A frequently asked question is: how realistic is the scene in 2001: A Space Odyssey where astronaut Bowman makes a space-walk without a helmet? How long could a human survive if exposed to vacuum? Would you explode? Would you survive? How long would you remain conscious?
一个经常被问到的问题是电影《2001：太空漫游》中宇航员鲍曼没有戴头盔进行太空行走的场景可能吗？ 如果暴露在真空中，一个人可以生存多长时间？ 你会爆炸吗？ 你会生存吗？ 您会保持意识多久？
The quick answers to these questions are: Clarke got it about right in 2001. You would survive about a ninety seconds, you wouldn’t explode, you would remain conscious for about ten seconds.
Astronaut Bowman ejected into space without a helmet
你能生存下来吗？Could You Survive?
The best data I have comes from the chapter on the effects of Barometric pressure in Bioastronautics Data Book, Second edition, NASA SP-3006. This chapter discusses animal studies of decompression to vacuum. It does not mention any human studies.
我得到的最好的数据来自《生物航空数据手册》（第二版，NASA SP-3006）中有关气压影响的章节。 本章讨论减压到真空的动物研究。 它没有提及任何在人类身上的研究。
page 5, (following a general discussion of low pressures and ebullism), the author gives an account of what is to be the expected result of vacuum exposure:
“Some degree of consciousness will probably be retained for 9 to 11 seconds (see chapter 2 under Hypoxia). In rapid sequence thereafter, paralysis will be followed by generalized convulsions and paralysis once again.
第5页（在对低压和 体液沸腾 进行一般性讨论之后），作者介绍了真空暴露的预期结果：
During this time, water vapor will form rapidly in the soft tissues and somewhat less rapidly in the venous blood. This evolution of water vapor will cause marked swelling of the body to perhaps twice its normal volume unless it is restrained by a pressure suit. (It has been demonstrated that a properly fitted elastic garment can entirely prevent ebullism at pressures as low as 15 mm Hg absolute [Webb, 1969, 1970].)
在此期间，水蒸气将在软组织中迅速形成，而在静脉血液中的形成速度将有所下降。 由于没穿宇航服保证压力，水蒸气的这种释放会导致身体明显肿胀，可能是正常体积的两倍。 （已经证明，正确地穿上合适的弹性服装可以在绝对压力低至15 mm Hg的情况下完全防止 体液沸腾 [Webb，1969，1970]。）
Heart rate may rise initially, but will fall rapidly thereafter. Arterial blood pressure will also fall over a period of 30 to 60 seconds, while venous pressure rises due to distention of the venous system by gas and vapor. Venous pressure will meet or exceed arterial pressure within one minute.
心率一开始可能会上升，但此后会迅速下降。 动脉血压还将在30到60秒的时间内下降，而静脉压力由于气体和蒸气对静脉系统的扩张而升高。 一分钟内静脉压力将达到或超过动脉压力。
There will be virtually no effective circulation of blood. After an initial rush of gas from the lungs during decompression, gas and water vapor will continue to flow outward through the airways. This continual evaporation of water will cool the mouth and nose to near-freezing temperatures; the remainder of the body will also become cooled, but more slowly.
几乎没有有效的血液循环。 在减压期间最初从肺中涌出气体之后，气体和水蒸气将继续通过气道向外流出。 水的不断蒸发会将口鼻冷却至接近冰点的温度； 身体的其余部分也会变凉，但速度会变慢。
“Cook and Bancroft (1966) reported occasional deaths of animals due to fibrillation of the heart during the first minute of exposure to near vacuum conditions. Ordinarily, however, survival was the rule if recompression occurred within about 90 seconds. … Once heart action ceased, death was inevitable, despite attempts at resuscitation….
“ Cook and Bancroft（1966）报告说，在接近真空条件下的第一分钟内，由于心脏的纤颤而导致动物灾难性的死亡。但是，通常，如果再压缩发生在90秒内，生存变得很残酷。 只要心脏已经不再跳动，死亡是不可避免的， 各种心脏复苏法也不管用。
[on recompression] “Breathing usually began spontaneously… Neurological problems, including blindness and other defects in vision, were common after exposures (see problems due to evolved gas), but usually disappeared fairly rapidly.
“It is very unlikely that a human suddenly exposed to a vacuum would have more than 5 to 10 seconds to help himself. If immediate help is at hand, although one’s appearance and condition will be grave, it is reasonable to assume that recompression to a tolerable pressure (200 mm Hg, 3.8 psia) within 60 to 90 seconds could result in survival, and possibly in rather rapid recovery.”
