To understand the cardiovascular reactions of the human body to changing conditions of gravity is an important aim of space science. In this context, cardiac output (CO) is a key value to estimate the human cardiovascular system.

The main objective of this experiment is to determine the effects of parabolic flight on intravascular volume, and how these changes modulate the complex haemodynamics induced by the parabolas.

Inclusion Criteria:

• healthy volunteers (men or women),
• aged from 18 to 55,
• affiliated to a Social Security system,
• who accept to take part in the study,
• who have given their written stated consent,
• who already participated in parabolic flights (even in the same campaign)
• All subjects will pass a medical examination similar to a standard aviation medical examination for private pilot aptitude. There will be no additional test performed for subject selection

Exclusion Criteria:

• person who took part in a previous biomedical research protocol, of which exclusion period is not terminated,
• pregnant women