2013 — Phobos Space Colony
February 27, 2013
Author: David Smitherman
Proposed Research: This research project will explore Phobos as the initial site for an orbital station designed to support ongoing robotic and human exploration missions on Mars by providing a staging point for transfers to and from the surface and radiation protection for the crews. The long-term development on Phobos is envisioned to serve as the first permanent colony in space. The Phobos Space Colony functions as a gateway for ongoing missions to develop the resources of both Phobos and Mars, and leads toward a capability for the permanent expansion of our civilization beyond Earth. The focus of the design work will be on the habitable structures, in particular a surface base, a 1/3-gravity (g) habitat, and a 1-g colony.
Figure 1 illustrates the overall infrastructure for the colony development where Phobos is planned to have a surface base attached to the face of Phobos pointing toward Mars; a tethered transportation elevator structure extending down toward Mars for surface access; a rotating 1/3-g habitat and rotating 1-g colony developed below the surface of Phobos; a central tunnel through the center of Phobos; and a tethered elevator structure extending beyond Phobos for vehicle transfers to higher orbits. Planning is included to show a logical development for infrastructure and transportation systems with some design and analysis based on previous transportation system studies. While the idea for developing Phobos is not new, the overall infrastructure development strategy is new as is the detailed analysis and design of rotating habitats below or embedded into the surface of Phobos for permanent human occupancy.
Phobos is the larger and the closer of the two moons orbiting Mars. It measures approximately 22 km in diameter and orbits the planet every 7.65 hours at an altitude of 9,377 km. The rotation rate of Phobos is synchronous with its orbital period around Mars such that the same side continuously faces the Martian surface. A base on the side facing Mars can view approximately 90% of the Martian surface, up to ~65 degrees latitude. Phobos is thought to have a thick regolith cover with a composition of primarily sand and boulders compressed under its own mass. Large cavernous voids and solid rock formed from a former molten interior are possible but unlikely.
This research project proposes a two-phase approach to this problem. Phase 1 will focus on the collection of design options for development of a surface base and a 1/3-g rotating habitat below or embedded into the surface of Phobos for providing crews with total radiation protection and long-term mission capabilities spanning 3 to 6 years per crew rotation. The research and design effort will examine the construction materials and methods for excavation and pressurization of a habitable volume below the surface of Phobos, construction of a rotating structure sized to produce 1/3-g at about 2 revolutions per minute, design of overall habitable areas with life-support systems, infrastructure requirements for ongoing operations, and defining the requirements for the larger 1-g colony for Phase 2. Infrastructure planning will rely primarily on existing studies to collect options that show how a transportation and support system for this development could be built up incrementally over time beginning with the systems we have today to the capabilities for large-scale colony construction. This would include infrastructure planning for the base, habitat, and colony on Phobos, the reusable transportation systems from Earth to Mars, the tethered elevator transportation systems from Phobos to the surface of Mars and from Phobos to high Mars obits, and the exploration and development concepts for self-sufficiency. Phase 2 will take the findings, designs, and various options identified in Phase 1 to develop a design for the larger 1-g rotating colony, and refine the supporting infrastructure requirements, including further development of the excavation and construction methods for opening up a large habitable volume below the surface. The design will include examination of the structures required for a large rotating system, layouts of habitable areas, life-support systems, infrastructures for ongoing operations, and requirements for self-sufficiency and permanent human occupancy.
Two major issues that impact long-duration human exploration missions beyond Earth are space radiation and the microgravity environment. Long-term exposure to galactic cosmic rays (GCR) can significantly increase the risk of cancer, and long-term exposure to the microgravity environment can cause significant deterioration to the human body’s skeletal and muscular structures. Both radiation protection and artificial gravity are needed to address these significant environmental issues for deep space exploration and permanent colony development. The Phobos Space Colony addresses both of these issues in an exploration and development scenario that will establish large-scale permanent habitation in space. An initial space station or base attached to the surface of Phobos will immediately provide half of the shielding needed for long-term exploration missions. Subsurface development of a 1/3-g rotating habitat will provide a safe haven for long- duration missions by providing total radiation protection and enhanced microgravity countermeasures, while also supporting Mars surface exploration missions. Utilization of these systems to build an even larger 1-g rotating colony below the surface of Phobos will provide for permanent human habitation. A significant issue for many former space colony designs has been devising structural systems that can support the massive shielding requirements and still rotate to provide artificial gravity. Building a rotating structure below or embedded into the surface avoids the problem of radiation by using Phobos’ mass as a shield.
Ongoing exploration of the surface of Mars will be a theme throughout the base, habitat and colony infrastructure developments. The close proximity of the Phobos base to Mars will make it possible to do efficient robotic exploration on the surface of Mars initially for 4 hours out of each orbit up to ~65 degrees latitude, and then continuously with the support of satellite communications around the entire planet. Transportation to the surface will be via a tethered elevator concept and suborbital lander. The concept will significantly reduce the lander propulsion requirements making the entire system reusable. Resources from both Phobos and Mars will be utilized for radiation protection, propellants, construction materials, and life-support systems.
This research is important because it shows how developing a basing approach for deep space operations can support a wide variety of ongoing missions as opposed to single- mission pursuits. Developing Phobos as a base of operations for human exploration of Mars will focus resources, technologies, and transportation systems on a basing approach. Beginning with the International Space Station (ISS) and current studies for a cis-lunar deep space habitat, a reusable transportation path can be routed through both of these bases for missions to Mars. A need exists for a safe haven in orbit around Mars to support intermittent and eventual ongoing operations. Phobos is a natural location for the Mars orbital station. The total infrastructure plan will support exploration and development on Earth’s Moon; development of asteroid resources; exploration of Phobos and Deimos, the two moons of Mars; reusable transportation to the surface of Mars; and eventually access to resources beyond Mars’ orbit. From a scientific perspective, all these systems will eventually provide a more complete understanding of the Earth’s Moon, Mars, the Martian moons, near Earth asteroids, and provide the capability to construct large observation platforms and deep space robotic systems for continued exploration within and beyond our solar system. The emphasis on the use of in-situ resources will provide a path leading toward self-sufficient systems that will greatly enhance the economic viability of exploration missions and commercial developments in deep space. The technologies developed for self-sufficiency in space will have applications on Earth, enabling a higher quality of life for everyone. Final documentation from this project will include a recommended space exploration and development strategy that extends current capabilities to the capabilities needed for Mars exploration and development utilizing the Phobos Space Colony.