Jump to content
Powered by

Space sickness - learning from fish

On 11th February 2008, ESA astronaut Hans Schlegel was supposed to take part in a space walk, but because the 56-year-old German did not feel well he remained inside the spaceship. He subsequently recovered and was able to work outside the ISS on 13th February. An ESA announcement stated that he had been the victim of space sickness – dizziness and illness due to weightlessness, a problem faced by many astronauts while adapting to zero gravity. Gravitation biologist Dr. Ralf Anken of the University of Hohenheim talks about his research with fish in an interview with Sandra Leppin from Hohenheim University.

The German astronaut Hans Schlegel’s space walk had to be postponed due to illness. Dr. Ralf Anken, you are currently planning a space trip for fish in which you hope to investigate the mechanisms of and therapies for space sickness. Why do people feel sick in space?

At zero gravity, the impressions received by the eyes and the organs of equilibrium do not coincide. The brain is therefore flooded with meaningless information.

And this is the reason for the sickness?

Let me give you an example from everyday life: Imagine that you are sitting in a train, and the train on the neighbouring track starts to move. Your eyes see this and the message to the brain is: we are rolling. However, since the train you are sitting in does not accelerate, the organ of equilibrium realises that you are not moving. The body reacts to this information with a dim sensation and it takes a while before the brain accepts the right information. People feel sick when the brain is unable to solve this informational conflict. The only thing the brain realises is that something is wrong in the body and assumes, as a protective mechanism, that the body has been poisoned. The consequence is that the stomach must be emptied. This is similar to what happens when astronauts complain of space sickness.
The special aquarium for the space fish kept at the University of Hohenheim. (Photo: University of Hohenheim)
The special aquarium for the space fish kept at the University of Hohenheim. (Photo: University of Hohenheim)

What do you hope to find out by sending the fish into space?

Our research group, which is led by Prof. Dr. Reinhard Hilbig, found out in previous experiments that the time fish take to adapt to weightlessness varies. Our theory is that adaptation depends on the small stones in the inner ear, known as otoliths. We assume that an asymmetry, i.e. size difference between the stones on the left and right side, is the reason why some fish require longer to adapt to zero gravity. The defective mineralisation of these otoliths might also be the cause of a number of equilibrium diseases in humans.

Which diseases for example?

Diseases such as Menière’s disease for example, of which little is known despite the fact that more than one per cent of all people suffer from this disease. Sufferers complain of a sudden onset of dizziness and disorientation. In our research group, we are currently working on the phenomenon of disturbance of equilibrium.

And what is the current state of research with regard to space sickness therapies?

Although medicaments are available, the disease cannot be cured – in principle, the brain has to learn to rely on visual information. Humans are likely to go through the same experience as the fish who eventually learn to rely on their eyes rather than on their sense of equilibrium.

Website address: https://www.gesundheitsindustrie-bw.de/en/article/press-release/space-sickness-learning-from-fish