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We're Breeding Flies to Live on Saturn's Moon (for Science)

To call the project “ambitious” would be an understatement.
Image: Andy Gracie. Used with permission.

Andy Gracie has been breeding fruit flies since 2012. By his own estimation, he's bred 60 generations of flies, or about 8,000 individual experimental flies. It would be going faster—I feel like 8,000 pass through my kitchen every time a plum becomes overripe—but Gracie's flies are being raised in an environment that is growing steadily colder. By “a lowered degree every few months,” Gracie's flies are being bred to live on the largest moon of Saturn, Titan.

Titan, as devoted Motherboard readers will know, is sort of a bizarro Earth: It has a thick atmosphere, dunes, rivers, coasts, even rain and a polar vortex. But the surface temperature is something like -180 degrees Celsius, the atmosphere is made of nitrogen, ammonia, and hydrocarbons, and has 1.5 times more pressure. Its lakes, the only known lakes in the solar system apart from those on Earth, are made of liquid methane and ethane. The Cassini probe confirmed just last week that Titan also has an ocean, but its below the moon's surface, and is kept liquid by being heated by the moon's core.

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Despite being hostile to all but (theoretically) the tiniest of microbes, this is the environment for which Gracie is selectively breeding fruit flies. The Drosphilia titanus need to withstand the 180 degrees-below-zero temperatures, live, breed, and breathe without oxygen, in increased atmospheric pressure and decreased gravity. To call the project “ambitious” would be an understatement.

So Gracie's shooting for just a few new traits by adapting the flies to colder temperatures and a circadian rhythm of 16-hour days and nights, and selecting the heartiest flies to reproduce. To learn about the particulars of the project, we emailed back and forth, working around a camping trip he was taking in his native Spain with his family.

Image: Andy Gracie, used with permission.

The breeding vials are bathed filtered, full-spectrum lights, in order to recreate the orange light that Titan is (likely) awash in. To find the heartiest cold weather flies, Gracie is using a temperature gradient, allowing one end of the vials to be two degrees above normal, and the other to be two degrees below normal. “The flies are placed into the midpoints of the channels to see which end they gravitate towards,” Gracie said. “The flies that tend to spend more time towards the cold end are selected for the next breeding stocks.”

The actual selection involved in selective breeding brings us to the extremely tedious-sounding task of sorting each new brood (batch?) of flies by sex, which Gracie assured me isn't as difficult as it sounds. “Under a magnification of 20 times, the sexual dimorphism is very apparent and even with the naked eye you can be fairly sure,” he said in an email. “The male is slightly smaller (in common with many animals) and has a slightly darker back and a distinct hairy black patch at the end of the abdomen. With a microscope you can clearly observe that the males also have a 'sex comb', a row of dark bristles on each foreleg that are used for gripping on to the female.”

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Sex combs aside, Gracie's choice of species is no accident, as he describes, the “Drosophila melanogaster is one of the so called 'model organisms', the workhorses of modern bio-science. Owing to its 95 percent genetic similarity to humans it has been used extensively in space based experiments to determine the effects of microgravity and radiation on the body, and has had a near continuous presence in space through the biosatellite programs of the 1960s, Mir, the space shuttle and the International Space Station.”

Lest you think the flies get nothing from the experiments, Gracie started with flies with “vestigal wing phenotypical mutation,” meaning their wings are there but don't work. “In the dense atmosphere and low gravity of Titan, these almost wingless insects will be able to rediscover the ecstasy of flight,” Gracie explains.

So, 60 generations in, they've got to be getting close to ready for Titan, right?

“To achieve the biological differences that I would need to achieve [Titan readiness] would require inducing mutations over many tens of thousands of generations of flies by natural means,” Gracie said, estimating that at this rate, it's going to take him something like 400 years to do. “I'm stuck with this project for life,” he said.

"I see these differences as irreconcilable in practice but also lots of fun to rub against each other."

Confession time: Gracie's an artist, and “Drosophila titanicus” is a “speculative art project” albeit one “built on a foundation of solid science,” that more than anything examines the intersection between art and science, if ever the two meet. Gracie seems skeptical about whether or where they actually do.

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“Many people talk of the desirable outcome of art and science being practiced together,” he said. “While the starting points of art and science are the same—questions about why things are the way they are—I don't actually see this as possible or beneficial.

“While an ongoing dialog between the disciplines is important, I think that each practice limits the other. Good science demands an increasing stripping away of extraneous information and of as much uncertainty as possible to reach a clear and coherent thesis. Good art demands ambiguity, metaphor and layered interpretations. I see these differences as irreconcilable in practice but also lots of fun to rub against each other.”

Gracie admits that the flies will never be able to live on Titan, in 400 years or well beyond. Insects need oxygen and temperatures warmer than those observed on the moon.

“This project isn't actually about the eventual development of a fruit fly which could actually survive on Titan. The project is more about following very rigorous scientific procedure and seeing where the artistic gesture and metaphor can be found and exploited,” he said. “By setting a tangible but impossible goal I am free to explore notions of speciation, biological perfection and the future of life forms in space. Thus a friction is established between the rigorous requirements of scientific practice (without which the project would be pointless) and the ambiguous demands of art.”

Image: Andy Gracie, used with permission.

The ambiguity and scope of the project open it to nearly any metaphor you want: how environment comes to be expressed in a species; where one species ends and another begins; the underlying Social Darwinism of seeking astronauts with “the right stuff”; our own readiness for a time some 6 billion years away, when the Sun expands to become a red giant and thaws Titan and swallows Earth.

To the latter point, look to Gracie's flies. “Readiness in this context is all about still being alive and still breeding,” he said. Well, as humans we're certainly there. Alive, still breeding, and still breeding flies. For Titan.