In Simple Terms
A four-person team spent five days living and working in a small underwater lab. They tested how people performed in a cramped, noisy place, how seeds handled pressure changes, and how sensors worked. The lab was not a space station, but the experience offered a way to practice for difficult missions and explore questions before sending people farther from Earth.
A Small Lab Beneath the Sea
Seven meters below the surface near Key Largo, Florida, the SEA STAR team spent five days inside an underwater research station, cut off from the surface and the rhythms of everyday life. It was not a trip to space, but the mission was designed to recreate some of the challenges of working aboard a space station: tight quarters, life-support systems running around the clock, several scientific tasks, and a crew that had to work closely together. The team used the simulation to explore human performance under pressure, the growth of vegetable seeds, and the conditions inside and around their habitat.
A Small Lab Beneath the Sea
The mission took place at Jules’ Undersea Lodge near Key Largo, Florida, about 22 feet—or roughly seven meters—below the surface. The crew stayed inside the habitat for five days straight without coming up to the surface. That made them aquanauts, a term for explorers who spend more than 24 hours underwater in saturation conditions.
Saturation does not mean that the body fills with water. It describes a state associated with breathing under pressure. When someone remains in a pressurized underwater environment long enough, body tissues absorb an inert gas, such as nitrogen, until they reach a level determined by the pressure and depth. That is why returning to the surface is not simply a matter of swimming up: the body must adjust as the pressure falls, and decompression problems remain a risk that calls for caution.
Inside the habitat, the crew lived surrounded by a green underwater world while life-support systems kept conditions suitable for their stay. Those systems also produced constant noise. The team faced practical problems, including plumbing trouble in the bathroom, as well as health concerns linked to staying under pressure. Dives outside the habitat—which crew members compared to spacewalks—demanded particular care because underwater visibility was not always clear.
A Useful Simulation, but No Substitute for Space
These missions are known as space analog missions: experiments on Earth that recreate selected aspects of spaceflight, not the full conditions of space. An underwater habitat is not an orbital station, and divers do not experience microgravity or the vacuum of space. But it does let researchers study work in an isolated habitat, observe how a crew performs, and practice procedures that require coordination and independence.
Such environments are also useful because they make it possible to run research projects without sending a team to the International Space Station. The number of crew members, the time available, and the activities that can be carried out there are limited. Underwater stations, by contrast, can serve as field sites for some training and preliminary experiments. The findings still depend on the conditions in which they were collected: a simulation may raise questions or reveal difficulties worth studying further, but it cannot automatically prove that people will respond in the same way in space.
Astrobiologist and explorer Michaela Musilova led the mission as crew commander. Before this expedition, she had led 40 simulated space missions to the Moon and Mars. The SEA STAR crew members also had experience in diving and analog missions, which Musilova said helped the mission run relatively smoothly. Their responsibilities covered both scientific work and daily operations, and they had to keep cooperating in an environment they could not easily leave.
Can Pressure Change Focus and Reaction Time?
One of Musilova’s projects asked a practical question for long missions: Do people’s thinking skills and reaction times change when they live and work under different environmental pressures? The work was carried out with the Center for Hyperbaric Medicine, the Faculty of Medicine at the University of Ostrava, and Ostrava City Hospital in the Czech Republic. The goal was to track crew members’ performance on cognitive tests and measure their response times during the mission.
The crew members noticed that their responses seemed slower during their stay than they had been beforehand. This was a descriptive observation reported as part of the experiment, not a numerical finding published in the available account. It gives no participant counts for the tests, measurements of the size of the change, or statistical analysis that would show how large the effect was. The observation should therefore be treated as an early signal from a short simulation—not as conclusive evidence that pressure alone slows thinking.
The question matters for long missions, when getting work done in an isolated environment depends on paying attention, making decisions, and responding to everyday situations. Conditions in the habitat involved more than pressure: limited space, constant noise, scientific tasks, and the need to stay alert to safety all played a part. To understand any change in performance, researchers must consider the whole environment rather than attribute it to a single factor without measurements that separate its effects from the others.
