Exit extravéhiculaire
A left extravéhiculaire , or activity extravéhiculaire , shortened EVA ( Extra-vehicular activity ) is an activity carried out in the space - outside a Space vehicle - by a Spationaute vêtu of a Spacesuit.
This term is generally used for extravéhiculaires activities undertaken in Orbite around the Ground near a space vehicle ( spacewalk ), but it also refers at the exits on lunar surface ( moonwalk ). Thus, the exits extravéhiculaires are useful to ends of assembly or repair of space shuttles and space stations like to the exploration and the harvest of lunar samples.
The first exit extravéhiculaire was carried out by the Russian Cosmonaute Alexei Leonov the March 18th 1965, starting from the vessel Voskhod 2. American Edward White follows it later a few weeks.
Dangers of the exits extravéhiculaires
The exits extravéhiculaires are dangerous for many reasons. The first is the risk of Collision with space remains or Micrométéorite S. Indeed, these objects move at very an high speed (about several kilometers a second) and the impact of remains can involve large damage on the combinations. The drilling of the Spacesuit would involve a depressurization, the Anoxie then the fast Mort of the Spationaute if it quickly did not return in the pressurized vehicle.
Another important reason is that the exits extravéhiculaires are generally envisaged tardily, in particular when unforeseen dysfunctions are discovered; the danger of this type of intervention inevitably leads to a emotional pressure intense of the spationauts, who, although selected for their exceptional stability under the pressure, remain the human ones.
Another possible problem is the rupture of the connecting cable with the space vehicle.
Today, no catastrophic Accident took place at the time of an exit extravéhiculaire, and no spationaut died during one of these activities. However, the Scientifique S develop Robot S specialized in the maintenance actions extravéhiculaires, in order to reduce the possible hazards for the human ones.
See too
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