Soulless space: Death in outer space. Man in space without a spacesuit

Many people often wonder “What would happen if...?” This article will tell you what happens to a person who finds himself in outer space without a protective suit. There are several erroneous versions, based not on real experimental data, but rather taken from science fiction films. The article will help you distinguish truth from fiction and understand cause-and-effect relationships.

The peculiarity of outer space is an almost complete vacuum. In a vacuum there is no atmospheric pressure; it is a highly discharged gas. But how does this affect a person? How much time is left for salvation and does it exist in principle?

There is an opinion that a person will instantly explode. It is a myth. Skin is a reliable protector. In addition, the skin perfectly helps maintain the internal pressure of the body at first, as a result of which the blood does not boil from a sudden change in pressure. The pressure will, of course, decrease, but gradually. Due to the decrease in pressure, ebullism will occur, expressed in the appearance of bubbles in the body fluids. In this case, the body can double in size.

But there are other liquids that do not have reliable protection, for example, saliva. It has been experimentally established that saliva can boil in outer space, since there is practically no pressure in a vacuum, and saliva has body temperature. But boiling will not happen instantly. In space, liquids evaporate quite slowly. In addition to saliva, other unprotected liquids from the mucous membranes and even the eyes will begin to evaporate.

Can a person freeze in space? Maybe, but this is a rather lengthy process. There is no thermal conductivity in space, it is neither hot nor cold there, so it will not be possible to transfer heat in this way. Heat is lost through radiation. A person constantly radiates heat, but in ordinary life it is almost unnoticeable. People are protected by clothing, warmed by the sun and the earth, the atmosphere insulates well, as a result of which the heat given off is returned. There are no insulators in space, so heat will begin to constantly escape.

In addition, due to the lack of insulators, there is a high probability of getting burns. There is incredibly strong ultraviolet radiation in space. Literally 10 seconds are enough to cause burns comparable to the consequences of a long stay on the beach.

In outer space, under no circumstances should you attempt to hold your breath. Such erroneous actions can lead to lung rupture. The lungs and airways are not designed to hold atmospheric pressure in a vacuum. Of course, holding your breath in space is quite difficult, since the air will begin to exert enormous pressure on the soft palate. The person will not be able to stand it and will instinctively exhale. But it's better not to even try.

How long can you live in space without a spacesuit?

The main danger of outer space for humans is complete absence oxygen. As was said, in space you cannot hold your breath while inhaling, so there will be no supply of oxygen in the body. But the circulatory system will continue to function as usual, as a result of which after 15 seconds even the most trained person will lose consciousness due to lack of oxygen in the brain. In addition, shortly before losing consciousness, a person will cease to navigate in space and see. But he is still alive and can be saved within two minutes. Other organs are not so sensitive to oxygen starvation. After two minutes the person will simply suffocate.

Provided that a person who finds himself in outer space is delivered to a safe place within the first minutes, he will survive and escape with ebullism, burns from ultraviolet radiation and temporary blindness. As you can see, the human body is extremely tenacious, because even in a vacuum, the time for rescue is calculated not in seconds, but in minutes.

1. A person won’t instantly turn into an ice cube?

Heating or cooling occurs either through contact with a cold external environment or through thermal radiation.

In a vacuum there is no medium, there is nothing to contact with. More precisely, in a vacuum there is a very rarefied gas, which, due to its rarefied state, gives a very weak effect. In a thermos, vacuum is used precisely to retain heat! Without having contact with a cold substance, the hero will not experience burning cold at all.

2. It will take a long time to freeze

As for radiation, then human body, once in a vacuum, it will gradually give off heat by radiation. In a thermos, the walls of the flask are made mirror to retain radiation. This process is quite slow. Even if the astronaut is not wearing a spacesuit, but he has clothes, they will help keep him warm.

3. Get fried?

But you can get a tan. If this happens in space not far from a star, then you can get sunburn on bare areas of skin - as from excessive tanning on the beach. If this happens somewhere in Earth's orbit, then the effect will be stronger than on the beach, since there is no atmosphere there that protects from hard ultraviolet radiation. 10 seconds is enough to cause a burn. But still, this is also not a burning heat, and besides, clothing should also protect. And if we're talking about about a hole in a spacesuit or a crack in a helmet, then you don’t have to worry about this topic.

