Whenever we see images of astronauts in space, they float in all directions, as if there is no gravity at all. However, those who think so could not be more wrong than that. NASA’s Flight Controller and Instructor, Robert Frost, explains the truth behind this common misconception.
Gravitational influences on astronauts
Gravity, the curvature of space-time in the presence of mass, is omnipresent in the universe. While in space, astronauts are affected by the gravitational influence of both the Sun and the Earth. Without these forces, not only the astronauts could not stay in orbit, but also the International Space Station and even the Moon. Compared to the influence of Earth’s gravity on the surface of the planet, which is 9.81 m/s^2, the astronauts that inhabit the ISS have to face Earth’s gravitational force of just 11% less or 8.75 m/s^2.
Freefall is responsible for the floating of astronauts
Since the gravitational influence from Earth is almost the same on the planet as it is in the ISS, there must be another explanation for the floating of people and objects in space. As Robert Frost says, the weightlessness is caused by a free fall. The gravity makes the spacecraft orbiting the Earth to fall towards our planet, but thanks to the high-speed, the space vehicle is able to move forward in the orbit that circles the Earth. Moreover, exactly the same force affects astronauts and since both are falling at the same time, their forces do not interact with each other, which creates a feeling of weightlessness.
Creating a similar free fall effect is also possible here on Earth. What we need in order to do this is to pump a tall chamber to a vacuum. The same could happen to a skydiver if it wasn’t for air’s resistance.