A spacesuit is not a single piece of clothing; it is a small personal spacecraft.
Here is how astronauts put on spacesuits, why the process takes so long, and what has to happen before they can safely leave the cabin.
What a spacesuit is designed to do
A modern NASA spacesuit, formally called the Extravehicular Mobility Unit (EMU), protects astronauts during spacewalks by supplying oxygen, removing carbon dioxide, maintaining pressure, and shielding the body from the vacuum of space.
It also provides thermal control, communications, vision protection, and mobility for work outside the International Space Station.
Putting it on is carefully choreographed because each layer, seal, and connector has a safety function.
Even a small mistake can affect mobility, suit pressure, or life support.
How do astronauts put on spacesuits?
In practice, astronauts put on spacesuits in a sequence that starts long before they step into the suit.
The process usually takes place in a crew equipment room or airlock area and involves suit cooling, medical checks, pre-breathing procedures, and multiple buddy checks.
Astronauts often get help from crewmates or ground teams, especially with heavier components like the hard upper torso and gloves.
For a spacewalk, the suit is assembled in parts rather than worn all at once like a jacket.
The main sequence is designed to reduce decompression sickness, ensure a proper fit, and verify that the suit can support life outside the spacecraft.
Pre-breathing and safety checks before suiting up
Before entering the suit, astronauts must reduce nitrogen in their bloodstream to prevent decompression sickness, sometimes called “the bends.” To do this, they typically breathe pure oxygen for a period of time before the spacewalk.
This step is especially important because the suit operates at a lower pressure than the station cabin.
- Medical and operational review: The crew confirms fitness, task plans, and any suit-specific concerns.
- Oxygen pre-breathe: Astronauts inhale oxygen to help flush nitrogen from the body.
- Equipment inspection: Suit components, hoses, cooling lines, and communications systems are checked for damage or wear.
- Fit confirmation: Engineers and crew verify the suit size and assembly configuration for each astronaut.
This preparation can take hours, but it is essential for safety and performance.
Getting into the suit: the main steps
1. Start with the liquid cooling and ventilation garment
Astronauts begin with a close-fitting liquid cooling and ventilation garment, often compared to athletic wear.
This undergarment circulates water through small tubes to remove body heat during the spacewalk and supports ventilation around the body.
It also helps manage humidity inside the suit.
2. Put on the lower suit assembly
Next comes the lower portion of the suit, which includes the waist area, legs, and boots depending on the suit design.
Astronauts step into or climb into this section while seated or positioned in a suit donning frame.
The goal is to align the body correctly before the rigid parts are joined.
3. Attach the hard upper torso
The hard upper torso is a rigid shell that forms the core of the suit.
Astronauts usually back into it and then secure themselves into place.
This component holds the shoulder bearings, chest controls, connection ports, and much of the life-support interface.
Because of its size and weight, crewmates may help guide it into position.
4. Install gloves, helmet, and seals
Once the torso is secured, astronauts attach gloves and the helmet assembly.
The gloves must seal tightly while still allowing dexterity for tools and handholds.
The helmet locks into place and connects to the communications and ventilation system.
Neck rings, wrist seals, and visor systems are checked for proper seating.
5. Connect life support and communications
The Portable Life Support System, or PLSS, is attached to the back of the suit.
It supplies oxygen, removes carbon dioxide, and controls cooling.
Astronauts then connect communication lines and verify radio contact with the crew and mission control.
At this stage, every connector has to be confirmed by procedure, not guesswork.
Why the suit is assembled in a specific order
The sequence matters because the suit must form a pressure-tight environment around the astronaut’s body.
If the undergarment, torso, seals, and life-support connections are not assembled correctly, the system cannot maintain the environment needed for a spacewalk.
The order also reduces the risk of pinching, misalignment, or contamination around critical seals.
Spacesuits are engineered for reliability, but they are not forgiving.
A twisted glove cuff or poorly seated connector can create problems once the astronaut is outside the station.
What happens after the suit is on?
After donning, astronauts undergo leak checks and functional tests.
They verify pressure integrity, communications, cooling flow, display readings, and mobility.
They also practice moving arms, bending joints, and confirming that the suit fits well enough for the specific tasks planned outside.
- Pressure checks: Confirm the suit can hold the correct internal pressure.
- Cooling checks: Ensure water circulation is working through the garment.
- Communications checks: Test microphone, speaker, and mission audio links.
- Mobility checks: Confirm hand movement, arm reach, and body rotation.
Only after these steps do astronauts enter the airlock, depressurize, and prepare to open the hatch for the spacewalk.
Who helps astronauts put on spacesuits?
Astronauts rarely suit up entirely alone.
Other crew members often assist with positioning, connector alignment, and final inspections.
On missions with more complex operations, ground teams provide procedures and realtime support.
This teamwork is not optional; it reduces error and keeps the process efficient.
At NASA, suit technicians and flight surgeons also play important roles on the ground before launch, ensuring each astronaut has the correct fit, configuration, and medical clearance.
In that sense, putting on a spacesuit is the end of a much larger preparation chain.
How long does it take to put on a spacesuit?
The donning process can take well over an hour, and the full pre-spacewalk routine often stretches much longer because of oxygen pre-breathing and checks.
The exact timing depends on the mission, the suit model, the astronaut’s fit, and the planned work outside the spacecraft.
The process is intentionally slow because every step supports astronaut safety.
Why spacesuit donning is a critical mission skill
Understanding how astronauts put on spacesuits reveals how much engineering and procedure goes into a single spacewalk.
A suit is not just worn; it is assembled, tested, and certified around the astronaut’s body so it can function as a life-support system in the harsh environment of space.
That is why the process demands patience, precision, and teamwork.
Every latch, hose, seal, and pressure check helps transform a crew member into a mobile explorer capable of working outside Earth’s atmosphere.