If you are going to start a civilization on another planet, it is given that you will face large obstacles. In my previous story I discussed the most important which is food and oxygen production. But for a long term sustainable colony we also have to be able to construct new things and expand the base.
One of the interesting things I’ve found when thinking about this, is that the goals and constraints would be surprisingly similar to those drawn up by environmentalists and makers. In fact one of may main inspirations when thinking about construction on other planets is the Global Village Construction Kit, which is an open source initiative to create blue prints for all the machines you need for starting a civilization on earth. The difference being a focus on design which are simple, practical and possible for anybody to build with some technical knowledge. That is the kind of approach you need on Venus and Mars, as we can’t rely on lots of experts and sophisticated machinery.
Modern Consumer Society and Manufacturing
Lets contrasts the ways products and made in our modern consumer society with the needs of space colonies.
Products Designed to Become Obsolete
Companies today tend to make products which don’t last very long. There is a strong economic incentive to do so. If it lasted, they wouldn’t be able to sell you new stuff. And if a product was easy to repair by you, that would be a bad thing, because there is a lot of money in repair and maintenance services. So repair requires highly specialize repairmen and equipment.
Beautiful and Appealing
To keep selling you stuff companies have to always tailor their products to trends and fashions. They have to appeal to your emotions, look and feel good. It might mean using exotic materials to make them look nice or complicated manufacturing techniques.
To get you to buy their product over the competition, they have to offer lots of features. Look at a microwave oven e.g. how many buttons it has which aren’t strictly necessary. You really only need a dial for power and one for time, most of the time.
Economic and Technological Legacy
A lot of the choices in how we do things today, comes down to history. One of the stories I love is how the design the boosters for the space shuttle was determined ultimately by the width of the rear end of a horse.
The short version is that the boosters had to be shipped on railroad, which ultimately derived its width from horse carriages in the roman empire.
Our electrical system today relies on high voltage AC current at all sockets, which doesn’t make much sense anymore. Electronic equipment is increasingly running on low voltage DC current:
- LED lights
The supply of electricity from batteries or solar cells is DC. Hence if you want to power some internal light from solar cells, you end up converting first the DC from the solar cells to AC and then converting the AC to DC for the LED light. This means significant power loss and lots of clutter from countless wall-warts dealing with these changes in current.
The primary reason why AC was originally chosen, was that there was no effective way of converting between different voltages when using DC. That was a big disadvantages as you want really high voltage when transferring electricity over long distances. That is becoming a much less relevant issue:
- Efficient DC-to-DC converters exist today.
- Power doesn’t need to travel far, as people will increasingly produce it locally.
The latter point is relevant for space colonies. Power will be generated from solar cells close to where it is being used, not hundreds of kilometers away.
Space Colony Demands on Manufacturing
The demands put on products used by space colonists will be a lot higher than for people on earth.
Some products can be made locally, while other products can only be made on earth. And naturally some products will be hybrids, depending on parts only found on earth in combination with locally sourced parts.
Durability and Repairability
Most critical are any products, tools or equipment which can only be made on earth. Resupply can take a long time. There are different ways of solving this. Things which take a tiny amount of space, could be supplied in large quantities and simply replaced as they wear out. Larger objects need to either have very long durability or be easy to repair. Preferably a combination of the two.
A space colony cannot rely on having a large selection of different tools and specialists. Products used has to be possible to repair by almost anybody with a minimum set of tools. Unlike e.g. consumer products today which prefer to hide things like screws. In a space colony we would prefer clearly visible screws of standard size.
If some little plastic piece breaks, then it should not render the whole things useless as is the case with many products today. It ought to be made easy to simply 3D print a replacement part.
You want things made of materials which are easy to repair, modify or reuse. A lot of impressive and advance materials are not suitable in this regard.
Composites materials will be best to avoid as they cannot easily be reworked, reshaped or repaired. So an object shouldn’t require say carbon fibre composite parts unless one can make similar kinds of carbon fibre composites locally.
Things We Don’t Have to Care About
All though there are extra demands made on products, what helps meeting those demands is knowing what we don’t have to care about.
