Four Russians and two Americans have emerged from four months in a land-based station designed to imitate conditions in outer space. 

The experiment, known as SIRIUS 2019, was held as a joint project between Russia and the U.S., with contributions from European space agencies.

During their time in isolation, the participants carried out some 71 experiments. The main focus of the exercise was to test the physical and psychological impacts of isolation as a way of preparing for long missions in space.

This particular SIRIUS experiment imitated a Lunar mission. The researchers carried out a mock Moon landing and completed tasks like those that astronauts would execute on the surface of the Moon. 

As NASA this year celebrates 50 years since man first landed on the Moon, space agencies around the world have started turning their attention back to Earth's nearest neighbor. 

India is planning a second attempt at sending a lander to the Moon and China recently completed a soft landing of the Chang'e 4 probe on the far side of the lunar surface. 

Russia has announced plans to send cosmonauts to the Moon by 2030 and eventually build a permanent base there, much like the International Space Station. 

The head of NASA's Human Research Program, William Paloski, said he believes the projects will be fulfilled if governments want them badly enough. 

He said: "From the time it was announced to the time we set foot on the Moon was eight years, and we had no rockets and no capabilities when it was announced. There was a will and some budget to do that work and we assembled a team and we did that work. If you look at commercial space fliers today, SpaceX is doing something very similar, changing the way we view how people can get into space and satellites get into space. Because there's a will and some money to support that will and the technology and technologists are available to do it."

The participants in the SIRIUS 2019 project said they enjoyed their time inside the space station, but all of them were looking forward to tasting real food again. 

Daria Zhidova, one of the participants, said: "It's been so long since I've seen so many people in real life and not through a screen. I hope that everything that we accomplished, all the experiments, methods, tests, will benefit not only the SIRIUS project but also the development of space, the Moon and Mars."

One of her colleagues in the facility was Russian cosmonaut Evgeniy Tarelkin, who spent six months in the International Space Station from 2012-2013. 

When asked how his experience in the isolation station compared to that on the ISS, he said: "We tried to create this as it would be on board a space station and for the most part it was very similar. Of course, the one difference was no zero-gravity or radiation. But really it was very similar."

The experience was not without its challenges, but the researchers said it gave them the opportunity to learn more about themselves. 

Stefania Fedyay, the participant who acted as the team's doctor during the experiment, said: "It was difficult but interesting to see the extent to which your personal strength, how it's spent, do you have enough endurance, how you react emotionally to the situation you've never been in before, like skydiving or a trip to a new country for a long time. So to track your own reactions, track how your perceptions change, your feelings about the situation, that was really interesting."