If you watch astronauts in space then you will know how they seem to float around their spaceship. Spaceships in orbit around the Earth are in free-fall, constantly falling toward surface fo the Earth with the surface constantly falling away from it. Any occupant is also in free-fall but living like this causes muscle tone to degrade slowly. One solution is to generate artificial gravity through acceleration in particular a rotating motion. A new paper makes the case for a rotating space station and goes so far that it is achievable now.
Acceleration is a change in either direction or speed. In a lift you can feel a deceleration as you feel heavier when the lift slows at the bottom of its descent. It would certainly be possible to generate an artificial force of gravity in a box travelling through space if it constantly accelerates. This would produce a sense of a floor and pin the occupants to the rear wall. This is however, a fairly inefficient way to produce gravity as significant amounts of fuel would be required to continually accelerate the box.
A recent paper published in Science Direct by lead author Jack J.W.A. van Loon shows how a spaceship that continuously rotates will produce an artificial gravity on the inner skin of the outer shell. The benefits to such an approach are significant; improved crew health and wellbeing, safety improvements, cost reductions and the simplification of numerous flight operations.
There are many ways that astronauts attempt to limit the impacts on health from micro-gravity. Treadmills with straps to pull the astronauts down onto the running platform are just one of the ways they attempt to keep bones and muscles in tip top condition. If they don’t then bone and muscle density declines. Research has sown that for every month in space, an astronauts’ weight bearing bones become 1% less dense. Muscles wean too and this causes problems on their return to Earth and ‘normal gravity’ so it is a vitally important part of their routine.
ESA astronaut Alexander Gerst gets a workout on the Advanced Resistive Exercise Device (ARED). Credit: NASA
The team go on to explore a number of options such as a short arm centrifuge. These would certainly generate artificial gravity but the short arm would mean the gravity gradient from foot to head of occupants would be too great and have a negative health impact. An alternate solution, and more efficient feasible solution is to build a large rotating spacecraft. Such a craft would have benefits for long term missions such as trips to Mars but also benefit those in orbit around Earth for months on end. Savings would be impressive as significant investments are made combatting the effect of microgravity.
The team discuss what would be needed to simulate and Earth-like 1g environment on a spacecraft. A donut shaped spacecraft with a 25 m radius would need to be spun 6 times per minute to generate a 1g environment. Larger spacecraft could be revolved at a slower rate. Doing so not only benefits the astronauts but nearly every aspect of life in space would be enhanced and safer; liquids would behave in a normal way, flames too would behave in a more familiar way, toilets can of a more normal design as can self care systems. The benefits are significant so I don’t think it will be long before we see astronauts walking around in revolving spacecraft enjoying the luxury of normal gravity again.
Source : Benefits of a rotating – Partial gravity – Spacecraft