Researchers Think Megastructures Can Help Seed Life Throughout the Galaxy
Image: NASA/Rick Guidice

Researchers Think Megastructures Can Help Seed Life Throughout the Galaxy

When you think of "conservation," you probably don't imagine blowing up Jupiter and building an energy-harvesting megastructure.

When you hear the word "conservation" you might think about newt-counting or anti-fracking actions. What you probably don’t think about is blowing up Jupiter and using its raw materials to build a megastructure enveloping the Sun. 

But this is exactly the idea suggested by the ingenious astrophysicist Freeman Dyson back in 1960. He suggested that we could construct a swarm of solar panels enclosing our sun, capturing all its energy. Dyson reasoned that as humans use more and more energy, eventually we are going to outrun what can be captured on Earth alone. Only by expanding the “energy metabolism” of our civilization beyond our planet could we avoid catastrophic resource exhaustion.


Nowadays, scientists don’t think this would require demolishing Jupiter. Anders Sandberg, senior researcher at Oxford University’s Future of Humanity Institute, explains that “it turns out making a sphere from thin metal foil made out of asteroids is way easier”. One benefit is that “we don’t need to disassemble planets”, he explains over Skype. 

Fortunately, it also turns out that there are more than enough asteroids in the Solar System to make that much foil.

Sandberg explains that such ambitious projects would ultimately provide ways to maintain things we value. If we value biology and biodiversity, then  we should preserve it from losses, whether caused by “mass extinctions or human stupidity," Sandberg said. But this also means encouraging growth. If biodiversity is good, then we want more of it, and for ecosystems to stick around longer. To this end, Sandberg refers to ideas like Dyson’s as “space gardening”. Because, in short, they would grant the ability to cultivate life beyond Earth and spread it throughout the Solar System.

'Necklaces of asteroids'

Sandberg’s plan for gardening space is new, but the idea that humanity should harness more of the sun to increase the amount of living things is an old one. In 1900, the Serbian inventor Nikola Tesla decided that the greatest problem of science is increasing the total energy flowing through human civilization. Because, he thought, with more energy, we could banish scarcity and live fuller lives.

Tesla didn’t propose exactly how to solve this, but he knew what the solution would roughly look like. It will, he said, ultimately involve increasing the amount of the sun’s energy we can put to use. Because, he figured, almost all complex and valuable things—from ecosystems to sentient brains—run on solar power. Civilization is just like a big plant: consuming sunlight in the indirect form of crops or coal. 


A few years before Tesla, a self-taught genius living in a modest shack in rural Russia had already considered the same problem. Konstantin Tsiolkovsky, who helped invent the rocket, did the math and estimated that our biosphere intercepts only about 4x10-10 of the sun’s total output. All the rest is squandered, pumped into frozen space. That’s a lot of waste.

Tsiolkovsky proposed a bold solution. He suggested that, in the far future, humans might rearrange the entire Solar System. At first, we could string together "necklaces of asteroids" into sun-girdling halos that could harvest more outgoing light. Later, we could reshape the mass of the planets—into "cubes, discs, rings"—for the same purpose. Then we could harness almost all the Sun.

Tsiolkovsky wanted to do this primarily because he wanted to spread life through the Solar System. At the moment, biology is stuck on one fragile planet. His motivations were, at heart, green: he thought a Solar System with more ecology was better than the current one which is almost entirely barren. Why not turn void and desert into a garden?

In ensuing decades, other scientists—like Vladimir Vernadsky—warned that the only way for humanity to ultimately avoid resource depletion would be to wean ourselves off meat and oil and somehow come to feed off the sun directly. This would phase out the inefficiency and immorality of more indirect methods, such as fossil fuels or food chains, they insisted.


Dyson, writing during the 1960s, was driven by similar motivations. Of course, some people didn’t like his suggestion of urbanizing a star. One suspicious journalist at the time complained that Dyson’s spheres would “turn stars into traffic lights”. But Dyson himself conceived of them as living systems, or “artificial biospheres," not industrial disruptions. He said that bringing the Solar System to life in this way would be the stepping stone towards spreading biology to other stars and ultimately “greening the galaxy”.

