人在宇宙中會怎麼死亡？

12-27

常看宇宙飛船艙體破裂，人被吸到宇宙里。但是怎麼死亡的？窒息還是凍死還是熱死的呢？

以下內容轉自果殼網

危害：
1、不會血液沸騰或爆炸？你的血液不會沸騰。因為一般來說，人的血壓是 75/120（單位是托，1 托約等於 1 毫米汞柱），這個數值描述的是：人的血壓比外部環境的壓力要高 75-120 托左右。當外部環境壓力是 0 時，血壓至少還能維持在 75 托左右，而在這個壓力下，水的沸點是 46 攝氏度。因此人體體溫（37 攝氏度）還不足以讓血液沸騰。這都是血管的功勞，彈性的血管保證了血液有一定的壓力，防止沸點降低而發生沸騰。（在下文將提到的1965年的案例中，暴露者也只是報告說舌頭上的水開始沸騰，這是因為舌頭處的壓力其實也就是環境壓力——注。）
2、不會被凍結？你不會被冰凍。與很多人理解不同，太空並非是一個「絕對零度」的環境（怎麼可能是呢？）。事實上，雖然空間環境一般非常寒冷，但由於太空中的分子很少，接近真空，所以它是一個良好的隔熱體，對短時間暴露的人來說並不足以感受到「溫度」的屬性，既不「冷」，也不「熱」。暴露於其中的人熱量不會在很短時間內離開人體，只會因為體表水分蒸發而略微感到有一點冷，但不會凍起來或立即凍死。
3、會缺氧！供氧不足的情況下，意識還可以維持約9-11 秒。緊接著，身體會發生癱瘓和抽搐。
4、會晒傷！如果你的皮膚沒有任何保護地暴露於直射陽光的強烈紫外線輻射下，你會有非常糟糕的灼傷。
5、會有其他損傷！些失明或視覺障礙等神經方面的問題以及各種原作者沒想起來的損傷

如果沒穿宇航服，首先應該是凍死，宇宙中的常規溫度好像是大約零下二百多度。
如果穿了宇航服，首先是憋死。

央視新科動漫做的一個科普向的視頻正好有一集就是這個內容
星際播報13
以下轉自豆瓣

NASA資料：人在太空中能活多久？
人沒有保護，在太空中能活多久？

如果你不試圖屏住呼吸，暴露於太空半分鐘左右不太可能造成永久性傷害。正如潛水員上升時需要注意的一樣，屏住呼吸可能會損傷你的肺，另外如果耳咽管有嚴重堵塞，耳鼓也會出問題。但理論預測和動物試驗證實，除了這些之外，暴露於真空並不會造成即時的傷害。你不會爆炸，血液不會沸騰，你不會凍死，也不會馬上失去知覺。

十秒鐘之後，會有很多較輕微的問題出現，包括晒傷，可能的減壓症（the bends），皮膚和皮下組織輕度，可逆，無痛苦的腫脹。然後你會因為缺氧失去知覺。傷害不斷累積，大概一兩分鐘後你將死去，但目前並不了解這個確切的時間限度。

由於你的皮膚和循環系統的包容功能，你不會爆炸，血液不會沸騰。雖然空間環境一般非常寒冷，但熱量不會在很短時間內離開人體，所以你不會立即凍死。只有在體內氧氣耗盡後人才會失去知覺。如果你的皮膚沒有任何保護地暴露於直射陽光的強烈紫外線輻射下，你會有非常糟糕的灼傷。

1965年，在NASA的載人航天器中心（現在更名為Johnson Space Center）一次真空艙宇航服泄露事件中，我們曾經有一名被試者不幸暴露於近似真空下（壓力小於1 psi）。他保持知覺的時間是14秒，這大概是氧氣從肺部到達大腦所需要的時間。（不過）他的宇航服中的條件大概沒有達到極強的真空，而且15秒後我們就開始給真空艙重新加壓。在大約與一萬五千英尺高度相當的壓力下被試者開始恢復知覺。後來被試者報告說他能感受並聽到空氣泄露出去，他在失去知覺前最後的記憶是舌頭上的水開始沸騰。

