harwit was born in Prague. "My father was a scientist, an immunochemist. Lots of science talk around the dinner table. My sister and brother-in-law are both biochemists. I grew up in Istanbul, but my parents wanted us to have an American education, so we came to the United States in 1946, and in 1948, my father became a professor at Indiana University. I was always interested in physics ... When I began to work on infrared radiation -- heat from stars, planets and nebulae -- which you have to go above the Earth's atmosphere to measure, I really became strongly interested in aeronautics and space."

Harwit received degrees from Oberlin College, the University of Michigan and Massachusetts Institute of Technology -- all in physics.

In the 1960s, he established research groups (in D.C. and at Cornell) to build the first rocket-borne telescopes to sense infrared radiation from distant cosmic bodies. In the 1970s he wrote "Cosmic Discovery," an influential book on space policy. He has also written three books on astrophysics and astronomy and 170 scientific articles, and he holds many patents for technical innovations. In 1983, he held the Air and Space Museum's chair in space history.

Currently he is chairman of the National Aeronautics and Space Administration's Astrophysics Management Working Group, a member of NASA's Space and Earth Science Advisory Committee, and associated with the Infrared Space Observatory in Noordwijk, the Netherlands.