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Ken Tapping, February 22, 2012
In the sky this week…
> Jupiter and Venus continue to dominate the southwestern sky in the evenings.
> Mars rises around 7 p.m. and Saturn at 11 p.m.
> The Moon was new on February 21st and will reach First Quarter on February 29.
Over the coming years, people will be spending more time in space. With current technologies, voyages around the Solar System will take weeks, months, or perhaps longer. There could be extended stays in bases on the Moon or Mars.
Testing the feasibility of being able to live and work in space for long periods of time is one of the purposes of the International Space Station. In addition to providing a platform for studies of the Earth and space, and development of new technologies, a major research topic is the astronauts themselves. What are the problems of living in space? How do we address them?
Problems like surviving in a vacuum and dealing with enormous temperature variations have been solved well. Moreover, solar energy provides plenty of electrical power to run everything. Radiation hazards, however, are more problematic. The Sun and other objects in space produce high-energy particles, and the Sun occasionally produces bursts of X-rays. On the surface of the Earth we are protected by the atmosphere and the Earth’s magnetic field. The International Space Station is above the atmosphere, but still lies inside the protection of the magnetic field. People on the Moon or en route to Mars, however, will be fully exposed. To deal with the problem, bases on the Moon or Mars could be safely built underground. Astronauts in space could use a screened “storm cellar”.
One other problem is the consequence of living with little or no weight. We often hear that there is no gravity in space, or that in the International Space Station we have a “microgravity environment.” Both of these statements are inaccurate. At the height of the International Space Station, the Earth’s gravitational attraction is only a little weaker than it is on the surface of the Earth. We feel weightless in Earth orbit because we are falling. It is exactly like being in a freely falling elevator. The only difference is an object in orbit is falling in a trajectory that never meets the surface of the Earth because the Earth is curving away beneath it.
Mother Nature is not wasteful, and abhors over-engineering. If you are in orbit and weightless, or living on the Moon or Mars, where you only weigh a fraction of what you weigh on Earth, your body senses that it does not need as much bone mass as you did on Earth, and discards it. This is why there is much discussion about how we can have something like gravity while in space to reduce this loss of bone material. After two or three years of being in space and on the Moon or Mars, how can you get yourself into a condition where you can safely return to Earth? That is why in the movie, “2001, A Space Odyssey,” the space station is a big, rotating wheel, which produces a sort of pseudo-gravity. Similarly, our spacecraft heading for Mars will be like a big, spinning dumbbell.
Imagine one day, when there are children growing up on the Moon or Mars weighing respectively a sixth and a third of what they would weigh on Earth. How would they prepare to visit their relatives back on Earth? Will it be possible for them to do so?