GENERAL BARRIERS TO SPACE SETTLEMENT
MILESTONE 2: Continuous Human Occupancy in Low Earth Orbit
Construction of continuously occupied pressured structures in Low Earth Orbit (LEO).
MILESTONE 3: Development of a Space Tourism Industry
Growth and development of a robust space tourist industry, including frequent orbital and suborbital flights and a growing number and sophistication of space hotels.
MILESTONE 4: Establishment of In-Space Commerce by Private Companies
Establishment of commerce in or between locations in space by one or more companies.
MILESTONE 5: Crew Habitats for Use Beyond Low Earth Orbit
Safe habitats for crews operating well beyond Low Earth Orbit and outside Earth’s protective magnetosphere.
MILESTONE 6: Use of Rotational Artificial Gravity for Habitats and Industry
Building rotating structures that can produce artificial gravity of the desired strength.
MILESTONE 7: Legal Protection of Property and Other Rights
Legal protection of property rights enacted to provide prospective off-Earth investors and settlers with the security to take financial risks.
MILESTONE 8: Land Grants or Other Economic Incentives for Space Settlement
Effective economic incentives, such as “land grants” or prizes, to encourage private investment in off-Earth settlement and any supporting ancillary development.
MILESTONE 9: Technology for Adequate Self-Sufficiency
People leaving Earth with the technology and tools needed to settle, survive and prosper without needing constant resupply of survival essentials from Earth.
MILESTONE 10: Demonstration of Multi-generational Human Survival off the Earth
Human reproduction and raising of children to adulthood over several generations in space.
MILESTONE 11: An Effective Asteroid Protection System
A system capable of detecting and defending against Earth-approaching asteroids or comets built and standing by for a deflection mission on short notice.
MILESTONE 12: In-space Fabrication and Construction of Large Pressurized and Unpressurized Single Piece Structures
Microgravity construction methods developed to fabricate structures that are too large to be launched intact from Earth.
MILESTONE 13: Use of Space Technology and Resources on and for Earth
Space technologies, techniques and resources used widely and benefiting all on Earth.
MILESTONE 14: An Integrated Cislunar Space Transportation and Logistics System
Infrastructure and transportation systems providing regular movement of people, cargo and propellant among locations in cislunar space.
MILESTONE 16: Development of the First ELEO Settlement
A small (about 100 m diameter), rotating habitat for permanent residents, providing about 1g in Equatorial Low Earth Orbit (ELEO) below about 500 km.
MILESTONE 17: Space Solar Power System (SSP)
Establishment of an operational space-based solar power system harvesting solar energy in space and transmitting that energy to markets on Earth.
MILESTONE 18: Robotic Confirmation of Lunar Resources
Orbiters and robotic landers to determine the nature and extent of lunar ice, volatile deposits and other lunar resources, and to provide the information necessary to guide the choice of the best sites for a lunar outpost and/or a lunar mining base.
MILESTONE 19: A Lunar Research and Development Facility
A crewed lunar research facility established to study human habitation, test various equipment and techniques, test mining of lunar resources, and conduct lunar science investigations.
MILESTONE 20: A Continuously Occupied Multi-Purpose Lunar Base
An initial lunar facility evolving into a permanently occupied, ever-expanding lunar base (or such a base created at another site), using what has been learned from the initial research and development facility, and increasingly performing commercial functions such as production of rocket fuel from volatile deposits and shipment of the fuel to orbit.
MILESTONE 21: A True Lunar Settlement
A lunar base or other lunar habitations evolving into a permanent settlement, increasingly self-sufficient and increasingly focused on commercial activities.
MILESTONE 22: Robotic Exploration of Mars for Local (In Situ) Resources
Satellites orbiting Mars and robotic landers, supplemented if needed by rovers teleoperated by an orbiting crew, determining the location, nature and extent of Martian resources, especially ice, guiding the choice of the best sites for follow-on human missions.
MILESTONE 23: An Integrated Martian Space Transportation and Logistics System
An integrated and sustainable system capable of safely transporting humans and cargo from Earth and/or cislunar space to the Martian surface, maintaining the crew on the surface, and having the ability to return the crew back to Earth or cislunar space.
MILESTONE 24: A Continuously Occupied Multi-Purpose Mars Surface Base
Following identification of a suitable base location and the selection of the particular infrastructure and equipment needed there, establishment of a continuously occupied multi-purpose Mars surface (or sub-surface) base.
MILESTONE 25: A True Martian Settlement (making us a multi-planetary species)
The Martian base evolving into a permanent settlement, increasingly self-sufficient and increasingly focused on commercial activities.
MILESTONE 26: Robotic Characterization of Asteroids
Remote or robotic characterization of near-Earth (and other) asteroid orbits, compositions and structures.
MILESTONE 27: Utilization of Asteroids
After robotic identification of suitable asteroids, robotic and human crews following to establish mining bases and habitats for transient occupation, and eventually building permanent human settlements nearby.
Orbital “cities in space” built from asteroid or lunar materials.
MILESTONE 29: Terraforming and Para-Terraforming
Modification of other planets or moons to support human, animal and plant life in a manner similar to the Earth.
Human travel to other solar systems and establishment of settlements in space and/or on extrasolar planets in these solar systems.
Through the general expansion of space settlement and the development of specific, isolated settlements designed to survive, space settlement increases the likelihood that the human species will survive in the long term.