Fifty years after man first stepped on the Moon, scientists are setting their sights on returning. Six astronauts have emerged from four months of isolation as part of research that could one day see a space station built on the lunar surface. From Moscow, Julia Chapman reports.

A breath of fresh air after months of confinement. Stepping back into the real world, these six researchers were met with flowers and applause.

DARIA ZHIDOVA RESEARCH PARTICIPANT "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."

For 120 days four Russians and two Americans lived inside this facility. During that time, they carried out 71 experiments. The main goal was to test the physical and psychological impact of isolation. For one participant, this was not an unfamiliar experience. Cosmonaut Evgeniy Tarelkin spent six months on the International Space Station.

EVGENIY TARELKIN RUSSIAN ASTRONAUT "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."

JULIA CHAPMAN MOSCOW "This environment is designed to mimic the conditions of a space station and put participants through challenges that they would encounter in outer space. The hope is that one day a station like this could orbit the Moon - and eventually, be built on its surface."

These volunteers took a first step in that direction. Among their tasks was a simulated moon landing and a stroll on an artificial Lunar surface. The Moon has once again become a target for space-exploring nations, half a century after the Apollo 11 mission brought the first humans there.

WILLIAM PALOSKI NASA HUMAN RESEARCH PROGRAM "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."

For now, this team is coming back down to Earth. Most of them say they would do it all again, but not before they get a bit of human interaction. Julia Chapman, CGTN, Moscow.