Should we leave space exploration to robots — or prioritize human spaceflight, making us a multiplanetary species?

Harvard professor Robin Wordsworth, who’s researched the evolution and habitability of terrestrial-type planets, shares his thoughts: * In space, as on Earth, industrial structures degrade with time, and a truly sustainable life support system must have the capability to rebuild and recycle them. We’ve only partially solved this problem on Earth, which is why industrial civilization is currently causing serious environmental damage. There are no inherent physical limitations to life in the solar system beyond Earth — both elemental building blocks and energy from the sun are abundant — but technological society, which developed as an outgrowth of the biosphere, cannot yet exist independently of it. The challenge of building and maintaining robust life-support systems for humans beyond Earth is a key reason why a machine-dominated approach to space exploration is so appealing...

However, it’s notable that machines in space have not yet accomplished a basic task that biology performs continuously on Earth: acquiring raw materials and utilizing them for self-repair and growth. To many, this critical distinction is what separates living from non-living systems... The most advanced designs for self-assembling robots today begin with small subcomponents that must be manufactured separately beforehand. Overall, industrial technology remains Earth-centric in many important ways. Supply chains for electronic components are long and complex, and many raw materials are hard to source off-world... If we view the future expansion of life into space in a similar way as the emergence of complex life on land in the Paleozoic era, we can predict that new forms will emerge, shaped by their changed environment, while many historical characteristics will be preserved. For machine technology in the near term, evolution in a more life-like direction seems likely, with greater focus on regenerative parts and recycling, as well as increasingly sophisticated self-assembly capabilities. The inherent cost of transporting material out of Earth’s gravity well will provide a particularly strong incentive for this to happen.

If building space habitats is hard and machine technology is gradually developing more life-like capabilities, does this mean we humans might as well remain Earth-bound forever? This feels hard to accept because exploration is an intrinsic part of the human spirit... To me, the eventual extension of the entire biosphere beyond Earth, rather than either just robots or humans surrounded by mechanical life-support systems, seems like the most interesting and inspiring future possibility. Initially, this could take the form of enclosed habitats capable of supporting closed-loop ecosystems, on the moon, Mars or water-rich asteroids, in the mold of Biosphere 2. Habitats would be manufactured industrially or grown organically from locally available materials. Over time, technological advances and adaptation, whether natural or guided, would allow the spread of life to an increasingly wide range of locations in the solar system.

The article ponders the benefits (and the history) of both approaches — with some fasincating insights along the way.

“If genuine alien life is out there somewhere, we’ll have a much better chance of comprehending it once we have direct experience of sustaining life beyond our home planet.”