A few months ago, at her office in Houston, Kate Rubins was feeling weird.
She was dizzy, she says — "staggering around like a 2-year-old who had just learned to walk." She was constantly looking at her desk to make sure the objects on top weren't floating away.
Rubins wasn't going nuts. She was just readjusting to Earth after living without gravity for four months, hundreds of miles above the planet's surface.
Floating around up there, with blood rushing to her head like she was hanging upside-down on monkey bars, had been disorienting at first, though she eventually learned to move around using all four limbs.
Coming back to Earth's gravity at the end of October was even more disorienting.
But Rubins is used to drastic transitions. Oddly enough, her journey to space had started years before, in central Africa.
"If you put your finger on a map in the middle of Africa, that's about where our field site was located," says Rubins, a microbiologist as well as an astronaut.
It was 2007, and an airplane touching down on a grass runway in the Democratic Republic of the Congo had brought Rubins and her colleagues to study a nasty outbreak of monkey pox in a remote village. She'd already spent time studying HIV, Ebola and smallpox in the lab.
This time the airplane wouldn't be back for six weeks.
Rubins didn't know it at the time, but that remote expedition gave her experience she'd eventually draw on during a much bigger journey — to outer space.
After the work in Africa, Rubins returned to Cambridge, Mass., and a fellowship at the Whitehead Institute for Biomedical Research, where she spent a lot of time writing grants.
All that paperwork was "mind-numbing," Rubins says. Just to get a break, a colleague suggested they try filling out a different sort of application — to become NASA astronauts.
"So, I found the application online," Rubins says, and filled it out on a lark. "I'll take this chance," she figured, "and maybe it'll be a good story someday of how I applied to be an astronaut."
A few months later, she got a call from Houston asking her to come down for an interview.
Rubins doesn't fit the normal astronaut profile. Many start out as military pilots, engineers or doctors — not microbiologists studying viruses. But she got the job.
"There's been a lot of growth in people's interest in doing biological research on the space station," explains Julie Robinson, NASA's chief scientist for the International Space Station program.
Before the shuttle program ended in 2011, Robinson says, "our commanders and our pilots had to be ready to land the shuttle, so that implied a really strong piloting [and] aerospace background, and that isn't as important now."
But once NASA's shuttle program ended and U.S. astronauts started hitching rides to space on Russian rockets, the focus for the American personnel shifted away from piloting skills — they no longer have to be counted on to land the shuttle.
"What's more important now is the time they spend in orbit, when they're carrying out a variety of experiments," says Robinson. "We can take what we learn in space to help us understand aging, disease processes, and even the basic biology of cells."
There's another reason it's useful to have molecular biologists and microbiologists in space: While there aren't viruses like Ebola or monkeypox on the space station (astronauts get quarantined before liftoff to make sure of that), space travel has never been sterile.
Take this moment from the Apollo 10 mission in 1969, for example, when three astronauts on board notice a loose turd floating through their spacecraft.
Back then, a few astronauts were sealed in a small capsule for a few days. But now there's the space station — a habitat the size of a six-bedroom house that circles the Earth, about 200 miles above our heads.
The station may have started out pristine, but its astronaut crews didn't.
And for 16 years straight, crew after crew has been sweating, pooping and puking inside the space station. The microbes they release tend to stick around, because the station is essentially sealed — like an airplane that never gets opened.
Today, it's teeming with non-human life. It has its own unique microbiome.
"Staphylococcus aureus we'll find once in a while; Staphylococcus epidermidis all the time," says Castro-Wallace, running down a list of resident space station microorganisms. There's also Staphylococcus hominis (usually harmless), Micrococcus luteus (lives in the mouth and throat), Burkholderia (common in soil; some types can cause lung infection), Sphingomonas (common in water, and rarely harmful), Penicillium (the fungus we find in bread mold) and Aspergillus (more mold), just to name a few.
Recently, an entire wall panel of the station turned green with mold.
"Imagine your shower curtain at its worst," says Castro-Wallace, pointing out that the wall of mold happened on the Russian side of the space station.
