This microscope could look for life on Jupiter’s moon
Shamu dreams of Europa.
Earth, far off now, looks like an unpopulated set of continents surrounded by empty ocean. You’d never know that all kinds of life—from staph to elephants to humans—move all over its surface. I just spent two years in a wide orbit around the blue marble, the first step in a circuitous journey toward Jupiter. We circled around the globe in this Space Launch System cargo capsule until our position was just right for Earth’s gravity to fling us toward the Jovian planet.
That isn’t meant to be my new homestead, though. I’m headed for Europa, a smaller sphere. Its exterior is sheathed in a miles-thick layer of ice. But underneath, enwombed like I am in this lander, there might be an ocean. Scientists say that with its water and its chemistry, it could be the place in the solar system (besides Earth) most likely to have life. Other spacecraft carrying other instruments have floated past it: Pioneer, Voyager, Galileo (great names, right?). Looking down with their farsighted cameras, they didn’t see any beings waving white flags. In fact, no human-made device has ever spotted definitive signs of alien existence. But maybe they simply didn’t—or couldn’t—look close enough.
I can. Hello, I’m Shamu. (Isn’t that another great name?) Seeing things close up is my raison d’être. I’ll land on Europa’s icy surface and a drill will cut down into the moon. I’ll suck up its liquid essence and spy magnified details that no one has seen before. Maybe my view will show only water, neat, no microbes. But maybe not.
Although willing and able to travel, Shamu—formally named the Submersible Holographic Astrobiology Microscope with Ultraresolution—is still very much on Earth, in a basement lab of the Science, Research and Teaching Center at Portland State University, where science writers can meet it. A rugged field instrument, Shamu uses lasers to create 3D movies of microorganisms moving in a liquid sample. While similar tools exist, the ones that boast high definition are too delicate to take into the wilderness, and the tough ones aren’t precise enough to see small bacteria. Shamu’s fans, meanwhile, think it’s well-suited to investigate not just weird life in Earth’s extreme environments, but also whether there is life beyond our planet. Shamu occupies a small space in the lab of scientist Jay Nadeau. One Friday in March, Nadeau is at work, leaning against a high rolling chair with two sweaters swung on its back. She wears another sweater (it’s the Pacific Northwest, after all), featuring a set of alpacas marching around her torso. There’s a Ridley road bike she uses for commuting stashed against the wall, and a helmet next to a CPU. Nadeau is small in all dimensions, and intense, with short curls springing from her head. She walks past the wet-lab benches, to a back room where a graduate student sits at a computer and mostly ignores her. There, Nadeau puts her hand against a mesh cage a few feet by a few feet. Inside sits a squirt bottle filled with 70 percent sterilizing ethanol solution, a roll of orange tape, and a Thorlabs temperature controller that resembles a cassette deck. But the primary occupant is a mysterious tube-like object, about 2 feet long and as wide as a wine bottle, bolted to a silver beam attached to the bottom of the cage. This, Nadeau says, is “The Microscope.” To be honest, Shamu looks pretty unassuming—like a toy spy glass. And the team Nadeau works with has created even simpler-looking versions. “We’ve made one that would fit inside a soda can,” she says, “with electronics the size of a few packs of cards.” For now, Shamu is grounded, relegated to looking at ice-cold water from Earth’s Arctic regions, super-salty desert water, and the wiggling extremophiles unlucky enough to be trapped there. Someday, though, Nadeau hopes it might get a peek at Europan liquid. Shifting her view from one place to another is nothing new for Nadeau. She got her doctorate in theoretical physics and moved into the life sciences at Caltech after that. When she walked into her first biology lab, the newness was almost overwhelming. “Everything looks like vials of clear liquid,” she says. The first time another lab sent her a DNA sample, she couldn’t find the genes. They had sent her an almost-empty envelope. “There was nothing inside it except a pencil circle with a couple of notes on it and a piece of filter paper,” she says. The DNA, of course, was on the paper, and she had to soak it to coax the sample into solution.
Thrown into the chilly deep end, she eventually learned what she was doing and moved her research to NASA’s Jet Propulsion Laboratory, where she stuffed microbes with luminescent nanoparticles that stuck to different chemicals, allowing Nadeau to track them. JPL was interested in how to obtain information about life on other planets. That quest starts with understanding life on Earth. And so Nadeau became part astrobiologist, and eventually a biomedical engineering professor at McGill University in Canada.
Around the time she started, in 2004, the country was doubling down on astrobiology—the study of signs of life off-Earth. The Canadian government had just funded a research network to identify various sites in northern North America that resemble other planets.
