Journey To Mars

One of the biggest challenges with space travel is keeping the human crew alive. Since the universe is vast and always expanding, traveling through space can take upwards of months or years to reach a far away distance. For a spacecraft to travel to the moon, it takes an average of 3 days for a one way trip. The earth is very close to the earth relative to other planets and the sun. For a reference to how far planets are, let’s use light as a reference. Light travels at 300,000,000 m/s or 3×10⁸ m/s. Light is so fast that it can travel around the world 7.5 times in one second. Even though light is very fast, since space is so large, it takes light minutes or even hours to travel to different planets in our galaxy. For light to travel from earth to mars, it would take 3 minutes when the earth and mars are closest together and 22 minutes when earth and mars are farthest apart. If a space shuttle were to be sent to mars, it would be at the time when mars and earth are closest together. According to NASA, a journey to mars carrying humans would take roughly six months there and six months to return home when earth is closest to mars. Due to this, there are many steps that need to be taken to ensure that life is inhabitable during space travel in a space shuttle or vessel.

One of the ways to make life more inhabitable in space (which is zero-gravity) is to create artificial gravity. Humans have always evolved through the gravity felt on earth. Due to the constant force of gravity, human body parts grow muscles strong enough to withstand gravity, thus being able to walk, run, and jump. In space, if humans are exposed to zero-gravity environments for long periods of time, muscles start to weaken since the body experiences no resistance. The absence of forces against the human body causes the muscles to become smaller and the bones to lose calcium and become brittle. The heart and blood vessels swell from the buildup of excess body fluids in the upper body.

The problems caused by extended free fall would still be catastrophic if humans traveled in space over the long periods needed to reach Mars. To combat this, human inhabited space vessels such as the International Space Station create their own “Artificial Gravity”. This is done through Rotating Frames of Reference and Centripetal Acceleration. By constantly rotating the whole spaceship at a constant velocity, “artificial gravity” can be created. If a spacecraft is spinning fast enough, the exact force of gravity on the planet earth (9.8m/s²) can be simulated allowing the crew to feel the same forces like on earth.

Using the centripetal acceleration formula below, if the radius of the spacecraft is known (r in meters), and the force of gravity on earth (g=9.8m/s²), the velocity that the spacecraft needs to spin can be found. Knowing this, the velocity can be put into the period (T) formula, inverse the formula to get frequency, then multiply it by 60 seconds to find how many rotations per minute must be done to recreate earths gravity.

FACT: Given a space station with radius 40m, The Space Station must rotate ~4.7 times per minute to produce the force due to artificial gravity equal to that of Earth’s gravity. (Using the formula above)