NASA is developing the electronic nose or E-Nose for
short. It's a device that can learn to recognize almost any
compound or combination of compounds. It can even be
trained to distinguish between Pepsi and Coke. Like a
human nose, the E-Nose is amazingly versatile, yet it's
much more sensitive. "E-Nose can detect an electronic
change of 1 part per million," says Dr. Amy Ryan, who
heads the project at JPL. She and her colleagues are
teaching the E-Nose to recognize those compounds like
ammonia, which cannot be allowed to accumulate in a
space habitat