Spacesuits keep astronauts alive by managing oxygen, temperature, pressure, and carbon dioxide all at once.
This article explains how do spacesuits remove carbon dioxide, what hardware does the work, and why the process is critical during spacewalks.
Why Carbon Dioxide Removal Matters in a Spacesuit
When an astronaut exhales inside a spacesuit, carbon dioxide quickly builds up in the helmet and breathing loop.
In a sealed system, even a small rise in CO2 can cause headaches, dizziness, shortness of breath, and impaired judgment.
Unlike on Earth, there is no open air to dilute exhaled gases.
A spacesuit must continuously clean the breathing atmosphere while keeping oxygen available at safe pressure.
This makes carbon dioxide control one of the most important functions of extra-vehicular activity, or EVA, life support.
How Do Spacesuits Remove Carbon Dioxide?
Most spacesuits remove carbon dioxide by pulling the astronaut’s breathing gas through a carbon dioxide scrubber.
The scrubber contains chemical or physical media that trap CO2 molecules before the cleaned gas is returned for breathing.
The process is usually part of a closed or semi-closed loop called the Portable Life Support System, or PLSS.
The astronaut exhales into the helmet and breathing circuit, fans move the gas through the system, and the scrubber removes carbon dioxide along with moisture and trace contaminants.
What the scrubber does
- Collects exhaled gas from the helmet and suit ventilation loop
- Uses absorbent material to capture carbon dioxide
- Returns cleaner gas to the breathing environment
- Helps prevent CO2 from pooling around the astronaut’s face
What Materials Capture Carbon Dioxide?
Spacesuit scrubbers have used different materials over time, but the basic principle is the same: bind carbon dioxide so it cannot re-enter the breathing air.
Some systems use consumable chemical absorbents, while newer designs aim for regenerable solutions.
Lithium hydroxide canisters
Lithium hydroxide is a classic CO2 absorbent used in spacecraft and life support applications.
It reacts chemically with carbon dioxide to form stable compounds, removing CO2 from the air stream.
Because the material is consumed during the reaction, the canister must eventually be replaced.
Metal oxide and regenerable sorbents
Some life support systems use regenerable sorbents, such as metal oxide-based materials or advanced adsorption media.
These are designed to capture CO2 and later release it under controlled conditions, reducing resupply needs for longer missions.
Ventilation fans and airflow paths
Even the best absorbent cannot work if exhaled gas sits still.
Small fans and carefully designed ducts keep air moving through the suit so carbon dioxide is delivered to the scrubber before it accumulates near the helmet.
How the Portable Life Support System Works
The Portable Life Support System is the backpack-like unit that powers many modern spacesuits.
It houses oxygen tanks, cooling hardware, pumps, communications gear, and the carbon dioxide removal system.
Inside the PLSS, the suit’s ventilation loop draws moist exhaled air away from the astronaut’s face.
The gas passes through components that remove water vapor and carbon dioxide, then the cleaned stream is mixed with oxygen and recirculated.
Main steps in the breathing loop
- The astronaut exhales into the helmet and suit circulation path.
- Fans move the gas through the ventilation system.
- A separator removes water vapor and condensation.
- A CO2 scrubber captures carbon dioxide from the airflow.
- Conditioned gas returns to the suit for reuse.
Why Microgravity Makes Carbon Dioxide Control Harder
On Earth, warm exhaled air rises and mixes with room air.
In microgravity, that natural convection does not happen, so carbon dioxide can linger around the astronaut’s face unless it is actively moved away.
This is why ventilation inside a spacesuit is so important.
Without forced airflow, astronauts could inhale their own exhaled CO2 repeatedly.
Even if the total amount of gas in the suit seems small, localized pockets around the nose and mouth can become hazardous.
What Happens If Carbon Dioxide Is Not Removed Properly?
Carbon dioxide buildup in a spacesuit can become dangerous quickly.
Astronauts may first notice a stuffy feeling or increased breathing effort, then progress to headache, fatigue, and confusion if the level continues to rise.
In extreme cases, elevated CO2 can lead to hypercapnia, a condition caused by too much carbon dioxide in the bloodstream.
For that reason, spacesuit life support systems include monitoring, redundancy, and strict operational limits.
- Early signs: headache, flushed skin, elevated breathing rate
- Moderate exposure: nausea, anxiety, reduced concentration
- Severe exposure: confusion, loss of coordination, medical emergency
How Do NASA Spacesuits Compare With Other Systems?
NASA spacesuits, including the Extravehicular Mobility Unit, rely on the PLSS to manage breathing gas during spacewalks.
The International Space Station also uses separate environmental control and life support systems inside the station, but those do not replace the suit’s own CO2 removal capability during EVA.
Russian Orlan suits and other EVA suits use similar principles: forced ventilation, absorbent scrubbers, and controlled gas circulation.
The exact engineering differs, but all modern spacesuits must solve the same problem of keeping carbon dioxide below safe limits in a sealed, wearable environment.
How Do Engineers Improve Carbon Dioxide Removal in Future Spacesuits?
Future suits are being designed for longer, more demanding missions, including lunar surface operations and deep-space exploration.
That puts more pressure on carbon dioxide removal systems to be lighter, more efficient, and easier to maintain.
Engineers are working on better airflow management, lower-pressure-drop scrubbers, and regenerable sorbents that reduce waste.
They are also improving sensors so the suit can detect CO2 issues earlier and alert the astronaut before symptoms begin.
Design goals for next-generation systems
- Lower power use for fans and pumps
- Higher carbon dioxide capture efficiency
- Reduced mass and volume
- Longer operating life without replacement
- Better monitoring and fault detection
What Else Does a Spacesuit Life Support System Remove?
Carbon dioxide is only one part of the problem.
Spacesuit life support systems also control heat, humidity, and contaminants.
Moisture removal matters because water vapor can condense and interfere with sensors, airflow, and comfort.
By balancing oxygen supply, CO2 removal, and temperature control, the spacesuit creates a habitable microenvironment around the astronaut.
The result is a wearable spacecraft that can support work outside the station, lunar lander, or vehicle.
Key Takeaways About Spacesuit Carbon Dioxide Removal
- Spacesuits remove carbon dioxide using scrubbers in the life support system.
- Fans and ventilation keep exhaled gas moving through the scrubber.
- Chemical absorbents such as lithium hydroxide or regenerable sorbents capture CO2.
- Microgravity makes forced airflow essential because gas does not naturally rise or disperse.
- Reliable CO2 removal prevents hypercapnia and supports safe EVA operations.