Space Habitats: a distant Dream or Reality?

When you think of space and space habitats, the image of Aliens or Elysium may come to your mind. But in the minds of the engineers at NASA, proposed designs of the next generation deep-space habitats will be in the form of modules that are derived from the existing ISS models as shown in Figure 3 [14]. With the privatization of space exploration, the dream of building a space habit on the scale of the Stanford Torus is now a possibility. Funds for space exploration and research are no longer bounded to NASA’s budget anymore. There are now many other major players involved in assisting NASA with space habitat research such as SpaceX, Orbital Science, Virgin Galactic, Blue Origin, and Bigelow Aerospace. Building a DSH like the one in Figure 3 would allow the astronauts and scientists to live and work safely in space for up to a year on missions to explore the space between geostationary and lunar orbit, near-Earth asteroids, and even Mars [10].

Figure 3. The ISS-derived Deep Space Habitat concept demonstrator. From left to right, is the Lab/Hab, tunnel, and Multi-Purpose Logistics Module.

On January 16, 2013, NASA has signed a $17.8 million contract with Bigelow Aerospace to build an inflatable, balloon-like module for the ISS as shown in Figure 4 [14]. This project is called Bigelow Expandable Activity Module (Beam) and it is intended to demonstrate the capabilities and progress of current available technologies. Working in conjunction with SpaceX, it is scheduled to arrive at the ISS in 2015 through the eighth SpaceX cargo resupply mission. Unlike traditional space modules which use aluminum and other metals, the interior walls of the Beam module is made of floppy cloth while the exterior walls are made of Vectran, a bullet-resistant material [14]. The light weight and flexible material allows for the ease of the Beam module to be attached to the payload of SpaceX Dragon capsule, much like packing a T-shirt in a suitcase. It would then be connected to an air lock on the ISS and inflated like a balloon where researchers are planning to test the long term viability of the module. The station crew members and ground-based engineers will gather performance data of the module pertaining to its structural integrity and leak rate. These tests are important because it would be one step towards the development of a large scale deep-space habitat like the Stanford Torus which will one day harbor the necessities for deep space travel. William Gerstenmaier, associate administrator for human exploration and operations at NASA Headquarters states that “As we venture deeper into Mars, habitats that allow for long-duration stats in space will be a critical capability. Using the station’s resources, we’ll learn how humans can work effectively with this technology in space…” [15] Nevertheless, such a feat would not only mark the Beam module’s capabilities but it would also display the payload capabilities of SpaceX’s rockets; the expected progress results are twofold!

Bigelow Aerospace LLC

Figure 4. Computer rendering of the Bigelow Expandable Activity Module (Beam) interlocking with the ISS. Beam is 13 feet long and 10 feet in diameter, with a volume of 560 cubic feet when fully expanded [14].

Although progress has been made towards lowering the cost of sending materials for the DSH into space, trouble may still loom over the actual construction of the DSH in space. Space is a vacuum and therefore friction doesn’t exist. Without friction, objects in space would be moving along a single trajectory endlessly until they hit something! This poses a threat to the existence of space habitats, as the goal is to eventually surpass the lower Earth orbit and keep the DSH stationary, independent of help from the ISS. Knowing the exact location of the DSH would allow astronauts to find their way back to it easier but space is also not as empty as we think it is. The force of gravity is everywhere in space even though we can’t see it with the naked eye. Every single spot in space is affected by the sphere of influence of a celestial mass, or its gravitational pull [15]. According to Newton’s 2^nd Law of Motion, force is equal to mass times acceleration [16]. This means that forces due to gravity will accelerate a mass in the same direction of the force. For us to create a self-sustaining habitat in deep-space, would require propulsion to counteract these invisible forces and maintain its position. Propulsion is very important in space because it allows a body to move freely from one point to another. Without propulsion and constant refueling, the ISS as we know it today would crash to the ground on Earth just as an asteroid would. Along with the 2^nd law, the 1^st law dictates that when an object is in motion; it will stay in constant motion unless acted upon by another force [16]. Propulsion is dictated by Newton’s laws and is the idea to eject a mass outward that will allow you to move in the opposite direction. This would make self-sustaining habitats a hard goal to achieve because the habitats would have to be refueled every once in a while just like the ISS. However, if in the future we find a way to extract hydrogen from asteroids, the basic building block of all other elements, then it may be possible to create fuel for deep-space habitats in the long term [17]. Despite the invisible forces from large celestial masses in space, all hope is not lost as there are always exceptions. Specially formulated points in space may provide the perfect locations to create indefinitely stationary, deep-space habitats. These points are called the Lagrange points and they was discovered by the French mathematician Louis Lagrange in 1772 during his gravitational study of how a smaller body would orbit around two orbiting large ones [15]. The idea behind his conjecture is simple; a Lagrange point is defined as “locations in space where gravitational forces and the orbital motion of a body balance each other” [15]. As shown in Figure 6, there are currently five Lagrange points close to Earth that may be viable and ideal to build a stationary, deep-space habitat on.

Figure 6: Lagrange points near Earth - not drawn to scale.

Another issue to address is financing large scale deep-space habitat projects equivalent to the ones we see in movies like Elysium. Ever since the launch of the ISS roughly over a decade ago, countries like the U.S. have delayed the idea of such space habitats because the launch and maintenance of the space station was about $3 billion per year including fuel costs [12]. However with many engineering companies such as SpaceX and Virgin Galactic providing methods for a cheaper mode of transportation, the idea of having space habitats and tourism may be more feasible than we think. SpaceX boasts that it can build a Falcon 9 rocket with a 150 metric ton payload at a cost of only $300 million. This means that sending a pound of mass into space would cost only about $1000,which is three times more cost-efficient than NASA’s SLS [18].

Conclusion

Now let’s take a second and think about whether is this is financially feasible or not. In the amount of dollars that was spent on constructing the facilities for the 2014 Sochi Winter Olympics ($56 billion), we could have built another International Space Station and send it into Earth’s orbit. The problem more or so lies in seeking enough financial support for the proposal of a large scale space habitat as it will take more than the efforts of a single country alone. This project would require the cooperation of many, if not all countries to help catalyze the construction process of the DSH. The space race isn’t just exclusive to the United States and USSR anymore, it is open to all countries. Although we may not currently be able to create a Stanford Torus or Space Torus like the one in Elysium, we can start to take action and prepare for it. We should not give up on our dream of building a self-sustaining space habitat just because it may be seemingly impossible to achieve. Landing on the moon was once thought to be an impossible feat, but it was proven wrong by individuals who continued to pursue that dream. We should follow in the footsteps of Neil Armstrong, always striving for better. The first man to step on the Moon had once said, “That’s one small step for man, one giant leap for mankind” [8]. With many startup engineering companies now on the rise in the space race, the existence of self-sustaining space habitats may be more realistic than we think.

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