How fruit flies will get us to Mars

NASA has announced plans to launch a Fruit Fly Lab to the International Space Station in 2014, as part of its long-term goal to assess how fruit flies – and, by extrapolation, humans – fare during long-duration space flights. Research on how well fruit flies weather spending most, if not all, of their lives in the cosmos is expected to help the space agency better understand the challenges that prolonged space travel, perhaps to destinations as far-flung as Mars, will present to humans.

“That fly you’re about to swat is a pretty valuable research tool,” says Sharmila Bhattacharya, principal investigator for the Fruit Fly Lab and a scientist in the Space Biosciences Division at NASA’s Ames Research Center.

The announcement follows a 2011 report from The National Research Council that identified assessing the effects of long-term space travel on human health as a top goal for future NASA research. No wonder: NASA has said that it will send a manned mission to Mars as early as 2021. That gives the agency less than a decade to assess how astronauts’ will manage, both physiologically and emotionally, during the eight-months-long trip there – and then on the eight-months-long trip back.

Several research projects have been launched to that end. An experiment this summer tested how humans might manage the culinary challenges of big distance space travel, while other experiments, some wrapped-up and some planned, have tested the psychological toll that long-term confinement with other people might put on the future Mars-bound. Ongoing experiments also test astronauts’ vitals during and after space flight.

But another good way to test how humans will manage long-term space flight is to look not at humans at all, but at fruit flies. 

Fruit flies, or Drosophila melanogaster, at much like us: They struggle to sleep well as they get older. They’ll get aggressive – even spiteful – when put off from their goals. Sleep-deprived fruit flies become stressed and, when they do, they make mistakes. Male fruit flies will treat emotional bruises from romantic flops with alcohol. It all sounds all too human. 

Scientists have also known for decades that fruit flies resemble us not just in behavior but at the genetic, cellular, and biological systems levels. About 77 percent of our disease-associated genes have an equivalent in fruit flies; their cardiovascular and immune systems, among other systems, function much as ours do.

But fruit flies are also not at all like us in that their bodies are much less complex than ours, which means that modeling them and inferring from those models is also much simpler than is trying to draw conclusions from human bodies. 

“There are so many questions you can ask,” says Dr. Bhattacharya. “You can learn a lot from a fruit fly.”

These flies, already well suited for biomedical research, are especially well suited for biomedical research in space, says Bhattacharya. That’s because even thousands of fruit flies take up little room, which is important since space is – oddly – at a premium in space, where lots of research projects vie for room in the International Space Station. Plus, an analysis of thousands of almost anything packs a lot of statistical might.

And one of the biggest advantages of using fruit flies is their attenuated life cycle, says Bhattacharya. Fruit flies reproduce in just two weeks, and live for about one and a half months. So, it’s possible to assess the impacts of space conditions on a fly’s wellbeing over the course of its entire life, as well as to trace space-induced changes in the insects over multiple generations. It’s then possible to extrapolate from those results how human bodies might weather prolonged space flight.

“Everything is compressed in the lifetime of a fly,” says Bhattacharya.

For these reasons, not-all-fruit-fly-sized hopes have been pinned on what these insects might teach us about how humans do in space. Fruit flies were first launched into the cosmos 66 years ago in a confiscated Nazi V-2 rocket. The ride lasted three minutes and 10 seconds, and the high-flying flies were recovered via a parachute landing. The Americans who sent the flies up there wanted to know if the high-altitude radiation would kill them. It didn’t.

The Fruit Fly Lab is expected to launch for the International Space Station in 2014 aboard the Space X Dragon Capsule. It will build on previous fruit fly research in space in allowing scientists to cart more flies into the cosmos: the first experiment will send up about 200 fruit flies, and about 10,000 insects will come home. It will also allow for an in-space control group where the fruit flies will be exposed to the same gravitational pull as exists on Earth, while the experimental groups are housed in fractional and micro-gravity. Previous experiments have had a control group back on Earth but not one in space, says Bhattacharya.

The first mission will follow-up on a 2006 experiment aboard the Discovery Space Shuttle, the results of which were published in a 2011 PLOS ONE paper, that found that fruit flies reared in space had compromised immune systems, says Bhattachayra, who is an author on that paper.

The second mission, launching in 2015 and coordinated through Sanford Burnham Medical Research Institute in La Jolla, Calif., will assess how fruit flies’ cardiovascular systems hold up in space. NASA also has an open call out for researchers to submit proposals for future projects using the fruit fly facilities, says Bhattachayra.

Not all the fruit flies that have been to space have had starring roles there. Sometimes, their roles are supporting ones: hunting game for lab spiders. When NASA put the first two spiders in space in 1975 – garden spiders Arabella and Anita – it also sent 702 fruit flies with them. Not all the flies got to come home. Two years ago, a video of a space-faring, golden orb spider leaping upon fruit flies and spinning them into fiber bundles, like a murderous ballerina, was a YouTube hit. None of the fruit flies in Fruit Fly Lab will be fed to spiders, says Bhattachayra.