4. Boiling saliva

The boiling point of liquids depends on pressure. The lower the pressure, the lower the boiling point. Therefore, in a vacuum, liquids will evaporate. This was discovered in experiments - not immediately, but saliva boils, since the pressure is almost zero, and the temperature of the tongue is 36 C. Apparently, the same thing will happen with all mucous membranes (in the eyes, in the lungs) - they will dry out, if only from the body will not receive new mucus.

By the way, if you take not just a liquid film, but a large volume of water, then, probably, there will be an effect like “dry ice”: evaporation occurs on the outside, heat is quickly lost with evaporation, due to this the inside freezes. It can be assumed that a ball of water in space will partially evaporate, but otherwise turn into a piece of ice.

5. Will your blood boil?

Elastic skin, blood vessels, and the heart will create enough pressure so that nothing boils.

6. The champagne effect is also not expected.

Scuba divers have such a nuisance as decompression sickness. The reason is what happens to the bottle of champagne.

In addition to boiling, there is also the dissolution of gases in the blood. When the pressure drops, the gases turn into bubbles. Dissolved in champagne carbon dioxide, and for scuba divers - nitrogen.

But this effect occurs at large pressure differences - at least several atmospheres. And when you get into a vacuum, the difference is only one atmosphere. The article says nothing on this topic, does not describe any symptoms - apparently, this is not enough.

7. Will the air burst from the inside?

It is assumed that the victim will exhale it - and therefore will not tear it apart. What if he doesn’t breathe out? Let's assess the threat. Let the pressure in the spacesuit be maintained at 1 atm. This is 10 kg per square centimeter. If a person tries to hold his breath, the soft palate gets in the way of the air. If there is an area of ​​at least 2x2 cm, then the load will be 40 kg. It is unlikely that the soft palate will withstand it - the person will exhale on his own, like a deflated balloon.

8. Will the person suffocate?

This is the main and real threat. There is nothing to breathe. How long can a person survive without air? Trained divers - a few minutes, an untrained person - no more than a minute.

But! This is during inhalation, when the lungs are full of air with oxygen remaining. And there, remember, you have to exhale. How long can a simple person hold out while exhaling? 30 seconds. But! When you exhale, the lungs do not “shrink” completely; a little oxygen remains. In space, apparently, there will be even less oxygen left (as much as can be retained). The specific time after which a person will lose consciousness from suffocation is known - about 14 seconds.

26.04.2012 00:52

1. A person won’t instantly turn into an ice cube?

Heating or cooling occurs either through contact with a cold external environment or through thermal radiation.
In a vacuum there is no medium, there is nothing to contact with. More precisely, in a vacuum there is a very rarefied gas, which, due to its rarefied state, gives a very weak effect. In a thermos, vacuum is used precisely to retain heat! Without having contact with a cold substance, the hero will not experience burning cold at all.

2. It will take a long time to freeze

As for radiation, the human body, once in a vacuum, will gradually give off heat by radiation. In a thermos, the walls of the flask are made mirror to retain radiation. This process is quite slow. Even if the astronaut is not wearing a spacesuit, but he has clothes, they will help keep him warm.

3. Get fried?

But you can get a tan. If this happens in space near a star, then you can get a sunburn on exposed skin - like from excessive tanning on the beach. If this happens somewhere in Earth's orbit, then the effect will be stronger than on the beach, since there is no atmosphere there that protects from hard ultraviolet radiation. 10 seconds is enough to cause a burn. But still, this is also not a burning heat, and besides, clothing should also protect. And if we are talking about a hole in a spacesuit or a crack in a helmet, then you don’t have to worry about this topic.

4. Boiling saliva

The boiling point of liquids depends on pressure. The lower the pressure, the lower the boiling point. Therefore, in a vacuum, liquids will evaporate. This was discovered in experiments - not immediately, but saliva boils, since the pressure is almost zero, and the temperature of the tongue is 36 C. Apparently, the same thing will happen with all mucous membranes (in the eyes, in the lungs) - they will dry out, if only from the body will not receive new mucus.
By the way, if you take not just a liquid film, but a large volume of water, then, probably, there will be an effect like “dry ice”: evaporation occurs on the outside, heat is quickly lost with evaporation, due to this the inside freezes. It can be assumed that a ball of water in space will partially evaporate, but otherwise turn into a piece of ice.

