How long can you survive in space without a spacesuit?
At most, an astronaut without a suit would last about 15 seconds before losing conciousness from lack of oxygen. (That's how long it would take the body to use up the oxygen left in the blood.) Of course, on Earth, you could hold your breath for several minutes without passing out.
If you do die in space, your body will not decompose in the normal way, since there is no oxygen. If you were near a source of heat, your body would mummify; if you were not, it would freeze. If your body was sealed in a space suit, it would decompose, but only for as long as the oxygen lasted.
- How cold is it in space? That question is sure to prompt the geeks among us to pipe up with “2.7K”. For 2.7 Kelvin, or 2.7 degrees above absolute zero, is the temperature produced by the uniform background radiation or “afterglow” from the Big Bang. But hang on.
- It boils, and it boils quite violently at that! The reason for this is that water, in its liquid phase, requires both a certain range of pressure and a certain range of temperatures. If you start with liquid water at a given fixed temperature, a low enough pressure will cause the water to immediately boil.
- Water poured into space (outside of a spacecraft) would rapidly vaporize or boil away. In space, where there is no air, there is no air pressure. That's why water boils much faster on a mountaintop than it does at sea level. In space, because there is no air pressure, water boils away at an extremely low temperature.
As you probably know, space is already very, very cold — roughly 2.7 Kelvin (-270.45 Celsius, -454.81 Fahrenheit). This is mostly due to a lack of atmosphere and the vacuum-like nature of space — with very few molecules to energetically bounce around, there can be no heat.
- The Coldest Place in the World. Dec. 10, 2013: What is the coldest place on Earth? It is a high ridge in Antarctica on the East Antarctic Plateau where temperatures in several hollows can dip below minus 133.6 degrees Fahrenheit (minus 92 degrees Celsius) on a clear winter night.
- Neptune has the wildest and strangest weather in the entire Solar System. It has huge storms with extremely high winds. Its atmosphere has dark spots which come and go, and bright cirrus-like clouds which change rapidly. Neptune has an average temperature of -353 Fahrenheit (-214 Celsius).
- Daytime on one side of the moon lasts about 13 and a half days, followed by 13 and a half nights of darkness. When sunlight hits the moon's surface, the temperature can reach 260 degrees Fahrenheit (127 degrees Celsius). When the sun goes down, temperatures can dip to minus 280 F (minus 173 C).
Despite the risks, no mission has ever lost a space-walking astronaut. NASA requires spacewalking astronauts to use tethers (and sometimes additional anchors). But should those fail, you'd float off according to whatever forces were acting on you when you broke loose.
- Astronauts float around in space because there is no gravity in space. Everyone knows that the farther you get from Earth, the less the gravitational force is. Well, astronauts are so far from the Earth that gravity is so small. This is why NASA calls it microgravity.
- If 90 percent of Earth's gravity reaches the space station, then why do astronauts float there? The answer is because they are in free fall. In a vacuum, gravity causes all objects to fall at the same rate. The mass of the object does not matter.
- The astronauts, the ISS itself and other objects in Earth orbit aren't floating, they are actually falling. But they don't fall to the Earth because of their huge orbital velocity. Instead, they fall around Earth. Since the astronauts have the same acceleration as the space station, they feel weightless.
Updated: 23rd September 2018