Life extension for Gaia

But what about plans for space gardening today? Going through a menu of plausible options, Sandberg points first to what he calls “biosphere life extension”. Our planet’s biosphere is resilient, but not immortal: in around a billion years our planet will become uninhabitable by natural causes like the expansion of our sun. However, Sandberg and his colleague Karim Jebari, of Sweden’s Institute for Future Studies, argue that putting solar shields into orbit could protect the biosphere from being scorched as the sun ages. This could prolong the existence of life on our planet for at least another billion years, Sandberg tells me.

“Of course, many people in environmental ethics would say, ‘Wait a minute, this stuff is very extreme: there’s a lot of hubris involved in trying to control the climate’. But we are already messing with the climate of the planet, so we are already altering it regardless," he said. 


Say you are an ecocentrist, or someone who cares about ecosystems (including Earth as a whole) beyond any use or value for humans. Even for the staunchest ecocentrist, the potential for using technology to extend the entire biosphere’s lifespan provides a great “reason to keep humans around rather than hoping they go extinct, because they actually are the only species around that can handle the solar radiation and keep ecosystems alive longer term," says Sandberg. 

So "gardening" could involve extending the lifespan of Earth. But what about extending life beyond Earth? A first step would be creating conditions for life to persist in space environments on its own, Sandberg explains. He imagines space stations with hydroponic gardens mining asteroids to build more space stations with hydroponic gardens, and this form of habitat filling up the Solar System.

“This would be a revolution in the history of life. Life would now actually have the vacuum of space as an ecological niche.” Someone could object that there is an awful lot of steel and plastic, compared to flowers, in that vision, he admits. “But it is really just some asteroid material getting turned into protective habitats for life. That’s a form of space gardening”.

We can think of grander visions. Since Gerard O’Neil, scientists have imagined larger space habitats, housing whole ecosystems. “Not just trays of hydroponic plants, but actual functioning forests," says Sandberg.


Fully engineered environments like these would allow not just for copies of ecosystems on Earth but experimenting with alternate ones. Indeed, rather than focusing on making other planets Earth-like—or ‘terraforming’ them—Sandberg suggests it might make more sense to simply make other planets amenable to biology “without necessarily having humans deciding what’s there”.

Life in the void

Finally, there’s the really radical proposals. How about life that thrives within the vacuum of space?

Dyson once spoke about genetically engineering plants capable of living on comets, without atmosphere. Sandberg said that he is skeptical of this idea, but if anyone did manage it, there might be no stopping it. 

“They would be bound to spread to other Solar Systems in the really long run. And, at that point, there’s of course going to be a greening of the galaxy—regardless of whether we are planning it or not," he said.

How long might greening the entire galaxy take? If the spores are left to drift and spread passively by their own accord, this could take around two billion years, which is a bit slow by human standards. “But, on the standard of the galaxy itself, that’s only around about 8 galactic rotations; that’s not an enormous amount of time to go from a galaxy that doesn’t have life in lots of corners to one that does," he added.

But it's also possible that intelligent life might intervene and help speed up this greening process. This could take as little as 100,000 years. If that happens, then we could be poised for a  "phase transition" between a mostly dead and a mostly living Milky Way. Indeed, Sandberg and others are skeptical that our galaxy is already green or has been ‘greened’ by anyone else.

Given that we may potentially have the technology to send out spores in a few decades, we had better decide on the ethics of doing so soon, because people may try regardless of if a  framework exists or not. We might, say, want to throw in a bit of intelligence and design—“so it’s more of a garden than a wilderness red in tooth and claw”—or it might be that we decide to let evolution take its course, Sandberg muses.

Of course, building sun-sapping spheres and seeding the galactic volume might seem ambitious. But, ultimately, if we want to safeguard a future for ecosystems within the universe in the longer term, then it might just be that gardening space and farming the stars is the only genuinely conservationist route.