From ESA: “Ten years of exploring hypergravity with ESA’s centrifuge”

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European Space Agency

8 November 2017
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After 14 million revolutions, ESA’s Large Diameter Centrifuge is about to mark its 10th birthday. The 8 m-diameter four-arm centrifuge gives researchers access to a range of hypergravity up to 20 times Earth gravity for weeks or months at a time.

At its fastest, the centrifuge rotates at up to 67 revs per minute, with its six gondolas placed at different points along its arms weighing in at 130 kg, and each capable of accommodating 80 kg of payload. Multiply those combined figures by 20 g and it adds up to an equivalent mass of 24 tonnes.

“The centrifuge’s surrounding walls and bulletproof glass wouldn’t protect us if one of those gondolas ever spun off,” explains Jack van Loon of the centrifuge team. “The glass is only there in case something like a nut or screwdriver gets left on the mechanism by accident.

“Of course, we have a strict maintenance cycle, checking on vibration and looking out for anything wrong with the motors, gearing and brakes, with visual checks made before each run.

“Additionally, the centrifuge rests on a seismic block of heavy concrete, making sure its running doesn’t interfere with sensitive instruments in other nearby ESA labs.”

Based within a scifi-style white dome, the centrifuge has been a place of pilgrimage for European researchers for the last decade, including student experimenters on regular Spin Your Thesis campaigns.

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Plasma arc under ascending hypergravity
Released 07/02/2014 10:41 am
Copyright GRAVARC TNG

The GRAVARC TNG team, made up of three PhD students from Masaryk University in Brno in the Czech Republic) tested the behaviour of gliding arcs of plasma in noble gases under hypergravity conditions. Seen above, the krypton plasma arcs shift lower and lower as the gravity level moves from 1g to 2g to 12g and finally 18g, acquired at 0.3 second intervals. The team’s objective was to improve scientific understanding of the physical phenomena involved. Studying electric discharges at different levels of gravity is important for safety in spaceflight, for the design of ion thrusters, and for the understanding of plasma-related processes in planetary atmospheres.

Jack adds: “We have some internal ESA testing – for instance to simulate static g loads experienced on some foreign launchers for key satellite systems – as well as a lot of academic teams, especially in the life and physical sciences, plus commercial experiments.”

Future internal studies will be looking at the behaviour of heat pipes and reactions wheels, used for satellite thermal and attitude control, respectively.

A lot of factors turn out to shift along with gravity: bubble sizes change, convection currents accelerate and alloys form in novel ways. Electrical plasmas alter and test animals lose fat mass.

All the computers and associated equipment used in experiments also need checking, because their performance might be degraded too: computers may fail to cool down, standard microscope light sources have been known to flicker.

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Northon college experiment in LDC
Released 13/05/2015 2:55 pm
Copyright ESA
Experiment in gondola

“Traditionally, scientists have taken the value of gravity for granted as a rigid, fixed number,” adds Jack. “But it isn’t: we’re able to manipulate and modulate the g term within an equation, which offers a lot of new approaches.

“For many years the scientific community maintained a central focus on microgravity, with the partial gravity of the Moon and Mars emerging as an interest in the recent years. But that’s a very human-centric approach, looking only at the planetary bodies people can inhabit.

“With this centrifuge, research teams can find out how systems respond across the entire spectrum of gravity, gaining a range of results they can use to validate models, observe the general direction of changes to varying gravity levels, then extrapolate higher or lower as needed.”

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Achilles students and supporting staff pose outside the LDC housing
Released 07/04/2017
Copyright ESA

ESA decided to build the centrifuge to enlarge the array of research infrastructure it could offer the European research community, with the encouragement of the European Low Gravity Research Association and financial backing from the Dutch government.

ESA’s Life and Physical Sciences Instrumentation section had a long tradition of building small centrifuges flown during space missions, typically offering a 1 g inflight control for microgravity experiments. Designing the centrifuge meant scaling up this approach, with engineering performed by Portuguese machining company Zeugma.

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Graphical view of the LDC when rotating at full speed with 6 gondolas swinging out.
Released 12/10/2011
Copyright ESA

Graphical view of the LDC when rotating at full speed with 6 gondolas swinging out. The 7th gondola for the rotation control and the gas and water bottles compartments are located at the centre of the centrifuge.

In January ESA will celebrate the centrifuge’s first decade, giving the team the opportunity to hear from their user community on desired future upgrades and new research ideas.

Further ahead, a next-generation centrifuge has been proposed from an ESA Topical team study: measuring around 200 m in diameter, this “Human Hypergravity Habitat” would be big enough for people to live in a hypergravity environment for months on end.

See the full article here .

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The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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