N° 53–2001: Physical and life science experiments "tested" in absence of gravity

Parabolic flights are practically the only terrestrial means of reproducing weightlessness with human operators on board. During a parabolic flight, the Airbus A-300 "Zero-G" pilot - flying at an altitude of approximately 6000 metres, usually in a specially reserved air corridor above the Bay of Biscay - first performs a nose-up manoeuvre to put the aircraft into a steep climb (to 7600m). This generates an acceleration of 1.8g (1.8 times the acceleration of gravity on the ground) for about 20 seconds. Then the pilot reduces engine thrust to almost zero, injecting the aircraft into a parabola. The plane continues to climb until it reaches the apex of the parabola (8500m), when it starts descending. This descent lasts about 20 seconds, during which the passengers in the cabin float in the weightlessness resulting from the free fall of the aircraft. When the angle below the horizontal reaches 45°, the pilot accelerates again and pulls the aircraft back up to steady horizontal flight. The manoeuvres are repeated 30 times per flight.

During the 15-19 October parabolic flight campaign, the 31st organised by ESA, preparations will be made for experiments to be conducted later on a Russian Foton satellite and on board the International Space Station. The campaign will focus on physical sciences, life sciences and biology. Ten experiments proposed by international teams of investigators, five in physical sciences, three in human physiology and two in biology, including one from a group of students, will be performed.

In the physical sciences field, one of the experiments is related to fluid physics, a combustion experiment will study diffusion flames, another experiment will investigate plasma and the last two will study interactions of cosmic and atmospheric particle systems in the framework of an international research programme.

In life sciences, three experiments will measure physiological parameters in human subjects and two biology experiments will investigate movements of plants and fish.

All these experiments have been reviewed and selected by peers prior to flight. A list of the experiments and scientists involved in the 31st parabolic flight campaign is attached.

The next (32nd) ESA parabolic flight campaign is scheduled for spring 2002 and will have a mixed complement of experiments in life and physical sciences, including experiments proposed by students.

Further information on ESA parabolic flights can be found on ESA's special parabolic flight internet pages at:

http://www.spaceflight.esa.int/users/file.cfm?filename=miss-parafl

For further information:

Vladimir Pletser

ESA/ESTEC

Directorate of Manned Spaceflight and Microgravity

Tel : +31.71.565.3316 (+33.(0)5.56.34.05.99 during the campaign)

Fax: +31.71.565.3141

e-mail : Vladimir.Pletser@esa.int Anna Brueck

ESA/ESTEC

Manned Spaceflight and Microgravity

Tel : + 31.71.565.5445

Fax: + 31.71.565.4499

e-mail : Anna-Brueck@esa.int

Experiments and scientists involved in the 31st parabolic flight campaign:

1."Liquid diffusion model experiments in low gravity" by Prof. G. Frohberg, Dr A. Griesche (Berlin Technical University, D) and Dr G. Matthiak, Dr R. Willnecker (DLR, Köln, D). This experiment will study diffusion coefficients of liquids which are difficult to measure on ground due to other mass transport induced by gravity-caused natural convection. In microgravity, diffusion experiments are conducted in long capillary cells and diffusion coefficients can be measured by separating parts of the cell volume after diffusion took place. The technique of shearing parts of the cells will be further investigated on different cell designs to prepare for a space experiment to be flown on the Russian Foton M1 in Autumn 2002.

2."Laminar diffusion flames representatives of fires in microgravity environments" by Prof. P. Joulain (CNRS, Poitiers, F) and Dr J.L. Torero (University of Maryland, USA). This experiment will study and characterize the structure of laminar diffusion flames in microgravity. Diffusion flames in the absence of natural convection, that removes hot gases from the combustion site in favor of cold gases, allow to study and better understand the transport in microgravity of the flame chemical components by diffusion only. An Ethane flame, subjected to a forced air flow in a combustion chamber, will be observed by advanced diagnostics techniques, including CCD visualization, spectroscopy, radiated flow measurements and thermocouples. The final experiment goal is to provide the scientific background necessary for the evaluation of material flammability in microgravity, allowing to reduce the risk of fire on board manned space vehicles.

3."Preliminary tests for the International Microgravity Plasma Facility (IMPF)" by Prof. G. Morfill, Dr H. Thomas and U. Konopka (Max Planck Institute, Garching, D). This experiment will investigate the shape and geometry of newly improved experimental chambers in which a complex (dusty) plasma, i.e. a mixture of ionized gas and microparticles, is formed, stimulated by radio-frequency electrodes. New effects were seen recently on previous microgravity flights, e.g. first, the interaction of electrostatic Coulomb forces transforming the disordered complex plasma into an ordered fluid and crystalline phase, a so-called "plasma crystal", and second a homogeneous distribution of microparticles in the plasma. These effects and the impact of the chamber geometry and shape is further investigated in order to improve the design of the IMPF for a future flight on the International Space Station.