- Products don’t have to look appealing or pretty.
- They don’t have to be tamper proof. In fact we want people to be able to modify them or tinker with them, unless perhaps if we are talking about vital life support systems.
- Cost is of little concern. Launching things with a rocket is so expensive, that the cost of the equipment you ship doesn’t matter. Hence using expensive materials like platinum, titanium etc is of no concern.
- Equipment doesn’t have to be compatible with stuff people already have. You don’t have to care about matching standard socket AC voltage e.g. The Space colony will have to build everything from scratch anyway.
Possible Solutions to Manufacturing and Building Challenges
I think one has to put emphasis on versatility and reusability. Colonists can’t be supplied with a large selection of specialized equipment. They have to be able to use a limited set of objects in many ways.
This suggest taking a lego approach: supply the colony with lots of standardized building blocks, which can used to build lots of different usable objects. As with real lego, you can then tear down the structure when when it is no longer needed and reuse the parts for new objects.
I would take cues from the Maker movement, since that involves people with limited skillsets building things with limited tools, which is why you see the equipment dominating there is:
- 3D printers
- Laser cutters
- Routers and CNC machines
If you look at Maker constructions of e.g. 3D printers they will be made from aluminum T-slots, which is a major favorite of mine. But there are many other standardized systems like MakeBlock.
Builders then work with beams in standardized lengths and with standardized screw types and sizes. To get flexibility one combines this with custom made laser cut or 3D printed plastic parts.
T-slots are often in aluminum because that is a metal which is easy to saw and drill. That would also make sense for space colonists. However since price is no option and many parts don’t need to be customized, I would assume that having lots of titanium parts would be even better, since they are very strong and light.
What are the kind of equipment, objects or structures space colonists would need?
We could start with things anybody needs, whether living on earth or extraterrestrial.
On Venus I would make this mainly out of plastic. There is no need for metal parts in furniture apart from potentially screws. But to save on metal needs, one would probably like to either print these as one big piece or as pieces which can be assembled without the need for metal screws.
On Mars, one could make something similar to concrete furniture. In hipster places on earth, people are already using concrete tables and chairs. Of course plastic is also possible source material on Mars as there is a thin CO₂ atmosphere, and plenty of water bound in underground ice. So we got all the atoms needed for plastic. The most efficient way of turning that into plastic is another question.
Bowls, containers, plates and utensils is easily made with a 3D printer using plastic. Although care has to be taken with respect to food safety, dealing with hot temperatures in beverages, hot washing etc.
For storing food one would need ways of performing drying, vacuum sealing and refrigerate. The latter is probably not strictly necessary. One can make food that lasts very long by just drying it.
Unique Needs for Space Colonists
Tanks, tubes and valves will be very important stuff for colonists. One has to always maintain tanks with all sorts of gasses:
- Oxygen for breathing, especially as a backup solution in case our oxygen producing plants or algae die. We also need oxygen for filling up tanks for extravehicular activities. That is colonists going outside the habitat.
- Various kinds of fuels for rockets, fuel cells or internal combustion engines. This could be hydrogen, methane, ethanol, ethylene, hydrogen peroxide.
- Water, for plants, human consumption, cleaning.
There will always be a bit need for many kinds of instruments. One cannot take air composition for granted, but have to be able to monitor whether levels or oxygen, carbon dioxide or various trace gasses are at safe levels.
On Mars radiation will be an important issue to consider so one needs instruments to measure this. All of this will be too complicated to create on Mars and hence has to be made on earth and made redundant by having many backup instruments if any one of them fails.
For larger structures like habitats we have different considerations. We need to build large structures without having to haul large construction machines and cranes. There are a wealth of ideas on how to do this. NASA e.g. has their own 3D printed habitat challenge. You can see some of the ideas submitted here.
I’ll cover some of the ideas I found interesting. Solarcrafting use the idea of sintering Mars sand by focusing sunlight, concentrated by a large lens on top of a huge balloon. By using a huge balloon one avoid having tall cranes.
