Many of us may have thought in our childhood, "I want to grow up to become an astronaut". Roaming into outer space surrounded zillions of celestial bodies, galaxies and constellations is immensely exhilarating and mesmerizing, to say the least. But the universe can be as lethal as it is beautiful and intriguing. Being in an endless vacuum surrounded by alien bodies and phenomena has its own risks.
The biggest identity of an astronaut is his space-suit. No comics, television series and movies ever depict an astronaut without a spacesuit. This space-suit doesn't have much use as long as the astronaut is safe inside his space-shuttle. But once the time comes to venture out into the unknown, no astronaut can step outside without a spacesuit. Now, every science geek will know that a spacesuit is not just an ordinary suit. It is fitted with all sorts of equipment and provisions necessary for humans to survive. But what exactly does happen if you do venture out without a spacesuit?
There are many myths surrounding this question, that have mostly arisen from facts distorted and exaggerated by media. Before I get to that though, I would like to brush up upon some scientific phenomena that is responsible for "what happens after".
Okay, so here's what the universe consists of- an endless vacuum, almost zero atmospheric pressure, all sorts of radiations, and an atmospheric temperature of around -270 degrees Celsius. Sounds pleasant, right?
Now, such extreme environmental conditions are bound to have certain consequences, which are not pleasant either. The high pressure difference due to vacuum is the biggest cause of these consequences.
Everything in this world strives to move from an area of high potential to an area of lower potential. Hence everything at a higher pressure will try to go to a lower pressure area. When a gas does this, it starts to expand. And when a liquid does this, its boiling point decreases. This is what happens to the bodily fluids and gases when your body is exposed to outer space.
The cosmic radiations in space are composed of all kinds of electromagnetic waves known to science, in weird combinations that can give you cancer. If you are too close to the celestial bodies emitting these radiations, you will be burnt to a crisp. But if you are stuck in one of those empty areas with celestial bodies for miles at an end, you may freeze. However, because of the unique structure and composition of the human body, these phenomena don't happen as per our expectations.
With this, I will now get to the myths and facts about what happens without a spacesuit, in space.
Myth: Your body explodes the minute you step out without a spacesuit
When our bodies are exposed to outer space, the gases within start expanding rapidly due to the immense pressure difference. This causes us to believe that our bodies will explode. However it won't happen, because our skin is extremely elastic. The human skin will stretch, but not break because of the expanding gases, and will hold everything in.
Fact: Your body will swell up like a balloon
Well, yes. Due to the extreme pressure difference, all the gases in our body (oxygen, nitrogen, hydrogen, etc) will start expanding rapidly. Because of this, our body swells up immensely, sometimes to twice its original size. The skin will hold all its contents in, but the body will still swell up, and you will be in great discomfort and pain.
Myth: Your blood will start to boil
Now, considering how low the atmospheric pressure is in outer space, the boiling point of all body fluids fall way below body temperature. This implies that our blood should start boiling, but it doesn't. And yet again, this is because of the layer of skin that covers our body. Our skin holds the blood in, reducing the exposure so that our blood pressure is maintained enough that the blood doesn't boil.
Fact: Gas bubbles start forming in body fluids
Our blood does not boil and evaporate right away doesn't mean that our body fluids don't start boiling. When the body is exposed to outer space, gas bubbles start to form in body fluids. This phenomenon of gas bubble formation is known as ebulism. It is partly due to lower boiling point of these fluids, and partly due to the expansion of gases dissolved in them.
Myth: Your body freezes completely
It should happen, considering the fact that the atmospheric temperature in space is -270 degree Celsius. But it doesn't. The reason? Absence of an atmosphere. If you can recall 9th grade Physics, you will remember studying the terms "conduction", "convection" and "radiation". These three phenomenon are responsible for heat exchange between two bodies. Your body will only freeze if it can dissipate body heat. To do this by conduction or convection a medium (the atmosphere) is required. For radiation, no such medium is required. However, heat dissipation by radiation is so slow that it may take thousands of years for your body to even start freezing.
Fact: You will get terrible burns all over the body
This is because of the numerous cosmic radiations emitted by the celestial bodies. Celestial bodies, especially stars and gas clouds (supernova) emit electromagnetic radiations. These radiations may or may not be radioactive, but they indeed are harmful to human skin. If our bodies venture too close to these celestial bodies, our skin will experience terrible burns. In fact, these radiations can be so harmful that if our body isn't burnt to a crisp, it will acquire cancer.