Note that this discussion covers the effect of vacuum exposure only. The decompression event itself can have disasterous effects if the person being decompressed makes the mistake of trying to hold his or her breath. This will result in rupturing of the lungs, with almost certainly fatal results. There is a good reason that it is called “explosive” decompression.
注意，此讨论仅涵盖真空暴露的影响。 如果被再加压的人犯了试图屏住呼吸的错误，那么减压事件本身可能会带来灾难性的后果。 这将导致肺破裂，几乎可以肯定是致命的结果。 有充分的理由将其称为“爆炸性”减压。
你会保持意识吗？Will You Stay Conscious?
The Bioastronautics Data Book answers this question: “Some degree of consciousness will probably be retained for 9 to 11 seconds…. It is very unlikely that a human suddenly exposed to a vacuum would have more than 5 to 10 seconds to help himself.”
A larger body of information about how long you would remain conscious comes from aviation medicine. Aviation medicine defines the “time of useful consciousness”, that is, how long after a decompression incident pilots will be awake and be sufficiently aware to take active measures to save their lives. Above 50,000 feet (15 km), the time of useful consciousness is 9 to 12 seconds, as quoted by the FAA in table 1-1 in Advisory Circular 61-107(the shorter figure is for a person actively moving; the longer figure is for a person sitting quietly).
关于您将保持意识多久的更多信息来自航空医学。 航空医学定义了“有用意识的时间”，即减压事件发生后飞行员将意识到要采取积极措施挽救生命的时间。 美国联邦航空局在61-107号建议通告中的表1-1中引用，在50,000英尺（15公里）以上的高度上，有用意识的时间为9到12秒（较短的数字适用于积极活动的人;较长的数字为 一个人静静地坐着）。
The USAF Flight Surgeon’s Guide figure 2-3 shows 12 seconds of useful consciousness above 60,000 ft (18 km); presumably the longer time listed is based on the assumption that Air Force pilots are well-trained in high-altitude procedures, and will be able to use their time effectively even when partially disfunctional from hypoxia.
Linda Pendleton adds to this: “An explosive or rapid decompression will cut this time in half due to the startle factor and the accelerated rate at which an adrenaline-soaked body burns oxygen.” Advisory Circular 61-107 says the time of useful consciousness above 50,000 ft will drop from 9 to 12 seconds down to 5 seconds in the case of rapid decompression (presumably due to the “startle” factor discussed by Pendleton).
琳达·彭德尔顿补充说：“由于 爆炸或快速减压 会很吓人，也会让肾上腺素分泌加快的身体燃烧氧气的速度加快，所以人有意识的时间很有可能要减少一半。” 咨询通告61-107表示，在快速减压的情况下（50,000英尺以上），有用意识的时间将从9~12秒，减少到5秒（大概是由于Pendleton讨论的“惊吓”因素）。
A slightly more general interest book, Survival in Space by Richard Harding, echoes this conclusion:
“At altitudes greater than 45,000 feet (13,716 m), unconsciousness develops in fifteen to twenty seconds with death following four minutes or so later.”
“monkeys and dogs have successfully recovered from brief ( up to two minutes) unprotected exposures…”
理查德·哈丁（Richard Harding）撰写的一本较为大众的有趣的书《太空中的生存》（Survival in Space）回应了这一结论：“在海拔超过45,000英尺（13716 m）的高度上，意识丧失在十五到二十秒内发展，四分钟后死亡，死亡。” 然后：“猴子和狗已经成功地从短暂（最多两分钟）无保护的暴露中恢复过来了……”
您的血液会沸腾吗？Would Your Blood Boil?
Your blood is at a higher pressure than the outside environment. A typical blood pressure might be 75/120. The “75” part of this means that between heartbeats, the blood is at a pressure of 75 Torr (equal to about 100 mbar) above the external pressure. If the external pressure drops to zero, at a blood pressure of 75 Torr the boiling point of water is 46 degrees Celsius (115 F). This is well above body temperature of 37 C (98.6 F). Blood won’t boil, because the elastic pressure of the blood vessels keeps it it a pressure high enough that the body temperature is below the boiling point– at least, until the heart stops beating (at which point you have other things to worry about!).
您的血液比外界环境承受的压力更高。 典型的血压可能是75/120。 “ 75”部分表示在心跳之间，血液的压力高于外部压力75托（等于约100 mbar）。 如果外部压力降至零，则在75 Torr的血压下，水的沸点为46摄氏度（115 F）。 这远高于37 C（98.6 F）的体温。 血液不会沸腾，因为血管的弹性压力使其保持足够高的压力，以至于体温低于沸点-至少直到心脏停止跳动前是这样的（此时您还需要担心其他事情）
To be more pedantic, blood pressure varies depending on where in the body it is measured, so the above statement should be understood as a generalization. However, the effect of small pockets of localized vapor is to increase the pressure. In places where the blood pressure is lowest, the vapor pressure will rise until equilibrium is reached. The net result is the same.
