How does the Gaganyaan’s Life-Support System Operate?

Why in News?

ISRO confirmed that approximately 90% of Gaganyaan’s development work is complete, with the crewed launch now rescheduled to the first quarter of 2027. A key milestone is the indigenous development of the ECLSS (Environmental Control and Life Support System).

What is the Environmental Control and Life Support System (ECLSS)?

• The ECLSS is the critical subsystem aboard a spacecraft that replicates Earth’s atmospheric conditions in the hostile environment of space. It manages breathable air, potable water, temperature, humidity, cabin pressure, waste handling, and fire safety needed to survive beyond Earth’s atmosphere.
  • For short-duration missions like Gaganyaan (3-7 days), all consumable supplies (oxygen, water, and food) are carried from Earth, and waste is stored in sealed containers for post-mission disposal. 
  • Long-duration missions (e.g., the International Space Station) recycle waste back into usable air and clean water through closed-loop systems.
• India’s development of the ECLSS is particularly significant: ISRO had no prior experience in building such a system, and despite extensive diplomatic efforts, no other space-faring nation agreed to transfer this technology. ISRO was therefore compelled to develop it entirely indigenously, making it one of the most challenging feats in the Gaganyaan programme.

How does Gaganyaan’s Life-Support System Work?

1. Air Revitalisation System (ARS): 

• In Earth’s atmosphere, carbon dioxide is naturally removed by photosynthesis and oceanic absorption. 
• In an enclosed spacecraft cabin, astronauts’ exhalation continuously increases the CO₂ concentration, which must be artificially managed. Elevated CO₂ levels cause hypercapnia, characterised by headaches, dizziness, and impaired cognitive function, which can be fatal if unchecked. 
• A healthy adult exhales approximately 1 kg of carbon dioxide per day at rest, and this increases substantially with physical exertion. The ARS performs three core functions: (i) supplying fresh oxygen, (ii) removing CO₂, and (iii) filtering trace contaminants and odours that accumulate in the enclosed cabin.
• In Gaganyaan, lithium hydroxide (LiOH) canisters are used to chemically absorb carbon dioxide. Each canister is also fitted with activated charcoal to adsorb cabin odours. A spent canister is replaced by the crew approximately every 20-24 hours.
• Oxygen is supplied from high-pressure gas bottles; a crew member requires approximately 0.84 kg of oxygen per day for baseline metabolic functions.

A critical design consideration in microgravity is the absence of natural convection. Without gravity-driven air circulation, pockets of lethal CO₂ or depleted oxygen can form around a crew member. Small fans within the ECLSS continuously circulate cabin air, serving as an artificial circulatory system to prevent such hazardous accumulations.

2. Pressure, Temperature and Humidity Control: 

• The Gaganyaan crew module is designed to maintain a cabin pressure of 101.3 kPa, equivalent to sea-level atmospheric pressure on Earth. This is achieved using electronic pressure sensors and safety valves that continuously balance oxygen and nitrogen levels. Any deviation from this range can cause barotrauma or hypoxia.
• Temperature is maintained between 20°C and 26°C, with relative humidity between 30% and 70%. The primary sources of heat inside the cabin are the metabolic body heat of astronauts (100-150 W per crew member) and continuously operating onboard electronics and avionics systems. An active cooling system circulates air through heat exchangers that radiate excess heat into the cold vacuum of space.
• Humidity management is equally critical. Too little humidity causes dry skin, eye irritation, and the risk of electrostatic discharge damaging sensitive electronics. Too much humidity encourages microbial growth and leads to condensation on electrical components, causing short-circuits or corrosion. Condensing units collect moisture from the air before it can accumulate to dangerous levels.

3. Water Supply and Management: 

• Water management in space poses unique challenges that do not exist on Earth. In microgravity, liquid does not pour or settle; it forms free-floating globules that can drift into electronics, causing short-circuits, or accidentally enter an astronaut’s respiratory tract if inhaled.
• In Gaganyaan, all drinking water is stored in specially designed pressurised pouches. Astronauts press the pouch to force water directly into their mouths, completely bypassing the need for gravity. Water is mechanically driven using pressurised bladder systems that prevent gas-liquid mixing, ensuring safe and controlled delivery.
• Since Gaganyaan is a short-duration mission, there is no onboard water recycling system. All potable water is carried from Earth. Long-duration missions such as those aboard the ISS recover water from urine and cabin humidity through regenerative life support systems — a technology ISRO will likely need for future deep-space or longer-duration missions.

