How do Spacesuits Work?

A spacesuit is far more than mere clothing for astronauts during spacewalks; it functions as a fully equipped, one-person spacecraft. Officially known as the Extravehicular Mobility Unit, or EMU, this advanced suit is designed for use on the space shuttle and the International Space Station, it should allow astronauts to move freely and efficiently within the suit. The spacesuit is essential for protecting astronauts from the numerous dangers present in the extreme conditions of outer space.

Figure 1. Diagram of Spacesuit (Nssa.gov.bh, 2019)

Spacesuit Basics

When it comes to the components of a spacesuit, the Maximum Absorption Garment (MAG) is responsible for collecting urine produced by the astronaut. Since it takes too much time to pressurize and depressurize the aircrafts, astronauts cannot simply go to the bathroom a human on earth would, instead, each spacewalking astronaut wears a large, absorbent diaper to collect urine and feces while in the space suit which is disposed of when the spacewalk is over. Secondly, the Liquid Cooling and Ventilation Garment (LCVG) helps remove excess body heat generated during spacewalks, laced with thin plastic tubes. cool water flows through these tubes to remove the heat produced by the astronaut. Thirdly, the EMU Electrical Harness (EEH) facilitates connections for communication systems and bio-instrumentation, while the Communications Carrier Assembly (CCA) houses the microphones and earphones used for communication.

The Lower Torso Assembly (LTA) makes up the lower half of the Extravehicular Mobility Unit (EMU) which includes the pants, knee and ankle joints, boots, and lower waist. The Hard Upper Torso (HUT) is a rigid fiberglass shell that supports various structures such as the arms, torso, helmet, life-support backpack, and control module. Additional components include the arms, outer and inner gloves, and helmets.

Moreover, the Extravehicular Visor Assembly (EVA) protects astronauts from bright sunlight, and the In-suit Drink Bag (IDB) provides drinking water during spacewalks. 

The most important component of the entire space suit is the Primary Life Support Subsystem (PLSS, which  supplies oxygen, power, carbon dioxide removal, cooling water, radio equipment, and a warning system. In addition, the Secondary Oxygen Pack (SOP) serves as an emergency supply of oxygen, while the Display and Control Module (DCM) features the controls and displays necessary to operate the PLSS.

Evolution of spacesuits

Figure 2. Space Suits Through Time (Ramirez, 2016)

Yuri Gagarin’s Training Suit - (1960)

Yuri Gagarin, the first human to travel into space, wore this training suit during his preparation for the historic Vostok 1 mission in 1961. His suit was designed for mobility and comfort, helping him to be “light-footed” during training exercises and simulations. It had various pockets for carrying essential tools and instruments during training ‌(Si.edu, 2021).

Alan Shepard's Mercury Pressure Suit - (1961)

This was first worn during his historic flight aboard Freedom 7 in 1961. It was pressurized to counteract the vacuum of space, preventing bodily fluids from boiling in the absence of atmospheric pressure. Unlike the Gagarin spacesuit, this suit contained a life support system that provided oxygen and removed carbon dioxide (Si.edu, 2025).

Edward White's Helmet - (1965)

Worn during his historic spacewalk on June 3, 1965 during the Gemini 4 mission, the helmet was made from a lightweight, high-strength material to withstand the harsh conditions of space, including extreme temperatures and micrometeoroid impacts. The featured gold-coated visor protected White's eyes from sun’s glare but still allowed vision. It also allowed White to communicate with astronaut James McDivitt during his spacewalk (NASA, 2023).

Neil Armstrong's Apollo 11 Spacesuit - (1969)

Neil Armstrong's Apollo 11 spacesuit, worn during the historic lunar landing in 1969, is an iconic piece of space exploration history. Key features include multiple layers for insulation and protection and a Portable Life Support System (PLSS). Designed for mobility, the suit allowed astronauts to move and operate equipment on the Moon, with specially designed boots for traction and insulation (Bennett, 2019).

SpaceX Dragon Launch and Entry Suits - (2016)

The SpaceX Dragon launch and entry suits, introduced in 2016, are designed for the Crew Dragon spacecraft. With a sleek, form-fitting design, these lightweight suits ensure comfort, mobility, and protection against heat and pressure. Used during the Demo-2 mission in May 2020, these suits mark a milestone in U.S. human spaceflight and represent a new era of commercial space travel, highlighting the partnership between NASA and SpaceX (Watch, 2024).

Works Cited

Bennett, J. (2019). Neil Armstrong’s Restored Spacesuit Put Back on Display at the Smithsonian’s National Air and Space Museum. [online] Smithsonian Magazine. Available at: https://www.smithsonianmag.com/smart-news/neil-armstrongs-restored-spacesuit-put-back-display-smithsonians-national-air-and-space-museum-180972654/ [Accessed 22 Jan. 2025].

NASA. (2023). Ed White - NASA. [online] Available at: https://www.nasa.gov/gallery/ed-white/ [Accessed 22 Jan. 2025].

Nssa.gov.bh. (2019). Astronauts – NSSA. [online] Available at: https://www.nssa.gov.bh/astronauts/ [Accessed 26 Dec. 2024].

Ramirez, F. (2016). How NASA’s space suits have changed through the years. [online] Chron. Available at: https://www.chron.com/news/science-environment/article/How-NASA-s-space-suits-have-changed-through-the-10601457.php [Accessed 26 Dec. 2024].

Si.edu. (2025). Pressure Suit, Mercury, Shepard, MR-3, Flown. [online] Available at: https://airandspace.si.edu/collection-objects/pressure-suit-mercury-shepard-mr-3-flown/nasm_A19770563000 [Accessed 22 Jan. 2025].

‌Si.edu. (2021). Yuri Gagarin Training Spacesuit | National Air and Space Museum. [online] Available at: https://airandspace.si.edu/multimedia-gallery/i19961104001-nasm2018-10130-sjpg [Accessed 22 Jan. 2025].

Watch (2024). Watch SpaceX Launch NASA’s CRS-16 and have a failed landing attempt! [online] YouTube. Available at: https://www.youtube.com/watch?v=r2R9o6hzB3M [Accessed 22 Jan. 2025].