A recent article in the Journal of Physiology raised some serious questions about the loss of strength and vitality an astronaut may suffer after returning to Earth after six months in the weightless void of space. Astronauts subjected to no more than half a year in space suffer from muscular degeneration that results in their bodies being comparable in strength to an 80 year old.
Even lying on your back on Earth’s gravity and moving your arms occasionally you are exerting a certain amount of force. The act of standing requires several muscle groups to contract and exert force in order to maintain balance. It’s such a simple act that we don’t even notice it, but the body actually burns several calories every day doing these simple activities. Even turning in one’s sleep results in several calories being burned as the body slowly regenerates. But the real atrophy seems to happen when these same people are subjected to an environment where their bodies are suspended 24 hours a day for extended periods of time in an environment where only minimal exertion is required. Normally when someone lifts their arm they must contend with the gravity of the Earth pulling it down. In space the only resistance ever felt is of the air. You may have experienced something similar floating underwater, but even in this case the resistance of the water itself would no doubt have caused much more resistance than the free air in the space shuttle. To illustrate this, imagine lowering your hand into water as opposed to simply lowering your hand outside of it. In the second instance you would actually likely be pulling up to avoid completely dropping your arm to your side. Put the two together and you have the environment astronauts live in while in orbit.
If after six months the human body degenerates as it does so quickly, then it’s safe to assume a similar amount would no doubt follow an astronaut making the six month journey from Earth or a Lunar refueling station and Mars where they would be expected to disembark and even build a colony on the planet’s surface. The result would be weakened individuals incapable of lifting building materials above their heads, let alone build an entire Martian colony.
The study illustrates yet another hurdle we must overcome if we are to ever stretch our fingers to the stars and take that final voyage into the undiscovered country around us, and count ourselves as cosmic residents rather than being eternally bound to the Earth.
Several solutions have been proposed, including one illustrated by Arthur C. Clarke in his classic novel 2001: A Space Odyssey. In 2001, Clarke illustrates a possible artificial gravity system developed for a pinwheel shaped spacecraft that would propel those on the inside toward the outer walls by centrifugal force. Could the design for the first manned Martian voyage take place on a spinning wheel designed to protect Astronauts so they retain their strength?