The Future of Extraterrestrial Construction
Reposted with permission from constructionexec.com, January 30, 2019, all rights reserved. Copyright 2019.
Exploring and colonizing Mars presents a wealth of opportunities and challenges that could advance human knowledge of the universe and technology.
Could extraterrestrial construction (construction of a structure on the surface of a foreign body outside of the Earth and its atmosphere) be a future market for the construction industry? The construction industry only needs to look to the aerospace industry for a role model by embracing “disruptive technology,” optimizing lifecycle performance, adapting to a human-centric purpose and pushing the limits of technology. While the aerospace industry can build modular habitats, the construction industry is better equipped for building long lasting structures that can house larger populations. By partnering the construction and aerospace industries, the technological challenges of extraterrestrial construction can be overcome. The question is how and when?
The Future of Extraterrestrial Construction explores the risks to life safety, available technologies, estimated costs for shipping materials through space, and how to bring together all the elements needed for extraterrestrial construction.
There are nine launch sites in the United States. All construction planning must be phased and scheduled according to available launch windows, considering many variables that determine the length of a launch window, including:
- position of the target;
- tilt of the Earth;
- rocket’s performance; and
- amount of fuel available.
It takes about six months to travel to Mars when it is closest to Earth and once on Mars, travelers would have to wait approximately 20 months for Earth and Mars to be near each other before returning home.
MATERIALS AND FUEL
Mars contains many resources that can be used for construction. The Martian soil is composed of clay-like minerals and silicone dioxide that could be used for manufacturing ceramics, glass products and structures. M. A. Bury1 notes the potential to use concrete on Mars by utilizing the same admixtures used on Earth coupled with aggregates found locally in the Martian environment. Concrete was successfully batched in the space shuttle Endeavor. The next step is to batch concrete on an extraterrestrial surface.
Currently, shuttles carry the millions of pounds of fuel needed for the entire trip. Robert Zubrin has developed a process for creating fuel from the Martian environment by combining hydrogen imported from Earth with the carbon dioxide from the Martian atmosphere to create methane and water. The methane would be used to fuel equipment, the water electrolyzed to create oxygen and the hydrogen recycled off the electrolysis for more fuel production.
Mars presents a host of environmental challenges, the greatest being radiation. Lightweight concrete structures could protect from radiation and underground habitats constructed for growing food, assisted by robots.
The lower atmospheric pressure on Mars requires space suits to provide compression for the human body and protection from radiation. Space suits need to provide enough pressure to protect workers yet remain flexible enough to allow for a wide range of mobility and dexterity. Current space suits are filled with air to provide pressure, but are rigid and inflexible. Dava Newman of MIT has developed a BioSuit, a “skin-tight” suit composed of elastic fibers and cabling.
The reduced gravity of Mars has advantages and disadvantages. Construction equipment may be able to lift heavier loads on Mars, allowing smaller and lighter equipment to be used. Humans might experience superhuman strength on Mars, but the human body will acclimate to the lower gravity and develop muscle atrophy, osteoporosis and cardiovascular problems. A simple regimen of weight lifting may help compensate for the lower gravity and to maintain physical strength for a return trip to Earth.
Mars is negative 195 degrees Fahrenheit. NASA uses radioisotope heaters to keep electronics and batteries warm on Mars rovers, so construction equipment may need to be retrofitted to survive Mars’ frigid temperatures. Adaptations may need to account for the oils, seals and lubricants that could potentially freeze. Fuel and power sources for equipment will also need to be addressed. One solution is to adapt equipment to run on methane rather than petroleum fuels.
The mission would most likely be a scientific expedition commissioned by a space agency, such as NASA, and that the agency would pay for the base costs of shuttle launches, while the construction firm would pay the costs associated with shipping the payload. SpaceX’s Falcon Heavy weighs 3,125,735 pounds and can carry a payload of 30,000 pounds. The unit cost for shipping per pound was developed by dividing SpaceX’s advertised launch cost of $90,000,000 by the shuttle’s weight, arriving at $29 per pound. Two scenarios are provided, one for an above ground colony and one for a subterranean colony. Both scenarios assume a 12,000 square foot facility is needed to house a colony of 20.
In Scenario 1, the colony on Mars is constructed of concrete. The components used in construction consist of a concrete tilt-up structure, approximately 12 feet in height with 12-inch-thick walls, using aggregate collected locally on the Martian surface. The structure has of a six-inch-thick concrete roof.
In Scenario 2, the habitat is subterranean and uses a tunnel boring machine to bore a system of tunnels and cavities under the Martian surface. This scenario is based on using the Robbins Double Shield Tunnel Boring Machine.
The dimensions of the shuttle’s storage bay along with the weight of the payload should be taken into consideration when planning deliveries of materials and equipment. Each payload launched by the Falcon Heavy costs approximately $870,000. Under Scenario 1, a medium sized excavator is about 22 feet long and it weighs about 55,400 pounds, which pushes the payload limits of the shuttle; therefore, the excavator may need to be disassembled and shipped in two launches.
The cost of work for Scenario 1 is estimated to be $50,083,546. The total weight of materials and equipment to be shipped is 22,160,599 pounds. The cost of shipping is estimated to be $728,130,801 and will consist of 739 launches. By combining the cost of work and shipping, construction for Scenario 1 is estimated to be $778,214,347. If all nine launch sites are used for one launch each during the optimum launch window, shipping resources may take up to 164 years.
The cost of work for Scenario 2 is estimated to be $105,535,919. The total weight of materials and equipment to be shipped is 2,191,840 pounds. The cost of shipping is estimated to be $703,449,444 and will consist of 74 launches. By combining the cost of work and shipping, construction for Scenario 2 is estimated to be $808,985,364. Shipping resources may take up to 17 years.
Mars is the stepping stone in space exploration and a possible colonization destination. It is possible to overcome the challenges that Mars presents and explore and study other planets and moons within the solar system. Each new destination will present its own unique environment, risks and technical challenges. Current technology is insufficient to construct a facility on Mars in a timely manner. More launch sites are needed and the payload of shuttles need to increase. The most expensive element of extraterrestrial construction is the cost to ship materials to an extraterrestrial site. The costs associated with construction on Mars may be comparable to the construction of a large airport terminal or a large sports stadium.