The closing of 2009 brings to an end the first 10 years of the International Space Station. It has been an endeavor that has required cooperation from across the globe, and brought about the first inhabitable living quarters beyond our atmosphere. Here is what has taken place over the last decade, and what we have to look forward to in the years to come.
Building A Home Away From Home
Assembly of the International Space Station (ISS) began on November 20 of 1998 when the Zarya Control Module was launched into space from a Russian Proton Rocket. Looking like little more than a large satellite, the Zarya supplies power and fuel storage to parts of the ISS. At this point, with only the Zarya in place, the ISS was unable to support human life -- mostly because there simply wasn't any room.
Over the next two years and 8 missions various components were added to the space station. These components included pressurized mating adaptors so astronauts could eventually "board" and live the ISS, as well as logistics systems, and the Zvezda service module which included living quarters and life support systems. In addition to these rather "major" additions, missions also installed vital components like smoke detectors, batteries and other necessities.
It was not until November 30, 2000, that the first crew began living on the ISS. The crew arrived on a Soyuz rocket, which then docked with the ISS. This was important because it allowed the Russian crew the ability to return to Earth onboard the Soyuz should anything go wrong (instead of having to wait for the Space Shuttle to retrieve them).
Shortly afterwards the first solar arrays were delivered and installed on the ISS, giving the station the ability to receive power from the Sun. The obvious benefits of not needing to rely on battery power made living on the ISS a much safer prospect.
A Laboratory Module was installed a few months later which allowed the astronauts to conduct various scientific experiments. Then on March 3, 2001 a new crew arrived at the ISS to replace the first crew who had been on board for more than 3 months. The second crew remained onboard the ISS for 5 months until crew number three relieved them.
During the next year several missions to the ISS took place to install or repair various electronics, modules and supplies. But after the Columbia Shuttle disaster, the Shuttle fleet was grounded and did not return to flight until July 26, 2005 when it docked with the ISS to replenish supplies and equipment.
Over the years several more science modules have been installed to conduct experiments and create a more comfortable, controlled environment aboard. Also, various docking systems have been installed to ensure that various spacecraft can successfully mate with the ISS.
There are several more modules and parts that are scheduled to be assembled onto the ISS during the coming years, but they all hinge on funding and the availability of a new transport system once the space shuttle fleet is retired in 2011.
Living Onboard the ISS
Naturally, life aboard the ISS is nothing like life here on Earth. The first, and perhaps, most obvious difference is the microgravity experienced by the inhabitants of the ISS. Most people assume, incorrectly, that the reason for the microgravity is due to it's distance above the Earth. While it is true that the altitude does contribute to an experience of gravity less than at sea level, it is only lower by about 12%. This would not be enough for someone to feel weightless at all, though it would be a noticeable difference. Instead the reason for the weightlessness is due to the fact that the ISS is in orbit around the Earth. As such it is constantly falling toward the Earth's surface. It never crashes though because its velocity always carries it around. This is the same phenomenon that keeps satellites in orbit.
Of course this presents another problem -- sleeping in space. Clearly you don't want to just float around in your sleep as you could bump into things and hurt yourself and the equipment onboard. So the crew have sleep stations. These are little more than a single person sized room with a tethered sleeping sack and an area for placing personal effects. However, this is somewhat nicer than what some visiting crew members receive -- a sleeping bag tethered to a random wall. Some visitors aren't assigned a sleep station so have to make due with less ideal arrangements. Once scary aspect of sleeping (or when you are awake) is that circulation of air is a must. If the air fails to circulate a crew member can wake up gasping for air. Since heat will not rise in a weightless environment, exhaled carbon dioxide can accumulate around the crew member, preventing them from breathing proper air.
One major problem with extended stays in space is the onset of muscle atrophy and other health problems. This is why it is important for the ISS crew to be able to exercise consistently. This is difficult because of the microgravity on the station, so astronauts are usually tethered to the exercise apparatus. For instance an astronaut can be tethered to a treadmill and run without the worry of being bounced around the compartment. Typically each astronaut needs to spend two hours a day exercising to prevent the various health problems.
With all of that exercising the astronauts can work up quite a sweat. So, there needs to be a way maintain good hygiene. Plans for the ISS originally included a shower, but this was scraped due to budgetary reasons. Instead, astronauts use a jet of water and wet wipes. Also, they use rinse-less shampoo and toothpaste that is edible, all in the name of using less water. The toilets use a suction system to evacuate the waste which is stored onboard until it can be disposed of. Liquid waste is recycled back into drinking water.
