EVA?
Extra-vehicular activity (EVA) is work done by an astronaut away from the Earth, and outside of a spacecraft. The term most commonly applies to an EVA made outside a craft orbiting Earth (a spacewalk), but also applies to an EVA made on the surface of the Moon (a moonwalk). It can be tethered or untethered. On November 13, 1966, Edwin "Buzz" Aldrin became the first to successfully work in space without tiring, on the Gemini 12 last flight. Aldrin worked outside the spacecraft for 2 hours and 6 minutes, in addition to two stand-up EVA's in the spacecraft hatch for an additional 3 hours and 24 minutes. Aldrin's interest in scuba diving inspired the use of underwater EVA training to simulate weightlessness, which has been used ever since to allow astronauts to practice techniques of avoiding wasted muscle energy."Weightlessness" Analogue or Simulation underwater?
Weightlessness (or zero-g) is the condition that exists for an object or person when they experience little or no acceleration away from the acceleration that defines an inertial trajectory, or the trajectory of pure free-fall. An astronaut inside an orbiting vehicle has the experience of "zero-g," because the action and acceleration due to gravity by itself does not cause a sensation of weight, and all of the other types of forces that do cause such sensations (such as mechanical pushes from the floor or other surfaces that cause g-force acceleration) are absent. Weightlessness can thus be realised for short periods of time in an airplane following a specific parabolic flight path. It is simulated poorly, with many differences, in neutral buoyancy conditions, such as immersion in a tank of water.Neutral Bouyancy?
Neutral buoyancy is a condition in which a physical body's mass equals the mass it displaces in a surrounding medium. This offsets the force of gravity that would otherwise cause the object to sink. An object that has neutral buoyancy will neither sink nor rise. The principle of neutral buoyancy is used to simulate the weightless environment of space. Astronauts experience no buoyant force and no rotational moment about their center of mass. One downside of using neutral buoyancy to simulate microgravity is the significant amount of drag presented by water. Generally, drag effects are minimized by doing tasks slowly in the water. Another downside of neutral buoyancy simulation is that astronauts are not weightless within their suits, thus, precise suit sizing is critical.
EVA Tethering Workshop Dr. Sarah Jane Pell (AU), Dr. Robert Thirsk (CA), Tim Roediger (DE) and Xavier Giralt (ES); ISU SSP06 Life Sciences Practical Laboratory: Strasbourg, France 2006. Photos Ed Chester.
Principal ARTi Aquabatics Research Team initiative 2002, Co-Founder Biological Enhancement Space Technologies BEST, 2002 and Director LiquidUni 2011.
Just Published!
Singularity University GSP10 - 780 Full colour plates 120pg by Pell.
ESA Appointment 2011
Appointed to ESA European Space Agency Topical Team for Space and Art!
Portugal 2012
Hydrophilia will be re-staged in Guimaraes 2012 European cultural capital.
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