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). As of September 13, 2006, 158 astronauts had made
spacewalks (out of 448 astronauts ever in space). These are some of the most interesting moments in spacewalks history:
1. Alexey Leonov, the pioneer (march, 1965)On March 18, 1965
Alexei Leonov became the first person to walk in space. He spent 12 minutes outside the spacecraft Voskhod 2, connected to the craft by a five-foot tether. At the end of the spacewalk, Leonov's spacesuit had inflated in the vacuum of space to the point where he could not reenter the airlock. Finally, he opened a valve to allow some of the suit's pressure to bleed off, and was barely able to get back inside the capsule. The images are still shocking:
2. Ed White, the first American (june, 1965)
On June 3, 1965,
Edgard H. White became the first American to conduct a spacewalk. As pilot of Gemini 4, White stepped outside the spacecraft for a 21-min spacewalk during which he maneuvered on the end of a 7.6-m lifeline by using a hand-held jet gun.
3. Bruce McCandless, floating free in space (1984)
At about 100 meters from the cargo bay of the space shuttle Challenger, Bruce McCandless II was further out than anyone had ever been before. Guided by a Manned Maneuvering Unit (
MMU), astronaut McCandless, pictured above, was floating free in space. McCandless and fellow NASA astronaut Robert Stewart were the first to experience such an "untethered space walk" during Space Shuttle mission 41-B in 1984.
[1] 4. Mark C. Lee, testing EVA Rescue unit (1994)
In 1994 astronaut Mark Lee tested the Simplified Aid for EVA Rescue (
SAFER) system for NASA. SAFER is a backpack propulsion unit that incorporates small nitrogen thrusters controlled by hand and moderated by computer. Pictured, Lee jets about the bay of Space Shuttle Discovery, over 200 kilometers above Earth in the first untethered space walk in ten years. SAFER, smaller than the Manned Maneuvering Unit, is designed as a backup system to help astronauts in the unlikely event that they become too separated from their work outside the International Space Station.
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5. Deep Space Spacewalkers (1971,72)
August 5, 1971. On the return journey, while about 275,000 km from Earth, Alfred Worden went on a 41-minute spacewalk during which he was attached to the CSM by a tether – the most distant EVA up to that time. In the picture, astronaut Ronald Evans performs an EVA during the Apollo XVII on December 17, 1972. Evans made three trips to the Service Module's Scientific Instrument Module (SIM) bay to retrieve file cassettes in the last spacewalk in deep space to date.
[1] [2] 6. First spacewalk from the Shuttle (1983)
Astronauts Musgrave and Peterson on the first spacewalk from the Shuttle, 1983. During the mission, both astronauts tested EVA equipment as well as construction and repair devices and procedures.
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7. Intelsat VI Satelite Rescue (1992)
May, 1993. Three crewmembers of mission STS-49 hold onto the 4.5 ton International Telecommunications Organization Satellite (INTELSAT) VI after a six- handed "capture" was made minutes earlier during the mission's third extravehicular activity (EVA). From left to right: Richard J. Hieb, Thomas D. Akers and Pierre J. Thuot.
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8. Spacewalks on the robotic arm Spacewalkers often work strapped to the tip of the shuttle's 50-foot robotic arm. The large robot arm attached to the Space Shuttle Orbiter was designed, and built by a Canadian company, and so is also known as Canadarm. It is 15.3 m long and weighs 408 kg. As part of the Remote Manipulator System (
RMS) it can retrieve, repair and deploy satellites, or provide a mobile extension ladder for spacewalking crewmembers. The arm has been supporting astronauts working in space for a long time, so these are some of the most interesting pictures:
Jerry L. Ross, anchored to the robotic arm of the Atlantis. [1]
Mark C. Lee and Carl Meade on Discovery shuttle, 1994. [1]
Stephen K. Robinson, Discovery, August 8, 2005. [1]
Wisoff and Low, Endeavour, december 1993. [1]
Michael Gernhardt, Endeavour robotic arm. [1]
Peter J.K. Wisoff, december 2003. [1]
David Wolf testing EVARM, october 10, 2002. [1]
Bruce McCandless over Canadarm, february, 1984. [1] 
November 14, 1984. Astronaut Dale A. Gardner holds up a "For Sale" sign refering to the two satellites, Palapa B-2 and Westar 6 that they retrieved from orbit after their Payload Assist Modules (PAM) failed to fire.