更严谨一些，血压会根据在人体中测量的位置而变化，因此，以上陈述应理解为一种概括。 但是，局部蒸汽小囊的作用是增加压力。 在血压最低的地方，蒸气压会上升直到达到平衡。 最终结果是相同的。
你会被冻住吗？Would You Freeze?
A few recent Hollywood films showed people instantly freezing solid when exposed to vacuum. In one of these, the scientist character mentioned that the temperature was “minus 273”– that is, absolute zero.
But in a practical sense, space doesn’t really have a temperature– you can’t measure a temperature on a vacuum, something that isn’t there. The residual molecules that do exist aren’t enough to have much of any effect. Space isn’t “cold,” it isn’t “hot”, it really isn’t anything.
但是从实际意义上讲，真空实际上并没有温度-您无法在真空中测量温度，真空里什么都没有。 真空中确实存在少量分子，但还不足以发挥任何作用。 真空不是“冷”的，不是“热”的，实际上它没法用温度描述。
What space is, though, is a very good insulator. (In fact, vacuum is the secret behind thermos bottles.) Astronauts tend to have more problem with overheating than keeping warm.
If you were exposed to space without a spacesuit, your skin would most feel slightly cool, due to water evaporating off you skin, leading to a small amount of evaporative cooling. But you wouldn’t freeze solid!
有人在现实生活中暴露在真空并幸存下来吗？Has Anybody Ever Survived Vacuum Exposure in Real Life?
Human experience is discussed by Roth, in the NASA technical report Rapid (Explosive) Decompression Emergencies in Pressure-Suited Subjects. Its focus is on decompression, rather than vacuum exposure per se, but it still has a lot of good information, including the results of decompression events involving humans.
There are several cases of humans surviving exposure to vacuum worth noting. In 1966 a technician at NASA Houston was decompressed to vacuum in a space-suit test accident. This case is discussed by Roth in the reference above. He lost consciousness in 12-15 seconds. When pressure was restored after about 30 seconds of exposure, he regained consciousness, with no apparent injury sustained.
有几例人类幸免于真空。 1966年，在宇航服测试事故中，休斯敦宇航局的一名技术人员被减压至真空。 罗斯在上面的参考文献中讨论了这种情况。 他在12-15秒内失去知觉。 暴露约30秒后压力恢复时，他恢复了意识，没有明显的受伤。
Before jumping to the conclusion that space exposure is harmless, however, it is worth noting that in the same report, Roth includes a report of the autopsy of the victim of a slightly longer explosive decompression incident:
“Immediately following rapid decompression, it was noted that he began to cough moderately. Very shortly after this he was seen to lose consciousness, and the picture described by the physicians on duty was that the patient remained deeply cyanotic, totally unresponsive and flaccid during the 2-3 minutes [to repressurise the altitude chamber] down to ground level.
… “Manual artificial respiration was begun immediately… The patient at no time breathed spontaneously; however, at the moment ground level was reached he was seen to give a few gasps. These were very irregular and only two or three in number.
“The conclusion of the [autopsy] report was as follows: “The major pathologic changes as outlined above are consistent with asphyxia. It is felt that the underlying cause of death in this case may be attributed to acute cardio-respiratory failure, secondary to bilateral pneumothorax…” “
Many other cases of death following decompression are noted in the aviation literature, including one spaceflight incident, the Soyuz-11 decompression accident, in 1971. A recent analysis of this accident can be found in D. J. Shayler, Disasters and Accidents in Manned Spaceflight.
