The Sweet Smell of Molecules

The Sweet Smell of Molecules
Jan 24, 2012 10:17:01 AM

That’s me with John Herrington in the Quest Airlock during the STS-113 Endeavour mission to the International Space Station in 2002. Credit: NASA / Don Pettit

A vacuum is a condition that is nearly devoid of molecules, and space is a molecular desert that makes the Empty Quarter of the Saudi Arabian peninsula seem like an oasis in comparison. But the space vacuum still has some molecules—residue from galactic processes, solar wind or atomic detritus spalled off from our atmosphere. And molecules, typically floating in the surrounding air, can be sensed via smell. To talk about the smell of space makes no sense at all. Even if we had space-adapted noses, there is no air to transport the trace molecules. However, space does have a definite smell, and we can smell it in a roundabout way.

I have had the pleasure of operating our space station airlock for many crewmates while they went on spacewalks. Each time, when I repressurized the airlock, opened the hatch, and greeted my tired returning friends, a peculiar essence drifting about the newly repressurized chamber tickled my olfactory senses. I noticed that the smell was coming from the spacesuit fabric, the tools, and any other equipment that had been brought inside. It was more pronounced on fabrics than on metal or plastic surfaces. It most definitely did not come from the air lines that pressurized the chamber.

At first I couldn’t quite place the smell. The best description I can come up with is that it’s rather pleasantly metallic. It brought me back to my college summers, when I used an arc welding torch to repair heavy equipment for a small logging outfit. It reminded me of sweet-smelling welding fumes. To me this is the smell of space.

Reptiles have smell sensors located not within their nasal passage, but on the roof of their mouth. They smell by waving their moist tongue in the air, then pressing it against the roof of their mouth, thus indirectly transferring molecules from the air to the olfactory sensors. It occurred to me that I was smelling the essence of space through an indirect transfer, in a manner not unlike that of our lizard friends.

Whisker Cleaning Time
Jan 25, 2012 04:09:32 PM

Lake Issyk Kul in Kyrgyzstan. Credit: NASA / Don Pettit

I have never been able to shave with a safety razor without slicing my face, so I use a rotary electric razor instead. In weightlessness they work just as well, and the whiskers are captured inside the shaving head. But how does one clean out the whiskers in weightlessness? On Earth, you simply open the head and shake them out. Doing that up here would be a disaster. So once a week, when vacuuming the accumulation of lint, dust, and detritus against the air inlet filters, I vacuum my razor. I hold the vacuum cleaner hose between my legs, and use both hands to carefully open the shaving head in front of the suction. A cloud of whiskers jumps out, appearing like a miniature asteroid field, then quickly disappears into a black hole, with no chance of escape.

The Eye of Issyk Kul
Jan 25, 2012 04:28:38 PM

Kyrgyzstan is wedged in the mountainous wrinkles between Kazakhstan and China, created long ago when the land mass we now call India, propelled by plate tectonics, slammed into the Asian plate. Living there are a proud people with a rich history, surrounded by natural, high-altitude beauty.

Out of numerous Kyrgyz lakes, one in particular stands out—Lake Issyk Kul. When seen from orbit, Issyk Kul appears to be a giant eye, looking at us looking down at it. The snow-covered mountains become aged eyebrows. The lake itself, having a fairly high salt concentration, does not typically freeze over, thus reflecting wintertime light in such a way as to form a “pupil” that seems to track us as we orbit overhead.