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space walk

 
Dictionary: space walk

n.
An excursion by an astronaut outside a spacecraft in space; extravehicular activity.

space walk space walk v.
space walker space walker n.

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Word Tutor: spacewalk
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pronunciation

IN BRIEF: v. - Move outside the Earth's atmosphere while not in a craft.

WordNet: space walk
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Note: click on a word meaning below to see its connections and related words.

The noun has one meaning:

Meaning #1: any kind of physical activity outside a spacecraft by one of the crew


Wikipedia: Extra-vehicular activity
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Mike Fossum works on the Kibo Module (JPM) during the second spacewalk of STS-124.

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). In the later lunar landing missions (Apollo 15, 16, and 17) the command module pilot (CMP) did an EVA to retrieve film canisters on the return trip; he was assisted by the lunar module pilot (LMP) who remained at the open CM hatch. These trans-Earth EVAs were the only spacewalks ever conducted in deep space.

Due to the different designs of the early spacecraft, the American and Soviet space programs also define an EVA differently. Russians define an EVA as occurring when a cosmonaut is in a vacuum. An American EVA begins when the astronaut switches the Extravehicular Mobility Unit (EMU) to battery power. A "Stand-up" EVA (SEVA) is where the astronaut does not fully exit a spacecraft, but is completely reliant on the spacesuit for environmental support.[1] Its name derives from the astronaut "standing up" in the open hatch, usually to film or assist a spacewalking astronaut.

EVAs may be either tethered (the astronaut is connected to the spacecraft, oxygen can be supplied through a tube, no propulsion is needed to return to the spacecraft) or untethered. When the tether performs life support functions such as providing oxygen, it is called an umbilical. Untethered spacewalks were only performed on three missions in 1984 using the Manned Maneuvering Unit (MMU), and on a flight test in 1994 of the Simplified Aid for EVA Rescue (SAFER). A SAFER is a safety device worn on tethered U.S. EVAs, since the capability of returning to the spacecraft is essential.

As of 2009, Russia, the United States, and China are the only countries with a demonstrated capability to conduct an EVA.

Contents

EVA hazards

Tear in glove during STS-118
Astronaut Bruce McCandless on an untethered EVA.

Spacewalks are dangerous for a number of different reasons, and are avoided for routine tasks. Consequently, EVAs are often planned late in the project development when problems are discovered, or sometimes even during an operational mission.

The primary danger is collision with space debris.[2][3] Velocity while orbiting 300 km above the Earth (typical for a space shuttle mission) is 7.7 km/s. This is approximately ten times the speed of a bullet. Nearly every space mission creates more orbiting debris, so this problem will continue to worsen.[3] Other possible problems include an astronaut becoming separated from his or her craft or suffering a spacesuit puncture which would depressurize the suit, causing anoxia and rapid death if the astronaut is not brought into a pressurized spacecraft immediately. Another reason for danger is that external environments in space are harder to simulate before the mission, although approximate simulations can be achieved at facilities like the Hydro-labs in Star City's Gagarin Training Center and NASA's Neutral Buoyancy Laboratory.

One astronaut has suffered a spacesuit puncture. During STS-37, a small rod punctured the glove of one of the astronauts (the name was not disclosed, but it was either Jerry L. Ross or Jay Apt). The puncturing object held in place, resulting in no detectable depressurization, and was not noticed until after the space walkers were safely back inside Atlantis.[4] Alexey Leonov's original EVA did not pass smoothly either. During the EVA, Leonov's suit became overinflated to the point he could no longer re-enter or seal the door of the airlock on Voskhod 2. Because he was breathing pure oxygen, he was able to reduce his suit pressure to under 4 psi (28 kPa) and, with effort, climb back inside.[5]

No catastrophic incident has ever occurred during an extra-vehicular activity, and no astronaut has ever died during one.[6] Nevertheless, given the considerable hazards inherent in EVAs, some scientists are working to develop tele-operated robots for outside construction work, in order to reduce or potentially eliminate the need for human EVAs.

Camp out

For EVAs from the International Space Station, NASA now routinely employs a camp out procedure to reduce the risk of decompression sickness.[7] This was first tested by the Expedition 12 crew. During a camp out, astronauts sleep overnight prior to an EVA in the airlock, and lower the air pressure to 10.2 psi (70 kPa), compared to the normal station pressure of 14.7 psi (101 kPa).[7] Spending a night at the lower air pressure helps flush nitrogen from the body, thereby preventing "the bends".[8][9]

EVA milestones

Capture of Intelsat VI in 1992 on STS-49. This hand-capture of a satellite is the only EVA to date to be performed by three astronauts.
Stephen Robinson riding the robotic arm during STS-114, doing a first in-flight repair of the Space Shuttle.(Landmass in the backdrop is the Bari region of Somalia).