航空文献中还记录了减压后的许多其他死亡案例，包括1971年的一次航天事故，即Soyuz-11减压事故。有关这种事故的最新分析可以在D. J. Shayler的《载人航天的灾难与事故》中找到。
On the subject of partial-body vacuum exposure, the results are not quite as serious. In 1960, during a high-altitude balloon parachute-jump, a partial-body vacuum exposure incident occurred when Joe Kittinger, Jr. lost pressurization in his right glove during an ascent to 103,000 ft (19.5 miles) in an unpressurized balloon gondola, Despite the depressurization, he continued the mission, and although the hand became painful and useless, after he returned to the ground, his hand returned to normal. Kittinger wrote in National Geographic (November 1960):
关于部分人体真空暴露的问题，结果并不那么严重。 1960年，在一次高空气球降落伞跳跃过程中，小乔·乔·基廷格（Joe Kittinger，Jr.）在上升到103,000英尺（19.5英里）的未加压气球吊篮时，右手套失去了加压，发生了部分身体真空暴露事故，尽管 减压后，他继续执行任务，尽管手很疼感觉快废了，但返回地面后，手却恢复了正常。 基廷格在《国家地理》（1960年11月）中写道：
“At 43,000 feet I find out [what can go wrong]. My right hand does not feel normal. I examine the pressure glove; its air bladder is not inflating. The prospect of exposing the hand to the near-vacuum of peak altitude causes me some concern. From my previous experiences, I know that the hand will swell, lose most of its circulation, and cause extreme pain…. I decide to continue the ascent, without notifying ground control of my difficulty.”
at 103,000 feet, he writes:”Circulation has almost stopped in my unpressurized right hand, which feels stiff and painful.”
But at the landing:”Dick looks at the swollen hand with concern. Three hours later the swelling will have disappeared with no ill effect.”
The decompression incident on Kittinger’s balloon jump is discussed further in Shayler’s Disasters and Accidents in Manned Spaceflight:
[When Kittinger reached his peak altitude] “his right hand was twice the normal size… He tried to release some of his equipment prior to landing, but was not able to as his right hand was still in great pain. He hit the ground 13 min. 45 sec. after leaving Excelsior. Three hours after landing his swollen hand and his circulation were back to normal.”
See also from Leonard Gordon, Aviation Week, February 13th 1996.
Finally, posting to sci.space, Gregory Bennett discussed an actual space incident:
“Incidentally, we have had one experience with a suit puncture on the Shuttle flights. On STS-37, during one of my flight experiments, the palm restraint in one of the astronaut’s gloves came loose and migrated until it punched a hole in the pressure bladder between his thumb and forefinger.
It was not explosive decompression, just a little 1/8 inch hole, but it was exciting down here in the swamp because it was the first injury we’ve ever head from a suit incident. Amazingly, the astronaut in question didn’t even know the puncture had occured; he was so hopped on adrenalin it wasn’t until after he got back in that he even noticed there was a painful red mark on his hand.
这不是爆炸性的减压，只是一个1/8英寸的小孔，但在困境中令人振奋，因为这是我们有史以来第一次因压力服事故而受伤。 令人惊讶的是，上面说的那位宇航员甚至都不知道自己的宇航服被刺穿了。 他如此兴奋，直到他回来后才发现他的手上有一个痛苦的红色标记。
He figured his glove was chafing and didn’t worry about it…. What happened: when the metal bar punctured the glove, the skin of the astronaut’s hand partially sealed the opening. He bled into space, and at the same time his coagulating blood sealed the opening enough that the bar was retained inside the hole.”
The discussion here has focussed only on exposure to vacuum. However, in general the action of being exposed to vacuum will also involve a rapid decompression. This event is generally known as “explosive decompression,” and apart from the simple effect of vacuum on the body, the explosive decompression event itself will be hazardous. As noted, explosive decompression will be particularly bad if the decompression subject attempts to hold his or her breath during decompression.
这里的讨论仅集中在真空中。 然而，通常，暴露于真空的动作也将涉及快速减压。 此事件通常称为“爆炸性减压”，除了真空对身体的简单影响外，爆炸性减压事件本身将很危险。 如上所述，如果减压对象试图在减压期间屏住呼吸，爆炸性减压将特别糟糕。
In The USAF Flight Surgeon’s Guide, Fischer lists the following effects due to mechanical expansion of gases during decompression.
- Gastrointestinal Tract During Rapid Decompression.
One of the potential dangers during a rapid decompression is the expansion of gases within body cavities. The abdominal distress during rapid decompression is usually no more severe than that which might occur during slower decompression. Nevertheless, abdominal distention, when it does occur, may have several important effects. The diaphragm is displaced upward by the expansion of trapped gas in the stomach, which can retard respiratory movements. Distention of these abdominal organs may also stimulate the abdominal branches of the vagus nerve, resulting in cardiovascular depression, and if severe enough, cause a reduction in blood pressure, unconsciousness, and shock. Usually, abdominal distress can be relieved after a rapid decompression by the passage of excess gas.