Tool Inc also suggest a 3D printed habitat using a collection of small robots sintering the Mars soil.
Venus is of course my main interest of space colonization, but it is seldom discussed, so I would have to make a lot of my own speculations on how you would build anything above the clouds on Venus.
The starting point I think would be disc shaped airships like the Skylifter, which allows a lot of stability and maintaining a fixed location, and easy movement in any direction.
The skylifter was designed specifically to be used as a sort of crane on earth for moving whole building into a designated spot. Hence I speculate it should be possible to use a similar design on Venus as a crane in the sky. Several of these skylifters would then have to coordinate among themselves to connect pieces in the air.
In many ways the challenges of construction in the air on Venus will have similarities with construction in outer space in orbit: There is no surface to put cranes, building machines, scaffolding and the structure being built on.
Ballon Scaffolding Alternative
One possible idea is to inflate a structure and use that as a scaffolding, similar to how Werner von Braun originally proposed for building a space station. Numerous small skylifters could then move parts to the balloon, and attach them to it. Perhaps it would be possible to cover this balloon with successive layers of carbon fibre? One can basically glue on one thin patch at a time and add the binding polymer (epoxy) afterwards, to harden it.
I assume this process could be repeated over and over again to build a thicker and thicker shell around the balloon. As this happens the problem will be that the balloon will become heavier. The solution would be to gradually change the gas composition inside. The inside of the large balloon with carbon fibre composite on the outside could contain mostly CO₂, as the surrounding Venus atmosphere. However there would be smaller partially inflated balloons inside, or ballonets, containing lighter gasses. When this expands there could be a valve expelling excess CO₂.
This is similar to how old Zeppelins controlled their altitude, except they did it in reverse. The Zeppelin envelope contained the lifting gas e.g. hydrogen. While the ballonets, contained air. By inflating these they would compress the lifting gas and reduce the lift.
Of course the whole structure will likely get too heavy to hold itself, eventually so one needs to attach some sort of balloons with a lifting gas to the top of it.
Space Station like Assembly Alternative
An alternative approach is to build new habitats in a similar fashion to how the ISS space station was built. It is made from 15 pressurized modules.
The twist would be to make inflatable modules, which inflate enough to keep them floating at the right altitude. Inflatable modules isn’t anything new. NASA is exploring using inflatable modules from Bigelow Aerospace.
The difference with these modules is that they have thick kevlar walls to protect against space junk, and to contain the pressure difference between the internal space and the vacuum of outer space.
The requirements would be different in a Venus atmosphere. Pressure inside and outside would be the same, and there would be no high velocity objects to protect against, nor any radiation. The thick Venus atmosphere takes care of that problem. Instead one needs some sort of protective coating to resist sulfuric acid, as this will be a problem in the cloud layers of the atmosphere and below. With thinner walls we can more easily make the whole module float.
Assuming the inflated module is larger than the construction hangar, we would initially have to either push it out, attached to a tether or have e.g. another Skylifter pull it out with a tether. Once outside it could be inflated to full size and float by itself.
If we build connection ports (berthing locations) on each end, the modules can dock with each other an assembly into a larger floating aerostat colony. To make this work, we would likely, as with ISS need a smaller rigid connecting module, with multiple berthing locations, to connect more than just two modules.
Above you can see two Bigelow modules connected to a connecting module, which also has two Soyuz spacecraft attached.
Unlike a space station, this sort of aerostat habitat will likely require some sort of weights underneath to stabilize its orientation. Possibly it is enough to simply concentrate the weight inside, towards the bottom.
Inside we would fill the module mainly with breathable air. A sealed off envelope could contain lighter lifting gas and ballonets, to be able to stabilize the altitude in cases of weight gain and weight loss, by inflating or deflating the ballonets.
Modern airships like the Aeroscraft, use a compressor to inflate or deflate ballonets with Helium gas from tanks. So whether ballonets are used to make the airship heavier or lighter will vary.
This article is definitely a work in progress. I would be happy to get suggestions for things to include, things that wont work or improvements.