N° 53–2003: Les lauréats du concours SUCCESS 2002 ont été désignés

C’est en effet le 28 août 2003 que les lauréats ont été désignés au Centre des astronautes européens à Cologne. Le concours SUCCESS est ouvert aux étudiants des universités européennes de toutes disciplines jusqu’au niveau maîtrise.

Il leur est demandé d’imaginer comment leurs expériences pourraient tirer parti des conditions physiques et opérationnelles qui règnent à bord de la Station. Les paramètres à prendre en compte sont l’absence de pesanteur, le vide spatial, l’altitude élevée au-dessus de la Terre et l’environnement confiné dans lequel vivent et travaillent les astronautes à bord de l’ISS.

L’objectif de ce concours est de faire des étudiants d’aujourd’hui les utilisateurs de demain de la Station en suscitant l’intérêt pour les recherches spatiales parmi ceux et celles qui n’ont pas encore terminé leurs études. Pour l’édition 2002, il avait été proposé de conduire des expériences dans des disciplines aussi diverses que les sciences de la vie, les sciences physiques, les sciences spatiales, la technologie et l’observation de la Terre.

Les étudiants désireux de participer au concours SUCCESS 2002 ont dû franchir plusieurs étapes. Tout d’abord, ils ont dû rédiger une présentation succincte de leur expérience. Une commission scientifique a sélectionné les meilleures d’entre elles en vue de la deuxième phase du concours. Très précisément 100 étudiants ont participé à cette première phase. 19 d’entre eux venaient d’universités du Royaume-Uni, 18 d’Italie, 13 d’Allemagne, 8 de Russie, 7 de France, 4 de Finlande, 4 des Pays-Bas, 3 de Belgique, 3 de Norvège, 3 du Portugal, 3 d’Espagne, 3 de Suède, 3 de Hongrie, 2 de Bulgarie, 1 du Canada, 1 d’Inde, 1 de Suisse, 1 des Etats-Unis, 1 de Roumanie, 1 de République tchèque et 1 de Biélorussie.

Lors de la deuxième phase, 40 étudiants ont été retenus sur les 100 participants initiaux et invités à visiter le Centre européen de technologie spatiale de l’ESA (ESTEC) à Noordwijk, Pays-Bas, en novembre 2002. 10 d’entre eux venaient d’Italie, 8 du Royaume-Uni, 4 de France, 4 d’Allemagne, 3 de Suède, 2 des Pays-Bas, 2 de Norvège, 2 de Russie, 2 de Bulgarie, 1 de Finlande, 1 du Portugal et 1 d’Espagne. Des informations leur ont été données au cours de leur visite sur l’ESA en général, et plus particulièrement la Station spatiale internationale, ainsi que sur les expériences réalisées par les scientifiques et celles qui ont été proposées par les autres étudiants. A l’issue de leur visite à l’ESTEC, il a été demandé aux concurrents de rédiger une proposition d’expériences détaillée afin de participer à la troisième et dernière phase.

Au vu des ces propositions détaillées, un jury scientifique a finalement sélectionné trois lauréats :

· Le premier prix a été attribué à Adalberto Costessi de l’Université de Trieste (Italie) pour sa proposition d’expérience intitulée "Etude cellulaire et moléculaire du comportement des ostéoblastes en microgravité" ;

· Le deuxième prix a été décerné à Roberto Rusconi de l’Ecole Polytechnique de Milan (Italie) pour son expérience intitulée "Utilisation de lentilles thermiques pour mesurer l’effet Soret" ;

· Le troisième prix est allé à Eric Belin de Chantemèle de l’Université de Lyon 1 (France) pour sa proposition d’expérience sur "Les besoins en énergie au cours d’un vol spatial de trois mois".

Le premier prix est un stage rémunéré d’un an au Centre européen de technologie spatiale de l’ESA (ESTEC), Pays-Bas. A l’ESTEC, Adalberto Costessi travaillera sur son expérience dans l’espoir de la voir qualifiée pour un embarquement sur la Station spatiale internationale ou sur une autre installation de recherche. Le titulaire du deuxième prix, Roberto Rusconi, aura droit à une visite du port spatial européen de Kourou (Guyane), le site de lancement d’Ariane. Le titulaire du troisième prix, Eric Belin de Chantemèle, recevra un ordinateur portable.

The three prizewinning experiments dealt with the following scientific issues:

- First prize, “Cellular and Molecular Study of Osteoblasts’ Behaviour in Microgravity” by Adalberto Costessi, University of Trieste:

Loss of bone mass is a major consequence for astronauts of extended periods spent in weightlessness conditions. Several studies have been performed on astronauts, establishing that bone mass loss in space is caused by a decrease in bone synthesising activity performed by osteoblast cells (the bone-building cells in the human body) and by a parallel slight increase in bone destruction, also called resorption, performed by osteoclast cells.

It has been demonstrated in several cell types that the absence of gravity directly influences molecular and cellular functions. In particular, both the cytoskeleton and intracellular signal transduction cascades appear to be sensitive to weightlessness. However, the underlying mechanism of these changes is far from being understood and the cellular gravity-sensing machinery is still mysterious.

Loss of bone mass in humans during long-duration spaceflights is analogous to osteoporosis on Earth. Osteoporosis is a disease marked by excessive skeletal fragility resulting in weakened bones that are susceptible to fracture. Millions of people around the world, estimated to be as much as 20% of the population, suffer from osteoporosis.

Until recently the general approach was to investigate general systematic changes related to bone loss, not the basic cellular responses to the lack of physical stress associated with weightlessness in space or with reduced mobility on the ground. In fact very little research has been aimed at understanding the molecular mechanisms of the reduced functionality of osteoblasts, the bone-building cells, which could lead to new treatments of osteoporosis. More than 120 experiments performed in the last 15 years have shown dramatic changes occurring in several types of single cells in weightlessness, but very little information is available on osteoblasts.

