Terraforming Mars has three major parts
1. Raising the temperature
2. Building the atmosphere
3. Building up a magnetosphere or creating some form of solar and cosmic radiation protection.
There is a new study which indicates that domed cities and colonies of various sizes could have the right temperature for liquid water with a 2-3 centimeter dome of silica aerogel without additional heating. They would heat up under the dome by 50 degrees kelvin without any heaters. Just the greenhouse effect would heat the area under the dome.
Regions on the surface of Mars could be modified in the future to allow life to survive there with much less infrastructure or maintenance than via other approaches. The creation of permanently warm regions would have many benefits for future human activity on Mars, as well as being of fundamental interest for astrobiological experiments and as a potential means to facilitate life-detection effort.
Large Domes Have Been Made on Earth
Mars has one-third of the gravity of Earth so making larger domes will be easier on Mars.
Singapore’s new national sports stadium (completed in 2014) is the world’s largest free-spanning dome, measuring 310-meters (1017 feet) across, and its roof can be opened or closed to suit the tropical climate.
The 55,000 capacity National Stadium has a 19,500 sq-meter (4.8 acres) retractable roof, which can open or close in just 20 minutes. The roof is made with a multi-layer ETFE pillow. The moving roof incorporates a matrix of LED lights, making it one of the largest addressable LED screens in the world.
The EFTE for the roof is a 0.15mm to 0.25mm-thick Fluon ETFE fluoropolymer film. Fluon ETFE Film is made of a high-performance thermoplastic fluoropolymer, and features excellent transparency, non-stick and insulation properties, and resistance to heat, chemicals and weather.
The Seagaia Ocean Dome (measured 300 meters in length and 100 meters in wide) was one of the world’s largest indoor waterparks, located in Miyazaki, Miyazaki, Japan.
Previously NASA scientist Jim Green proposed a concept of placing a magnetic dipole satellite with a 1-2 tesla magnet placed in an orbit between Mars the Sun would allow Mars to restore its atmosphere. Simulations indicate that within years, the planet would be able to achieve half the atmospheric pressure of Earth. The magnetic field would also protect Mars colonists from some solar radiation.
Without solar winds stripping away at the planet, frozen carbon dioxide at the ice caps on either pole would begin to sublimate (change from a solid into a gas) and warm the equator. Ice caps would begin to melt to form an ocean.
The atmosphere of Mars is relatively thin and has a very low surface pressure.
Silica aerogel can mimics Earth’s atmospheric greenhouse effect to warm Mars to a temperature where the ice melts and Earth plants can survive. Through modeling and experiments, the researchers show that a 2- to 3-centimeter-thick shield of silica aerogel could transmit enough visible light for photosynthesis, block hazardous ultraviolet radiation, and raise temperatures underneath permanently above the melting point of water, all without the need for any internal heat source.
Regions of the Martian surface could be made habitable with a material — silica aerogel — that mimics Earth’s atmospheric greenhouse effect. Through modeling and experiments, the researchers show that a two to three-centimeter-thick shield of silica aerogel could transmit enough visible light for photosynthesis, block hazardous ultraviolet radiation, and raise temperatures underneath permanently above the melting point of water, all without the need for any internal heat source.
There was a National Space Agency study for 25-mile wide domed city on the moon. A similar scale domed city could be built on Mars.