A European spacecraft orbiting a distant comet has finally answered a question we've all been wondering: What does a comet smell like?
"It stinks," says Kathrin Altwegg, a researcher at the University of Bern in Switzerland who runs an instrument called ROSINA that picked up the odor.
The European Space Agency has posted a full rundown of the comet's BO on its website. The mix includes ammonia (NH3), hydrogen sulphide (H2S), formaldehyde (CH2O) and methanol (CH3OH).
Of course, anyone visiting the comet would be wearing a spacesuit (on top of that, the sense of smell is notoriously numb in space). Nevertheless, taking a whiff of this comet would be like sharing a horse barn with a drunk and a dozen rotten eggs.
"It's quite a smelly mixture," she says.
Why didn't we know comets smelled so bad before?
"That's mostly because we've never been that close to a comet," says Altwegg. The Rosetta mission is now just 5 miles from the comet's surface.
It's just like a person: You can't really get a good sense of a person's body odor until you're right up next to him.
These chemicals are also clues to how the comet — and maybe how our solar system — formed. And for that reason, Altwegg doesn't really mind the stench.
"It's a little smelly, but at the moment it's a lot of fun to go to work every morning," she says.
Fun for now. But that could change. The comet is currently getting closer and closer to the sun. And like anything you leave out in the sun too long, it will soon start to smell even worse.
STEVE INSKEEP, HOST:
We have news of a space race. A European spacecraft has been trying for a decade to catch up to a comet called 67P, and the spacecraft is now close enough to answer that age-old question - what does a comet smell like? Here's NPR's Geoff Brumfiel.
GEOFF BRUMFIEL, BYLINE: The chemicals coming off of the surface of comet 67P - water, carbon monoxide, ammonia, hydrogen sulfide. The scientific conclusion?
KATHRIN ALTWEGG: It stinks.
BRUMFIEL: Kathrin Altwegg is a researcher at the University of Bern who has waited 10 years to discover that comets smell awful. Ammonia - think horse manure. Hydrogen sulfide? Rotten eggs. There's some alcohol in there, too.
ALTWEGG: It's quite the smelly mixture.
BRUMFIEL: Imagine being trapped in a stable with a load of rotten eggs and a drunk person. That's what it's like to ride along next to this comet. Why didn't we know comets smelled so bad before?
ALTWEGG: That's mostly because we have never been that close to a comet.
BRUMFIEL: Right, right, I mean, it's just like a person. You can't really get a good sense of their BO until you're right up next to them.
ALTWEGG: (Laughter) Exactly.
BRUMFIEL: These chemicals might actually tell scientists something about how this comet and maybe how our solar system formed. And for that reason, Altwegg doesn't really mind the stench.
ALTWEGG: Yeah, yeah, it's a little smelly. But at the moment, it's a lot of fun to go to work every morning.
BRUMFIEL: Fun for now. But as her research continues, the comet is getting closer and closer to the sun. And like anything you leave out in the sun too long, it will soon start to smell even worse. Geoff Brumfiel, NPR News. Transcript provided by NPR, Copyright NPR.