This is space.
This is bacon.
What the astronauts are smelling are polcyclic aromatic hydrocarbons, which form during combustion, which occurs during the death of stars. You probably (hopefully) won't be smelling them in space any time soon, because you'd die, but you can smell them in bacon right here on Earth.
The universe also smells like burned almond cookies.
Space tourist and engineer Anousheh Ansari wrote about it on her blog:
Another note in the universe's perfumed bouquet is not so sweet.
Specifically, comets smell like total trash — we've got the spectrometer results to prove it.
According to Kathrin Altweg, one of the key scientists working with the Rosetta Orbiter Sensor for Ion & Neutron Analysis, comets — or specifically the comet 67p/C-G, has the "odor of rotten eggs (hydrogen sulphide), horse stable (ammonia), and the pungent, suffocating odour of formaldehyde. This is mixed with the faint, bitter, almond-like aroma of hydrogen cyanide. Add some whiff of alcohol (methanol) to this mixture, paired with the vinegar-like aroma of sulphur dioxide and a hint of the sweet aromatic scent of carbon disulphide, and you arrive at the 'perfume' of our comet."
The moon also has a pungent smell, so distinct that NASA enlisted perfumer Steven Pierce of Omega to re-create the odor for training simulations. Apollo 17 astronaut Gene Cernan describes the smell as "spent gunpowder."
Cernan didn't smell space directly, of course. After a moonwalk, he'd smell the dust of the moon on his equipment.