Phil Ritchie
Phil Ritchie is a Melbourne-based journalist.
Spreading life to the farthest reaches of space sounds like science fiction straight out of Star Trek, but the technology needed for this kind of exploit is just decades away, according to a theoretical physicist.
Claudius Gros from Germany’s Goethe University describes the Genesis project, which involves a fleet of autonomous robots that drop microbes onto suitable exoplanets in the hope they survive and flourish, in Astrophysics and Space Science.
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Since the first exoplanet discoveries were confirmed in 1992, the catalogue has skyrocketed to more than 3,500, according to the Extrasolar Planets Encyclopaedia.
And while many of these finds are gas giants, balls of molten rock or frozen tundras, sometimes a planet is in just the right spot with just the right makeup at just the right time to support life, at least for a while.
These are called “transiently habitable”, and are located within the habitable or “Goldilocks Zone” of their host star where water can exist in liquid form.
An exoplanet’s habitable period could be extended if it formed and held on to an atmosphere – perhaps one produced by photosynthesising microbes.
“We know for sure there will be planets which are a little bit, or transiently habitable, and that’s what this project needs,” says Gros.
“If everything goes well you can change the planet forever.”
He envisions the Genesis project (not to be confused with the NASA mission to trap solar wind particles) will propel smart micro-spacecraft, inspired by the likes of Breakthrough Starshot and Project Dragonfly, to distant planets at about 20% of light speed, or around 60,000 kilometres per second.
Upon arrival the spacecraft would hit the brakes, enter the planet’s orbit and, with on-board artificial intelligence, determine if the exoplanet has the right properties to allow life to flourish.
Only planets without life, but with the potential for at least a few hundred million years of habitability, would get the go-ahead.
The spacecraft would then synthesise a variety of single-celled organisms using its on-board gene laboratory. From there it’d be up to these cells to survive the drop tucked inside nano-sized capsules, start inhaling carbon dioxide and churn out oxygen.
This would slowly form an ecosphere.
The spacecraft would keep orbiting, though, and microbial rain would continue for hundreds of years until life gained a foothold and could look after itself. The spacecraft would then power down, Gros says, and remain floating in orbit to eventually crash on the planet.
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If life establishes, it could evolve into multicellular organisms. Such was the case on Earth, and it happened at least 25 separate times (with the first major multicellular life emerging 590 – 540 million years ago).
But Aditya Chopra, an astrobiologist at the University of Washington in the US, says it “cannot be assumed universal” because the “quirkiness associated with biological evolution and the selection pressures that led to the diversity of life on Earth means life elsewhere will not always evolve on the same timescales or in the direction as life did on Earth”.
Bearing in mind that the idea is still very much theoretical, Jonti Horner, an astrobiologist from Australia’s University of Southern Queensland says the paper contains a few out-dated references.
For instance, the Late Heavy Bombardment – a barrage of asteroids, comets and other objects that pummelled the solar system around four billion years ago – probably lasted much longer than the 100 million years Gros writes in his paper.
Still, Horner adds, now is the time to talk about such ideas.
“If we want, we can do it,” Gros says. “And we have to discuss and think about our place in the cosmos.
“Do we want to observe or do we want to be active?”
