This illustration landed in the inbox yesterday. As evident, it shows some prominent designs for Space Stations that have emerged in the past. Of these, 4 designs were actually built & launched into Space & have been inhabited by humans. The others were either designs that did not get approved due to varied reasons, or were simply outcomes of creative artistic pursuits.
Currently, only the International Space Station [ISS] still orbits the earth, and can be visited & lived in. It is expected to remain in operation till around the second half of this decade [2016-2020]. Some successor plans for a Space Station in the western world, include,
- Bigelow Commercial Space Station, a private venture
- Russian-lead Orbital Technologies Commercial Space Station
- Excalibur-Almaz, a private venture, which has a design for a Space Station based on Russian military Space Station, Almaz
- Non-Atmospheric Universal Transport Intended for Lengthy United States Exploration, aka, Nautilus-X, a NASA proposal
- A design from the winner of Google Lunar X Prize, Galactic Suite
- Boeing-proposed design called the Exploration Gateway Platform to be assembled at the International Space Station for use further away
Similar to the Boeing proposal, Russia, too, has come up with a concept called the Orbital Piloted Assembly and Experiment Complex that would, in fact, be used for the purpose of constructing & assembling the Space Stations up in Space itself. This would help overcome weight limitation of current & future rockets used for Space launch. India, currently, has no known plans to build one of its own. It recently joined the multi-national International Space Station program as a partner nation.
It was important to mention the term 'western world', because China has a program to build & launch its own such Space Stations. The process towards realising a practical Space Station solution began with the launch of the Tiangong-1 space laboratory, essentially to enable China to perform its first docking in Space. Subsequently, progressive variants of Tiangong are to be launched, expanding the envelope of its capabilities, testing & validating technologies & procedures that would eventually be incorporated into its full-fledged Chinese Space Station.
This approach taken by the Chinese, is similar to that followed by the erstwile Soviet Union. Working towards its goal of building a Space Station, to be known as Mir, the Soviets launched a series of smaller stations earlier, known as the Salyut series, with the Almaz stations, that had military applications, being a sub-set of the Salyut. Finally, in 1986 the Soviets launched portions of what was to be their full-fledged Space Station, Mir. Construction on Mir continued till 1996 & it stayed in orbit for nearly 15 years till 2001, & following the end of the Cold War, played host to Space farers from either side of the ideological divide. Scientist Norman Thagard became the first American Astronaut to inhabit the Mir in 1995.
One interesting commonality seen among the Space Stations in the infographic above were their torus shape. The shape was necessitated to implement an idea of its designers to simulate gravitational effect in the space stations. Spinning the Space Station in Space would induce a Centrifugal Force proportional to the mass, angular velocity and the radius of the Space Station. The acceleration developed due to the force would, therefore, substitute for acceleration due to gravity & the Astronaut/Cosmonaut/Vyomnaut/Taikonaut would no longer experience weightlessness, currently felt.
However, owing to Engineering limitations, and even more importantly economic considerations, no such Space Station has been built so far that has an artificially-created gravitational environment. The Gemini-11 mission, flown by U.S.A in 1966 did succeed in creating small amount of artificial gravity, using the rotary motion described earlier. However, it was primarily a proof-of-concept, and not a practical solution. Moreover, certain experiments that Scientists perform specifically require a microgravity environment. Hence, the sense of weightlessness too has benefits. The Nautilus-X proposal [above], if developed, would be able to create its own artificial gravity environment.
The idea of Space Stations & Space exploration has taken on a newer significance in recent times, over and above that of pursuit of knowledge & attainment of excellence. Depleting natural resources, deteriorating environmental condition and a growing population, has meant that continued inhabitation on the surface of the Earth is no longer guaranteed. Although much into the future, it may become necessary to leave the comforts of the Earth, emasse, & take refuge on a planet that could also support life such as ours. We may even have to live in vast living quarters rights here on earth, that would cut off our contact with the polluted outside, keeping us safe & breathing, albeit perpetually, by present definitions, indoors. Another alternative, as presented by Space Station concept would be to build such a Station on massive scales that can support life in numbers equivalent to that of cities. It remains to be seen if such a stage might actually arrive. But if & when such a stage does come, solutions must be at hand to address/escape them. Considering the decades of work needed for such program to reach maturity, it is essential that efforts towards the goal must be unhindered by myopic views & considerations.
Godspeed
1st illustration by: Lee Hulteng
Also: Space Agencies & Manned Moon missions: International Astronautical Congress 2009