Life Support Systems
While any manned mission into the vacuum of space will require some form of reasonably sophisticated life support system, the idea of longer-term missions leading towards the potential goal of off-world colonisation will require much additional research and development. Again, we might use the idea of a manned mission to Mars as the initial benchmark for more advanced life support (ALS) systems, which may start to address the longer-term requirements for air, food, water and energy. Even the initial manned missions to Mars may require over 100,000kg of equipment, which might have to be multiplied by a factor of 10 in terms of the total amount of ancillary equipment lifted into low Earth orbit (LEO). However, such long-term missions cannot rely on recycling resources forever in a closed system, such that the discovery and exploitation of in-situ resources, such as water, air in the form of composite gases and alternative sources of energy will probably be a priority. In this respect the life support systems developed for the ISS might only be described as the first-generation of ALS systems, which do not have the scope, longevity or reliability required by longer-term missions to other planets, such as Mars. The following diagram outlines the general scope of the ISS Environmental Control and Life Support System (ECLSS).
However, it is hoped that the ISS ECLSS might be extended to meet the initial requirements of a small manned Mars mission by extracting resources on Mars in order to create a habitable living environment for the crews on the early exploratory missions, e.g.
- Electrical energy can be generated by deploying of thin film solar
photovoltaic panels, which are flexible enough to be rolled up for compact
transportation to Mars.
- Water can be created by heating of water ice found in the Martian
soil. When the water condenses, a portion will be stored, while the
remaining portion can be used to produce oxygen.
- ·Nitrogen and argon gas can also be extracted from the Mars atmosphere and injected into the habitable space as the inert gas components of air, where 80% is nitrogen.
Within this upgraded life support system, the living habitat used by the crew will be connected to the ALS system, which will then provide the necessary oxygen, nitrogen, and argon to create a survivable atmosphere and the necessary water purification and removal of waste gases, e.g. carbon dioxide, from the atmosphere.
But what is the current state of the next generation of ALS?
Despite the implied optimism of extended ECLSS outlined above, all the components of an ALS system are still in the relatively early stages of research and analysis, which is based on limited experimental data, such that the reliability and lifetime of these systems is uncertain. There is also some reservation that much of this research might be optimistic or limited in scope when translated into off-world situations, which may require considerable margins of error in terms of spares and fail-safe backup in-order to handle unplanned events, e.g. accidents, where the return to Earth is some 6-8 months away. In this respect, the initial estimate of 100,000kg might easily have to be doubled, such that an ALS system will represent a significant mass cost and risk to any manned mission, which may initially prove to be a ‘show-stopper’ to any initial ambitions for large-scale off-world colonisation. Of course, some may see this position as overly pessimistic based on the assumption that technology is already on the way to providing the necessary solutions to all the perceived problems, albeit very much dependent on both time and money. However, longer term stays on Mars will require more than basic survival and will need to factor in all the potential health risks associated with zero and low gravity environments on the human metabolism.
So might we try to quantify the requirements of an extended ALS system?
While we have already defined the initial scope of any basic ALS system requirements, i.e. air, food, water and energy, we might reasonably add a number of more sophisticated requirements to this list:
- Human Habitat Systems
- Environmental Control Systems
- Monitoring, Safety and Emergency Systems
- External Activity Systems
- Health and Emergency Systems
While this discussion will not attempt to detail all the issues, each of these sub-system elements have to be maintained within an overall ALS system, which maximizes recycling of all waste products, but also monitors for any contaminants in the various systems and is capable of removing them to some accepted level. In this context, an ALS system will have to handle the scope of all waste products associated with a manned mission, e.g.
product packaging, clothing, paper, grey water, faeces, urine
and other bodily wastes, inedible biomass and wasted food,
In addition, the complexity of these issues needs to be defined for each leg of the mission, outbound journey, the stay on Mars and return journey to Earth. For we might recognise that the system requirements for each leg might differ both in terms of the environment and duration, such that each will have a distinct goal for recycling some specific resources, e.g. air and water, in the absence of any in-situ alternatives. However, while any under estimation could be life threatening, any over estimation might lead to unnecessary mass that would affect fuel requirements. This said, NASA has recently outline a plan called the ‘Mars Ice Home’ that would be an inflatable, inner-tube-like compartment, which when inflated would be covered with a thick sheet of protective ice, as illustrated below.
