Most plans for Mars bases make becoming a colonist about as desirable as setting up house in an oil drum, but an MIT team has come up with a plan for a Mars city based on the architecture of a tree. Taking out first place in the Architecture section of the Mars City Design 2017 competition, the Redwood Forest concept is intended to provide settlers with not only protection against the harsh Martian environment, but open public spaces filled with plants and abundant water.
As Sir Elton John said, Mars ain't the kind of place to raise your kids. Though the Red Planet is the most habitable of the planets, aside from our own, in the Solar System, it is still a terribly hostile place. The nighttime temperatures put the Antarctic to shame, the air is only a hundredth the pressure of Earth's and is composed mostly of carbon dioxide, deadly UV radiation rains down during the day, and cosmic rays are present 24/7. It's also dry to the point where the soil is composed of corrosive substances with very unpleasant properties.
Due to these drawbacks, it's difficult to come up with designs for manned outposts that don't look like a collection of tins that make the Amundsen-Scott South Pole Station look like a luxury resort. To break away from this stereotype, the MIT team of nine students led by MIT postdoc Valentina Sumini and Assistant Professor Caitlin Mueller took an interdisciplinary approach that uses location and system architecture, as well as water harvested from the Martian polar ice caps to supply tree-like habitats, for a design capable of housing 10,000 inhabitants in shirt-sleeve comfort.
At first glance, the MIT habitats don't look very tree-like. They look more like giant glass balls sitting on the Martian plains, each housing 50 people. But, like real trees, much of the habitat is below the surface in the form of intricate tunnels that connect the spheres and provide protection from cold, radiation, micrometeorites, and other surface hazards.
"On Mars, our city will physically and functionally mimic a forest, using local Martian resources such as ice and water, regolith or soil, and sun to support life," says Sumini. "Designing a forest also symbolizes the potential for outward growth as nature spreads across the Martian landscape. Each tree habitat incorporates a branching structural system and an inflated membrane enclosure, anchored by tunneling roots. The design of a habitat can be generated using a computational form-finding and structural optimization workflow developed by the team. The design workflow is parametric, which means that each habitat is unique and contributes to a diverse forest of urban spaces."
The habitats rely heavily on water, but not just for drinking, agriculture, or public fountains. It's a key ingredient in making the domes habitable.
"Every tree habitat in Redwood Forest will collect energy from the sun and use it to process and transport the water throughout the tree, and every tree is designed as a water-rich environment," says Department of Aeronautics and Astronautics doctoral student George Lordos. "Water fills the soft cells inside the dome providing protection from radiation, helps manage heat loads, and supplies hydroponic farms for growing fish and greens. Solar panels produce energy to split the stored water for the production of rocket fuel, oxygen, and for charging hydrogen fuel cells, which are necessary to power long-range vehicles as well as provide backup energy storage in case of dust storms."
The team believes that the Mars tree habitats could find a niche on Earth as well, at high latitudes, deserts and the sea floor, for example. In addition, the hydroponics technology could provide city dwellers with fresh food and the tunnels could be used to ease congestion in urban areas.
The team took out first place in the Architecture section of the 2017 Mars City Design competition
Source: MIT
That isn't the way the physics work (and why do you imagine that the MIT folks couldn't do basic physics?)
Mars has less than 1% the atmosphere of earth's (which absorbs about 25% of the insolation). Combined with Mars' greater distance, a solar panel on Mars gets 50-70% (Mars' orbit is very eccentric) as much sunlight as one would on a sunny day on earth. Which is still a lot of power.
But wait (as they would say on the late night commercials), there's more! A high percentage of days on earth are not sunny. Whereas a very low percentage of days on Mars are not sunny. This varies LOTS with location, but overall it means roughly a 20+% efficiency loss on earth. That means Martian solar panels will generate between 65% and 90% of the power they would on earth. A very rough calculation, to be sure, but good enough to indicate that solar panels would work perfectly well on Mars.
Which is not to say you also don't want nuclear. (non-interruptible and diverse power supplies — good idea!)
As for the temperature differential, again, look to the atmosphere. Most heat loss from greenhouses on earth are due to conduction and convection with the atmosphere. Radiation is a very inefficient remover of heat. On Mars, conduction and convection losses through the atmosphere are less than 1% of what they are on earth. Even with very large temperature differentials it's likely that a bigger problem for the colony will be disposing of excess heat, not keeping things warm. Humans and human activity create lots of waste heat!
pax / Ctein
No Sigh.
That really isn't the way any of that works.
Heat is not in short supply on Mars. Mars would only be 6% colder than Earth, due to less insolation, except for the fact that Earth has a nice thick insulating atmosphere that keeps the heat in. That boosts the earth's temperature by another 12%.
Mars still gets plenty of heat from the sun. Solar thermal is easy to collect, with high efficiency — look at the specs for well-designed solar water heaters on earth. On Mars, peak value is 500-700 W per square meter. Furthermore, all human activities generate heat and ultimately any energy consumed degrades to heat. Without an atmosphere to conduct/convect heat away, you have to WORK to get rid of the heat humans produce.
You're wrong about the primary source of heat loss in greenhouses - do the math, do the physics. Really, this is not arguable.
You're also wrong about what trees require. Go measure the light levels interior to a heavily forested area, and you'll find that the non-canopy trees (and other plants) get 10%-20% as much sunlight as trees out in the open. As already mentioned, the average sunlight on Mars is 50-70% of Earth's. Plenty of varieties of trees will be quite happy.
And, again, you just assume that the folks at MIT wouldn't bother to look up something this elementary. Because, really, it is very elementary. Instead of just arguing, try paying attention and learning Something. Maybe even look up their study and try seeing what they actually did consider and didn't consider? Instead of just assuming you're so much more brilliant and knowledgeable than people in MIT.
You keep harping on the "inefficiency" of solar panels, but that doesn't mean they're not adequate for generating electricity. A high-efficiency unit on Mars will produce about 2.5 kWh per square meter per day. A 20 m x 20 m array, which is hardly unreasonably large, gets you a megawatt hour per day. Oh yeah, and the stuff that doesn't get converted electricity can be captured as heat (because the panels absorbed most of the light that hits them)… and all that electricity ultimately goes back into heat. Like I said, heat is not in short supply! (Not so aside — your preferred solution of a nuclear power plant generates copious waste heat. Plenty for everyone.)
Again, this doesn't preclude the need for alternative power sources — storing overnight isn't a problem, but since dust storms on Mars can last for weeks you either need huge storage capacity or alternative ways of producing power. Probably you have both. Belt and suspenders.
This is all I'm going to say. If you want to come back with more irrelevant facts, be my guest. I'm posting this so that other people reading this article have accurate facts. Done here.
pax / Ctein