She's particularly interested in Staph. aureus; a strain of the bacterium that's resistant to multiple drugs is a particular problem in hospitals, and can turn something as simple as a paper cut dangerous.
"If it got into a cut, it could be life threatening," Castro-Wallace says.
It's become clear that scientists need to know what else is living up there, she says — particularly because research suggests that microgravity can change gene expression in certain bacteria and make them more virulent. (Castro-Wallace has found that Staph. aureus changes color in simulated microgravity, an indicator that the bacterium might act differently in space than on Earth.)
Right now, astronauts swab surfaces of the station and send samples back to Houston for identification. But that can take weeks or months.
It's a big reason why NASA hired Kate Rubins — and shot her into the sky.
Last July, after seven years of training at NASA — working at Mission Control, doing mock space expeditions underwater and flying supersonic fighter jets to keep her reflexes sharp — Rubins blasted off from Kazakhstan aboard a Russian rocket.
She had 115 days to help set up a microbiology lab on the station. She drew on her earlier experience studying viruses — working quickly in a remote place, with minimal equipment.
"There's actually an incredible amount of parallels between working in central Congo in a remote, isolated village and doing research aboard the space station," Rubins says.
When I called her in space, while she was on the station last fall, Rubins had just gotten the lab up and running and was really excited about it.
"It's absolutely a working laboratory," she told me, as she floated around, describing the scene. "We have experiments all over the place."
Just weeks before, Rubins had sequenced DNA in space — the first time anyone had ever done that. The fact that the technology worked in microgravity showed that, in the near future, it should be possible to swab a moldy wall, for example, and immediately determine the type of mold.
She'd also grown stem cells into heart cells without gravity, and — peering through a microscope that she'd set up — watched them beat in unison.
Rubins has proved that it's possible to do molecular biology at least 200 miles beyond Earth — and maybe 200 million miles away, too.
"The world of sequencing and molecular biology has opened up to us on the space station," she says.
She and NASA's Julie Robinson are the kind of people who start sentences with the words "When we go to Mars," as if the journey to that planet is as inevitable as their next trip to the grocery store.
"It's the plan," says Robinson. "Absolutely," says Rubins, who is now Deputy Director of Human Health and Performance at Johnson Space Center.
When -- or if -- that expedition happens, Mars-based biology labs will be crucial resources for astronauts there. They'll need the tools of molecular biology to identify non-human life, so these emissaries from Earth can make sure that they aren't contaminating Mars with their own microbes, and to be able to detect any new life forms they might encounter. They'll also need the labs to diagnose sick space travelers, so they don't waste precious antibiotics or antivirals.
And, of course, they'll need the technology to figure out what's growing on their walls. Because one thing is for sure: Any human-built Mars habitat will soon become at least as gross as the International Space Station.
RACHEL MARTIN, HOST:
A few years ago, an airplane touched down on a grass runway in the Democratic Republic of Congo, and out stepped microbiologist Kate Rubins.
KATE RUBINS: If you put your finger on a map in the middle of Africa, that's about where our field site was located.
MARTIN: Rubins and her colleagues were there to study an outbreak of monkeypox, which is a cousin of the deadly smallpox virus. She didn't know it at the time, but that expedition was actually the beginning of a much bigger journey to outer space. NPR's Rae Ellen Bichell has the story of how Kate Rubins became a new kind of astronaut.
RAE ELLEN BICHELL, BYLINE: When Rubins got back to Boston after studying deadly viruses in the Congo, a heap of less exciting work was waiting for her. She was a fellow at MIT. And she was writing grants for money to support the lab she just started. It was grueling work, says Rubins, enough so to prompt a colleague to suggest that they take a break and do something fun like apply to become astronauts.
RUBINS: So I found the application online. And I said, you know, why not? I'll take this chance. And maybe it'll be a good story someday about how I applied to be an astronaut.
BICHELL: A few months later, she got a call from Houston.