5. Will your blood boil?

Elastic skin, blood vessels, and the heart will create enough pressure so that nothing boils.

6. The champagne effect is also not expected.

Scuba divers have such a nuisance as decompression sickness. The reason is what happens to the bottle of champagne.
In addition to boiling, there is also the dissolution of gases in the blood. When the pressure drops, the gases turn into bubbles. Champagne releases dissolved carbon dioxide, while scuba divers release nitrogen.
But this effect occurs at large pressure differences - at least several atmospheres. And when you get into a vacuum, the difference is only one atmosphere. The article says nothing on this topic, does not describe any symptoms - apparently this is not enough.

7. Will the air burst from the inside?

It is assumed that the victim will exhale it and therefore will not tear it. What if he doesn’t breathe out? Let's assess the threat. Let the pressure in the spacesuit be maintained at 1 atm. This is 10 kg per square centimeter. If a person tries to hold his breath, the soft palate gets in the way of the air. If there is an area of ​​at least 2x2 cm, then the load will be 40 kg. It is unlikely that the soft palate will withstand it - the person will exhale on his own, like a deflated balloon.

8. Will the person suffocate?

This is the main and real threat. There is nothing to breathe. How long can a person survive without air? Trained divers - a few minutes, an untrained person - no more than a minute.
But! This is during inhalation, when the lungs are full of air with oxygen remaining. And there, remember, you have to exhale. How long can a simple person hold out while exhaling? 30 seconds. But! When you exhale, the lungs do not “shrink” completely; a little oxygen remains. In space, apparently, there will be even less oxygen left (as much as can be retained). The specific time after which a person will lose consciousness from suffocation is known - about 14 seconds.

1. During the first 10-15 seconds, you remain conscious and feel the moisture evaporating from your tongue.
The same thing happens with the entire surface of the body - as with heavy sweating.
Therefore, in an airless space a person feels icy cold.

2. Attacks of nausea and vomiting are possible, as gases from the stomach and intestines are rapidly pushed out.
(Note: before going into outer space, it is better to refrain from soda and hot sauces).

3. If the Eustachian tubes in the ears are blocked by earwax or something else,
then there may be problems with the inner ear, if not, everything is in order.

4. The heart rate increases sharply, then gradually drops, as does blood pressure.
Venous pressure rises steadily as gas bubbles form in the body.

5. The body may swell to twice its normal size, the skin becomes tight,
unless, of course, you are wearing a tight elastic suit.

6. According to the Compendium of Space Biology,
Precisely fitted elastic clothing can completely prevent the formation of gas bubbles
when the pressure drops to 15 torr (millimeters mercury).
For comparison, normal atmospheric pressure is 760 torr, and the pressure on the surface of the Moon is about 10–11 torr.
Blood boils at 47 torr. The body swells due to the fact that the liquid in the soft tissues turns into a gaseous state.
However, the skin is strong enough to withstand this pressure.
So, you won't be torn apart, you'll just inflate like a balloon.

7. As the body expels steam through the nose and mouth and the body's fluid content decreases,
you feel increasingly cold. The mouth and tongue become icy.

8. If with all this you also find yourself under straight lines sun rays(without special protective equipment),
you will get a severe sunburn.

9. Due to lack of oxygen, the skin takes on a bluish-purple hue, known as cyanosis.

10. The brain and heart remain relatively in order for about 90 seconds.
When blood pressure drops to 47 torr, the blood begins to boil and the heart gradually stops.
After this, nothing will help you.

11. But if the pressure is restored in time, the body will gradually return to normal.
However, for some time you will lose your vision and ability to move. But over time, both functions will be restored.
In addition, you will not be able to taste the food for several days.

12. On the other hand, if you hold your breath or try to prevent free
air escape during sudden decompression in some other way,
then “an increase in intrapulmonary pressure will lead to such a strong expansion
chest, which can cause ruptures in the lungs and destruction of capillaries.
The trapped air is forced out of the lungs into the chest and enters through damaged blood vessels.
directly into the general bloodstream. And through the bloodstream, air bubbles spread throughout the body
and can easily reach vital organs such as the heart and brain.”
Something similar can happen during decompression on board an airplane flying at high altitude.
If this happens, remember that you should never hold your breath.