“You write a proposal of why you want to go, and you can go,” Nadeau says. And she did—to Nunavut territory, where cold springs flow from the permafrost, carrying strange little life-forms. On her regular trips to these Martian-like locations, she took along a fluorescence microscope to test its capabilities for an extreme, alien landscape—and to see what might live in such a place. To use it, she injected each sample with fluorescent dye, which stained specific chemical targets. The microscope beamed high-intensity light at the sample, illuminating the dye, and the instrument’s optics produced a magnified image of the specimen, its relevant molecules shining bright.
The microscope could handle only small samples, however, making it harder to find the organisms she was looking for. And the instrument itself was both fragile and difficult to miniaturize, making it unsuitable for the otherworldly backcountry. Plus, if those dyes someday were to spill on the Martian surface, NASA’s planetary protection office might be all over her.
Next, she considered holographic microscopes because they could make 3D movies that played in real time, and didn’t require contaminating dyes or anyone to focus them. These instruments shoot lasers at the samples and, based on the way the samples scatter the light, construct an all-dimensions digital movie of what’s inside.
At first, Nadeau and her team used a commercially available scope, but it didn’t provide crisp-enough footage. When, in 2014, she remarked to colleagues at the Jet Propulsion Laboratory that she wished somebody could build a better one, they responded, “We can.”
Together they developed Shamu. She and the JPL engineers discuss the specs that each iteration should have, and then they build it. After, Nadeau schleps it into the field to see if it works. You don’t have to focus it, and it slurps up a lot of liquid. That’s a plus if the population is sparse and the sample isn’t teeming with life, which can be the case in harsh environments.
Simple though Shamu might seem on the outside, it contains hidden depths. It’s different from other field-ready holographic microscopes, which have just a single laser. Shamu splits one into two: One is the so-called reference beam, which shoots straight through a sample of pure water, encountering nothing. The other is the science beam, which passes through the sample—of glacier melt, or salty water, or (maybe someday) Europan ocean water—and changes based on what it encounters. The microscope combines and compares the two rays: The difference between the nothing beam and the something beam equals the living somethings inside. The process happens instantaneously, leaving microbes swimming in your vision. As Nadeau puts it, “We know life when we see it.”
More specifically, Nadeau believes that we know life when we see it moving, thus giving up seemingly indisputable evidence of its existence. “Our visual systems are probably better than any possible method of saying if this is alive or not.” We need, she believes, to just look.
Nadeau would prefer if we looked for alien life using Shamu, of course. She pats the copper mesh and goes over to the computer, where she tries to find a white paper she co-authored called “Just Look!” As in, look for actual extraterrestrial microbes, not just for indirect evidence of living beings, like chemicals that result from metabolism.
Nadeau can’t find the paper but reiterates the idea behind it like so: When scientists wanted to see what was swimming around the Mariana Trench, they put a chunk of bait on a stick and watched with a camera. Marine beasts swam out of their hiding spots and came up to investigate. The scientists caught it on film, and so learned that beings lived way down there. “This is exactly what we’re trying to do, but on the microbe scale,” Nadeau says.
On Europa, a drill would bore more than 10 centimeters into the ice—far enough to reach liquid that seeps through the surface cracks—and Shamu would have a look. But before the JPL-Nadeau team could try to persuade NASA to give the scope a shot, they needed to try it out on more-familiar territory. Like Greenland. Which they did, in 2015.
Sheathed in my case—bright-orange plastic, with a killer whale painted in black on it—I couldn’t see anything. But I’d heard we were going to Greenland, by way of Iceland. At the airport, someone sent me on a conveyor belt through a metal detector. Words came muffled through my walls. “It’s a scientific instrument,” someone said. Other voices asked so many questions about what I was, and what I was here to do, it made me existential.
Soon enough, there was a rumble. Thrust. Lift. Then stillness. I imagined it was my launch into space, until a voice came over the plane’s PA. “We’ll have you in Reykjavik shortly,” it said.
Eventually, the humans set me down somewhere and began asking more questions. Not to me, but about me. They were nervous. “Is this going to work?” they asked. And then they just left!
After what seemed like hours, they returned and shot cloudy water into my sample holder to test me. I found out they’d been to a place called the Blue Lagoon. It was gross, they said. You could see the skin cells from all the bathing people. And trash on the bottom. So of course there were microbes feeding out there.
I quickly showed them a hologram. They sounded relieved, and we continued to the Greenland Climate Research Center for some real work. It was freezing out, and the humans put on orange-and-black puffy jumpsuits. Their arms were as big as their legs. In a place they called “the swimming pool,” but which they never would have swum in, they cut 6 inches or so into the ice with a drill that looked like a pogo stick. “Not enough, not enough,” they kept saying, as they pulled frozen cylinders from the drill’s mouth, checking for the ice’s depth.
