Lost in Space

Humans can become confused and disoriented - and even a little queasy - in an alien world where up and down have no meaning. It can be difficult feeling Lost in Space.

Imagine waking up, startled by the bright flash of a cosmic ray inside your eyes. Groggy from sleep, you wonder ... which way is up? And where are my arms and legs? Throw in a dash of vertigo and occasional mild illusions, and you're beginning to sense what it can be like to live in orbit.

Of course, it's not always so bad - otherwise no one would want to become an astronaut! Nevertheless, first-time space travellers can be surprised by some very unearthly sensations that can confuse and amuse the astronauts who feel them.

Consider, for example, "up" and "down." On Earth we always know which way is up because gravity tells us. Sensors in the inner ear, which are part of the body's vestibular system, can feel the pull of gravity. They signal the brain with information about our body's orientation.

In space, however, the vestibular system doesn't sense the familiar pull of gravity. The world can suddenly seem topsy-turvy.

Former shuttle astronaut Robert Parker recalls: "One of the questions they asked us during our first flight was, 'Close your eyes ... now, how do you determine up?'" With his eyes closed, he couldn't tell. Up and down had vanished.

Another astronaut reported a strange experience when he woke up one day in orbit. As he opened his eyes the room was rotating around him!

more The vestibular system is a fluid-filled network of canals and chambers deep within the human ear that help us keep our balance and sense which way is up.

Or so it seemed.

Space travellers in science fiction rarely have such problems. On Star Trek's USS Enterprise, for example, artificial gravity provides direction cues for the crew. Captain Kirk never gets out of bed upside-down.

Without artificial gravity, however, the designers of the real-life International Space Station and the Space Shuttle must rely on different tricks to establish a common sense of "up". For example, all of the modules on the ISS have a consistent "up" orientation. And the writing on the walls points in the same direction, too.