- 快速减压过程中的潜在危险之一是体腔内气体的膨胀。 快速减压过程中的腹痛通常不比缓慢减压过程中发生的腹痛严重。 但是，腹胀确实发生时可能会产生多种重要影响。 隔膜通过胃中捕获的气体膨胀而向上移位，这会阻碍呼吸运动。 这些腹部器官的膨胀也可能刺激迷走神经的腹部分支，导致心血管压抑，如果严重到足以引起血压降低，意识丧失和休克。 通常，在迅速减压后，多余气体可以通过缓解腹部不适。
- The Lungs During Rapid Decompression.
Because of the relatively large volume of air normally contained in the lungs, the delicate nature of the pulmonary tissue, and the intricate system of alveolar airways for ventilation, it is recognized that the lungs are potentially the most vulnerable part of the body during a rapid decompression. Whenever a rapid decompression is faster than the inherent capability of the lungs to decompress (vent), a transient positive pressure will temporarily build up in the lungs. If the escape of air from the lungs is blocked or seriously impeded during a sudden drop in the cabin pressure, it is possible for a dangerously high pressure to build up and to overdistend the lungs and thorax. No serious injuries have resulted from rapid decompressions with open airways, even while wearing an oxygen mask, but disastrous, or fatal, consequences can result if the pulmonary passages are blocked, such as forceful breath-holding with the lungs full of air. Under this condition, when none of the air in the lungs can escape during a decompression, the lungs and thorax becomes over-expanded by the excessively high intrapulmonic pressure, causing actual tearing and rupture of the lung tissues and capillaries. The trapped air is forced through the lungs into the thoracic cage, and air can be injected directly into the general circulation by way of the ruptured blood vessels, with massive air bubbles moving throughout the body and lodging in vital organs such as the heart and brain.
The movement of these air bubbles is similar to the air embolism that can occur in SCUBA diving and submarine escape when an individual ascends from underwater to the surface with breath-holding. Because of lung construction, momentary breath-holding, such as swallowing or yawning, will not cause sufficient pressure in the lungs to exceed their tensile strength.
- Decompression Sickness.
(also known as “Bends”)
Because of the rapid ascent to relatively high altitudes, the risk of decompression sickness is increased. Recognition and treatment of this entity remain the same as discussed elsewhere in this publication.
- 减压病。 （也称为“弯曲”）。由于迅速上升到相对较高的高度，减压病的风险增加了。 此实体的识别和处理与本出版物其他地方讨论的相同。
While the immediate mechanical effects of rapid decompression on occupants of a pressurized cabin will seldom be incapacitating, the menace of subsequent hypoxia becomes more formidable with increasing altitudes. The time of consciousness after loss of cabin pressure is reduced due to offgassing of oxygen from venous blood to the lungs. Hypoxia is the most immediate problem following a decompression.
- 缺氧。尽管快速减压对增压客舱乘员的直接机械作用几乎不会使人丧失工作能力，但随着海拔的升高，随后缺氧的威胁变得更加可怕。 失去机舱压力后的意识时间由于从静脉血中的氧气释放到肺部而减少。 缺氧是减压后最直接的问题。
- Physical Indications of a Rapid Decompression.
(a) Explosive Noise. When two different air masses make contact, there is an explosive noise. It is because of this explosive noise that some people use the term explosive decompression to describe a rapid decompression.
(b) Flying Debris. The rapid rush of air from an aircraft cabin on decompression has such force that items not secured to the aircraft structure will be extracted out of the ruptured hole in the pressurized compartment. Items such as maps, charts, flight logs, and magazines will be blow out. Dirt and dust will affect vision for several seconds.
(c) Fogging. Air at any temperature and pressure has the capability of holding just so much water vapor. Sudden changes in temperature or pressure, or both, change the amount of water vapor the air can hold. In a rapid decompression, temperature and pressure are reduced with a subsequent reduction in water vapor holding capacity. The water vapor that cannot be held by the air appears in the compartment as fog. This fog may dissipate rapidly, as in most fighters, or not so rapidly, as in larger aircraft.
(d) Temperature. Cabin temperature during flight is generally maintained at a comfortable level; however, the ambient temperature gets colder as the aircraft flies higher. If a decompression occurs, temperature will be reduced rapidly. Chilling and frostbite may occur if proper protective clothing is not worn or available.
如果宇宙飞船被刺破，减压的速度有多快？How Fast Will A Spaceship Decompress If It Gets Punctured?
