John Edgar Ainsworth, 84, a well-read man of many interests who investigated the atmosphere of the planets Venus and Earth for a living and launched a movement to create a community ice rink in his spare time, died Sept. 30, following complications from a stroke, at Renaissance Gardens in Silver Spring.

He had recently moved to Riderwood Village in Silver Spring, after living in Bowie for 42 years.

Mr. Ainsworth, an atmospheric physicist at NASA's Goddard Space Flight Center, was the primary designer of the Pioneer Venus probe. His awards from NASA and Goddard praised his contributions to its Venus missions, and he held patents on a pressure measuring device and a rocket-borne television system.

At his retirement in 1984, he was working on measurements of ozone in the Earth's atmosphere. He published more than a dozen research articles on the atmosphere of Venus and ozone measurements and co-wrote an article on "the structure and internal motion of 1,2-dichloroethane" with Nobel Prize winner Jerome Karle.

A man who believed in a well-rounded life, Mr. Ainsworth was an accomplished ice dancer and, with his wife, won a jitterbug contest in his 60s. He started taking flying lessons at age 79, when arthritis curtailed his ice-dancing, and loved reading about the Founding Fathers and the Constitution.

Born in New Haven, Conn., and raised in rural Maryland and Pennsylvania during the Great Depression, Mr. Ainsworth enrolled in St. John's College in Annapolis in 1938, shortly after its "100 Great Books" program was launched.

The day after the Japanese attack on Pearl Harbor in 1941, he interrupted his studies to enlist in the U.S. Army Air Forces. Sent to the Pacific, he took with him two books, both on calculus, and taught himself the discipline while in the military.

Mr. Ainsworth earned a Bronze Star training B-24 flight crews in the use of radar in the Pacific. After returning from the service in 1946, he enrolled at Harvard University, where he received his bachelor's degree in mathematics in 1947.

For the next dozen years, Mr. Ainsworth pursued graduate studies in physics at the University of Maryland and worked as a physicist at the U.S. Naval Research Laboratory. He joined NASA in 1959. In 1980, he received a NASA Exceptional Service Medal and the Goddard Special Achievement Award for his work studying the atmosphere of Venus.

Every winter, he built an ice rink in his back yard for his children, which invariably attracted the neighbors. After a few years, when the city of Bowie planned a new recreation center, Mr. Ainsworth urged officials to include a combination ice rink, pool and small theater. He didn't succeed at that effort, but didn't give up. He presented the government with research on the pent-up demand and made studies to help determine how to create the best ice. The ice arena opened in 1971 to "overflow popularity," the city said in a commendation to Mr. Ainsworth, which also cited his "perseverance and quiet modesty."

His civic activism continued later in life, when the Rouse Co. proposed building a housing development at the foot of the 50-year-old Freeway Airport. One of his daughters said he measured the decibel level of takeoffs and landings at the small airport in an effort to advance the discussion. In a letter to the editor of The Washington Post's Prince George's Extra in April 2001, he excoriated the Rouse Co.'s "indefensible plan to place 150 to 200 houses directly under the airport's takeoff pattern, in obvious disregard for both the degrading effect on the lives of future occupants and of the great danger to both our student and experienced pilots."

Among Mr. Ainsworth's other interests were sailing, skiing, camping, windsurfing, hang-gliding, flying small aircraft, ballroom dancing and jazz. He was a lifelong supporter of world federalism with strong interests in national and international politics.

Mr. Ainsworth met his future wife on a student trip to Britain in 1952, after which they traveled 10,000 miles on a motorcycle throughout Europe. After they married, they continued to travel the world.

Survivors include his wife of 51 years, Anne K. Ainsworth of Silver Spring; three children, Martha Ainsworth of Bowie, Julie Ainsworth of University Park and Paul Ainsworth of Cape Elizabeth, Maine; and three grandchildren.

John Edgar Ainsworth's interests ranged from the atmosphere of Venus to a backyard ice rink to reading history to jitterbugging.