[Version française sur le site de La Recherche]
Our habitat is more than just a white cupola. It is a highly controlled and monitored environment.
From outside, it is a white dome on the slopes of a volcano, at 2.5 km of altitude, surrounded by reddish rocks as far as one can see. Connected to the dome is a brick-shaped container that we call the Sea Can.
To one side of the dome, a dozen meters away, are water tanks which can hold a bit over 3.5 thousand liters. As our extraction system has not been scaled up yet, these tanks are filled-in by a third party when needed. Before it happens we put some covers on the portholes and some headphones on our heads, so that we do not sense the outsiders’ presence. Our first resupply was after three weeks, and we still had some water. To last that long, we had to be very careful: nothing was wasted. We are taking 1’30” showers every three days, do laundry in a bucket when we can, and for washing dishes we use only a small amount of water, changed every other day, at the bottom of a container. Grey water is collected and used for washing the floor. A little extra is collected from Christiane’s prototype of a system for collecting mineral’s hydration water from Martian soils.
Some water, mostly used for showering, is heated by a solar heating unit on top of the Sea Can. Unfortunately you have to run water for above a minute before hot water reaches the shower, so the first person to shower on a given day usually has a cold one.
When water is too dirty to be of any use, it is sent to a tank. There, particles (food pieces, dirt…) sediment at the bottom. The tank already contains water, which levels up to just below a pipe perpendicular to the tank. When new water comes in, the level goes up and water flows through the pipe to an area outside the dome where it evaporates. The evaporating field features, under a layer of rocks, a tarp where remaining residues are collected.
You might have noticed that I did not mention the toilets in the water system, and that’s because they are not part of it. Our two toilets are composting ones. Our metabolic waste is falling into a drum containing saw dust (there to absorb liquids, mitigate odors and help the decomposition process) where it meets an army of microbes eager to feast on it. Those microbes are aerobic – they need oxygen – so every other day we are rotating the drum. If we don’t, then the drum becomes kingdom of anaerobic microbes, which will snack on our feces too but in a smelly way. Remember that we cannot open the windows here. Every three weeks the drum must be emptied, which we did yesterday. That part is not the most glamorous of the mission, but if everything goes well we harvest an almost odorless compost. Hint: everything does not go well.
To the other side of the dome is a photovoltaic array made of 36 solar panels of about 1.7 m2 each. In theory, this array can generate up to 10 kW, but in practice we are rarely above 5 kW and generally much lower. We are dependent on sunlight hours and weather. Electricity generated by the solar panels is stored in battery banks located in the Sea Can, which can store a bit less than 20 kWh. When the weather is good they are generally full in the early afternoon; then we try to complete as many energy-consuming tasks (running on the treadmill, using the washing machine instead of a bucket, baking…) as possible, as electricity generated beyond this point is lost. At any other time we are carefully sparing power.
If we run out of solar-generated power we start using a back-up dihydrogen fuel cell generator, located next to the entrance of the dome. This dihydrogen is generated by breaking water (H2O) into oxygen (O2) and dihydrogen (H2), by passing an electric current through it; it could thus be produced on Mars from water mined on site. Note that cyanobacteria could also be used for generating some dihydrogen there. We have barely needed this backup system so far, as we are closely watching our electricity consumption. The downside is that the dome is a relatively cold and dark place most of the time.
If we ran out of dihydrogen, we would turn on the back-up gasoline generator, located close to the solar panels. On Mars running out of power, even for a short period of time, would have awful consequences as life support systems rely on it. Here, the punishment would not be that dramatic but it is nonetheless dreaded. We don’t want the toilet fans to stop. Hell no.
At the top of the ridge adjacent to the dome is a repeater, there to retransmit radio signals and extend radio range. A cable runs from this repeater to a radio in the dome. This allows to keep contact with crewmembers in EVA.
Last thing worth mentioning: the dome is full of sensors. Over a hundred of them. We have access through digital interfaces to accurate videos and data (time- and location-dependent) on water levels, temperature, power consumption, generation and stocks, carbon dioxide concentrations in the air, and so on.
I had never been so aware of my resource consumption.