Bernhard Lettau, a National Science Foundation program director for 31 years before retiring in 2007, died Dec. 14 at Capital Caring hospice in Arlington County. He was 75.

The cause was sepsis and cancer of the appendix, said his wife, Kathryn Lettau.

Mr. Lettau, an Annandale resident, began working at the National Science Foundation, which manages the U.S. Antarctic Program, in 1976. He spent his career as program director for polar ocean and climate systems in the office of polar programs.

During his tenure, he made 25 trips to Antarctica. A triangular peak west-northwest of Fogle Peak in the Royal Society Range in Antarctica was named in his honor in 1992.

Before that, he worked as an assistant professor of atmospheric science at State University of New York at Albany.

Bernhard Lettau was born in Leipzig, Germany, and moved to the United States when he was 10. He became a U.S. citizen in 1955 and was a 1959 graduate of Yale University. He received a doctorate in meteorology from the University of Wisconsin in 1966 and a decade later settled in the Washington region.

Survivors include his wife of 52 years, Kathryn Lange Lettau of Annandale; three sons, Christopher Lettau of Arlington, Michael Lettau of Silver Spring and Steven Lettau of Honolulu; two brothers; and five grandchildren.

Megan McDonough