Physicist and futurist Freeman Dyson says we should search for extraterrestrial life where it is easiest to find, even if the conditions there are not ideal for life as we know it. Specifically, he says spacecraft should look for flowers 鈥� similar to those found in Earth鈥檚 Arctic regions 鈥� on icy moons and comets in the outer solar system.
鈥淚 would say the strategy in looking for life in the universe [should be] to look for what鈥檚 detectable, not what鈥檚 probable,鈥� he said on Saturday at a in Cambridge, Massachusetts. 鈥淲e have a tendency among the theorists in this field to guess what鈥檚 probable. In fact our guesses are likely to be wrong,鈥� Dyson said. 鈥淲e never had as much imagination as nature.鈥�
He said spacecraft should hunt for signs of life on Jupiter鈥檚 ice-covered moon Europa, since it would be detectable there.
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Cracks in the ice
Europa, which is thought to have an ocean of liquid water beneath its icy shell, has long been a target for astrobiologists, who suspect the interior could be salubrious for life.
But digging deep into the moon鈥檚 icy shell could be difficult. Estimates of the thickness of the ice have ranged between less than a kilometre to more than 100 km.
Life could be visible from orbiting spacecraft, however, if it made a home in cracks in Europa鈥檚 shell that connect the surface to the interior, Dyson said.
Parabolic flowers
Such life might take the form of flowers with a parabolic shape that focuses the dim sunlight falling on Europa on the interior of the plant. Flowers with such shapes (pictured) are found in Arctic climes on Earth, where the .
Europa flowers could be detectable through a phenomenon called , in which light gets reflected back to its source, Dyson said. This optical effect is seen in light reflected from animals鈥� eyes, and was used in the design of road signs and mirrors left behind on the moon by Apollo astronauts.
Although Dyson鈥檚 鈥榮unflowers鈥� may get their start on Europa, they could conceivably spread elsewhere in the solar system. 鈥淵ou can imagine once you have flowers that get nourished from below, they could evolve in the direction of being independent,鈥� Dyson said.
If plants spread to smaller, more distant objects in the solar system鈥檚 two cometary reservoirs, the Kuiper belt and the Oort cloud, they would be less subject to gravity and could easily grow in size to maximise solar collection, Dyson said.
Good target
John Baross, an astrobiologist at the University of Washington in Seattle, says he respects Dyson because 鈥渉e thinks out of the box and is always provocative鈥�.
鈥淲hile I might reject his idea, it frequently makes me rethink my own preconceived notions on the subject,鈥� he told New 杏吧原创. 鈥淣ow he鈥檚 got me thinking about life on Europa.鈥�
Baross says he thinks Europa is the second most likely place in the solar system, after Mars, to be capable of supporting life as we know it. But he says there is not yet enough evidence to know whether the icy moon boasts hydrothermal activity, which would provide energy and key elements necessary for life.
鈥榁ery radical鈥�
As for Dyson鈥檚 flower suggestion, he says it is 鈥渁 very radical鈥� idea. 鈥淥n Earth, flowering plants evolved during the and became diverse by co-evolving with insects. . . . I would not include flowering plants to my list of life-forms to look for.鈥�
鈥淎ny photosynthetic system on Europa would have to live at a depth removed from the high radiation bombarding the ice surface and still get light,鈥� Baross says. 鈥淗aving said this, it would be worthwhile to make more comprehensive observations and analysis of some of the surface features, including the deeply coloured ridges [see ],鈥� he says. 鈥淥ne might find evidence for biosignatures or very interesting chemistry.鈥�
Europa will be one of two moons explored in depth by a planned collaboration between NASA and the European Space Agency beginning in 2026, when a pair of orbiters are set to reach Jupiter.
