Being exposed to the vacuum of space without protection is extremely dangerous for human beings. The lack of oxygen and pressure will rapidly lead to death in just minutes. However, the exact effects on the human body can vary depending on the circumstances and duration of exposure.
Why you need a spacesuit in space
A spacesuit is necessary to survive in the harsh environment of space. Here are some of the main reasons why:
- Lack of air pressure – Air pressure on Earth at sea level is about 14.7 psi (pounds per square inch). In space it is almost 0 psi. The lack of pressure causes gases to expand, which can damage lungs and tissue.
- Lack of oxygen – Without an oxygen supply, you will rapidly suffocate in space. There is no breathable oxygen in space.
- Extreme temperatures – In direct sunlight in space, temperatures can swing from 250°F down to -250°F when in shadow. A spacesuit protects you from these extremes.
- Radiation exposure – Spacesuits are designed to shield from solar and cosmic radiation, which can damage cells and DNA.
- Micrometeoroids – Tiny meteors and debris can strike at very high speeds in space. A helmet and suit protect you from penetration injuries.
In summary, you would rapidly die from lack of air, pressure, heat or radiation exposure if unprotected by a spacesuit in space. You need a self-contained source of oxygen, pressure and temperature regulation, and radiation shielding to survive.
Immediate effects of exposure
As soon as you are exposed to the vacuum of space without a spacesuit, a number of life threatening effects will immediately begin to take place.
- Lack of oxygen – You will be unable to breathe and your oxygen supply will be instantly cut off. Consciousness may be lost after 15 seconds.
- Decompression – Air in lungs will rapidly decompress and potentially rupture. Pressure differences can cause tissue damage.
- Ebullism – The reduction of pressure can allow dissolved gases in blood and tissues to bubble and expand. This can block circulation and lead to edema.
- Temperature extremes – Body will rapidly radiate heat without insulation and skin/tissues can freeze. In sunlight, body can overheat.
- Dehydration – Any exposed moisture on skin, eyes, mouth or lungs will rapidly evaporate away.
These initial effects alone can kill in less than 2 minutes in the vacuum of space. But other longer term effects will also begin to take their toll on the body.
Longer term effects
If you were able to survive the initial effects of exposure, other long term impacts on the body will accumulate over time. These include:
- Asphyxiation – Lack of oxygen will lead to brain death in just a few minutes.
- Hypoxia – Inability of tissue to absorb oxygen can cause long term damage and cell death.
- Anemia – Without oxygen, red blood cells can rupture and cause bleeding.
- Radiation – Increased risk of cancer, DNA damage, and cell mutation from cosmic radiation.
- Freezing temperatures – Potential crystallization of water in cells and tissue damage from freezing.
The longer the exposure, the more severe these effects will become. After about 2 minutes, a human would certainly be dead from asphyxiation and ebullism. But more exposure can allow damage like cell death, tissue loss, and radiation poisoning to accumulate.
What it feels like to be exposed
Based on limited experiences by astronauts, we have some idea of what it might feel like in those initial moments after exposure:
- Difficulty breathing – The lack of air pressure makes it feel like you are suffocating.
- Swelling skin/tissues – Gases under the skin can inflate tissue and cause swelling.
- Bubbling sensation – Liquids on tongue or eyes begin to boil away.
- Discomfort from extremes – Body alternates between freezing and burning sensations.
- Disorientation – Lack of oxygen quickly leads to loss of cognitive function and consciousness.
The overall experience has been described by some astronauts as painful and distressing. But loss of oxygen will lead to merciful unconsciousness in just 15-30 seconds, even if death may take a bit longer.
How long you can survive
Given the brutal environment, how long could someone in theory survive if suddenly exposed to the vacuum of space without a spacesuit?
| Time | Effects |
|---|---|
| Instantly | Lack of oxygen and air pressure, exposure to temperature extremes and radiation. |
| 15 seconds | Loss of consciousness as oxygen runs out. |
| 30-60 seconds | Potential development of edema in tissues as gases expand. Skin can balloon. |
| 1-2 minutes | Asphyxiation and circulatory collapse. Loss of bodily functions. |
| 5-10 minutes | Freezing temperatures start crystallizing water and damaging cells. |
| 15-20 minutes | Radiation exposure leads to DNA damage, mutation, and higher cancer risk. |
Given the above, it’s reasonable to assume someone exposed could remain conscious for up to 15 seconds and alive for 1-2 minutes maximum before being deceased. But certain levels of damage and harm will continue to occur for some time.
Animal experiments in space
Some data on the effects of exposure comes from animal experiments conducted in space environments:
- Dogs exposed to near vacuum in the 1960s were able to tolerate up to 90 seconds.
- Chimpanzees in NASA tests survived up to 3.5 minutes in vacuum.
- Spider monkeys undergoing rapid decompression showed paralysis after 15 seconds.
The record for the longest animal survival appears to be a pair of Russian dogs named Otvazhnaya and Snezhinka placed in vacuum for 5 minutes and 11 seconds. They suffered cardiac arrest but were successfully resuscitated. This demonstrates that short term exposure does not necessarily mean certain death if treated quickly.
