A reasonable estimate is several centuries to a few millennia , with the most plausible answer being around 3 to 10 centuries for a truly resilient off-world backup of civilization. That said, the exact timing depends less on rocket launches and more on whether humans can build self-sustaining space habitats, closed-loop agriculture, industrial supply chains, and independent energy systems.

Why it takes so long

Surviving a stone-age-level collapse means more than having people in space. It means those off-world communities would need to be able to:

  • Produce food, water, air, medicine, and spare parts without Earth shipments.
  • Manufacture tools, electronics, and machinery from local or recycled materials.
  • Maintain breeding populations, governance, and technical knowledge over generations.
  • Withstand major failures like radiation, isolation, power loss, and equipment decay.

Today, humanity is nowhere near that level of independence. We can keep people alive on the ISS only because Earth continuously resupplies it, and even lunar or Martian settlements would initially be just as dependent. The gap between “a base that exists” and “a civilization that can survive Earth’s collapse” is enormous.

Best-case and likely-case timelines

A simple way to think about it:

Stage| What it means| Rough timeline
---|---|---
Orbital or lunar outposts| Humans live off Earth with heavy resupply| Decades
Partial self-sufficiency| Some food, water, and maintenance are local| 1 to 2 centuries
Industrial independence| Habitats can build most needed equipment locally| 3 to 10 centuries
True backup civilization| Off-world society survives Earth-level collapse with little or no support| Several centuries to millennia

The optimistic scenario assumes rapid progress in robotics, asteroid mining, closed-loop ecosystems, and space manufacturing. The slower scenario assumes the usual bottlenecks: cost, politics, technical failures, and the difficulty of making ecosystems truly closed.

What could speed it up

A few breakthroughs would shorten the timeline a lot:

  • Reliable closed-loop life support.
  • Large-scale space-based solar power or other resilient energy systems.
  • Autonomous mining and manufacturing on the Moon or asteroids.
  • Bioengineered crops suited to sealed habitats.
  • Better radiation shielding and long-duration health protection.

If those arrive quickly, an off-world “insurance policy” for humanity could become realistic within a few centuries. Without them, it could take far longer.

Plain-language answer

If you mean “when could humans have off-world colonies capable of surviving a total Earth collapse?” , the best honest answer is not this century, probably not the next one either, but maybe within a few hundred years if progress is unusually strong. A safer estimate is roughly 300 to 1,000 years for something genuinely durable, and longer if development is uneven. TL;DR: likely several centuries , with 3–10 centuries being a reasonable working estimate for true off-world civilizational backup.