The decompression time will depend on how big the hole is. For a fast estimate, you can assume that the air exiting through the hole will travel at the speed of sound. Since the atmosphere drops in pressure as it moves through the hole, the effective rate at which the atmosphere leaves is at about 60% of the speed of sound, or about 200 meters/second for room-temperaure air (see derivation by Higgins):
减压时间将取决于孔的大小。 为了快速估算，您可以假设通过孔排出的空气将以声速行进。 由于大气在通过孔时会降低压力，因此大气离开的有效速率约为声速的60％，对于室温空气而言约为200米/秒（请参见希金斯的推论）：
P = Po exp[-(A/V)t*(200m/s)]
This gives you a quick rule of thumb, the one-one-ten-hundred rule:
A one square-centimeter hole in a one cubic-meter volume will cause the pressure to drop by a factor of ten in roughly a hundred seconds.
(for quick approximations; only roughly accurate). This time scales up proportionately to the volume, and scales down proportionately to the size of the hole. So, for example, a three-thousand cubic meter volume will decompress from 1 atmosphere to .01 atmosphere through a ten square centimeter hole on a time scale of a sixty thousand seconds, or seventeen hours. (it’s actually 19 hours by a more accurate calculation).
这给了您一个快速的经验法则，即一百一十法则：一个1立方米的容积中的一个1平方厘米的孔将导致压力在大约一百秒钟内下降十分之一。（用于快速近似；仅大致准确）。 此时间与体积成比例地增大，而与孔的大小成比例地减小。 因此，例如，三千立方米的体积将通过一个10平方厘米的孔从1个大气压减压到0.01个大气压，时间尺度为6万秒或17个小时。 （通过更精确的计算，实际上是19个小时）。
The seminal paper on the subject is by Demetriades in 1954: “On the Decompression of a Punctured Pressurized Cabin in Vacuum Flight.”
The decompression rate can be derived for laminar viscous flow (that is, near atmospheric pressure) using Prandtl’s equation in the limit Po/P is zero, and assuming a simple aperture (a pipe of zero length). The gas flow conductance is Cvisc= 20 A liters/second (for A in square centimeters). As the pressure decreases the flow changes to molecular flow, and the depressurization rate decreases by about a factor of two. This is for air at 20 C; for the case of pure oxygen, the leak rate is about 10 percent slower.
可以使用 Prandtl方程的Po / P中的极限为0，得出层流粘性流（即接近大气压）的减压速率，并假定孔径为零（管长为零）。 气体流导为Cvisc = 20 A升/秒（对于A以平方厘米为单位）。 随着压力的降低，流体变为分子流，降压速度降低约两倍。 这是用于20°C的空气； 对于纯氧气来说，泄漏率要慢大约10％。
For reference, when the pressure drops to about 50% of atmospheric, the subject will be entering the region of “critical hypoxia”; when the pressure drops to about 15% of atmospheric, the remaining time of useful consciousness will have decreased to the 9-12 seconds characteristic of vacuum.
Professor Andrew J. Higgins of McGill University had written a more detailed answer to the question of how fast a spacecraft will decompress through a given size hole; which I have reprinted with his permission here.
麦吉尔大学的安德鲁·希金斯（Andrew J. Higgins）教授对航天器通过给定大小的孔减压有多快提出了更详细的答案。 经他的允许，我在这里转载了此内容。【本译文将放在最后】
- Charles E. Billings, “Barometric Pressure,” in Bioastronautics Data Book, Second edition, NASA SP-3006, edited by James F. Parker and Vita R. West, 1973.
- Arnauld E. Nicogossian, Carolyn L. Huntoon and Sam L. Pool, Space Physiology and Medicine, 2nd Edition, Lea and Febiger, Philadelphia 1989.
- Emanuel M. Roth, Rapid (Explosive) Decompression Emergencies in Pressure-Suited Subjects, NASA CR-1223, November 1968.
- Tam Czarnik, “Ebullism at 1 Million Feet: Surviving Rapid/Explosive Decompression” (unpublished review, 1999).
- Richard Harding, Survival in Space: Medical Problems of Manned Spaceflight, Chapter 3: “Pressure and density”, Routledge, New York 1989.
- Paul W. Fischer, Chapter 2: High-altitude Respiratory Physiology, in USAF Flight Surgeon’s Guide.
- U.S. Naval Hospital Flight surgeon Manual, 3rd Edition 1989 (see also 2nd edition, 1998).
- M. A. Bodin, “Brief Human Vacuum Exposure in Relation to Space Rescue Operations,” Journal of the British Interplanetary Society, Vol. 30, Feb. 1977, p.55
- Dacid J. Shayler, Disasters and Accidents in Manned Spaceflight, Springer-Praxis Books in Astronomy and Space Science, Chichester UK, 2000.
- Hypoxia information on Everest page
- S. T. Demetriades, “On the Decompression of a Punctured Pressurized Cabin in Vacuum Flight,” Jet Propulsion, January-February, 1954, pp. 35-36.
