If humanity is to live for a long time, we may have to colonize other planets. Either we ourselves will make the Earth uninhabitable, or it will simply come to a natural end and will not be able to support life - one day we will be forced to look for a new home.
Hollywood films such as The Martian and Interstellar give us an idea of what might be in store for us. Mars is by far the most habitable planet in our solar system. However, there are thousands more exoplanets orbiting other stars that could replace our Earth. What technologies do we need to make this possible?
We already have one space colony - the International Space Station (ISS). However, it is located only 350 km from Earth and the crew of six, who is there, needs to constantly supply resources. Most of the technologies developed for the ISS, such as radiation shielding, water and air recycling, and solar energy harvesting, will certainly be available for future space settlements. However, creating a permanent space colony on the surface of another planet or moon could cause many new problems.
Unnatural habitat
The main requirement for a human settlement is a habitat - an isolated environment that can maintain air pressure, its composition (amount of oxygen) and temperature, and protect residents from radiation. This is likely to be relatively difficult to achieve.
Launching large and heavy objects into space is costly and difficult. Spacecraft from the days of the Apollo missions, which consisted of several modules capable of detaching and docking, were sent into space in pieces and assembled by astronauts. However, given the impressive progress in autonomous control, the parts will be able to assemble independently. Today, maneuvers like the Apollo docking are performed completely automatically.
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3D enclosures
Alternatively, you can take a small set of tools from Earth with you and create a habitat using locally harvested resources. In particular, 3D printers can be used to transform minerals from local soil into physical structures. Incidentally, this has already begun to be seen as a possibility. Private firm Planetary Resources demonstrated how 3D printing works using a metal-rich asteroid that was found on Earth at the impact site. NASA installed a 3D printer on the ISS to show it can be used in zero gravity as a potential method for making components for spacecraft in space.
Water as a vital ingredient
Once the habitat is built, the colony will require a constant supply of water, oxygen, energy and food to sustain its inhabitants. This will be necessary in case the colony is not built on an idyllic planet like Earth in terms of abundance of resources. Water, as we know, is the basis for life. It can also be used to make fuel or protect against radioactive radiation.
The first settlement will have to take a certain amount of water with them, and then dispose of all liquid waste. This is already practiced on the ISS, where not a single drop of liquid (water after washing, sweat, tears, or even urine) is wasted. Also, the colony may have to extract water from the groundwater reserves that may exist on Mars, or the ice that can be found beneath the surface of some asteroids.
Water also serves as a source of oxygen. On the ISS, oxygen is generated by a process known as electrolysis to separate oxygen from hydrogen in water. NASA is also working to develop methods to recover oxygen from the atmosphere by byproducts such as carbon dioxide, which we breathe out when we breathe.
Energy production
Energy production is probably the technological aspect of colony creation that we are best prepared for thanks to photovoltaic panels (solar panels). However, depending on the location of the colony on the planet, we may need to improve this technology. At the distance of the Earth, we can get about 470V of electricity for every square meter of solar panels. This number will be lower on the surface of Mars because it is located 50% farther from the Sun than Earth, and has a thick atmosphere that partially screens out sunlight.
In particular, sandstorms periodically occur in the atmosphere of Mars, which are known to be problematic. Sand further limits the amount of light received and can also accumulate on and cover the panels. However, the solution to this problem is already being dealt with by upgrading the existing Mars rovers that are sent to Mars. For example, NASA's two Mars rovers Spirit and Opportunity were designed for 90 days of operation, but more than 12 years later, they are still operational. It has also been found that the Martian wind periodically clears dust from the panels.
Hydroponics
The colony must be self-sustaining so that even without the Star Trek Replicator, agriculture is of great importance to food production. Crops can also be used to convert carbon dioxide in the air into breathable oxygen. Growing plants on Earth is not that difficult because they have adapted to this environment for thousands of years. However, growing fruits and vegetables in space or on another planet is not that easy.
Temperature, pressure, humidity, carbon dioxide levels, soil composition, and gravity all affect the survival and growth of plants, to varying degrees in a variety of species. Several studies and experiments are under way to grow plants in controlled chambers that mimic the environment of a space colony. Hydroponics is one possible solution to this problem, as has been demonstrated on Earth with radish, lettuce, and green onions. Hydroponics involves growing plants in a rich nutrient fluid without any soil.
Changing of the climate
The final requirement for a space colony is a climate suitable for life. The composition of the atmosphere and climate on other celestial bodies is very different from the Earth. There is no atmosphere on the Moon or asteroids, and on Mars, the atmosphere is mostly carbon dioxide. Here, surface temperatures range from 20 ° C all the way to -153 ° C at the poles during winter, and air pressure is only 0.6% of that on Earth. In such conditions, settlers will be forced to live in isolated habitats, outside of which will be possible only with the use of space suits.
Can we create life on Mars?
Alternatively, we can change the planet's climate on a large scale. “Geoengineering” is already being studied as a way of responding to the Earth's climate change. This requires a tremendous amount of effort, but similar methods can be extended and applied, for example, to other planets such as Mars.
Potential solutions are also bioengineered organisms that can convert carbon dioxide in the atmosphere into oxygen, or darkening Mars' polar caps to reduce the amount of sunlight they reflect and thereby raise surface temperatures. In addition, creating a large orbiting solar mirror will help reflect the sun's light to specific regions, such as the poles, for localized temperature increases. Some believe that such relatively small changes in temperature could affect climate change, creating much higher air pressure. This could be the first step towards terraforming Mars.