Many have probably seen science fiction films scenes with a person going into outer space without a spacesuit (for example, “Total Recall”, “Inferno”, “A Space Odyssey”, etc.).

Moreover, in different films these exits ended in different ways - a person could survive, die from the cold, suffocate, burn from sunlight etc. The issue was also raised in many pseudo-scientific forums. Let's try to answer the question of what will happen to a person when going into outer space without a spacesuit from a scientific point of view.
Most of the answers to the questions can be found here (in English), but I will try to outline their essence here. In short, these answers sound like this:

1. A person can survive if he is returned from outer space to normal atmosphere within 90 seconds.

2. The person will not explode.

3. The person will be conscious and will be able to perform active actions for about 5-10 seconds.

4. If a person is not saved, then the primary cause of his death will be lack of oxygen (i.e. he will suffocate).

Now let's look at these questions in more detail.

Can man survive?

The most complete answer to this question can be found in the chapter on atmospheric pressure in the Handbook of Space Biomedicine, Second Edition, NASA SP-3006. This chapter describes studies of the effects of vacuum decompression on animals. On page 5 (after general discussion low pressures and ebullism (ebullism, the formation of bubbles in body fluids with a sharp decrease in external pressure)), the author describes the expected results due to exposure to vacuum:

"Some degree of consciousness will probably be maintained for 9 to 11 seconds (see Chapter 2 under Hypoxia). Soon after this paralysis sets in, followed by general convulsions and then paralysis again. At the same time, rapid formation of water vapor occurs in the soft tissues and somewhat slower - in the venous blood the formation of water vapor will be noted as swelling of the body, perhaps twice as much as before. normal volumes, if not prevented by a tight suit. (It has been experimentally found that well-fitted elastic clothing can completely prevent ebulism when the pressure is reduced to 15 mmHg.) Heart rate may increase initially, but then quickly decrease. Arterial blood pressure will also drop within 30 to 60 seconds, while venous pressure rises due to the expansion of the venous system by gas and steam. Venous pressure will equal or exceed arterial pressure within one minute. There will be virtually no effective blood circulation. After the initial breakthrough of gas from the lungs during decompression, gas and water vapor will continue to flow out through the airways. This continuous evaporation of water will cool the mouth and nose to near freezing temperature; the rest of the body will also cool, but more slowly.

"Cook and Bancroft (1966) reported occasional cases of death of animals due to ventricular fibrillation within the first minute of exposure to near-vacuum conditions. However, animals generally survived if recompression (restoration of pressure) occurred within approximately 90 seconds. .. After cardiac arrest, death was inevitable, despite attempts at resuscitation....

[After recompression] "Breathing usually began spontaneously... Neurological problems, including blindness and other visual defects, were quite common (see problems due to gas boiling), but usually disappeared quite quickly.

"It is very unlikely that a person suddenly subjected to a vacuum would have more than 5 to 10 seconds to escape. But if help arrives, despite severe external and internal damage, it is reasonable to assume that recompression to a tolerable pressure (200 mmHg pillar) within 60 to 90 seconds could lead to survival, and possibly to fairly rapid recovery."

Thus, a person is more likely to survive than to die if he can be rescued from open space and returned to a room with atmospheric (or at least more than 200 mm Hg) pressure within 60-90 seconds. It is worth noting that this only applies to the effect of explosive decompression. If a person makes the mistake of trying to breathe in a vacuum, it will lead to decompression sickness with much more serious health consequences. Also, an attempt to retain air in the lungs can lead to their rupture and almost inevitable death. That is why such decompression is called “explosive”.

Will the person be conscious?

The Directory of Space Biomedicine answers this question:

"Some degree of consciousness will probably be retained for 9 to 11 seconds.... It is very unlikely that a person suddenly subjected to a vacuum would have more than 5 to 10 seconds to help himself."

