What's inside modern Space suits?
Anatomy of Advanced Space Suit Designs
🔭 Space Trivia
OV-099, OV-101, OV-102, OV-103, OV-104, OV-105 are designations of what?
The right answer is provided at the end of this article, with more details.
Modern space suits are a testament to human ingenuity and technological advancement, offering a delicate balance between life support and mobility. In this article, we will delve into the key features and technologies that make these suits a marvel of engineering.
Pressure Garments: The Heart of the Suit
At the core of every space suit is a pressure garment, designed to maintain a life-sustaining environment for astronauts in the vacuum of space. This garment consists of multiple layers, each serving a specific purpose.
Layers of a Pressure Garment
A good space suit should allow the wearer to move freely without feeling restricted. Most designs aim to maintain a constant volume regardless of the wearer's movements. This is important because changing the volume of a space suit under constant pressure requires extra effort.
For example, if bending a joint reduces the suit's volume, the astronaut must exert more effort each time they bend the joint, and they need to apply force to keep the joint bent. Even if this force is small, it can be tiring and hinder delicate movements. While it's generally true that suits are more flexible at lower pressures, life support requirements set a minimum internal pressure. So, to reduce the effort needed, the best option is to minimize volume changes.
To achieve this the most common solution involves using multiple layers. The innermost layer, the bladder, is a rubbery, airtight layer similar to a balloon. Outside the bladder is the restraint layer, which gives the suit its shape. Since the bladder is larger than the restraint layer, the restraint layer bears the pressure stresses. The bladder, not being under pressure, won't burst like a balloon even if punctured.
The restraint layer is designed so that bending a joint causes pockets of fabric, known as "gores," to open up on the outside of the joint. Simultaneously, folds called "convolutes" form on the inside of the joint. The gores compensate for the lost volume inside the joint, maintaining the suit's nearly constant volume. However, once the gores are fully open, bending the joint further requires a significant amount of effort.
So, all in all, we have 4 sets of layers described below—
Innermost Layer - Liquid Cooling and Ventilation Garment (LCVG): The LCVG is a form-fitting garment worn by the astronaut. It contains tubing through which cool water circulates, regulating the astronaut's body temperature. Additionally, it provides ventilation to remove excess heat and moisture.
Pressure Bladder: The pressure bladder is the second layer, made of rubberized material. Its primary function is to create a pressurized environment around the astronaut's body, preventing bodily fluids from boiling in the vacuum of space.
Restraint Layer: This is situated between the pressure bladder and the outer layers, helps maintain the shape of the suit, and distributes pressure evenly across the astronaut's body.
Outer Layers - Thermal Micrometeoroid Garment (TMG): These consist of multiple layers collectively known as the Thermal Micrometeoroid Garment. This serves multiple purposes including providing protection from extreme temperature and micrometeoroid impacts. The TMG consists of multiple layers of advanced materials like Mylar, Kevlar, and Nomex.
Example: Extravehicular Mobility Unit (EMU):
The EMU, used by NASA for spacewalks, is an excellent example of a spacesuit with pressure garments. It incorporates all the mentioned layers, providing astronauts with a life-supporting environment in the harsh conditions of space. Developed during the Apollo program, the EMU has undergone continuous improvement, with input from astronauts and engineers to enhance comfort, mobility, and safety.
The Apollo/Skylab A7L suit included eleven layers in all: an inner liner, a LCVG, a pressure bladder, a restraint layer, another liner, and a Thermal Micrometeoroid Garment consisting of five aluminized insulation layers and an external layer of white Ortho-Fabric. This space suit is capable of protecting the astronaut from temperatures ranging from −156 °C to 121 °C.
Types of Pressure Garments:
Soft Suits:
Description: Soft suits are flexible and more comfortable for astronauts, resembling airtight coveralls. They use a constant-volume, gas-pressurized design, meaning they maintain a consistent pressure by using a gas, typically oxygen.
Application: Soft suits are suitable for intravehicular activities, such as inside spacecraft, where full mobility isn't as critical.
Hard Suits:
Description: Hard suits have a rigid exoskeleton that provides structural support. They are often used for more physically demanding extravehicular activities (EVAs) on the lunar or planetary surfaces.
