Spending a long time in a weightless environment has an impact on the human body, and
evidence exists of changes to the bone and muscles of astronauts who have participated in
long-duration missions in space. To cope with the requirements of long-stay missions aboard
the International Space Station, the European Space Agency, together with the French space
agency CNES and the Japanese space agency NASDA, are validating countermeasures through a
preventive-medicine ground-based simulation that makes use of the bed rest model.

The study runs over two periods of four months, one starting in August this year, the other in
March next years. Each time, fourteen test subjects will lie in bed for a period of three months,
to produce sufficient scientific data. The total duration of each campaign is 120 days: 90 days in
strict -6° head down tilt, with a preparatory period of 15 days beforehand and a 15 day recovery phase after.
Previous studies, where the inclination varied from 0 to -15°, have shown that the -6° position is the best for
simulating the effects of the weightless environment of space.

This is the first ever long-term bed rest study of such complexity and duration to be carried out
in Europe. The main objective is to assess the changes to muscles and bone typically arising on
long-duration space flight and evaluate methods of counteracting such changes. Additional
experiments will also investigate the cardiovascular system and neuro-endocrine regulation of
urine production, psychological behaviour and changes in the sleep-wake cycle. The study is
also aimed at improving the medical aspects of healthcare for people afflicted with muscle and
bone-wasting diseases.

The experiments have been proposed by European scientists in answer to an ESA
announcement of opportunity, and by NASDA scientists for the research into bone physiology. A
dozen scientific groups representing about eighty researchers are involved.

Throughout the study, the subjects will have to undergo many investigations such as tests
during exercise, osteodensitometry (measurement of bone-density) and magnetic resonance
imaging. Analysis of muscle biopsies and extensive biochemical analysis of biological samples
will be performed.

In their spare time the test subjects will be able to read, play games, watch TV and use
computers. Meals will be served in bed, but the test subjects will not be allowed to sit. They will
be able to make calls to their families, but during the three months they will have only very
limited opportunity to make contact with the outside world.

Progress will be reported via a dedicated website at http://www.medes.fr

At the end of the study, the test subjects will be followed up with specialised medical check-ups
at forty-five days, three months, six months and one year with a follow-up questionnaire after
three years.

A team of medical and psychological experts from the MEDES Institute for Space Medicine and
Physiology selected the candidates during the first half of the year and is in charge of the
implementation of the study. The Toulouse-based institute has over ten years of experience of
conducting bed rest simulation experiments. Since 1996 personnel from the “space clinic” have
participated in six different bed rest studies.

Since the study has to be as homogeneous as possible, only male candidates aged between
25-45 have been selected. The fourteen test subjects selected out of a total of 450 applicants
are between 29 and 41 and are all French nationals. Their occupations range from history and
geography teachers to builders, from psychiatrists to postmen and from gardeners to
accountants.

For further information:

Benny Elmann-Larsen

ESA, Physiology co-ordinator and Project Manager for the Bed Rest Study

Tel. +31 71 565 3322

Fax. +31 71 565 3661

E-mail: benny.elmann-larsen@esa.int

CNES Press Office :

Sandra LALY : Tel : +33 1 44 76 76 87 – E-mail : sandra.laly@cnes.fr

Eliane MOREAUX : Tel : + 33 5 61 27 33 44 – E-mail : eliane.moreaux@cnes.fr