Long-term exposure to the weightless environment of space has significant
effects on astronaut physiology, notably changing the skeleton and muscle.
To meet the requirements of long-stay missions aboard the International
Space Station, the European (ESA), French (CNES) and Japanese (NASDA)
space agencies are jointly conducting ground-based research to evaluate
ways of countering the adverse effects. Countermeasures are tested on the
healthy subject using an experimental model reproducing the effects of
weightlessness by sustained bed rest, i.e. lying in a minus 6° head-down
tilted (HDT) position. Experimentation of this type is currently taking
place at the MEDES Space Clinic in Toulouse, France.

The first study period ran from August to December 2001 with 14 volunteers
participating; they are all being tested through to the end of the
experiment. The results of their follow-up medical check-ups in January
and March are satisfactory.

The second period started on 22 March and will end on 27 July 2002. 11
volunteers have been selected this time. Like the first period, the study
comprises a 15-day preparation phase, a three-month bed rest phase and a
15-day recovery phase.

This is the most complex and the longest HDT bed rest study ever
undertaken in Europe. During the campaign, experiments are also being
conducted on the cardiovascular system, neuroendocrine system control,
psychological behaviour and sleep-wake cycle changes. From the medical
viewpoint, the study should improve our knowledge of the impact on bone
mineral loss and muscle status atrophy and thus help prevent prolonged
periods spent bed-ridden following accidents or long illness. It is also
testing new techniques, such as measuring activity and movement using
specially designed mattresses, which are very promising for preventing
eschar and monitoring sleep disturbance.

The research protocols were proposed by European investigators in response
to a call for proposals issued by ESA and also by NASDA investigators
studying bone physiology. Ten teams of scientists representing around
eighty researchers are participating.

As over the first period, the volunteers will undergo stress response
tests, bone densitometry, magnetic resonance imaging and muscular biopsy.
In-depth histological, biochemical and biological analysis will evaluate
body cell and molecular-level response to the experimental living

The volunteers will also undergo special medical check-ups 45 days, 3
months, 6 months and 12 months after bed rest and then monitoring over
three years.

In their free time, the subjects may read, watch TV and use a computer.
Continuous confinement means that they are not allowed to sit up, even at
mealtimes. Over the three months, they have no direct contact with the
outside world. They can regularly phone family and close friends.

To make the group as homogenous as possible and enable sound
interpretation of the scientific results, it was decided to use male
subjects aged 25 to 45. Of the 450 candidates, 11 were selected, 10 French
and one Belgian, their ages ranging from 26 to 35. They have various
professional backgrounds: managerial, IT and mobile telephony,
biochemistry student, musician, catering management, etc.

Candidate selection and the study itself are being carried out by a team
of doctors and psychologists from the French Institute for Space Medicine
and Physiology. Based at Toulouse, MEDES has over ten years’ experience
in the area of HDT simulation. Since 1996, staff at its Space Clinic have
taken part in six different bed rest studies.

For further information contact:

Benny Elmann-Larsen

ESA – Physiology experiment coordinator, HDT study project manager

Tel : +31 71 565 3322

Fax : +31 71 565 3661

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

Antonio Guell

CNES – Head of life sciences programmes, HDT study programme committee

Tel : +33 561 28 2577

Fax : +33 561 27 3091

E-mail : antonio.guell@cnes.fr

For any other further information, contact:

Eliane Moreaux

Service de Presse du CNES

Tél. : +33(0)

Fax : +33(0)

Franco Bonacina

ESA Media Relations Office

Tél. : +33(0)

Fax : +33(0)