Later this month, when she launches off from Baikonur, Kazakhstan, Jessica Meir will rapidly ascend further than any bird, past the Earth’s atmosphere, to the International Space Station. Among the ISS’s usual crew of engineers, she will be the rare physiologist, looking at how the body reacts to space travel.
Meir has always been interested in extreme environments, and how the planet’s hardiest animals cope with them. In the early 2000s, she coordinated experiments at the NASA Johnson Space Center on how human bones, muscles, and lungs react to the rigors of spaceflight. She earned her doctoral degree diving in Antarctic waters, studying emperor penguins and elephant seals as they did the same. And in the summer of 2010, a few years before she realized her lifelong dream of becoming an astronaut, she hand-raised a dozen bar-headed geese—the highest-flying birds in the world.
“It was even more ambitious than I realized,” she says. “I didn’t know anything about waterfowl. I hadn’t even worked with flying birds before, only with penguins.”
Twice a year, bar-headed geese migrate from their breeding grounds in China and Mongolia to their wintering sites in India—a 5,000-mile journey that happens to take them across the Himalayas, the tallest mountain range on Earth. Perhaps they first made that trek in deep prehistory, when the Himalayas were still young and low. As eons passed and mountains rose, the geese had to traverse ever-higher barriers. One early explorer, while camping at 15,000 feet, claimed to have heard “the distant honking of these birds flying miles above me unseen against the stars.” Another watched from the slopes of Everest as a flock of geese flew over the mountain’s 29,000-foot summit. These anecdotes were controversial, but scientists who fitted geese with GPS trackers showed that they do indeed reach altitudes of up to 24,000 feet.
Flapping flight is already the most energetically demanding style of movement, but bar-headed geese must do it in extremely thin air that provides half as much lift as at sea level, and contains a third as much oxygen. They manage because their bodies have a slew of adaptations that make them extremely effective at extracting and using oxygen.
Compared with other geese, their lungs are larger, and their breaths are deeper and more efficient. Once oxygen enters their blood, it is bound by the same red pigment—hemoglobin—that other birds use, but their version grabs the gas far more tightly. The blood vessels in their muscles are more densely packed, allowing them to deliver oxygen more quickly. Even the cells in those muscles have special tweaks: The mitochondria—small structures where energy is produced—are more numerous and located closer to the surface, making it easier for oxygen to reach them. “It’s not just one thing,” Meir says. The geese “have adaptations at every step of the way.”
These tricks have been uncovered through decades of research, but almost always with bar-headed geese that were resting or walking on treadmills. Only one group of scientists studied the birds as they flew in a wind tunnel, and they used air with normal oxygen levels. Meir wanted to duplicate the low-oxygen conditions of a Himalayan crossing, and measure the performance of flying geese using instruments mounted on masks and backpacks. A wild-caught goose would never fly in a tunnel with such equipment. “You’d just be studying a fear response,” Meir says. The only solution was to raise some of the birds herself.
Meir found a bird park in North Carolina that houses bar-headed geese, and headed over before a dozen eggs were set to hatch. When the young goslings emerged, they immediately “imprinted” on Meir, psychologically categorizing her as their parent forevermore. She fed them, cared for them, and trained them to fly by riding a scooter down country roads while the birds flapped next to her. “They’d fly so close that their wingtips would brush my arm,” Meir says. “And I’d be looking into the face of this animal flying next to me, and not just any animal but my baby.”
Occasionally, an oncoming car would spook the birds, which would veer up and away. If they lost sight of Meir, they’d alight in populated areas and chase anyone that could have conceivably been their mother. One landed in a hockey field and started running after the players. Another found a grocery store and followed people in and out of the automatic doors. “I pulled the scooter over, grabbed the goose, and everyone was just like: What’s going on?” Meir says. “I’ve always wanted to write a children’s book about this.”
For several weeks, she cemented her bond with the goslings by taking them for walks, playing with them, and letting them pile on top of her for naps. “I joked that as a woman in my 30s, I suddenly had these 12 babies following me around,” she says. “I was a modern-day Mother Goose. It was an exceptional experience.”
When the birds were big enough, Meir took them to the University of British Columbia—one of the few facilities with a suitable wind tunnel. (Most of the tunnels used in animal research are too small for geese, while those that are big enough are meant for airplanes, and produce Mach-level winds.) The tunnel is like an invisible treadmill: An assistant would lift each goose into the fast-flowing airstream, while a mask pumped nitrogen over its beak to simulate the low oxygen levels of a Himalayan flight. Two tubes in the mask recorded how much oxygen they consumed and how much carbon dioxide they produced, while backpacks measured their heart rate. Meir, for her part, stood to the side, clapping and shouting.
Despite that encouragement, many of the birds refused to fly. “They’re all capable but they just wouldn’t,” Meir says. “They’re not really trainable like a dog. You can reinforce them with fresh lettuce. but they’re not that kind of animal.” Only seven birds cooperated, but they provided a wealth of data. For a start, they proved that bar-headed geese can indeed fly through severe oxygen deprivation, of the kind they’d encounter at the highest Himalayan peaks.
One might assume that as oxygen disappears, the birds would compensate by increasing their metabolism and sending more oxygen-rich blood coursing through their bodies. Actually, they do the opposite. When the oxygen around them vanishes, they conserve the gas by dramatically slowing their metabolism.“That wouldn’t have been my first thought,” Meir says. “Flying is the costliest form of locomotion, so it’s incredible that they can lower their metabolic rate and still exist.”
She suspects that the geese achieve this feat by changing their flight patterns to favor more efficient strokes. They might also selectively shut down nonessential organs to focus on their flight muscles—a trick that diving animals also use when descending to oxygen-poor depths.
With the goose studies complete, Meir is now focused on her trip to the ISS on September 25, both as a researcher and a research subject. “I’ve been waiting my whole life for this,” she says.
Humans aren’t adapted to space the way that bar-headed geese are to high altitudes, but our bodies do react strangely to being there. Arteries tend to thicken and stiffen in space, accumulating a decade or two worth of aging in a mere six-month mission. Eyeballs become flatter, blurring astronauts’ vision. If humans are to ever travel to far-off worlds like Mars, we’ll need to understand why those changes happen and how to remedy them. Once aboard the ISS, Meir will run a number of physiological experiments to help find those answers. For once, she likes to say, she will be “the one being poked and prodded.”
“It’s kind of fitting,” she says. “It’s time for me to pay my dues.”