Now, can we ever colonize Mars? NASA has been trying to find a solution to a problem that we learned about in exercise physiology a long time ago.
When you decrease the stress on the human skeleton, calcium leaches out of the skeleton making it more brittle. This leaching begins surprisingly fast and occurs in relation to the decrease in stress on the skeleton.
In other words, less gravity causes our bones to quickly get weaker and become more susceptible to breaking.
This is very serious because it is a form of gravity induced osteoporosis and has the same potential hazards.
With regular osteoporosis, a decrease in bone density of just 10% greatly increases bone breakage from falls or impacts. Now imagine living on Mars for a few years where the gravity is only 38% of Earth's gravity. Your bone density would quickly decrease to less than 50% of its regular density.
You could not return to Earth to visit relatives because the force of the impact of just landing on Earth would crush your bones and possibly cause your death. And there are other problems caused by decreased gravity on the body such as weakening of muscles and connective tissue.
Now imagine living in zero gravity for the six months required to reach Mars, living on Mars for the minimum of one year that it will take before Earth and Mars are again close enough to travel between the two planets, and then living in zero gravity for the six months required to return to Earth. Until NASA can solve the problems caused by decreased gravity, we cannot even send a manned expedition to Mars. They could never return to Earth.
One possible solution for an expedition is to have a space vehicle which rotates to use centripetal force to create the force effects of gravity on the body. This vehicle would have to be used as a base of operations in orbit above Mars with the scientists commuting back and forth between the space vehicle and the surface of Mars.
They could not stay on the surface of Mars for prolonged periods of time. This type of vehicle would be very expensive and, maybe, prohibitive.Such a vehicle could not be used for the colonization of Mars unless they plan to live on the space station and only commute to the surface of Mars for brief periods of time.
Simply put, it is not possible to colonize Mars unless we first develop artificial gravity.
We can never live outside of pressurized shelters on Mars because of the inadequate atmospheric pressure. You have to understand that the atmosphere around us is constantly pushing in on our bodies with the pressure of one bar of atmospheric pressure. In order to keep our bodies from being crushed by our atmospheric pressure, our bodies are pushing out with one bar of atmospheric pressure.
If we significantly increase the atmospheric pressure on our bodies, we will be crushed and, if we significantly decrease the atmospheric pressure on our bodies, we will expand very quickly or explode.On Mars, our bodies will be pushing out with a force at least 200 times greater than the force of the atmosphere pushing in on it.
Two things will happen almost instantly if you were to step outside without a space suit.
That much of a decrease in outside pressure on your body will cause the water in your body and cells to vaporize very quickly which will greatly increase the outward force of your body to much more than 200 times the atmospheric pressure.
With this much of an imbalance in pressures, every cell in your body will turn into a very powerful, tiny bomb and you will turn into a cloud of molecules almost instantly. There wont be one cubic inch of tissue left.
The explosion will probably destroy anything within a block or more of you and you will leave a really nice crater. But don't worry, it will happen so fast that your nerve and brain cells wont have time to process any signals so you wont fell a thing. You will be standing there one instant and then...POOF!!!
The stuff you see in the movies and on TV about people being blown out of air locks and floating off into space completely intact is incorrect. As soon as the pressure in the air lock decreased to a certain level, your body would explode with enough force to rip a hole in the side of the space ship and cause it to also explode or at least spew everyone and everything inside of it into space.
All of the organic objects in the space vehicle would quickly explode. It is a matter of relative pressures. If an object exerts an outward force 200 to thousands of times greater than the inward pressure of the atmosphere, we call it a bomb. In Mars' atmosphere, you would be a bomb.