A Trip Into Space - Orbit

In yesterday’s post, I got you into orbit.

You are now floating above the equator. While you enjoy weightlessness, the pilot is checking over the systems after launch and making plans to rondezvous with the space station.

You are encouraged to remain seated until the ship docks with the space station. There are a number of reasons for this.

There will be a few rocket burns along the way. With every burn, everything floating in the cabin will approach the part of the ship opposite the direction of acceleration. If the pilot speeds up, everything floating moves towards the back of the ship. If the pilot slows down, everything moves to the front.

However, there will be long periods where no burn is expected. At these times, the captain will turn off the seat-belt sign and allow those who wish to do so to experience weightlessness. "You are now free to float about the cabin."

There is another reasons to remain seated, however.

Weightlessness itself is more than “floating”. If you are in a pool, floating, you weigh just the same as you do on land. The water is holding you up in the same way that a floor holds you up – it simply changes its shape fit your body.

Even a sky diver in free fall is not “weightless”. When the sky diver reaches terminal velocity, the pressure of the air blowing past balances the pull of gravity. The sky diver us still falling, but she has stopped accelerating.

To get a better idea of what true weightlessness is like, imagine falling with your eyes closed – with no wind or anything else actually telling you that you are falling. Still, nothing holds you up. Alternatively, if you have ever been flying and hit turbulence, those few seconds where it feels that the plane is falling away from you, you are approaching weightlessness. That feeling is what it will feel like to be weightless. Only, it never ends.

In space, you are in a perpetual state of falling.

Some people will have difficulty when experiencing this. Some training is useful to get a person accustomed to the sensation. An airplane can simulate weightlessness for about 25 seconds. It is odd that this is called a “simulation”, since the passengers for those 25 seconds are actually weightless.

Even with training, it takes some professional astronauts several days to become accustomed to weightlessness lasting more than a few seconds. Not knowing which way is “up” (because there is no “up”) their brain struggles to make sense of these new sensations. As the trip to the space station continues, and the sensation of gravity remains absent, more and more fellow travelers will begin to experience increasingly severe motion sickness.

NASA gives a day or two for its astronauts to become accustomed to weightlessness. The best relief seems to be to remain still, eyes closed, and to not move one's head. Motion-sickness medication also works.

This is not only a problem for those who enter space. The best place to work and live in space is in an environment of simulated gravity. However, this means transitioning to weightlessness on a regular basis. Some people can work in a weightless environment by day and return to simulated gravity when their shift ends, but not many.

Solving this problem will reduce one of the most significant costs of living and working in space.

The best place to do research on these types of problems is in space itself. One needs to send people into space for a day or two to try different things. There is a chance, when space travel is more common, that medical science will find another solution - one that allows people to avoid these sensations entirely.

Another issue that will become apparent after a few minutes springs from the fact that we evolved in a gravity well. Our bodies evolved to push liquids to the head and upper body against gravity. These systems continue to work in space. The face becomes swollen as you feel a pressure of the blood (and other liquids) pooling in the head - much like the sensation of standing on one's head.

After a couple of hours, you will be asked to return to your seat for docking. The spaceship you are travelling in has drifted near enough to the space station to start docking maneuvers. You can see the space station out the window. I will describe it to you in the next post.