NASA astronaut Suni Williams works on the Plant Water Management at the space station.
Indian astronaut Group Captain Shubhanshu Shukla is visiting a home away from Earth that has seen continuous human presence for a quarter of a century and is floating around 400 kilometres above Earth.
For most millennials, the idea of humans living and working in space has been a constant reality. Since November 2000, the International Space Station (ISS), a football-field-sized laboratory orbiting 400 kilometres above Earth, has hosted a continuous human presence. But beyond the awe of astronauts floating in microgravity, the ISS has quietly become one of the most important biological laboratories in human history.
In an exclusive conversation with NDTV, influential NASA biologist Dr Sharmila Bhattacharya shared how two decades of biological research aboard the ISS are not only preparing us for long-duration missions to the Moon and Mars but also transforming our understanding of human health on Earth.
Dr Sharmila Bhattacharya is a Space Biology Program Scientist at NASA and a guest speaker at Ashoka University
A Living Lab in Orbit
"The first few years were about building the station," Dr Bhattacharya explained. "But for the last 15 to 20 years, we've been doing very active science as an international community."
That science spans a wide range of biological disciplines. Researchers studied how spaceflight affects muscle loss, bone density, cardiovascular health, immune function, and even kidney-stone formation. These studies are essential because space is an extreme microgravity environment, radiation and isolation take a toll on the human body.
And yet, astronauts have not only survived but thrived. "They go fit and come back fit," said Dr. Bhattacharya. "But that's because they're some of the fittest people on Earth and follow strict exercise and diet regimens."
The Brain in Space
One of the most fascinating areas of research has been the effect of spaceflight on the brain. Dr Bhattacharya's team used fruit flies, Drosophila, as a model organism to study neurological changes. "We found that in space, there were definite effects on the brain," she said.
To test whether these effects could be mitigated, her team created artificial gravity using a centrifuge aboard the ISS. "We were able to partially reverse some of the defects we saw in the nervous system," she noted. This has major implications for future missions, especially those lasting years, such as a round trip to Mars.
Preparing for Mars
A journey to Mars could take six to nine months one way, with astronauts staying for several months before returning. That means humans will need to survive in deep space for up to two years, facing elevated radiation and reduced gravity.
"The ISS has taught us a lot about microgravity," Dr Bhattacharya said. "But the Moon has one-sixth Earth's gravity, and Mars has one-third. We need to understand how partial gravity affects biology."
A recent collaboration between NASA and the Japanese Space Agency used mice to study biological changes under different gravity levels-Earth, Moon, Mars, and microgravity. "It was a really interesting experiment," she said, adding that "because it helped identify thresholds where certain biological systems begin to change."
Plants in Space: More Than Just Food
Beyond human biology, the ISS has also become a greenhouse in orbit. Astronauts have successfully grown lettuce, tomatoes, and other crops. "Some of the tomatoes were very well appreciated by the crew," Dr. Bhattacharya said.
NASA astronaut Jasmin Moghbeli smiles next to the Advanced Plant Habitat, where multiple tomato plants grow as part of Plant Habitat-06
Photo Credit: nasa.gov
Plant habitats on the ISS are not just functional; they are emotional anchors. "They're well-lit, so when crew members celebrate birthdays or holidays, they often gather near the plants. It's like the beautiful garden in space."
These experiments are crucial for future missions, where astronauts will need to grow their food. They also help scientists understand how plants respond to microgravity, which could lead to agricultural innovations back on Earth.
The Microbial Frontier
Space is also a frontier for microbiology. Dr Bhattacharya's team studied how bacteria behave in space and found that some, like Serratia marcescens, became more virulent after spaceflight. "They killed fruit flies faster than bacteria that hadn't gone to space," she said.
Interestingly, this increased pathogenicity disappeared when the bacteria were grown again on Earth. "We wanted to understand the molecular biology behind that change and what made them more dangerous in space," she explained. "These enclosed environments give us insights into microbial ecosystems, not just in space but also in places like submarines or hospitals on Earth," Dr Bhattacharya said.
Axiom Mission 4 private astronaut Tibor Kapu (at left) from Hungary loads a research sample-packed cryogenic storage unit, called a dewar
Photo Credit: nasa.gov
Astronauts as Test Subjects
Over 600 astronauts have flown to space, many of them to the ISS. Their bodies have become invaluable data sources.
"We've grown multiple generations of fruit flies, Caenorhabditis elegans, and even plants in space," Dr. Bhattacharya said, adding that "Now we're doing longer and longer experiments."
One of the most exciting upcoming studies involves MRI scans of astronauts' brains before and after spaceflight, as part of the Axiom 4 mission. "Given what we've seen in fruit flies, I'm very interested to see what the human data shows," she said.
The End of an Era, and the Start of Another
The ISS is expected to be retired by 2031. But Dr Bhattacharya is optimistic. "I celebrate what the ISS has given us," she said. "But I'm also looking forward to the next platform."
That next step could be a commercial space, perhaps Axiom, Haven, or VAST. China already has its space station, and India is planning one too. "The more platforms we have in space, the more science we can do as a global community," she said.
Why It Matters for Earth
While the focus is often on preparing for Mars, the benefits of space biology are already being felt on Earth. From understanding immune responses to developing better exercise regimens, the research done in orbit is improving healthcare on the ground.
"Basic biology helps us understand not just how to live in space, but how to live better on Earth," Dr Bhattacharya said.
A New Age of Exploration
As humanity looks beyond Earth, the ISS stands as a testament to what international cooperation and scientific curiosity can achieve. It has been a proving ground for the biology of the future where humans may one day live on the Moon, Mars, or even beyond. And thanks to scientists like Dr. Sharmila Bhattacharya, we're not just dreaming about that future, we're building it, one fruit fly at a time.