- M. Saad, Compressible Fluid Flow, 2nd Ed., Pearson Education, 1998.
- Andrew A. Pilmanis, and William J. Sears, “Physiological hazards of flight at high altitude,” The Lancet, Volume 362, Supplement 1, December 2003, Pages s16-s17, doi:10.1016/S0140-6736(03)15059-3. Cited in Tubious, Nov. 2007.
For more technical details, a paper discussing the medical effects of sudden vacuum exposure on a human, and discussing the emergency medical response to a decompression emergency, can be found in Dr. Tam Czarnik’s paper Ebullism at 1 Million Feet.
Geoffrey A. Landis is a scientist now working at the NASA Glenn Research Center. He has been on the science team of the Pathfinder mission to Mars and the Mars Exploration Rovers mission. His novel Mars Crossing is available from Tor Books, and his short-story collection Impact Parameter (and other quantum realities) from Golden Gryphon.
When the original version of this document was written, the author was not employed by NASA. This document is not a work of the U.S. government, and any opinions expressed in it are the views of the author, and not NASA or the U.S. government.
- Other pages discussing human survival in vacuum:
- Kubrik FAQ
- Some Science fiction stories and movies featuring unprotected humans in space.
- Mike Brotherton’s page ofRevised 27 June 2000
Revised 7 August. 2007
copyright 2000, 2007 by Geoffrey A. Landis
航天器需要多久减压How long will it take a spacecraft to decompress?
Is there a formula or rule-of-thumb for making a rough estimate of the rate of air loss in a space craft for a given size air leak?
The quick approximation is that the air will flow out of the hole at the speed of sound.我们近似空气从孔中流出的速度是声速。
For a more detailed calculation, Professor Andrew Higgins of McGill University gives the following answer:为了进行更详细的计算，麦吉尔大学的安德鲁·希金斯教授给出了以下答案：
The air will leak through the hole at sonic velocity (Mach one at constriction of the leak).空气将以音速从孔中泄漏出来（泄漏时收缩速度为1马赫）。
So, the mass flow rate is:因此，质量流量为：
dm/dt = rho V A (eqn. 1)
where rho is density, V is velocity, and A is the area of the hole. The velocity equals the speed of sound (sonic orifice), but this is slightly lower than the speed of sound in the spacecraft cabin due to expansion of gas as it flows through the hole. Density is lower also. So, it is more practical to express the mass flow rate in terms of stagnation conditions, i.e., the conditions in the cabin, which I will denote po and To:
其中rho是密度，V是速度，A是孔的面积。 速度等于声速（音速孔），但是由于气体流经孔时膨胀，因此它略低于航天器舱中的声速。 密度也较低。 因此，用停滞条件（即机舱中的条件）来表示质量流量是更实际的，我将用po和To表示：
dm/dt = A po Sqrt [(g/(R To)) (2/(g+1))^((g+1)/(g-1))) ] (eqn. 2)
here “g” is gamma, the ratio of specific heats (g = 1.4 for air) and R is the gas constant (R = 287 J/kg-K for air). You can find this derived in any compressible fluid dynamics textbook (or any fluids book with a chapter on compressible flow).
这里的“ g”是伽马，比热之比（空气= g = 1.4），R是气体常数（空气= R = 287 J / kg-K）。 您可以在任何可压缩流体动力学教科书（或任何包含有关可压缩流的章节的流体书）中找到它。
For air, this simplifies to:对于空气，这简化为：
dm/dt = 0.04042 A*po/Sqrt[To] (eqn. 3, “Fliegner’s formula”)
if you stick to MKS units (using Pascals for pressure and K for temperature), this will give you the mass flow rate of air leak in kg/s.如果您坚持使用MKS单位（使用帕斯卡作为压力，使用K作为温度），这将为您提供漏气的质量流量，单位为kg / s。
So far, we have assumed that the spacecraft remains at the same po, To. Of course, as the leak progresses, the pressure in the spacecraft begins to drop, and this affects the mass flow rate through the leak. Thus, dm/dt is no longer constant, and we have to integrate the above differential equation coupled to the decrease in po and To as the spacecraft leaks. You can find the details of this in Saad’s Compressible Fluid Flow (2nd Ed., pp. 103-106). The answer is that, to leak from an initial pressure of pi to a final pressure of pf, the time required is:
到目前为止，我们已经假设航天器保持在相同的位置To。 当然，随着泄漏的进行，航天器中的压力开始下降，这会影响通过泄漏的质量流率。 因此，dm / dt不再恒定，我们必须对上述微分方程进行积分，并随着航天器泄漏而降低po和To。 您可以在Saad的可压缩流体流（第二版，第103-106页）中找到详细信息。 答案是，要从pi的初始压力泄漏到pf的最终压力，所需的时间是：
t = 0.43 V/A [(pi/pf)^0.143 – 1]/(Sqrt[Ti]) (eqn. 4)
Again using MKS units, where V is the volume of the spacecraft (Ti = initial temperature), this gives you the time “t” to leak down to pf in seconds (assuming the cabin gas is air).