Finally, apparently, there was enough. They stuck me into a shallow hole they’d dug, to keep me at the same cold temperature as the environment, and fed me a sample. Again, as always, I made them a movie. Later I learned this was yet another test, not what we were really here to do.
At last, we went to Malene Bay. In a white, flat landscape surrounded by white, pointy mountains, the orange-swaddled people-blobs found a suitable spot, sucked out a cylinder of ice, set me down in the hole, and fed me a sample with a syringe. In a minute, they all exclaimed, “Ooooo!” They could see something—algae, diatoms, marine bacteria—swimming. I could do this all day, and I did, showing them again and again what had been there the whole time, waiting for us to find it. At her computer, Nadeau pulls up a SpaceNews article from the day before, a story that would cast doubt on Shamu’s future itinerary: “Europa lander concept redesigned to lower cost and complexity,” reads the headline. The text describes a presentation that the Jet Propulsion Laboratory’s Kevin Hand, a deputy chief scientist in the solar system exploration directorate, made on March 28 to the National Academy of Sciences. According to Hand, the lander doesn’t need to look directly for actual life on the icy moon. “That’s a very high bar,” Hand said. “That bar runs the risk of setting expectations too high, perhaps.” There’s historical context for that attitude. NASA has been hesitant to look explicitly for life ever since it sent the Viking missions to Mars, in 1976. Those landers carried several experiments to look for biosignatures. Two came back negative, but one study showed possible evidence that microbes were there metabolizing. The problem was that a promising chemical signature could come from, say, geology and not biology. Ultimately, scientific consensus settled on “not aliens.” The agency has steered away from life detection ever since. “NASA has been kind of gun-shy about adding a mission that’s looking for life,” astrobiologist Alison Murray says. She co-chaired the Europa lander’s science definition team, and has been close to the mission-planning process. It’s partly to save face. But it’s also partly because that quest is hard. “There’s no one thing you can look at and say, ‘Aha, life,’” says Curt Niebur, the lander’s program scientist. Unless, he continues, a fish swims in front of the camera.
Niebur doesn’t think that seeing small life swimming is the same thing. “Just looking” for and at moving specks isn’t enough. Instead, multiple lines of evidence need to provide the same biological answer.
Nadeau will get a chance to convince NASA of Shamu’s worthiness, though. In late May, the agency released an official call for Europa mission instrument proposals. Nadeau has been ready for months to submit hers.
It will be a while before the agency makes its final decision. Sometimes, big missions like this one seem to exist only in the perpetual future, like science fiction. There’s a 2013 movie called Europa Report in which humans go to the Jovian moon and discover single-celled organisms and a strange light beaming underneath the ice. It turns out to be a macro predator. Nadeau has seen the movie, and she thinks it reaches into reality. “Everybody’s saying, ‘We’re going to look for these molecular-scale biosignatures,'” she says. “In the back of their minds, they’re really hoping to see a sea monster.”
I’ve been in space for five years by the time anything exciting happens. When NASA sends up astronauts, it gives them movies and books and games and music. When NASA sends a microscope and a spectrometer to space, we get nothing.
So, like some prisoner in solitary, I think about what I’ll do when I get out. Slurp up samples. Shoot lasers at them. Use my software to find any swimmers. Beam data nearly 400 million miles to Earth. Do that for 20 days. Then die alone on an alien planet.
Near my transit’s end, I haven’t seen anything—big or small—in a long time. But I can feel the tugs from every mass out there.
When I sense the first shift after years of the constant, one-directional slog, I know it’s Jupiter’s moon Ganymede, slowing me down so I’m not going too fast relative to Europa.
For the next 18 months or so, another moon, Callisto, and Ganymede tug on the lander and spiral me toward Europa. I get closer and closer and closer and slower and slower and slower, till Europa finally swings me into its own orbit.
The long voyage is almost over. I coast toward the surface, and a thruster fires backward to slow the lander down. Its camera looks at the ice, and a laser fires, hunting for a flat spot. Then the lander faces straight down, and a sky crane lowers me 60 feet toward the icy crust.
The surface looks like a giant agar plate, full of bacteria that have spawned in global lines of streaked Staphylococcus. It’s an illusion, though. The grooves are actually cracks in the frozen glaze where water might burst through. Maybe a sea monster swims below. Or perhaps some single cells. Or only inanimate molecules. Regardless, I’m going to find out. So good night and good luck: I have work to do now.
This article was originally published in the Fall 2018 Tiny issue of Popular Science.