4."Tests of an ICAPS facility for ISS" by Prof. J. Blum and Dr T. Poppe (University of Jena, D). This experiment will study processes of aggregation of cosmic dust particles, an important step in the formation of planets in our Solar System. Previous experiments have shown that, in addition to mechanical and electrostatic effects, magnetic coagulation of proto-planetesimal dust proceeds rapidly forming aggregates in a few seconds. In this experiment, magnetized and non-magnetized dust is injected in turn in an aggregation vacuum chamber by pyrotechnical and mechanical devices. The dust aggregates are imaged by in-situ microscopy and collected for later analysis.

5."Aerosol particle motion in temperature and concentration gradients", by Prof. J.C. Legros and Dr A. Vedernikov (University of Brussels, B) and Prof. F. Prodi (Istituto ISAO-CNR, Bologna, I). This experiment will study the thermophoretic movements of particles suspended in heated gas, i.e. the movement caused by the different momentum and energy transferred to the particles by gas molecules colliding with them from their hot and cold side. A digital holographic microscope is used a main diagnostic tool, allowing real-time three dimensional image analysis and tracking of micron sized aerosol particles. The study of their motion in an aerosol gas gives information on the nature of chemical reactions taking place at the surface of the particles, to improve the understanding of the chemistry of gas-particle systems. These processes are important in several engineering fields (surface coating, gas cleaning, optical fiber production) and in atmospheric physics (interaction of atmospheric gases with water droplets and pollutant particles).

The experiments 4 and 5 prepare for the ICAPS facility to be developed for long term experiments on board the International Space Station.

6."Dynamics of prehension in microgravity and its application to robotics and prosthetics" by Prof. J.L. Thonnard, Dr O. White (University of Louvain, B). This experiment will study the hand-eye coordination in subjects requested to move a hand held load in a rhythmic manner. Previous parabolic flight studies on the hand prehension dynamics have shown differences in the strategy adopted by subjects accustomed to microgravity and naive subjects when requested to perform up and down arm movements with a hand held mass, or 'manipulandum' that measured grip and tangential finger forces. The present study will focus on the hand-eye coordination and the visual feedback by varying the arm trajectory and the subject posture while performing arm movements while holding an improved 'manipulandum'. These experiments have applications in robotics and prosthetics where the balance between external forces acting on the object and the minimal grasping effort is the key to dexterous robotic hand. Future development could be applied to improve the functional restoration of humans with handicaps of the upper limbs.

7. "Does weightlessness induce peripheral vasodilatation ?" by Dr P. Norsk (DAMEC, Copenhagen, DK). This experiment will test the hypothesis of the dilatation of the heart and the peripheral vascular system that could be caused by weightlessness, following measurements on human subjects on ground, during water immersion and during previous ESA parabolic flight campaigns. According to this hypothesis, the organism may have a protective mechanism that protect the heart and the brain in microgravity from an increase of arterial pressure by dilating the vascular system to cope with the body fluid shift from the lower to the upper part of the body in 0 g. During the present experiment, the maintenance of arterial pressure is investigated in several human subjects. Several physiological parameters are measured, including the cardiac output by the non-invasive rebreathing method, using a specially designed portable device.

8. "Imaging autonomic regulation during parabolic flight" by Prof. M. Moser, Dr D.M. Voica (University of Graz, AU) and Prof. A. Noordergraaf (University of Pennsylvania, USA).This experiment will investigate the adaptation of the vegetative nervous system before, during and after parabolic flights. Several sets of physiological parameters are recorded on human subjects with two portable devices, the Heartman and the Kymo. First, the heart rate variability (HRV) is recorded by the Heartman and the HRV structural changes are analyzed by the method of Autonomic Imaging, specially developed by the Investigators. Second, three other parameters, the cardio-respiratory coherence (or triggering of breath by heartbeat), the pulse wave velocity and ballistocardiograms, are recorded by the Kymo to support the analysis of the data obtained by the Heartman.

9. "Investigation of physiological parameters of gravitaxis in Euglena gracilis" by Prof. D.-P. Häder (University of Erlangen-Nuremberg, D). This experiment will investigate the phenomenon of gravitaxis, the motion away from the center of gravity. On Earth, without other stimuli, Euglena gracilis, a fresh water flagellate orients itself upward in the water column. Some theories claim that gravitaxis is exclusively based on passive buoyancy effects. The experiment investigates possible physiological mechanisms in the gravitactic orientation, involving physico-chemical reactions inside the cells which contribute to the phenomenon of gravitaxis.

10. "Flying fish" by a group of Students from the University of Lund, Sweden, has been selected from the group of thirty experiments that flew in July during the fourth ESA Student campaign organized by ESA's Outreach Department. In this experiment several fishes are observed in an aquarium. Two light sources are located on top and at the bottom of the aquarium. The behaviour of the fishes in 0g is recorded during several parabolas with the light coming from the top and during other parabolas with the light coming from the bottom. It appears that fishes use the light as a reference in microgravity to orient themselves. The goal of this investigation is to assess whether an external reference frame given by light conditions can be used in space to stabilize fish movements and to allow fishes to have quasi-normal functions during long term space flights, to be used eventually as a food source for astronauts.

 

For further information:

Vladimir Pletser

Tel: Vladimir.Pletser@esa.int

Fax: +31.71.565.3141