Fortunately astronauts have the answer. As they reenter spacecraft after space walks outside, the odor of space is discernible on spacesuits and equipment.
Apparently the chemical reactions way up there smell like burned steak and melting metal, according to reports. Some have even compared it to the fumes from welding, while others add that it has a hint of cooked beef. Experts are now making the effort to recreate it on earth for astronaut training (Life's Little Mysteries, "What Does Space Smell Like?" FoxNews.com, July 23, 2012).