Application: Hard suits offer enhanced mobility and protection in environments where a soft suit might be insufficient.
The development of pressure garments can be traced back to the early days of space exploration. Pioneering work by individuals like Wiley Post and Dr. Paul Webb laid the foundation for understanding the physiological challenges faced in space. Over the years, this technology has evolved, with contributions from NASA, the Russian Space Agency, and other international space organizations.
Advanced Materials for Durability and Flexibility
Spacesuits must withstand the harsh conditions of space, including extreme temperatures, micrometeoroid impacts, and radiation. To achieve this, modern space suits incorporate advanced materials like Nomex, Kevlar, and Gore-Tex. These materials provide durability, flame resistance, and protection against abrasions.
Kevlar, in particular, is used in the outer layers of the suit to shield astronauts from micrometeoroid impacts. Developed by chemist Stephanie Kwolek at DuPont in 1965, Kevlar has since become a staple in space suit design, offering remarkable strength-to-weight ratios.
Beta cloth, a fire-resistant silica fiber fabric, was crucial in making Apollo/Skylab A7L space suits and other specialized gear. Composed of woven silica fibers, it doesn't burn and melts only at high temperatures. Teflon coating adds durability. Its tight weave makes it resistant to atomic oxygen exposure, serving as an outer layer in space applications like the Space Shuttle and the International Space Station. It was also used in the Skylab shower enclosure and extensively covered the Space Shuttle payload bay. Beta cloth is even utilized on the Curiosity Mars rover.
Beta cloth was incorporated into NASA space suits after the deadly 1967 Apollo 1 launch pad fire, in which the astronauts' nylon suits burned through. After the fire, NASA demanded any potentially flammable materials be removed from both the spacecraft and space suits.
Gore-Tex, a waterproof and breathable material, is utilized in the suit's outer layer to regulate temperature and manage moisture. Developed by Robert W. Gore in 1969, this material has found applications beyond space suits, becoming synonymous with high-performance outerwear. The spacesuits used during the NASA’s Space shuttle missions benefitted immensely from Gore-Tex material.
Mobility and Joint Articulation
Astronauts need to perform a wide range of tasks in space, from conducting experiments to repairing spacecraft. To facilitate mobility, space suits are equipped with joint articulation mechanisms. The joints, often called "hard joints," use bearings and mechanical linkages to allow astronauts to move their limbs freely.
The development of joint articulation mechanisms can be attributed to the tireless efforts of engineers and designers at NASA's Johnson Space Center. The Apollo program marked a significant milestone with the introduction of the Extravehicular Mobility Unit (EMU), featuring a redesigned joint design for enhanced flexibility. Subsequent improvements and refinements have been made to address the challenges posed by the vacuum of space.
A flexibility rating is a numerical measure that shows what percentage of movements a person can make in a spacesuit, compared to the movements they could make without the suit.
For example, the NASA Ames Research Center experimental AX-5 hard-shell space suit had a flexibility rating of 95%. The wearer could move into 95% of the positions they could without the suit on.
Life Support Systems: Breathing in Space
Breathing in the vacuum of space requires a sophisticated life support system. Space suits are equipped with a Primary Life Support System (PLSS) that includes components such as a backpack, oxygen tanks, and a system for removing carbon dioxide.
The development of life support systems can be credited to the work of individuals like Alan Shepard, the first American in space, who recognized the need for a reliable breathing apparatus during his historic flight in 1961. Over the years, engineers and scientists have continuously refined these systems, incorporating advancements in technology to ensure astronaut safety and comfort during extravehicular activities.
In our next part, we will cover this in further detail as well as more fascinating stuffs related to space suits.
🔭Answer to the Space Trivia:
The designations OV-099, OV-101, OV-102, OV-103, OV-104, and OV-105 refer to the space shuttles of NASA's Space Shuttle program. Each OV (Orbiter Vehicle) designation corresponds to a specific space shuttle:
OV-099: Space Shuttle Challenger
OV-101: Space Shuttle Enterprise (used for atmospheric testing and never flown in space)
OV-102: Space Shuttle Columbia
OV-103: Space Shuttle Discovery
OV-104: Space Shuttle Atlantis
OV-105: Space Shuttle Endeavour