Extra-vehicular activity

The spacewalk (English Extra - vehicular activity, outboard activity ', or EVA for short ) is a term from the aerospace industry. You defined as collective term includes all works of a spaceman outside a spacecraft, especially outside working on space stations or the exits of the Apollo astronauts on the lunar surface (sometimes called Lunar Extra Vehicular Activity ( LEVA ) refers ).

EVAs are considered dangerous because of the spaceman must go to the free vacuum for this purpose from the (relatively) safe environment of a vehicle, protected only by a space suit. The radiation exposure is about twice as large as in the spacecraft. In quiet sun it amounts to 400 mSv / year; in the case of violent activity EVAs be shortened or moved. Early spacewalks were performed backed by linen and / or supply lines, and later free flights with the help of rockets knapsacks ( Manned Maneuvering Unit MMU ) were common. From the standpoint of celestial mechanics, the spaceman moved during this time on his own satellite orbit, which by its movements - may deviate from the path of the spaceship - with tool or a recoil gun.

You go out

• For shooting or hauling of measuring instruments - for example, for the measurement of micrometeorites
• To construction and repair work, for example on the ISS or the Hubble Space Telescope
• For scientific purposes
• To experiment with new techniques

The first space trip took place on March 18, 1965 by Alexei Leonov from Voskhod 2 The first American was on June 3, 1965, astronaut Edward H. White, who got out of the Gemini 4 spacecraft. At his within minutes of getting off his space suit hung for safety at a 25-foot (7.6 m) long supply line. In these first experiments quickly showed that for a meaningful spacewalk special devices ( grab handles and rails ) on the spacecraft are required, as well as the need to be adapted to use tools. The astronauts fatigued much faster than expected, which could be improved only through the introduction of specific training in large plunge pool.

With the first EVA of the NASA mission STS -102, the record for the longest spacewalk was erected. The withdrawal began on March 11, 2001 at 5:12 clock and ended 14:08 clock the same day. This took the spacewalk total of 8 hours and 56 minutes. During this EVA, the astronauts of the Space Shuttle Discovery among them were before the docking of the multi-purpose logistics module Leonardo to the ISS.

In conjunction with the EVA is in German usage, the term spacewalk, a translation of the English term spacewalk used. This is the tremendous physical stresses to which is exposed while a spaceman, poorly again. After all, he is constantly exposed to the enormous noise pollution from the built- in suit air conditioning. He is also a motorized severely limited by the rigid space suit, although astronauts during EVAs usually have to take on tasks.

In each case, before leaving and before entering the spaceship pressure locks are used.

Since ISS Expedition 12 takes place at the exits on the ISS in the night before the spacewalk a so-called camp out instead, in which the spaceman is sleeping instead of air under atmospheric pressure of 1010 hPa eight hours in the lock and is air at a reduced pressure of 700 hPa inhaled, to reduce the partial pressure of nitrogen in the tissues. This decompression sickness is prevented by nitrogen supersaturation under the pressure of the space suit of only 350 hPa. A necessary hygiene break out of the lock is carried out with an oxygen mask, which offers 70 minutes supply.