1995年2月13號的《航空周刊與空間技術》發表了Leonard Gordon報道另一次真空時間的信件：「宇航員在做事時將一隻無加壓的手長時間置於接近真空下的試驗1960年8月16日發生在了真實生活中。在使用開放式的gondola（不是纜車吧？？？）上升到102,800英尺（19.5英里）高度的過程中，Joe Kittinger的右手上的加壓出了問題。他決定繼續任務，如預期的一樣，他的手很疼並失去了功能。但是在這次破記錄的跳傘後，一回到低海拔，他的手恢復了正常。」

翻譯自：http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970603.html

更多有用資料可見於Explosive Decompression and Vacuum Exposure（一個MIT宇航學系客座教授的網頁，有非常詳細的解釋）

How long can a human live unprotected in space?

If you don"t try to hold your breath, exposure to space for half a minute or so is unlikely to produce permanent injury. Holding your breath is likely to damage your lungs, something scuba divers have to watch out for when ascending, and you"ll have eardrum trouble if your Eustachian tubes are badly plugged up, but theory predicts -- and animal experiments confirm -- that otherwise, exposure to vacuum causes no immediate injury. You do not explode. Your blood does not boil. You do not freeze. You do not instantly lose consciousness.

Various minor problems (sunburn, possibly "the bends", certainly some [mild, reversible, painless] swelling of skin and underlying tissue) start after ten seconds or so. At some point you lose consciousness from lack of oxygen. Injuries accumulate. After perhaps one or two minutes, you"re dying. The limits are not really known.

You do not explode and your blood does not boil because of the containing effect of your skin and circulatory system. You do not instantly freeze because, although the space environment is typically very cold, heat does not transfer away from a body quickly. Loss of consciousness occurs only after the body has depleted the supply of oxygen in the blood. If your skin is exposed to direct sunlight without any protection from its intense ultraviolet radiation, you can get a very bad sunburn.

At NASA"s Manned Spacecraft Center (now renamed Johnson Space Center) we had a test subject accidentally exposed to a near vacuum (less than 1 psi) in an incident involving a leaking space suit in a vacuum chamber back in "65. He remained conscious for about 14 seconds, which is about the time it takes for O2 deprived blood to go from the lungs to the brain. The suit probably did not reach a hard vacuum, and we began repressurizing the chamber within 15 seconds. The subject regained consciousness at around 15,000 feet equivalent altitude. The subject later reported that he could feel and hear the air leaking out, and his last conscious memory was of the water on his tongue beginning to
boil.

Aviation Week and Space Technology (02/13/95) printed a letter by Leonard Gordon which reported another vacuum-packed anecdote:

"The experiment of exposing an unpressurized hand to near vacuum for a significant time while the pilot went about his business occurred in real life on Aug. 16, 1960. Joe Kittinger, during his ascent to 102,800 ft (19.5 miles) in an open gondola, lost pressurization of his right hand. He decided to continue the mission, and the hand became painful and useless as you would expect. However, once back to lower altitudes following his record-breaking parachute jump, the hand returned to normal."

References:

Frequently Asked Questions on sci.space.*/sci.astro

The Effect on the Chimpanzee of Rapid Decompression to a Near Vacuum, Alfred G. Koestler ed., NASA CR-329 (Nov 1965).

Experimental Animal Decompression to a Near Vacuum Environment, R.W. Bancroft, J.E. Dunn, eds, Report SAM-TR-65-48 (June 1965), USAF School of Aerospace Medicine, Brooks AFB, Texas.

Survival Under Near-Vacuum Conditions in the article "Barometric Pressure," by C.E. Billings, Chapter 1 of Bioastronautics Data Book, Second edition, NASA SP-3006, edited by James F. Parker Jr. and Vita R. West, 1973.

Personal communication, James Skipper, NASA/JSC Crew Systems Division, December 14, 1994.

內壓壓死

為什麼不首先想到憋死。。。