The materials of the Ice Home will be designed to withstand many years of use in the harsh Martian environment, including ultraviolet radiation, charged-particle radiation, as well as dust storms. It will also be designed to be lightweight to minimise the payload mass and be deployed using simple robotic drones, then filled with water before the crew arrives. The next illustration provides a little more technical detail.
But why do we need life support systems?
While this might initially appear to be a rather stupid question, as any ALS system is clearly required to keep the crew alive while on Mars or in-transit, it is actually alluding to a different question:
Why do we need to send people to Mars?
We already know that we can send unmanned missions to Mars, e.g. Curiosity Rover or InSight Lander, to undertake important exploratory work before we necessarily send people. We might also assume that an extended manned mission to Mars might be preceded by several robotic missions that establish and test some of the key ALS systems, as well as the small system needed to produce the propellant for the return trip to Earth. However, in terms of a competitive ‘Race to Mars’ between nations and possibly private companies, there may be a temptation to shortcut the number of preliminary unmanned missions in order to go down in history as the first manned mission to Mars. Equally, if we put the issue of long term colonisation and the idea of having a backup plan for planet Earth to one side, we might also consider that we will probably send people into space and other worlds for two other more basic reasons. First, simply because of the desire to learn about the wider universe and, second, a growing economic necessity to exploit resources beyond Earth. In this respect, the goal of any future manned mission to Mars will not be to just sit inside the relative safety of the main habitat supported by the ALS system, but rather to extend the scope of the ALS systems to allow the crew to enter and move around a variety of external environments, either for exploration or repair missions. These external missions will require both individual survival suits and vehicles, possibly for in-space and on-Mars exploration, which will add to the mission payload and its overall complexity. We might also realise that these exploratory missions will not be sight-seeing expeditions, but rather part of some discovery program, e.g. scientific or commercial in scope, which will also require more equipment to be added to the mission payload.
So will we send people to Mars?
Clearly nations and private companies have now set their sights on Mars and return trips to the Moon, such that we might reasonably assume that humans will renew their exploration of the solar system in the 21st century with increasing success and sophistication. However, all the previous discussions have deliberately focused on the technical difficulties of such an undertaking rather than simply adding to the marketing hype before such possibilities can be realised. This stated, it is believed that the exploration of space will be one of the most important components of the brave new worlds being discussed. While still at an early stage, space exploration has the potential to be a key catalyst for much technical innovation, which in-turn might reinvigorate and refine the scope of a ‘global’ economy, at least, from the perspective of a few developed nations. However, humanity’s physical exploration of the wider universe, even when primarily limited to the solar system, may not only profoundly change the scope of the human ecosystem encompassing its social, economic and political institutions, but the very nature of humanity. For while space exploration may result in the colonisation of ‘other worlds’, it may be realised that these worlds are not really that suitable for long-term human colonisation given the incompatibility of low-gravity, unbreathable atmosphere and incompatible temperatures. For within the solar system, all planets and moons appear to provide no natural environment for humans to live outside of the confines of an enclosed ALS habitat, such that they may only become locations where key resources can be replenished when far from Earth. If so, large rotating space-stations may offer a better environment by simulating Earth’s [1g] gravity, such that they may prove to be a better environment in which to live and explore space. However, such speculation will require technology developments that extend beyond the 21st century, but we shall save the speculation on these issues to the final discussion entitled ‘A Future in Space’ . However, before this, we need to consider the increasing potential role of AI-telepresence systems in the context of future space exploration.