再次使用MKS单位，其中V是航天器的体积（Ti =初始温度），这使您有时间“ t”以秒为单位泄漏到pf（假设机舱气体是空气）。
This assumed that the blow-down was isentropic. In practice, any blow-down that will last tens of seconds to minutes, the process in the spacecraft is more likely to be isothermal: mass of spacecraft has huge thermal capacity compared to the (decreasing) mass of gas inside and will keep the gas warm as it expands. With the assumption of isothermal blow-down, the time required becomes:
这假定流失其他是等熵的。 实际上，任何可能持续数十秒到几分钟的排空，航天器中的过程更可能是等温的：与内部（不断减少）的气体质量相比，航天器的质量具有巨大的热容量，并将保持气体 膨胀时变暖。 假设等温流失气体，所需时间为：
t = 0.086 (V/A) Ln[pi/pf]/(Sqrt[T]) (eqn. 5)
where T is the (constant) spacecraft temperature.其中T是（恒定）航天器温度。
If the atmosphere inside the spacecraft starts out at room temperature, 293K, this simplifies to:如果航天器内部的大气始于室温293K，则可以简化为：
t = 0.005 (V/A) Ln[pi/pf] (eqn. 6)
A spacecraft with a volume V=10 m^3 is initially pressurized with air at 300 K. It has a 1 cm x 1 cm hole. V/A is (10/10^-4)= 10^5, so the time it takes the pressure to drop from 1 atm to 0.5 atm (pi/pf = 2) is (from equation 5):
最初用300 K的空气对体积为V = 10 m ^ 3的航天器加压。它有一个1 cm x 1 cm的孔。 V / A为（10/10 ^ -4）= 10 ^ 5，因此压力从1个大气压下降到0.5个大气压（pi / pf = 2）所花费的时间为（从公式5中得出）：
t = 0.086 *(10^5) * Ln/(Sqrt) = 344.2 s
or about six minutes。
Andrew J. Higgins
Mechanical Engineering Deptartment
Assistant Professor, Shock Wave Physics Group
McGill University, Montreal, Quebec CANADA
- Demetriades, S.T., “On the Decompression of a Punctured Pressurized Cabin in Vacuum Flight,” Jet Propulsion, January-February, 1954, pp. 35-36.
- Saad, M., Compressible Fluid Flow, 2nd Ed., Pearson Education, 1998.
This document is not a work of the U.S. government, and any opinions expressed in it are the views of the author, and not NASA or the U.S. government.
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Page by Geoffrey A. Landis, copyright 2003
【quora Mike Miller, Materials Engineer补充 】
Besides the obvious problem with lack of air, there are secondary factors:
- Sunlight. On the moon, sunlight peaks at a slightly greater intensity (1366 Watts per square meter) than Earth (peak of about 1100 Watts per square meter). A few seconds exposure to slightly brighter sunlight won’t fry or blind you.
- 阳光。 在月球上，日光的峰值强度（每平方米1366瓦）比地球（峰值约1100瓦）略高。 暴露在略微明亮的阳光下几秒钟不会使您感到被烤焦或致盲。
- Ultraviolet light. Without an ozone layer, you are exposed to a lot more UV light, but a few seconds shouldn’t add up to a serious sunburn.
- 紫外光线。 没有臭氧层，您会暴露于更多的紫外线下，但是几秒钟不应该造成严重的晒伤。
- Temperatures. Vacuum has no substance to transfer heat or cold; it is an excellent insulator. While exposed to vacuum for a few seconds you won’t lose heat as quickly as when your suit was circulating air past your face. You’re at risk if you touch the lunar surface or hardware with bare skin – those surfaces can get very hot and cold.
- 温度。 真空没有任何物质可以传递热量或寒冷。 它是一种极好的绝缘体。 当暴露在真空中几秒钟时，您失去的热量的速度非常慢，甚至没有宇航服往你脸上输送循环空气的速度快。 如果您裸露的皮肤接触月球表面或硬件会有危险，因为这些表面会变得非常冷和热。
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