It’s annoying when someone unwraps a philly cheese steak and stinks up the whole subway car, right? Or when your roommate leaves the bathrooms smelling… um, less than clean.

Imagine how you’d deal with various odors if you were orbiting high above the Earth in a space station where opening a window isn’t an option. In space, no one can stand your smells.

Noxious odors can actually be a hazard to astronauts. An acrid stench on board Soyuz-21 ended the 1976 Soviet mission because the odor “became unbearable” to the cosmonauts, reports Angela Swafford for Wired. To prevent such calamities, NASA employs specialists who test all the materials and components needed on spacecrafts. Perhaps the most famous member of that team is George Aldrich, a man with a specialized nose.

Aldrich’s job title is Chemical Specialist at NASA’s White Sands Test Facility in New Mexico. There he has sniffed and whiffed hundreds of NASA’s smell requests. Other than the parts of the spacecraft itself, he also breathes deep to check astronauts personal items: Family photos, bibles, parts to build a model ship in a bottle—he smells them all.

“I used my sense of smell for 38 years to smell stuff before it goes into space,” he told odditycentral.com. “What makes me really important to NASA is that I actually use my sense of smell to help protect the astronauts from obnoxious odors in space. I feel like I’m a bodyguard for the astronauts. I’ll smell it here, you know? I’ll-take-the-bullet type thing, before you are actually subjected to it.”

Thanks to Aldrich’s work, astronauts can work relatively fragrance-free. That leaves their noses free to notice something else: The smell of space inside spacecraft is different from that outside, as International Space Station science officer Don Pettit explained in this fascinating post:

… Each time, when I repressed the airlock, opened the hatch and welcomed two tired workers inside, a peculiar odor tickled my olfactory senses. At first I couldn’t quite place it. It must have come from the air ducts that re-pressed the compartment. Then I noticed that this smell was on their suit, helmet, gloves, and tools. It was more pronounced on fabrics than on metal or plastic surfaces. It is hard to describe this smell; it is definitely not the olfactory equivalent to describing the palette [sic] sensations of some new food as “tastes like chicken.” The best description I can come up with is metallic; a rather pleasant sweet metallic sensation. It reminded me of my college summers where I labored for many hours with an arc welding torch repairing heavy equipment for a small logging outfit. It reminded me of pleasant sweet smelling welding fumes. That is the smell of space.

Scientists analyzing the chemical compounds floating through far-flung corners of space can predict what other odors we might encounter. At Discover, Veronique Greenwood reports that a dust cloud in the center of our galaxy called Sagittarius B just might smell like raspberries and rum. Yum.

H/T geek.com | screengrab via Science Channel/Youtube.com