Recently, ISRO Chairman S. Somanath stated that ISRO will be independently developing the Environmental Control and Life Support System (ECLSS) for the Gaganyaan mission. The development of the ECLSS for the forthcoming Gaganyaan mission heralds a transformative phase in the country's space exploration narrative. The system is being termed pivotal by experts for sustaining human life beyond the Earth's confines. ISRO's determination to craft this system independently will be a major achievement for ISRO.
“The ECLSS, a technological cornerstone, intricately manages air quality and water supply essential for astronaut survival in the challenging environment of space. Through meticulous mechanisms incorporating activated charcoal beds, catalytic oxidizers, and molecular sieves, this system impeccably regulates cabin air quality, ensuring a breathable atmosphere for the crew. The Oxygen Generation System, employing cutting-edge electrolysis, separates water molecules into oxygen and hydrogen gas. This closed-loop process ensures a constant oxygen supply for breathing while efficiently utilizing hydrogen byproducts to generate water. Additionally, the Water Recovery System reclaims and purifies water from diverse sources, including crew members' urine and cabin humidity,” explained Srimathy Kesan, founder and CEO of Space Kidz India, which is into design, fabrication and launch of small satellites, spacecraft and ground systems
Explaining further, Kesan said that NASA (United States), Russia's Roscosmos (Russia), ESA (European Space Agency), and other space agencies have contributed significantly to the development of their respective ECLSS systems through decades of research, collaboration, and technological innovations. “NASA's system on the International Space Station (ISS), for instance, involves various components for air revitalization, water recovery, and oxygen generation. Similarly, Roscosmos and ESA have designed and implemented their systems, each with its unique technological approaches. Of course, all these space agencies have tested and tried this in ISS physically for many years and ISRO, India, is a baby which is yet to try the systems physically,” added Kesan.
This decision by ISRO to develop the ECLSS has primarily been due to the reluctance of many other countries to share technology and research. So what is ECLSS? Living beings require air, water and food for survival. On our planet, different parts of nature take care of these needs. Plants help keep our air clean by adding oxygen and removing carbon dioxide. Lakes, rivers and groundwater supply our drinking water. The soil nourishes the plants we grow and consume. The Earth operates like a closed system for matter, meaning it does not exchange matter with space. Everything gets recycled within our global ecosystem, except for a small amount of meteorites and space dust that occasionally reach Earth.
About 400 kilometres above Earth is the low-Earth-orbit where astronauts need air, water and food. Unlike on Earth, there are no ecosystems in space to provide these essentials. Instead, astronauts depend on life-support systems to handle their air, water and waste.
“The ECLSS is crucial for astronaut survival. It is a network of connected machines working together to supply astronauts with breathable air and drinking water. Similar to Earth, astronauts in the Space Capsule breathe in oxygen and exhale carbon dioxide. Yet, it is crucial to maintain the right balance of oxygen and carbon dioxide in the air they breathe. Excessive carbon dioxide can impact an astronaut’s mental and physical well-being. That is why special machines, as part of the ECLSS, work to remove excess CO2 from the air”, space expert Girish Linganna said.
“Taking CO2 out of the air is known as carbon capture or carbon scrubbing. Machines, called scrubbers, handle the removal of excess CO2. These scrubbers work like filters you may have in a fish tank, containing a substance called zeolite. Zeolite easily attaches to CO2, taking it out of the air. The waste CO2 from the scrubbers used to be released into space. However, in 2012, the Carbon Dioxide Reduction System, also known as the Sabatier System, was implemented in the ECLSS. This system utilizes waste carbon dioxide and hydrogen gases to produce water. Additionally, the Sabatier reaction also produces methane gas, which humans cannot breathe and, so, it is expelled into space,” Linganna explained.
Linganna added that the air quality is not solely determined by the levels of oxygen and CO2. There are also various other gases present in the air, some of which can slowly be released by different materials. These gases, even though they may be colourless and odourless, can be toxic and need to be eliminated. Additionally, when humidity is high, microorganisms can thrive and spread. The air systems in space capsules control humidity and are capable of filtering out microorganisms that could otherwise multiply and cause illnesses.
“Proper ventilation is crucial in space capsules due to the different way air flows in microgravity. For instance, sleeping astronauts require fans near their faces to prevent the formation of CO2 bubbles around them. This is essential as it would be similar to placing one’s head inside a plastic bag, which we know is extremely dangerous. The ECLSS has the ability to recycle approximately 90 per cent of the water utilized by astronauts. However, the recycled water cannot be consumed immediately as it requires purification to ensure that it is safe to drink. The Water Processor Assembly is responsible for collecting water from various sources, including the Sabatier System, used water from washing, water vapour from sweat and even urine. It processes and purifies this collected water to make it suitable for drinking, preparing meals, handwashing and showering. Additionally, this purified water is also used in the production of oxygen by the Oxygen Generating Assembly,” added Linganna.
Experts point out that items such as packaging, containers, plastic bags, hygiene wipes, used clothing and faecal waste make up solid waste in space. The waste is collected and stored until it can be transferred to a vehicle designated for waste disposal. When this waste-filled vehicle re-enters Earth’s atmosphere, both the waste and the storage system are burned up and destroyed. Thus, the waste management process in space functions as an open system.
NASA is working towards minimizing solid waste on the ISS by adopting strategies to reduce packaging. Additionally, they are exploring methods to repurpose packaging materials in space. “One idea is to utilize packaging as building materials for shelters by either using it as it is or melting it down to create tiles. This approach holds significance for upcoming long-duration missions, such as those aimed at reaching Mars. The ECLSS is a vital component of space missions and has been developed by various countries and space agencies, who have collaborated and made significant advancements in ECLSS technology to ensure the sustainability of life support systems in space missions,” remarked Linganna.