Key experiments on animals in space vacuum
| Animal | Exposure time | Effects |
|---|---|---|
| Spider monkey | 15 seconds | Loss of motor functions |
| Chimpanzee | 3.5 minutes | Survived with no issues |
| Dog | 90 seconds | Survived but with impairment |
| Dog (Otvazhnaya) | 5 minutes | Survived after resuscitation |
Animal testing has provided important data on survivability timeframes and physiological responses that are difficult to obtain from human testing.
Accidental human exposure
There have also been some accidental cases of humans exposed to space vacuum providing insight on effects:
- In 1965 a NASA technician was exposed for 14 seconds in a space chamber accident. He lost consciousness but survived.
- In a Soviet launch accident in 1971, three technicians died after exposure when a valve opened by accident. Exact exposure times were unknown.
- Astronaut Gene Cernan experienced a spacesuit failure in Gemini 9 in 1966 that exposed his hand for just over a minute. His hand swelled but he was otherwise unharmed.
The technician in the NASA case reportedly described the experience as “feeling every little air bubble in his body moving around very rapidly” before blacking out. These stories illustrate that very brief exposure under 20 seconds may be survivable. But any duration over a minute is likely to lead to permanent harm or death.
Accidental exposure cases
| Person | Amount of exposure | Result |
|---|---|---|
| NASA technician | 14 seconds | Unconscious, recovered |
| Soviet technicians | Unknown | Died |
| Gene Cernan | 1+ minute | Injured hand, survived |
Self-experiments in vacuum
A few daring scientists over the years have intentionally exposed themselves briefly to vacuum conditions to determine the effects on humans. Here are a couple notable cases:
- In 1962 at Wright-Patterson Air Force Base, researcher Jim LeBlanc voluntarily placed his head in a vacuum chamber for 5 minutes. He reported the sensation of water boiling off his tongue before quickly losing consciousness.
- Physicist E.H. Wood experienced 30 second vacuum exposure during WWII British aviation experiments. He recalls his last memories were feeling tightness in his ears before passing out.
These self-experiments provided insight on the rapid onset of unconsciousness due to lack of oxygen as well as the sensation of bodily fluids boiling away. They demonstrated brief exposures under 30 seconds can potentially be survived if the person is quickly repressurized.
Key self-experiments in space vacuum
| Person | Exposure time | Effects reported |
|---|---|---|
| Jim LeBlanc | 5 minutes | Unconsciousness, boiling saliva |
| E.H. Wood | 30 seconds | Tight ears, passed out |
Hazards if helmet ruptures in space
If an astronaut’s helmet were to crack or rupture in space, it would immediately expose their head to the vacuum environment with potentially catastrophic results:
- Asphyxiation – Any remaining air would be sucked out leaving no oxygen to breathe.
- Ebullism – Saliva and moisture on facial tissues would boil away.
- Swelling – Gases trapped under the skin could cause the head and neck to swell grotesquely.
- Frozen tissues – Exposure of moist areas like eyes and mouth could lead to freeze damage.
- Brain damage – Lack of oxygen would lead to rapid loss of consciousness and potential brain injury.
Sudden decompression of a helmet or visor in this manner would almost certainly be fatal given the sensitive nature of the exposure. Areas with higher moisture content like eyes or areas with trapped gases could risk severe damage or rupture. Death could occur in less than 30 seconds and resuscitation would need to be nearly immediate to prevent brain death.
Potential effects from ruptured helmet
| Effect | Consequence |
|---|---|
| Lack of oxygen | Rapid asphyxiation and loss of consciousness |
| Ebullism | Facial swelling from tissue gas bubbles |
| Freezing | Potential tissue damage to facial epithelia |
| Swelling | Ballooning of head and neck tissues |
Long term impacts for survivors
In the extremely unlikely event someone was able to survive brief exposure to vacuum in space, there could still be serious long term repercussions:
- Brain damage – Lack of oxygen can cause permanent brain injury and impairment of cognitive function.
- Tissue death – Swelling and rupture of skin or internal organs may require removal of damaged tissue.
- Radiation cancers – Increased lifetime risk of cancer due to greater radiation exposure.
- Embolisms – Gas bubble blockages formed in blood vessels during decompression can rupture and travel to the heart or brain.
- Vision problems – Eyes can be damaged from swelling or from vitreous fluid boiling away.
Surviving the exposure event itself is only the first step. The deleterious effects on the human body still need to be managed in the aftermath. Quick repressurization and treatment will be necessary to prevent permanent harm or death from secondary effects.
Potential long term effects
| System | Effects |
|---|---|
| Neurological | Hypoxic brain injury, cognitive deficits |
| Circulatory | Embolism formation, cardiovascular damage |
| Integumentary | Tissue necrosis, skin/organ swelling |
| Sensory | Loss of vision, eye damage |
| Whole body | Increased cancer risk, radiation damage |
Conclusion
Exposure to the airless vacuum of space without protection is extremely hazardous and most certainly fatal within less than 2 minutes. Lack of oxygen and air pressure along with extreme temperatures and radiation bombard the body immediately. Subjective experiences report discomfort, swelling, and the sensation of boiling fluids. Studies of animals, accidental exposures, and planned experiments provide most knowledge of space vacuum effects.
While it’s possible for a human to survive exposure for up to 15-30 seconds if repressurized quickly, any duration longer than that risks permanent disability or death. Rapid asphyxiation, ebullism, and tissue damage will occur. Any survivors may sustain serious long term medical complications. Overall, removal of your spacesuit helmet in space is a catastrophic outcome that will likely cause death within seconds.