Robert A. Citron, an aerospace engineer and entrepreneur whose boyhood fantasy of traveling beyond Earth inspired pioneering ventures to commercialize space, died Jan. 31 at his home in Bellevue, Wash. He was 79.

He had complications of prostate cancer, said his son Kirk Citron.

During an extraordinarily varied career, Mr. Citron founded an adventure travel agency, built satellite tracking stations, produced National Geographic documentaries and monitored natural phenomena such as insect invasions and falling meteorites. He even organized a 20-member expedition to watch the Russian space station Mir reenter Earth’s atmosphere.

“Bob had an intense passion for opening the space frontier to humanity,” said Charles Miller, former senior adviser for commercial space at NASA. “At the core, he was a visionary, but he was also a pragmatic businessman.”

In 1983, Mr. Citron developed Spacehab, a pressurized module that would fit inside the cargo bay of a space shuttle. He had envisioned it for human cargo.

NASA was opposed to carrying people in the module for safety reasons but eventually agreed to another use: Since 1993, Spacehab, which was patented by Mr. Citron and co-designer Thomas C. Taylor, was deployed to hold scientific experiments on more than 20 space shuttle missions, including the 1998 flight of Discovery, when John Glenn returned to space.

Mr. Citron sold the Spacehab company in 1986.

One of Mr. Citron’s most important contributions was demonstrating that the private sector could build space hardware far more cheaply than the government. He built two Spacehab modules for $150 million, substantially less than NASA’s estimate of $1.2 billion, said James A.M. Muncy, a space policy consultant in Washington.

“The power of Bob’s ideas, technical designs and business concepts made space business, including businesses involving humans in space, more real,” Muncy said.

Mr. Citron was born Sept. 14, 1932, in Brooklyn and moved to Los Angeles when he was 12. He served in the Air Force during the Korean War and earned degrees in liberal arts from the University of the Philippines and in aeronautical engineering from Northrop University in Inglewood, Calif.

In 1957, while still at Northrop, he became technical director of the Pacific Rocket Society’s satellite tracking station in Canoga Park, Calif., and received a congratulatory call from President Dwight D. Eisenhower when he managed to track Sputnik 1, the Soviet Union’s satellite.

He later built and managed satellite tracking stations for the Smithsonian Astrophysical Observatory in Asia, Africa and Europe.

In 1968, Mr. Citron launched the Smithsonian’s Center for Short-Lived Phenomena in Cambridge, Mass., where he was its director. He told Popular Mechanics magazine in 1970 that using Teletype machines and a network of more than 2,000 correspondents around the globe he could contact almost any inhabited place in minutes and quickly alert scientists about unusual natural events — earthquakes, fireballs, fish kills and rare animal migrations.

In 1969, when a friend suggested that they could finance a free trip to view a solar eclipse if they organized a group excursion, he formed Educational Expeditions International, which took scientists and others on such adventurous experiences as climbing into an active volcano.

He later sold the company, which is now part of the Boston-based Earthwatch Institute.

Mr. Citron was married three times.

Survivors include his partner, Audrey Woodin; seven children; a brother; two sisters; 23 grandchildren; and a great-grandchild.

— Los Angeles Times