[1] 9. Hubble Repair Missions 
The Hubble Space Telescope (HST) is a telescope in orbit around the Earth and the only telescope ever designed to be serviced from space by astronauts. To date, there have been four servicing missions, with a fifth and final mission planned for September 2008.
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Astronaut F. Story Musgrave, anchored on the end of the Remote Manipulator System (RMS) arm, prepares to be elevated to the top of the Hubble Space Telescope (HST) to install protective covers on the magnetometers.
[1] 10. International Space Station assembly 
The International Space Station (ISS) is a research facility currently being assembled in space. It travels at an average speed of 27,744 km (17,240 miles) per hour, completing 15.7 orbits per day. Since 1998, astronauts have worked hard completing the station. In the picture above, International Space Station assembly EVA made during the STS-116 spaceflight by astronauts Robert Curbeam and Christer Fuglesang as they fly over New Zealand.
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April 13, 2002. Anchored on the International Space Station’s (ISS) Canadarm2 some 240 miles above the blue and white Earth, astronaut Lee M.E. Morin totes one of the S0 (S-zero) keel pins, which were removed from their functional position on the truss and attached on to its exterior for long-term stowage.
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Astronaut Piers Sellers working on ISS.
And here you can see two videos of the ISS works, simply amazing:
ISS space golfInternational Space Station flight engineer Mikhail Tyurin became the world's third space golfer on November 22, 2006, as he took swing with a six iron at the start of a scheduled six- hour spacewalk. A company paid the Russian Federal Space Agency for the demonstration:
[1] Suni Williams loses her camera in Space June, 2007. While doing an EVA on the ISS, Space Shuttle astronaut Suni Williams’ camera broke free of its bracket and floated away from her into space. A button designed to lock the camera in place might have failed, resulting in the camera's loss. NASA's debris analysts studied the camera's trajectory.
Image credits:
NASAMore info and sources:
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8See also:
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Best pictures of Earth from outer space-
Golf on the Moon-
Top 10 Most amazing facts about the Earth
Con sus cinco toneladas de peso, los elefantes de la isla de Andaman, en el Golfo de Bengala, son capaces de nadar largas distancias sin ningún tipo de problema. Cada día, después de una dura jornada de trabajo en la madera, los elefantes regresan nadando de isla a isla conducidos por sus cuidadores.
Pero ¿a qué se debe esta habilidad de los elefantes bajo el agua? Los científicos creen ahora que los elefantes dejaron atrás la vida acuática hace alrededor de 30 millones de años y que desde entonces no han dejado de adaptarse a la vida terrestre. Según algunos estudios, los elefantes podrían descender de la vaca marina y cuentan entre sus parientes más cercanos con criaturas como el manatí.
Analizando los embriones de varias especies, Ann Gaeth, de la Universidad de Melbourne, Australia, ha descubierto la presencia de un vestigio ancestral en los embriones de elefantes, un pequeño conducto conocido como nefrostoma, que solo poseen los animales que viven en el agua. Otros especialistas, como John B. West, de la Universidad de San Diego, creen haber descubierto la causa por la que los elefantes son capaces de bucear a profundidades considerables sin que sus pulmones se dañen, como ocurre con otros mamíferos. Según West, los elefantes han reemplazado las membranas pleurales normales por capas de tejido conectivo denso que permiten a los pulmones soportar la intensa presión.
El fotógrafo surafricano Steve Bloom ha dedicado varios años de su vida a seguir a los elefantes nadadores de Andaman y el resultado ha sido su libro “¡Elefante!”, algunas de cuyas imágenes podéis ver en este post. Por último, en el siguiente vídeo de David Attenborough para la BBC, podréis observar la reacción de los elefantes africanos al encontrar agua tras meses de estación seca. Una auténtica maravilla.
