As he was hurtling into orbit, Cosmonaut Gherman Titov had the distinct feeling that his body was cartwheeling through the air. It started as soon as Vostok 2 separated from its booster and he was thrust into weightlessness. “I felt suddenly as though I were turning a somersault and then flying with my legs up,” he said later on. In reality, there was no cartwheel – the feeling was simply an illusion, something akin to an out-of-body experience.

For many astronauts, these sensations tend to stop after a couple of days in space, but others suffer the discombobulating feelings throughout their trip. “I knew I was standing upright… and nevertheless I felt upside down, despite the fact that everything was normally oriented around me,” is how one astronaut described his experience on the Spacelab space station.

And disorientation is not the only strange experience faced by astronauts. Space travel can also cause distorted vision and duller thinking, and might even influence mood. These mind-bending consequences are sometimes known as the “space stupids”, and could potentially put future missions in jeopardy. So what is the solution?

At least some of the skewed perceptions of astronauts can be blamed on the stress and loneliness of space travel. A crew on the Salyut-5 space station once reported an acrid, toxic smell – leading them to return home early – but although the real reason is still not clear, some psychologists have suggested that it was a hallucination caused by the pressures of the mission.

But many of the strange illusions are caused by something that is even less easy to escape: the simple lack of gravity. Without the weight of the body to give it cues, the brain becomes easily confused about its orientation, causing, for instance, the uncanny feeling that you are permanently upside down or Titov’s strange sensation that he was spinning through space.

Cosmic confusion

To get to the bottom of those feelings, one of the first questions is to find out what level of gravity is necessary to align our sense of orientation and keep it stable. Would we feel the same effects on another planet like Mars, for instance? That could be crucial to know if we are ever to set up home elsewhere in the solar system.

Early experiments had suggested that the threshold was very low – much less than the gravity found on the Moon. Yet observations of moon walkers would suggest otherwise; it was surprisingly common for those pioneers to take one small step for man, only to fall flat on their faces (see video, below).