With this in mind, the experiment proposed by Adalberto Costessi involves the first use in space of “Proteomics Analysis”. This type of analysis is based on 2D-gel electrophoresis coupled with mass spectrometry. It is able to separate and identify hundreds or thousands of different proteins from a certain cell culture and also evaluate quantitative differences of a protein between different samples. Since one of the key aims of scientific research in space is to obtain large amounts of data from the smallest and fastest experiment, the proteomics approach is particularly suitable for space research.

The objective of the experiment proposal is to study the signal transduction pathways of osteoblasts that regulate their most important physical functions (i.e. collagen synthesis, differentiation) in the ideal weightlessness conditions of the International Space Station. Understanding the molecular mechanisms of the reduced functionality of osteoblasts could lead to new treatments for bone mass loss due to long-term stays in space and for osteoporosis on Earth.

- Second prize, “Thermal Lens Measurement of the Soret Effect” by Roberto Rusconi, Politecnico di Milano:

This experiment proposal aims to ascertain the feasibility of investigating in space “Thermal Diffusion”, also called “Soret Effect”, a puzzling and still very poorly understood physical effect, by using a simple optical set-up that can be easily designed, is relatively inexpensive and can make very good use of weightlessness conditions. Thermal diffusion plays a crucial role in many naturally occurring processes ranging from convection in oceans to component segregation in solidifying volcanic lava, but it can also seriously affect industrial processes like the manufacture of semiconductors, oil-in-water emulsions or protein solutions for crystallisation.

The Soret effect still lacks a general microscopic picture. Optical techniques are privileged candidates for experimental methods to investigate the Soret effect. Yet, the classical optical techniques require sophisticated, complex, time-consuming and costly equipment, often unsuitable for sample manipulation. It is however possible to conceive an optical method, called “Thermal Lensing”, where thermal gradients driving thermal diffusion are generated by a focused laser beam partially absorbed by the sample and the Soret effect is directly probed by detecting distortion of the beam profile induced by the refractive index profile due to the thermodiffusive motion. The basic optical system is extremely simple and the measurements are much faster.

Thermal lensing has long been used as an extremely sensitive spectroscopic tool for simple fluids, but in order to apply this method to the investigation of the Soret effect, two impediments have to be surmounted:

1) most of the interesting systems are aqueous solutions but water absorbs visible light very weakly, and 2) formation of the thermal lens is unavoidably associated with horizontal temperature gradients and associated thermally convective currents, which are relevant for liquid mixtures and could easily destroy Soret-induced concentration profiles.

Roberto Rusconi’s experiment proposal intends to overcome the first difficulty by using a fibre-coupled laser tuned on a specific near-infrared water vibrational overtone and obtain reliable measurements on suspensions of particles having a density not too different from the solvent. The second difficulty, convection, can be reduced by using a specific optical and mechanical set-up structure, but is still partly unavoidable. Hence the strong case for performing these measurements under weightlessness conditions in space.

- Third prize, “Energy Requirement during a Three-Month Spaceflight” by Eric Belin de Chantemèle, University of Lyon 1: Determination of food and water requirements of astronauts during spaceflight is a clear prerequisite for any long-term mission, whether on the International Space Station or on a mission to the Moon or Mars.

On the one hand, spaceflights are associated with a combined loss of fluids, bone, fat and muscle in a context of negative energy balance. If such a negative balance is acceptable for short-term missions due to the high energy density of fat mass, it becomes detrimental to astronauts on long-term missions because health and performance are affected.

On the other hand, knowledge of how much food and water is needed by astronauts in space is important when considering the quantity and cost of food and water to be transported together with the astronauts. For a crew of 6 astronauts leaving on a three-year mission to Mars as much as 26 tonnes of food will need to be carried. Even if this food is 90% dehydrated, it will still weigh 2.6 tonnes. Thus, even a 10% error in the estimation of energy requirements can have a large impact on the cost of the mission.

These considerations are particularly challenging when energy requirements for astronauts are still poorly characterised. This is because accurate energy requirements must be derived from free-living total energy expenditure measured by the state-of-art, cost-limited and expertise-requiring “Doubly-Labelled Water Method”. In addition, it is essential to evaluate the resting metabolic rate, the diet induced thermogenesis and the activity energy expenditure during spaceflight.

The aim of Belin de Chantemèle’s experiment proposal is to perform a comprehensive evaluation of energy and water metabolism adaptations to spaceflights using stable isotope, i.e. non-radioactive methodologies. The experiment protocol is simple, non-invasive and will provide very important information on energy and water metabolism, useful for long space missions: energy expenditure will be measured using the stable isotope doubly-labelled water method before, during and after a spaceflight. The different components of total energy expenditure will be determined by indirect calometry before and after spaceflight. The energy cost of physical activity will then be calculated by difference, and the body composition will be assessed by bio-impedance spectroscopy before and after the spaceflight.

For more information on the SUCCESS 2002 Student Contest in general, visit the SUCCESS website at

http://spaceflight.esa.int/users/success

or contact:

Ulf Merbold

ISS Utilisation and Promotion Division

Directorate of Human Spaceflight

European Space Agency

Noordwijk (the Netherlands)

Tel: +31 (71) 565 4820

Fax: +31 (71) 565 3663

E-mail: Ulf.Merbold@esa.int

The next SUCCESS Student Contest will take place in 2004.

 

For further information:

ESA, Service des Relations avec les Médias

Tel: +33(0)1.53.69.7155

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