What would happen if you touched the cosmic vacuum?

On August 16, 1960, American pilot Joseph Kittinger set a record for the highest altitude jump in the world. A huge balloon filled with helium lifted the pilot to the height of  31,300m (102,800 feet). During his ascent, the pressurization for his right glove malfunctioned which caused his right hand to swell up to twice its normal size and Kittinger experienced immense pain. This incident occurred in the stratosphere not outer space .Imagine what would happen to an astronaut if they literally touched a vacuum in space.

                                                                                                       Source: Ridddle

But let’s review the basics first to get a better understanding. The higher you are above the surface of the Earth, the lower is the atmospheric pressure. We are aware of the fact  that the atmospheric pressure at the sea level is 1 atm.On the highest mountain on the Earth, Mount Everest, it amounts up to ⅓ atm. And about 93 kilometres ( 63,000 feet) above the Earth a terrible fate awaits for anyone without a spacesuit. So imagine if a maniac decided to test the effect of the cosmic vacuum on themself. Well, there is no going back once they are in extraterrestrial space and there are no hospitals or space ambulances in case of an emergency. But if our subject is not afraid then let's get started.

Our subject (let’s call them Bob) drops a glove. The first and powerful thing an astronaut would feel in an unpressurized spacesuit is enormous pressure that would act inside the muscles and skin. Human bodies are designed for life on the surface of the Earth and a layer of the atmosphere is constantly pressing upon ourselves. So why don't we die from one tonne of air pushing against our bodies? The answer is simple: the atmospheric pressure is balanced by the air inside our bodies. 

Source: NASA

However,space is a vacuum, which means that any person unfortunate enough to find their self unshielded in such an environment will experience rapid internal decompression. Even if the external pressure in one of our limbs drops to zero then the balance would be unstable. Gases which usually dissolve in our blood will immediately turn into blisters and burst in the muscles and skin. Moreover, under these conditions the fluids in the tissues will also start evaporating. This would cause Bob’s (subject) arm to swell up and the bubbles of gas would block blood flow resulting in the feeling of numbness in Bob. Due to the lack of oxygen the subject’s hand would start turning blue. But, will this sudden pressure drop cause the hand to explode?

There is one specific case in history where a persons’ entire body came in contact with a vacuum accidentally yet the person survived. This is evidence to the fact that the human body is really strong. So it is unlikely if the sudden pressure drop of a spacesuit will result in an astronaut’s hand( even without a glove) to explode. But, tissue damage under these conditions would still be possible.Yet, this doesn’t mean that the threat of dying completely departs.

Deep sea divers are sometimes diagnosed with a disorder called decompression sickness. During deep sea diving, divers become pressurized by columns of water with the force of several atmospheres. If for some reason they suddenly rise to the surface their body doesn't have enough time to adjust to the pressure drop. With the sudden rise, the gases dissolved in the blood ,especially nitrogen, turn into bubbles. Visualize a bottle of soda when you open it . The liquid inside literally foams with a thousand of bubbles. Now, imagine something similar happened to the blood in your body. Symptoms of decompression sickness are unpleasant. They include: severe headache, muscle and joint pain and loss of vision. 

Source: NASA

Let’s get back to Bob. The worst scenario now is that the air bubbles that appeared in our subject’s could get into the other parts of the body via the bloodstream like the heart. Such a condition can cause myocardial infarction commonly known as a heart attack. But we know that the most important organ of our body is the brain. If the air bubbles clot the blood vessels, bulk structures of the brain would be left without oxygen. When this happens, in a matter of minutes, a stroke can occur and possibly even death. However, since Bob only removed his blood he might be able to avoid this from happening. Damaged tissues and clogged vessels in his hand wouldn't cause gas bubbles to flow further through the body. Therefore, Bob should mainly expect pain in the hand and possibly treatment and long recovery period. 

Now getting back to space because the experiment continues. What else could happen to Bob? The answer is bitter cold. Afterall, everyone knows that in space the temperature is close to absolute zero. However,events in space would unfold a little differently because Bob(our subject) would not only not freeze but also receive a severe sunburn. How is that possible? The temperature in outer space is extremely low i.e, -270.42°C ( -454.75°F).  A spacesuit-less human just outside the space station would surely either boil alive or get turned into a popsicle in under a minute, right? However, you’re thinking of heat transfer on Earth. 

Source: NASA

In space, there is no air, so heat can’t be transferred through conduction (direct contact between two objects) or convection (energy transfer through a fluid like water or air). The only viable means of heat transfer between two objects — in this case the human body and space — that you’re left with is radiation. Humans radiate heat at a rate of only 100 Watts, much like an incandescent light bulb. Given the sheer mass of the human body, it will take a long time before you freeze. Another danger is awaiting Bob in space - the most powerful solar radiation. 

On Earth’s surface, the intensity of solar radiation averages to about 635 W/m2. However, in space there is no atmosphere to absorb light. Therefore, the sun shines  much brighter there. It’s power in low Earth orbit reaches to 1,360 W/m2. Hence, the ultraviolet rays in space are extremely dangerous and will cause sunburn. Suppose Bob prepared himself for the assignment and brought sunscreen. Will it be enough to protect him from the burn? Unfortunately no because in addition to visible and ultraviolet light in the cosmos there is a lot of ionizing radiation and cosmic rays.

 Now imagine how many charged, subatomic particles will be in the hands of our subject if he removes his glove. Even though, radiation rarely kills a person instantly. Most likely, our subject won't even feel those charged particles hitting their body. But, radiation damage is the cause of many illnesses so after returning to Earth Bob would run the danger of developing cancer or something worse. In short, a hand caught in a vacuum can be saved especially if the rest of the spacesuit remains airtight. However, it is possible that when you remove the glove air may escape the protective suit. In this case, the person would lose consciousness due to Hypoxia in under fifteen seconds and add to this the effects of decompression sickness. So if you ever find yourself in space then avoid taking off your glove.