4. Waste Management:

• Since gravity does not pull waste downward, liquid and solid waste do not follow predictable paths. Without active intervention, waste would float freely in the cabin, creating serious hygiene, health, and contamination hazards.
• In Gaganyaan, suction-based airflow systems are used for both liquid and solid waste collection. Urine is drawn through specially designed funnels using negative air pressure, while solid faecal matter is collected in specialised faecal collection bags. 
• All waste is then chemically treated to neutralise odours and inhibit bacterial growth, before being sealed in airtight containers for storage until the crew returns to Earth.

This approach prevents the buildup of toxic gases such as ammonia, controls microbial contamination, and maintains a hygienic environment throughout the mission duration.

5. Fire Detection and Suppression: 

• On Earth, gravity-driven convection causes hot gases to rise and flames to form a teardrop shape, making them predictable and easier to suppress. In microgravity, fire expands omnidirectionally into a sphere, is harder to contain, and produces significantly more toxic smoke in an enclosed cabin.
• In Gaganyaan, smoke detectors provide the first line of defence by triggering an audible alarm to alert the crew at the earliest stage of ignition. The primary suppression tool is a fine water mist extinguisher, which both cools the fire rapidly and physically scrubs toxic smoke particles from the cabin air. 

Key fact: Russia’s Soyuz spacecraft retains a last-resort option of depressurising the cabin to starve a fire of oxygen, but only after the crew has donned pressure suits.

What is Gaganyaan Mission?

• India’s first human spaceflight programme led by the Indian Space Research Organisation.
• Aim: To carry 3 astronauts (Vyomanauts) to Low Earth Orbit  (400 kilometres) for a short-duration mission (~3–7 days), and bring them back safely to Earth by landing in the Indian waters. 
• Launch: Crewed launch is scheduled for the first quarter of 2027. 
• Crew members: Astronauts have been shortlisted by the Indian Air Force (IAF) & ISRO, and trained with international collaboration. The crew will perform microgravity, technology demonstrations and other scientific experiments. 
• Launch Vehicle: Human-rated Launch Vehicle Mark 3 (LVM3)
• Human Space Flight Centre will coordinate the implementation of the project. 

Upon completion, India will become the fourth nation to conduct an independent human spaceflight after Russia, the United States and China.

Components of Gaganyaan Mission: 

• Crew Module (CM) and Service Module (SM): The Orbital Module of Gaganyaan consists of:
  • Crew Module (CM): Habitable capsule for astronauts.
  • Service Module (SM): Provides propulsion, power, avionics and thermal systems. 
• Crew Module Atmospheric Re-entry Experiment (CARE): CARE (2014) was a key precursor experiment launched using LVM3 (then GSLV Mk III). It validated the full-scale thermal protection and parachute systems essential for surviving the extreme heat of a sub-orbital re-entry, i.e., the capsule’s ability to withstand extreme temperatures (~1600°C+) during atmospheric re-entry.
• Crew Escape System (CES): CES is the emergency escape system to quickly separate the crew module from the rocket during launch failure. Pad Abort Test (PAT) successfully demonstrated the escape system. Further validated through Test Vehicle missions (TV-D1, TV-D2, etc.).
• Environmental Control and Life Support System (ECLSS): Engineering models of ECLSS have already been developed and tested. ECLSS ensures a habitable environment inside the crew module: Functions include- Maintain cabin pressure, Regulate oxygen levels, Remove carbon dioxide, Control temperature & humidity, Detect and suppress fire, Manage waste and air purification. 
• Vyom Mitra: ISRO’s female humanoid robot astronaut. Will fly in upcoming uncrewed mission before the crewed launch (~2027). It will test life-support systems and simulate human presence.

UPSC PYQ 2025

Q. Consider the following space missions: 

I. Axiom-4 

II. SpaDex 

III. Gaganyaan

How many of the space missions given above encourage and support microgravity research?

(a) Only one 

(b) Only two 

(c) All three 

(d) None 

Answer: (c)