More information about how long a person could remain conscious can be gleaned from aviation medicine. Aviation medicine determines "useful consciousness time," which is how long after decompression pilots will be awake and able to take active measures to save their life. Above 50,000 feet (15 km), the time of useful consciousness is 9 to 12 seconds, as specified by the FAA in Table 1-1 in Advisory Circular 61-107 (shorter time for an actively moving person; longer time for a person sitting quietly). USAF Flight Surgeon Guide Image 2-3 shows 12 seconds of useful consciousness above 60,000 feet (18 km); Presumably the longer time listed is based on the assumption that Air Force pilots are well prepared physically for high altitude flights, and will be able to use their time effectively even when partially unconscious from hypoxia. Linda Pendleton adds to this: "Explosive or rapid decompression will cut the time of useful consciousness in half due to damaging factor caused by the adrenaline-accelerated rate at which the body burns oxygen." Advisory Circular 61-107 says that the time of useful consciousness above 50,000 feet will drop from 9-12 seconds to 5 seconds in the event of rapid decompression (presumably due to " damaging" factor described by Pendleton).

A little more interesting book, Richard Harding's Survival in Space, echoes this conclusion:

"At altitudes greater than 45,000 feet (13,716 m), unconsciousness develops in fifteen to twenty seconds, with death after about four minutes."

"monkeys and dogs have been successfully brought back to life after being subjected to vacuum for up to two minutes..."

Will a person's blood boil?

The blood inside the body is under higher pressure than in external environment. Normal blood pressure is 75/120. "75" means that between heartbeats, the blood is at a pressure of 75 Torr (approximately 100 mbar) above external pressure. If the external pressure drops to zero, at a blood pressure of 75 Torr the boiling point of water is 46°C (115°F). This is significantly higher than a body temperature of 37°C (98.6°F). The blood will not boil because the elastic pressure of the walls of the blood vessels will keep the pressure high enough that the body temperature will be below the boiling point - at least until the heart stops beating. (To be precise, blood pressure varies depending on where in the body it is measured, so the above statement should be understood as a generalization. However, due to the occurrence of small pockets of steam, the pressure there increases. In places where blood pressure is lower , the vapor pressure will increase until equilibrium is reached, resulting in the same total pressure.)

Will the body freeze?

Several recent Hollywood films have shown how people, caught in a vacuum, are instantly frozen. In one of them, a scientist character notes that the temperature is “minus 273 degrees” - that is, equal to absolute zero.

But in a practical sense, there is no temperature in space - you cannot measure the temperature of a vacuum, because there is none there. There are not enough residual molecules of a substance in a vacuum for the temperature effect to manifest itself. Space is neither “cold” nor “hot”, it is “nothing”.

But space is a very good insulator. (Basically, the vacuum is what is between the walls of the thermos). Astronauts usually experience more problems with overheating than with maintaining the required temperature.

If you find yourself in space without a spacesuit, your skin will feel slightly cool due to the fact that water will evaporate from the surface of the skin. But you won't freeze solid!

Has anyone survived the effects of the vacuum?

The human case was described by Roth in a NASA technical report " Emergency situations“Rapid (Explosive) Decompression Emergencies in Pressure-Suited Subjects.” The report focuses on decompression rather than the actual effects of vacuum, but there is still a lot in the document useful information, including results from human decompression cases.

There have been several recorded cases of people staying in a vacuum without visible consequences. In 1966, a NASA technician in Houston was decompressed into the vacuum of space in an accident during a space suit test. This incident is mentioned by Roth. The technician lost consciousness within 12–15 seconds. When the pressure was restored after about 30 seconds, he regained consciousness, without obvious damage to the body. Some details can be found here.

Before concluding that space exposure is harmless, it should be noted that in the same report, Roth provides an autopsy report on a victim of explosive decompression: “Immediately after rapid decompression, he was noted to have developed a mild cough. Shortly thereafter, it was observed that he began to lose consciousness; the doctors on duty described the patient as becoming completely lethargic, inactive, and unresponsive for the 2–3 minutes [required to restore atmospheric pressure in the chamber].

The artificial respiration procedure was immediately started... The patient inhaled spontaneously, and when atmospheric pressure was reached, he took several breaths. They were extremely irregular, numbering two or three...

The [autopsy] report states the following: Basic pathological changes, as stated above, are associated with suffocation. It is believed that the main cause of death in this case may be acute cardiovascular and respiratory failure, the secondary cause is bilateral pneumothorax..."

Many other deaths due to decompression have been reported in the aviation literature, including one space incident due to decompression of the Soyuz 11 landing capsule in 1971. An analysis of this accident can be found in D.J. Shayler “Disasters and Accidents in Manned Spaceflight.”

