“These old space station studies now look completely archaic,” says David Baker, editor of Spaceflight magazine and a former Nasa engineer who worked on the concepts. “The Skylab missions [of the mid 1970s] proved that the whole point of having a space station was to do microgravity research, so we abandoned the artificial gravity idea.”
“Now, though,” he says, “they might be worth revisiting.”
Inflatable space
I find Baker’s 1971 reports on the project tucked away on a top shelf of the British Interplanetary Society Library in London. One, the McDonnell-Douglas “space base”, is formed of a series of cylindrical modules. The base includes a separate artificial gravity section, providing crew with around half the gravity they would experience on Earth.
A competing design, from North American Rockwell, is more ambitious and features a central core with four cylinders projecting from it on spokes. Each of these modules contains the living and working areas and, just like Ross’ 1949 concept, would spin around the central axis to generate artificial gravity.
Although both these designs are enormous – housing between 12 and 50 “men” with individual cabins, tables, comfy chairs and even a sickbay – the basic ideas are sound. In fact, they are not dissimilar to a 2011 proposal known as the Nautilus-X, or Multi Mission Space Exploration Vehicle, put forward by a consortium from Nasa, academia and industry.
This $3.7bn spacecraft is designed for six people and looks similar to a flying space station – with large solar arrays and a series of interconnecting tubes. However, the major difference is that surrounding the centre of the ship is a larger hollow wheel. This wheel would be a bit like a bicycle inner tube, made of a series of rigid rings connected by soft-walled inflatable sections. It is similar in structure to a module that Nasa has just ordered from Bigelow aerospace, with the intention of fixing it to the ISS in 2015.
There is a good reason why the ship looks similar to the ISS, according to Mark Holderman, one of the team behind the design. “Nautilus-X was to be assembled in orbit… [using] the skill and lessons learned from assembling the International Space Station.”
The ship’s design emerged in2011 from the Space Shuttle program's Technology Applications & Assessment Team (TAAT), a group formed to look at relatively near-term human space missions that could build upon or extend the use of existing technologies. The team envisaged building a prototype that attached to the ISS to prove the concept, before building a full-sized ship.
“It…would have been the first true spacecraft to provide a crew with artificial gravity,” says Holderman. “The Nautilus-X was also designed to provide the evolutionary basis for the spacecraft that would eventually take a crew of 9 to 12 to Mars.”
Ultimately, the project was cancelled due to changing priorities and a lack of funds at the space agency.
Sick idea
So with budgets only ever getting smaller, space agencies may want to follow a simpler – and cheaper – route. If that is the case, they could copy a method tried out on Nasa’s Gemini missions of the mid 1960s where astronauts stretched a tether between their capsule and an unmanned docking module and allowed the two bodies to spin around each other. The theory is the same as twirling a bucket around on the end of a string where a centripetal force is generated in the bucket.
Or for space agencies on a very tight budget, there may be an even cheaper option. Researchers at MIT, for example, have conducted a series of experiments using a small centrifuge – effectively a spinning table or chair. The idea is to fly something similar on the ISS, with astronauts strapping themselves to the device and spinning themselves round and round to simulate gravity. Although the setup has a habit of giving people motion sickness (particularly when they move their head), the experiments suggest that regular sessions on the wheel can offset some of the deleterious effects of weightlessness.