RUBINS: They said, well, we'd like you to come down to Houston for a job interview (laughter). You know, you feel like saying, well, is this a real job that people actually do?
BICHELL: Rubins doesn't fit the normal astronaut profile. Most tend to start out as Navy pilots or engineers, maybe doctors, not molecular biologists studying viruses. But as it turns out, Rubins was just the kind of person NASA needed at this moment in its history. See, space travel has never been sterile.
(SOUNDBITE OF ARCHIVED RECORDING)
TOM STAFFORD: Oh, who did it?
JOHN YOUNG: Did what?
EUGENE CERNAN: What?
STAFFORD: Who did it? Get me a napkin quick. There's a turd floating through the air.
YOUNG: I didn't do it. It ain't one of mine.
BICHELL: This is archival tape from the Apollo 10 mission. And they're discussing exactly what you think they are - a loose turd floating through their spacecraft.
(SOUNDBITE OF ARCHIVED RECORDING)
CERNAN: I don't think it's one of mine.
STAFFORD: Mine was a little more sticky than that.
YOUNG: God almighty.
BICHELL: Back then, astronauts were sealed in a small capsule for a few days. But now, there's the space station, a habitat the size of a six-bedroom house that circles the Earth 200 miles above our heads. The station may have started out pristine, its astronaut crews - not so much.
SARAH CASTRO-WALLACE: We cannot send up a sterile crew.
BICHELL: That's Sarah Castro-Wallace, a microbiologist at NASA's Johnson Space Center. For 16 years straight, crew after crew has been sweating, pooping and puking up there on the station. The microbes they release tend to stick around because the station is sealed like an airplane that never gets opened. Today, it's teeming with non-human life.
CASTRO-WALLACE: Staphylococcus aureus we'll find once in a while, Staphylococcus epidermidis all the time, Staphylococcus hominis, Micrococcus luteus, Burkholderia, Sphingomonas, Penicillium, Aspergillus.
BICHELL: Recently, an entire wall panel turned green with mold.
CASTRO-WALLACE: I mean, imagine your shower curtain at its worst. It was a, you know, a panel, like a large section.
BICHELL: Castro-Wallace says it's becoming really clear that scientists need to know what else is living up there.
CASTRO-WALLACE: If we see something growing on the wall, what is it? If a crew member gets an infection, what is it?
BICHELL: And that's a big reason why NASA not only hired Kate Rubins, they sent her up.
(SOUNDBITE OF ARCHIVED RECORDING)
RUBINS: Five, four, three, two, one.
UNIDENTIFIED WOMAN: Engines at maximum thrust.
RUBINS: And liftoff.
BICHELL: Rubins had 115 days to help set up a molecular biology lab onboard the station. She drew on her experience working in remote places quickly and using minimal equipment.
RUBINS: There's actually an incredible amount of parallels between working in central Congo in a remote isolated village and doing research aboard the space station.
BICHELL: And while she was on the station last fall, I called her up.
Station, this is Rae Bichell with NPR. How do you hear me?
RUBINS: I've got you loud and clear. It's great to be talking to you today.
BICHELL: She'd just gotten the lab up and running and was really excited about it.
RUBINS: So I'm in the U.S. laboratory. And as you can tell, it's absolutely a working laboratory. We have experiments all over the place.
BICHELL: Rubins had just sequenced DNA for the first time in space, showing that in the near future it would be possible to, for example, swab a moldy wall and figure out right then and there what fungus was responsible. While she was floating on the station, she also grew stem cells into heart cells, and peering through a microscope that she set up, watched them beat in unison.
RUBINS: Now really the world of sequencing and molecular biology has opened up to us on a space station.
BICHELL: She's proven it's possible to do molecular biology a couple hundred miles from Earth, and by doing so, that it's also possible a couple million miles away. And that's really important if astronauts are going to Mars because any Mars habitat will be at least as gross as the space station. Rae Ellen Bichell, NPR News.
(SOUNDBITE OF BLUE SKY BLACK DEATH'S "ONLY PROMISES") Transcript provided by NPR, Copyright NPR.