As for the effect of vacuum on parts of the body, there are significantly fewer materials here. In 1960, during a high-altitude balloon parachute jump, a vacuum exposure incident occurred when Joe Kittinger, Jr. lost pressure in his right glove while ascending to 103,000 feet (19.5 miles). or 31.4 km) in an unpressurized gondola. Despite the loss of pressure, he continued the flight, although severe pain appeared in his arm and it lost mobility. After he returned to earth, his arm returned to normal.

Kittinger wrote in National Geographic (November 1960): “At 43,000 feet (13.1 km) I realized what was wrong. My right hand behaves incorrectly. I checked the pressure in the glove; there was no air bubble in it. The prospect of putting my hand under almost complete vacuum at the peak of the climb caused me some anxiety. From my previous experience, I knew that the arm would swell, blood circulation would almost stop, and severe pain would arise... I decided to continue the climb, and did not inform ground control about my difficulties.”

At 103,000 feet (31.4 km), he writes: “The circulation had almost stopped in my depressurized right arm, it became stiff and painful.”

And during boarding: “Dick looks at my swollen hand with concern. Three hours later, the swelling subsided without leaving any consequences.”

Kittinger's decompression case is discussed in Shayler's book, Disasters and Accidents During Manned Operations. space flights"(Disasters and Accidents in Manned Spaceflight):
[When Kittinger reached the peak of his climb] “his right arm was twice as big as normal size... He tried to turn off some equipment before landing, but was unable to because his right arm was causing terrible pain. He landed at 13:45. leaving Excelsior. Three hours after landing, his swollen hand and the circulation in it returned to normal.”

See also Leonard Gordon's article in Aviation Week, February 13, 1996. (Leonard Gordon, Aviation Week, February 13th 1996.)

Finally, in the sci.space conference, Gregory Bennett describes a real space incident: “We had one case of a puncture in a spacesuit during shuttle flights.” On STS-37, during one of my flight experiments, one of the stiffening ribs on the palm of the glove of one of the astronauts became loose in its fastening, shifted inside the glove and punctured it between the thumb and index finger. There was no explosive decompression, just a small hole 1/8 inch long (about 3 mm), but it was quite interesting since it was the first injury ever to occur due to damage to the suit. Surprisingly, the astronaut didn’t even know there was a puncture! He was so pumped up with adrenaline that it was only upon returning from the flight that he noticed a painful red mark on his arm. He thought the glove was just rubbing his hand and didn't worry about it... What happened: when the metal plate pierced the glove, the skin of the astronaut's hand partially sealed the hole. He bled into space, and immediately his clotted blood sealed the hole so that it remained inside the hole.”

Explosive decompression

In “The USAF Flight Surgeon's Guide,” Fisher lists the following consequences caused by the expansion of gases during decompression.

1. Gastrointestinal tract during rapid decompression
One of the most likely problems during rapid decompression is the expansion of gases in the body cavities. Abdominal upsets during rapid decompression are generally not much different from those that may occur during slow decompression. However, abdominal distress can have significant consequences. Due to the expanding gas in the stomach, the diaphragm moves upward, which can impede breathing movements. Abdominal disorders can also affect the vagus nerve, which can cause cardiovascular depression and, in the most severe cases, cause decreased blood pressure, loss of consciousness and shock. Typically, intra-abdominal distress after rapid decompression disappears as soon as excess gas is released.

2. Lungs during rapid decompression
Because the lungs typically contain a relatively large volume of air and because of the delicate structure of lung tissue and the presence of a complex alveolar system for air passage, the lungs are considered to be potentially the most vulnerable part of the body during rapid decompression. During rapid decompression overpressure increases faster than the lungs can compensate for it, as a result of which the pressure in the lungs will increase. If the air exit paths from the lungs are blocked completely or partially, there is a risk of high pressure, which can cause the lungs and chest to become overly inflated.

If the airway is open, no serious injury will occur as a result of rapid decompression, even if an oxygen mask is worn, but the consequences will be catastrophic, even fatal outcome, if the pulmonary passages are blocked - for example, if the pilot tries to hold his breath with his lungs full of air. In this case, the air in the lungs cannot escape during decompression, so the lungs and chest expand greatly due to excessively high intrapulmonary pressure, which leads to rupture of lung tissue and capillaries. The air inside, breaking the lungs, penetrates the chest and enters the circulatory system through breaks in the walls of blood vessels. Air bubbles in large quantities are carried throughout the body and end up in vital organs such as the heart and brain.

