Space exploration is the use of astronomy and space technology to explore outer space. While the exploration of space is carried out mainly by astronomers with telescopes, its physical exploration is conducted both by uncrewed robotic space probes and human spaceflight. Space exploration, like its classical form astronomy, is one of the main sources for space science.
Space colonization is the use of outer space or celestial bodies other than Earth for permanent habitation or as extraterrestrial territory.
Terraforming or terraformation ("Earth-shaping") is the hypothetical process of deliberately modifying the atmosphere, temperature, surface topography or ecology of a planet, moon, or other body to be similar to the environment of Earth to make it habitable for humans to live on.
The Case for Mars: The Plan to Settle the Red Planet and Why We Must is a nonfiction science book by Robert Zubrin, first published in 1996, and revised and updated in 2011.
Mining the Sky: Untold Riches from the Asteroids, Comets, and Planets, is a 1997 book by University of Arizona Planetary Sciences professor emeritus John S. Lewis that describes possible routes for accessing extraterrestrial resources, either for use on Earth or for enabling space colonization. Each issue or proposal is evaluated for its effects on humanity, physics and economic feasibility based on planetary science. For instance, Chapter 5 exhaustively catalogs the types of near-Earth objects, assessing both the harms likely from possible collisions with Earth on the one hand, and their potential for profitable exploitation on the other.
The concept of self-replicating spacecraft, as envisioned by mathematician John von Neumann, has been described by futurists including physicist Michio Kaku and discussed across a wide breadth of hard science fiction novels and stories. Self-replicating probes are sometimes referred to as von Neumann probes. Self-replicating spacecraft would in some ways either mimic or echo the features of living organisms or viruses.
Marshall T. Savage is an entrepreneur, business executive, energy innovator and futurist from Rifle, Colorado.
The Great Filter is one possible resolution of the Fermi paradox. It posits that in the development of life from the earliest stages of abiogenesis to reaching the highest levels of development on the Kardashev scale, there exists some particular barrier to development that makes detectable extraterrestrial life exceedingly rare.
John S. Lewis is a Professor Emeritus of planetary science at the University of Arizona’s Lunar and Planetary Laboratory. His interests in the chemistry and formation of the Solar System and the economic development of space have made him a leading proponent of turning potentially hazardous near-Earth objects into attractive space resources.
The planet Venus has been used as a setting in fiction since before the 19th century. Its impenetrable cloud cover gave science fiction writers free rein to speculate on conditions at its surface; the planet was often depicted as warmer than Earth but still habitable by humans. Depictions of Venus as a lush, verdant paradise, an oceanic planet, or fetid swampland, often inhabited by dinosaur-like beasts or other monsters, became common in early pulp science fiction, particularly between the 1930s and 1950s. Some other stories portrayed it as a desert, or invented more exotic settings. The absence of a common vision resulted in Venus not developing a coherent fictional mythology, in contrast to the image of Mars in fiction.
Colonization or settlement of Mars is the theoretical human migration and long-term human establishment of Mars. The prospect has garnered interest from public space agencies and private corporations and has been extensively explored in science fiction writing, film, and art.
The colonization of Venus has been a subject of many works of science fiction since before the dawn of spaceflight, and is still discussed from both a fictional and a scientific standpoint. However, with the discovery of Venus's extremely hostile surface environment, attention has largely shifted towards the colonization of the Moon and Mars instead, with proposals for Venus focused on habitats floating in the upper-middle atmosphere and on terraforming.
Asteroids, including those in the asteroid belt have been suggested as a possible site of human colonization. Some of the driving forces behind this effort to colonize asteroids include the survival of humanity, as well as economic incentives associated with asteroid mining. The process of colonizing asteroids does have many obstacles that must be overcome for human habitation, including transportation distance, lack of gravity, temperature, radiation, and psychological issues.
The terraforming of Mars or the terraformation of Mars is a hypothetical procedure that would consist of a planetary engineering project or concurrent projects, with the goal to transform Mars from a planet hostile to terrestrial life to one that can sustainably host humans and other lifeforms free of protection or mediation. The process would involve the modification of the planet's extant climate, atmosphere, and surface through a variety of resource-intensive initiatives, and the installation of a novel ecological system or systems.
The terraforming of Venus or the terraformation of Venus is the hypothetical process of engineering the global environment of the planet Venus in order to make it suitable for human habitation. Adjustments to the existing environment of Venus to support human life would require at least three major changes to the planet's atmosphere:
- Reducing Venus's surface temperature of 737 K
- Eliminating most of the planet's dense 9.2 MPa (91 atm) carbon dioxide and sulfur dioxide atmosphere via removal or conversion to some other form
- The addition of breathable oxygen to the atmosphere.
NASA has made many concepts of moonbases for achieving a permanent presence of humans on the Moon. The American government agency requested an increase in the 2020 budget of $1.6 billion, in order to make another crewed mission to the Moon by 2025, followed by a sustained presence on the Moon by 2028.
Wolf Hartmut Hilbertz was a German-born futurist architect, inventor, and marine scientist. Notable contributions to science include the discovery of artificial mineral accretetion / biorock and its use to create electrified reefs.
The Seetee series is a golden age science fiction cycle by the American writer Jack Williamson It follows late-22nd century Asteroid Belt colonists in an attempt to harness the titular seetee, both for the advancement of humanity and the defeat of the undemocratic authority of the High Space Mandate.
Mars to Stay missions propose astronauts sent to Mars for the first time should intend to stay. Unused emergency return vehicles would be recycled into settlement construction as soon as the habitability of Mars becomes evident to the initial pioneers. Mars to Stay missions are advocated both to reduce cost and to ensure permanent settlement of Mars. Among many notable Mars to Stay advocates, former Apollo astronaut Buzz Aldrin has been particularly outspoken, suggesting in numerous forums "Forget the Moon, Let’s Head to Mars!" and, in June 2013, Aldrin promoted a crewed mission "to homestead Mars and become a two-planet species". In August 2015, Aldrin, in association with the Florida Institute of Technology, presented a "master plan", for NASA consideration, for astronauts, with a "tour of duty of ten years", to colonize Mars before the year 2040. The Mars Underground, Mars Homestead Project / Mars Foundation, Mars One, and Mars Artists Community advocacy groups and business organizations have also adopted Mars to Stay policy initiatives.
Many planets within the Solar System have been considered for colonization and terraforming. The main candidates for colonization in the inner Solar System are Mars and Venus. Other possible candidates for colonization include the Moon and even Mercury.
