McQueron Engineering Will Simulate Space Saunas. The Idea Started in Antarctica.

Corentin Macqueron has spent more than a decade pointing serious simulation software at saunas. His day job is computational fluid dynamics at Orano, the French nuclear group, where he models safety scenarios. On his own time he built a full thermal model of a wood-fired sauna in NIST's Fire Dynamics Simulator, validated it against a real room, followed it with an electric-sauna model, and keynoted the Sauna Innovation Conference last December on the state of sauna thermal modeling. If sauna design has a physics department, he is most of it.

Now, in a LinkedIn post, he has given his firm McQueron Engineering its strangest assignment yet: "MQE will simulate space saunas in the upcoming few months."

He already has a name picked out for the first one to fly on a Starship. SaunaX.

The Document That Set Him Off

What prompted the post was not a client. It was a 141-page NASA contractor report from 1987 that Macqueron found while digging through the agency's archive: Human Adaptation to Isolated and Confined Environments, a study of nine men wintering at Palmer Station, Antarctica. NASA funded it because an Antarctic winter is the cheapest available rehearsal for a long spaceflight, and one of the researchers, Sybil Carrere, lived on the station for the full seven months, logging how the crew used every room in the place.

Buried in the building inventory is a sauna, and the entry is a small comedy of undercounting:

"A total of 36 hours of use was reported for the sauna. This building was used only for personal activities. Several individuals took saunas most every day either after work or after their exercise in the gym. The personal projects information indicates that people took saunas alone, although there were some unreported uses of this room when as many as four people took saunas at the same time."
— Evans, Stokols & Carrere, NASA-CR-181502

Read that again. The crew logged every session as solo. The researchers watched four people go in at once. Out of every room at the station, the gym, the pub, the labs, the darkroom, the sauna is the only one where the report says the paperwork and the behavior disagreed. In one of the most heavily monitored small communities on Earth, the sauna was the room people used more than they bothered to write down.

The report proves nothing about health, and Macqueron does not claim it does. There was no sauna group, no control, no measurement of a single bather. What it records is behavior: confined, stressed people with a fixed set of rooms picked the hot one most days. Which is roughly the finding the University of Greenwich team reached this year with 1,907 participants and actual instruments, at the cost of only one Antarctic winter and nine guys.

Why His Simulation Is the Interesting Part

Space agencies have been told before that crews want more than calories and oxygen. What nobody has done is put numbers on whether a sauna can physically work up there, and that is precisely the kind of question Macqueron's tooling exists to answer.

The problem is not heat. His own published model needed 8.75 kilowatts to hold a small room at 176°F, a big draw on a spacecraft but a solvable one. The problem is that a sauna runs on gravity. Löyly works because hot, humid air is buoyant: it rises off the stones, rolls along the ceiling, and sinks down the walls onto your shoulders. In orbit there is no buoyancy, so there is no rising steam, no stack effect, no natural convection at all. A zero-g sauna is a box of still, hot fog with a fan in it. On the Moon, at one-sixth gravity, convection comes back weakly. On Mars, at three-eighths, a little more.

So the question his simulations can actually settle is one nobody has ever had a reason to ask: how much gravity does löyly need before it behaves like löyly? That number does not exist. A validated CFD answer would be a genuine first, and it would come from the sauna industry's side of the fence, not NASA's.

It Has Flown Before

There is precedent, and it is Soviet. Engineer Alexander Massarsky built a collapsible steam cubicle that flew on Salyut 6, Salyut 7 and Mir, where by his account it worked well enough that cosmonauts used veniks in it. It burned up with Mir in 2001, and nothing replaced it; the International Space Station does not even have a shower. Russia's life-support institute floated shower-and-sauna development again in 2018 and nothing public has come of it. The field is, in other words, wide open for a one-man French engineering firm with a good mesh.

Whether SpaceX ever returns the call, the terrestrial record Macqueron surfaced keeps making its own argument. Palmer Station still has its sauna, plus a hot tub. The South Pole station limits crew to two two-minute showers a week for water conservation and keeps a sauna running at 200°F, where winter-overs use it to launch the 300 Club run to the pole at minus 100°F. Australia's stations have them. ESA's Concordia crew gets theirs on Sundays. Nobody at any of these agencies ran a trial first. They just kept specifying the room.

The Palmer study began in April 1985. Macqueron was born the same month, a coincidence he flagged himself. Some assignments pick their engineer.

The source: Evans, G.W., Stokols, D., & Carrere, S., Human Adaptation to Isolated and Confined Environments, NASA-CR-181502 (1987). Nine male winter-over subjects at Palmer Station, Antarctica, April to November 1985. Sauna: 36 reported hours, 0.2% of all logged station hours, every session logged as solo, up to four occupants observed. No control group and no physiological measurement tied to sauna use. Macqueron's sauna CFD work: arXiv:1404.6774 and subsequent validation studies.