The movement of these air bubbles is similar to the air embolism that occurs in scuba divers and during emergency rescue from a submarine, when a person rises from the depths while holding his breath. The human lungs are designed in such a way that short periods of breathing (such as swallowing or yawning) do not create pressure in the lungs that exceeds their tensile strength.

3. Decompression sickness (caisson sickness)
Given the speed of ascent to relatively high altitudes, the likelihood of decompression sickness increases.

4. Hypoxia (oxygen starvation)
After depressurization of the cabin, those in it are immediately subjected to the mechanical effects of rapid decompression, and the threat of subsequent hypoxia becomes more serious with increasing altitude. The time to loss of consciousness after a drop in cabin pressure is reduced due to the fact that oxygen passes from the venous blood into the lungs. Hypoxia is the biggest problem after decompression.

Observable signs of rapid decompression
...
a) Sharp, “explosive” noise. When two different air masses there is a loud noise. It is because of this explosive noise that the term "explosive decompression" is often used to describe rapid decompression.

b) Flying debris. The rapid flow of air from the aircraft cabin during decompression is so great that loose objects in the cabin will be pulled into the resulting hole by the force of pressure. For example, maps, charts, flight logs and other similar items will fly out through the hole. Dirt and dust reduce visibility for a few seconds.

c) Fog. Air at any temperature and pressure has the ability to hold a certain amount of water vapor. Sudden changes in temperature or pressure change the air's ability to hold water vapor. With rapid decompression, temperature and pressure decrease, and the amount of water vapor retained by the air also decreases. Water vapor that is not retained by the air becomes visible as fog. This fog dissipates quickly (for example, in the cockpit of a fighter jet). If it is the cabin of a larger aircraft, the fog will dissipate more slowly.

d) Temperature. Typically, during a flight, the temperature in the cabin is maintained at a comfortable level, but as you ascend, the temperature outside decreases. In the event of decompression, the temperature in the cabin quickly drops. If the pilot does not have the appropriate protective suit, hypothermia and frostbite can occur.

d) Pressure.

What determines the speed of decompression?

Decompression time depends on the size of the hole. For speed estimation, it can be assumed that the air exits through the hole at the speed of sound. Since the pressure drops as air flows through the hole, the speed of the air flow is approximately 60% of the speed of sound, or about 200 meters per second at room temperature air (see Higgins equation):

P = Po exp[-(A/V)t*(200m/s)]

This allows us to derive a very simple (and very approximate) rule: in a volume of one cubic meter, a hole with an area of ​​one square centimeter will cause a tenfold decrease in pressure in about a hundred seconds.

This is a very rough estimate. Time is directly proportional to volume and inversely proportional to the size of the hole. For example, in a volume of three thousand cubic meters through a hole of ten square centimeters, the pressure will decrease from 1 atmosphere to 0.01 atmosphere in 60 thousand seconds, or seventeen hours (with a more accurate calculation, we will find that this will be 19 hours).

The definitive work on this issue is Demetriades (1954) “On the Decompression of a Punctured Pressurized Cabin in Vacuum Flight.”

For reference. When the pressure drops to about 50% atmospheric man finds itself in the region of "critical hypoxia", and when the pressure drops to approximately 15% of atmospheric pressure, the remaining time of useful consciousness is reduced to 9-12 seconds, depending on the properties of the vacuum.

The effects of radiation on humans in outer space

Since habitable space stations fly below the Earth's radiation belts, then the impact cosmic radiation per person will be insignificant, whether he is in a spacesuit or without it. In all solar system There is only one area in which a person can die from radiation faster than from suffocation - this is the region of Jupiter’s radiation belts (several of its satellites are located in it), but a spacesuit will also not protect a person from radiation.

Thus, we can summarize: the primary cause of death for a person entering outer space will be suffocation. What to do if you suddenly find yourself in a vacuum without a spacesuit? The first thing you need to do is exhale so that your lungs don't burst. Next, you have 5-10 seconds to take some active action to save your life. If this time is not enough, you can only hope that help will arrive within 90 seconds.