Jordi Isern Institut de Ciències de l’Espai (CSIC-IEEC) MSc in Economics of Science & Innovation Innovation & Challenges: Nanotechnology & Space (6d) Microgravity

Sometimes it is necessary to remove the gravity Influence to understand how a phenomenon works! The ambients with reduced gravity are called microgravity ambients μg = g One possible solution could be to move far away from the influence of the Earth But this happens at a distance of 6.37 millions of km to obtain 1 μg 5 m If a = g, t = 1 s If a = 0.01g, t = 10 s If a = g, t = s There are easier issues! Influence of gravity: Thinks drop Buoyancy Sedimentation

Accelerated reference systems S is the force measured by the weighing machine 1) a = 0; S = mg 2) a > 0; S = m(a+g); larger weight 3) a < 0; S = m(a+g); lower weight 4) a = -g; S = 0

Systems to obtain microgravity ambients

Drop towers NASA Lewis Research Center: # 2.2 s, 24 m tower # 5.2 s, 132 m tower NASA Marshall Space Flight Center # 4.5 s, 100 m pipe ZARM Bremen # 4.74 s, 120 m tower Japan: # 10 s, tower + mine well 490 m

ZARM (Bremen) m g

240 cm 80 cm

Airplanes Flight: 3 h, 40 micro-g events

Rockets Residual accelerations of g during minutes

The typical orbit of the Shuttle is about 320 km height. The microgravity ambient is excelent and experiments can last for a couple of weaks

Skylab

MIR Space Station

International Space Station

Microgravity quality: In orbit there are several residual forces that degrade the μg quality: Atmospheric drag Centrifugal forces caused by the rotation of the satellite Any object not placed at the center of masses moves in a different orbit The residual gravity caused is ~10 -6 g And is nearly stationary The onboard operations introduce severe perturbations to the μg quality Fans, pumps, centrífuges, Astronauts movements… Residual accelerations ~10 -4 g One astronaut raised his arm 8 times!

Foton Especialized platforms are more efficient!

Biotecnology The main problems are sedimentation and convection. Sedimentation induces a bidimensional cellular growth and perturbates the growth of crystals Convectin introduces tensions and prevents the cellular or atomic aggregation

Insuline crystals

Combustion Burning is a selfsustained reaction that releases energy. It requieres fuel, an oxidizer and an ignition agent Fuels can be solid (paper, wood, coal), liquid (gasoline, gasoil), gas (hydrogen, propane). Oxidizers can also be solid (perclore amonium), liquids (hydrogen peròxide), gas (oxygen). Convection and sedimentation are critical for the flames

ESA microgravity research programme ESA facilities already developed or under development : Material Sciences Double Rack SLED - weightlessness on human vestibular system BIORACK - study of cells and complex biological systems ANTHRORACK - physiological measurements Fluid Physics Double Rack - fundamental fluid properties EURECA facilities - materials & life sciences research Bubble Drop and Particle Unit Critical Point Facility Advanced Gradient Heating Facility Autonomous Fluid Physics Module Advanced Protein Crystallization Facility Glovebox.