Dr. Valeri Polyakov holds the record for the longest-duration spaceflight, spending fourteen and a half months aboard the Russian space station Mir in 1994-95. He had previously spent eight months aboard Mir in 1988-89. His total time in space, 678.69 days), ranks third behind cosmonauts Sergei Krikalev (804 days) and Sergei Avdeyev (747 days). Polyakov was inducted into the International Space Hall of Fame in 1996.
I am convinced that human can fly to Mars, work on the surface of Mars, and come back safely. Because with the flights that I performed, they created a medical biology of the model of the flight to Mars, and the model was really successful. After the first flight, which was eight months long, and after the second one, which was fourteen and a half months long, I was able to come out of the capsule by myself, to walk around, to undress, to dress, to do pretty much everything. And be conscious of everything. That was pretty much the goal of the flight. I had to show that it is possible to preserve your ability to function after being in space for such a long time. But the gravity on Mars is 0.37 [of the Earth's], and since I was able to stand up and walk on the Earth wearing a space suit, it shows that human will be able to stand up and walk on Mars.