multiplanetary

Multiplanetary is an adjective used to describe or advocate the presence or settlement of humans on more than one planetary body, most commonly Earth and Mars. In policy discussions and space strategy, a multiplanetary human civilization is one that maintains permanent or long-duration settlements beyond Earth, supported by cargo routes, life support, and resource utilization across worlds.

Historical and cultural background: The idea predates current technology; early science fiction and spaceflight visionaries argued for planetary colonization. In contemporary discourse, organizations and entrepreneurs have framed multiplanetary as a long-term objective to reduce existential risk from a single-planet catastrophe and to access extra-terrestrial resources and inspiration.

Feasibility and requirements: Achieving this requires advances in propulsion (to transport people safely and efficiently), robust life support and health systems, radiation protection, reliable energy, habitat design, and in-situ resource utilization. It also depends on sustainable governance, economics, and resilient supply chains to support settlements.

Challenges and considerations: Technical, economic, legal, and ethical issues include planetary protection, equitable access to space, environmental stewardship of other worlds, and the potential impacts on Earth and space-based ecosystems. The timeline remains uncertain; milestones such as lunar habitation, crewed missions to Mars, and longer stays are often proposed as steps toward wider settlement.

See also: space colonization, Mars Direct, in-situ resource utilization, planetary protection, space law.