Vegetable Seeds Put Pressure Changes to the Test
Another project examined how seeds respond to pressure changes while being transported to the underwater station. Brandi Nunez, the mission’s health and safety officer, prepared kale and a mix of baby salad greens, growing some seeds before the mission began while others started growing underwater. The team compared groups moved under different conditions: a gradual change in pressure and a sudden change during the descent to the habitat.
After harvesting the plants, the team noticed signs of damage in seeds exposed to the sudden change. This kind of damage, sometimes called pressure damage, is associated with a rapid shift in air pressure. The observation illustrates why the details of transporting living material into a pressurized habitat may matter, even when the difference is simply how the material gets there. But the account provides no seed counts, germination rates, or quantitative measurements of the damage, so it cannot establish the size of the effect or show whether it applies to other plant species.
The aim was not to grow a large crop inside the station, but to study small plants in a relatively controlled experiment. Microgreens such as kale and salad greens make it possible to follow seeds and plants over a short period, providing a practical way to examine how habitat conditions affect growth. Tests like these could help researchers design more detailed experiments on transporting and germinating plants in environments unlike the usual conditions at Earth’s surface.
Sensors, Buoyancy, and Experiments Outside the Habitat
Paul Bakken, the crew’s deputy commander, worked on regulating pressure inside supply containers as they were exposed to major changes in environmental pressure. Jane Bint, the mission specialist, worked with Interstellar Performance Labs to develop a classification system for analyzing environmental factors and interactions among crew members on analog missions. These varied responsibilities reflect the fact that the station was not a site for just one experiment; it was an environment for testing different aspects of daily operations.
During dives outside the habitat, the team tested neutral buoyancy—the adjustment of a person’s movement so they can remain in the water without easily rising or sinking. They also tested environmental sensors developed by high school and university students in Slovakia. The sensors provided additional information about living conditions inside the habitat, supporting the project that tracked cognitive performance. The crew also used an underwater suction tool to help protect the environment around Jules’ Undersea Lodge.
The mission also included an educational outreach effort. The crew contacted a team in Slovakia called Kosmic Regon that was simulating a space station and gave them a tour of their underwater home. During the call, some crew members entered the water and carried out a demonstration dive to show what working outside the habitat was like. The mission thus brought together scientific observations, equipment testing, and a look at everyday life in an underwater station.
The Return to the Surface Takes Planning
When the five days were over, the crew put on their diving gear for the last time and left the habitat. They did not go straight to the surface. Instead, they took a longer route around the lagoon to help their bodies adjust to the drop in pressure. Although the habitat was only about 22 feet deep, decompression problems remained possible after a stay in saturation conditions, so the return had to be gradual and careful.
The ascent marked the practical end of a mission that had combined life in a confined environment with a return to the open air. The crew breathed fresh air and felt the sun, but Florida’s heat soon made staying in the sunlight uncomfortable. Musilova described the return as bringing two opposing feelings: relief at being home, with fresh food and familiar comforts, and a sense of missing the crew and the experience they had shared.
Musilova described a feeling she called the “deep-sea overview effect,” drawing a comparison with the effect some astronauts report after seeing the whole Earth from orbit. In the habitat, she watched sunlight pierce the water from a distance she could not reach and felt that her everyday life was both close and far away. This was not a scientific experiment measuring psychological change with a specific score. Instead, it expressed how isolation and the surrounding view shaped her perspective on the planet and strengthened her desire to care for it.
The Bottom Line
Over five days at a depth of about seven meters, the SEA STAR mission offered a practical way to study some of the demands of living and working in an isolated habitat. Its projects tracked reaction times, examined seeds transported under different pressure conditions, and tested sensors, buoyancy, and underwater equipment. The early observations suggested that crew members felt their responses had slowed and that seeds exposed to a sudden pressure change showed signs of damage, but the account provides no numbers to measure those findings precisely. Underwater stations cannot recreate space, yet they offer useful opportunities for training and testing—and show that success in extreme environments depends as much on the details of daily life as on scientific experiments.