Capability milestones

Personal cumulative duration records


National, ethnic and gender firsts

International Space Station assembly EVA made during the STS-116 mission. Robert Curbeam (with red stripes) together with Christer Fuglesang over Cook Strait, New Zealand.

See also

References

  1. ^ NASA (2007). "Stand-Up EVA". NASA. http://history.nasa.gov/alsj/a15/a15.seva.html. Retrieved October 21, 2008. 
  2. ^ Leonard David (January 7, 2002). "Space Junk and ISS: A Threatening Problem". Space.com. http://www.space.com/missionlaunches/junk_iss_020107.html. Retrieved November 30, 2008. 
  3. ^ a b Damien Fletcher (November 20, 2008). "Female astronaut loses toolbag in Space... but what else is floating up there?". The Daily Mirror. http://www.mirror.co.uk/news/top-stories/2008/11/20/female-astronaut-loses-toolbag-in-space-but-what-else-is-floating-up-there-115875-20909288/. Retrieved November 30, 2008. 
  4. ^ Landis, Geoffrey (2000-06). "Human Exposure to Vacuum". Geoffrey A. Landis personal website. http://www.sff.net/people/Geoffrey.Landis/vacuum.html. Retrieved 2007-08-20. 
  5. ^ Encyclopedia Astronautica (2007). "Berkut Chronology". Encyclopedia Astronautica. http://www.astronautix.com/craft/berkut.htm. Retrieved November 8, 2007. 
  6. ^ Traci Watson (January 16, 2006). "NASA's spacewalkers step into a new era". USA Today. http://www.usatoday.com/tech/science/space/2006-01-16-spacewalking_x.htm. Retrieved November 30, 2008. 
  7. ^ a b NASA (2006). "Preflight Interview: Joe Tanner". NASA. http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts115/interview_tanner.html. Retrieved February 8, 2008. 
  8. ^ NASA. "International Space Station Status Report #06-7". NASA. http://spaceflight.nasa.gov/spacenews/reports/issreports/2006/iss06-7.html. Retrieved 2006-02-17. 
  9. ^ NASA. "Pass the S'mores Please! Station Crew 'Camps Out'". NASA. http://www.nasa.gov/mission_pages/station/expeditions/campout.html. Retrieved 2006-04-01. 
  10. ^ NASA (2001). "STS-49". NASA. http://science.ksc.nasa.gov/shuttle/missions/sts-49/mission-sts-49.html. Retrieved December 7, 2007. 
  11. ^ a b c William Harwood (2007). "ISS EVA Statistics". CBS News. http://www.cbsnews.com/network/news/space/evastats.html. Retrieved November 8, 2007. 

External links


Translations: Spacewalk
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Dansk (Danish)
n. - rumvandring
v. intr. - gå på rumvandring, vandre i rummet

Français (French)
n. - (Aérosp) sortie dans l'espace
v. intr. - sortir dans l'espace

Deutsch (German)
n. - Spaziergang im Weltraum
v. - im Weltraum spazierengehen

Ελληνική (Greek)
n. - περίπατος στο διάστημα
v. - περπατώ στο διάστημα

Italiano (Italian)
passeggiata spaziale, fare una passeggiata spaziale

Português (Portuguese)
n. - passeio espacial (do astronauta fora da nave)
v. - mover-se de um lado para outro no espaço

Русский (Russian)
выход в открытый космос

Español (Spanish)
n. - paseo espacial
v. intr. - efectuar actividad física fuera de la nave espacial

Svenska (Swedish)
n. - rymdpromenad
v. - att färdas i rymden

中文(简体)(Chinese (Simplified))
太空漫步, 航天舱外活动, 在太空中行走, 进行舱外活动

中文(繁體)(Chinese (Traditional))
n. - 太空漫步, 航天艙外活動
v. intr. - 在太空中行走, 進行艙外活動

한국어 (Korean)
n. - 우주 유영
v. intr. - 우주 유영을 하다

日本語 (Japanese)
n. - 宇宙遊泳

עברית (Hebrew)
n. - ‮הליכה בחלל, טיול בחלל‬
v. intr. - ‮נע בחלל‬


 
 

 

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