How to keep humans alive on Mars - Abstract Surface Habitat ECLSS Conceptual Design

On July 1st, 2015, Mars One released the conceptual design of the Surface Habitat Environmental Control and Life Support Systems (ECLSS) performed by Paragon Space Development Corporation®. The ECLSS is required to support a human outpost on Mars and will create a safe environment for the Mars inhabitants, supplying them with clean air and water while recycling wastes. We hereby present a concise abstract of the independent Paragon report. The abstract was written by Mars One Round Three Candidates Josh Richards (AU), Oscar Mathews (US), and Ryan MacDonald (GB).

Summary — Paragon Space Development Corporation has conducted an initial conceptual design study outlining an Environmental Control and Life Support Systems (ECLSS) architecture that could be successfully employed to allow a sustained human presence on the surface of Mars. In-situ resource utilization reduces the requirement of life-support consumables during resupply missions significantly. The mass requirement of the ECLSS is found to be 7434 kg, necessitating increased efficiencies and developments in future studies to comply with anticipated Mars landing systems in the mid-2020s. Mars One will make use of this study to update its mission of establishing a permanent human settlement on Mars.

Background

In March 2013, Paragon Space Development Corporation was contracted by Mars One to conduct a conceptual design study of an Environmental Control and Life Support System (ECLSS) module – one of the key systems required to support a permanent human presence on Mars. This document provides an executive summary of the key findings and conclusions of Paragon’s work to-date. The full technical report is readily available from Mars One’s website.

Sustained Human Presence on Mars

Much like in Antarctica or aboard the International Space Station, human life is impossible in challenging environments without the aid of life support systems. Keeping a crew alive, comfortable and healthy is vital to ensuring the first Mars pioneers effectively carry out habitat operations at peak efficiency.



Both the crew and the systems within the outpost require a narrow range of conditions for optimal performance, summarized in Table 1. Note that these figures are for a single ECLSS module and habitat sustaining a crew of four, while under Mars One’s framework there will be two ECLSS modules and two habitats supporting each crew. This provides additional redundancy in case any key system requires maintenance.



Since shipping consumable resources from Earth is neither practical nor cost efficient, all breathable air and drinkable water will be produced locally using Martian resources. This approach, known as in-situ resource utilization (ISRU), is vital to the long term goal of self-sufficiency for humans on Mars.



Safety and redundancy were given the highest priority in the ECLSS design. Each ECLSS module can autonomously detect and recover from a fire (fine water mist fire suppression is recommended), self-regulate the environmental conditions of the habitat, as well as provide storage for 30 days of consumables in the event of the module going offline. This functionality has been designed to mitigate the effects of dust storms, where electrical power provided by the solar panels can be severely limited.

ECLSS Design Architecture

Mars One’s ECLSS has been designed by Paragon with a specific focus on simplicity, reliability and ruggedness, with mean repair time of all sub-systems minimized. All required life support functionality is provided by physical and chemical processes, designed to operate independently of atmospheric regeneration from plants/biomass.

Mass and volume requirements were relaxed in this initial study, with an aim to achieve the simplest possible design utilizing only existing materials, physical processes and fundamental technologies. Future reductions in the system mass and volume will require more complex and efficient product solutions, with increased development costs. The physical and electrical characteristics of an individual ECLSS module are displayed in Table 2, whilst Figure 1 illustrates the ECLSS modules’ overall layout and key subsystems, which are now summarized.

The In-Situ Resource Processing System (ISRPS) provides two key functions: water production from Martian regolith, and nitrogen/argon production from the Martian atmosphere. Regolith is heated to vaporize the water, which is then condensed and transferred to the Water Management System (WMS) for purification. Nitrogen/argon is separated from the predominantly CO2 atmosphere (~95%) by Joule-Thomson cooling to create liquid or solid CO2.

The WMS collects non-drinkable water from the ISRPS and excess humidity in the habitat to produce water suitable for drinking, food preparation and hygiene. The WMS also supplies water to the Air Management System (AMS) for oxygen production. Waste-water in the WMS is purified by passing through particulate filtration, activated carbon, an aqueous phase catalytic reactor and two ion exchange beds. Ultra-violet disinfectant lamps are fitted at each water distribution point in the habitat, as well as at three points within the WMS to reduce the risk of microbial contamination of the storage tanks.

The AMS controls CO2 levels using a four bed molecular sieve, produces oxygen via electrolysis of water, controls the absolute and partial pressures of different gases, detects and recovers from fires, removes particulate matter and contaminants and monitors overall air quality.

The Thermal Control System (TCS) is responsible for balancing the heat dissipated from electrical devices (~75% of all electricity) with losses to the surroundings. Active components such as liquid cooling loops and electrical resistance heaters are used alongside passive components (such as insulation and surface coatings) to achieve this.

Finally, the Wet Waste Processing System (WWPS) isolates human wet waste and extracts water by blowing dry air across one side of a humidity exchange membrane. The dried waste is stored for future recycling.

Figure 1: Mars One Habitat ECLSS Functional Layout

Conclusions and Future Work

Paragon’s Conceptual Design Study has identified a promising ECLSS architecture with local resources supplying all the consumable needs of the Mars One outpost. Further design studies will require a particular focus on the ECLSS mass, as the estimated payload mass of each ECLSS module (~7500 kg) is greater than initially envisioned. Mars One anticipates working with Lockheed Martin on a scaled up landing system, with improvements in the ECLSS design being driven by the landing system’s upper mass limit.

It was also identified that the ECLSS would receive insufficient power during the shortest day of the Martian year. Therefore a trade-off analysis is required to determine whether increasing the solar array size or increasing the air storage tank capacity is the most efficient solution.

Finally, it is expected that many of the ECLSS components could be manufactured via 3D printing, potentially reducing long-term resupply costs.