Astronauts --- Spacesuit --- The Current Spacesuit
Extravehicular Mobility Unit (EMU), which is the current spacesuit, is used for spacewalking from the shuttle and International Space Station.
Early spacesuits were individually tailored for each astronaut. In contrast, that the EMU has component pieces of varying sizes that can be put together to fit any given astronaut.
The EMU has a combination of soft and hard components to provide support, mobility and comfort.
The suit itself has 13 layers of material, including an inner cooling garment (two layers), pressure garment (two layers), thermal micrometeroid garment (eight layers) and outer cover (one layer).
The dimensions and facts of the EMU:
Weight - 127 kg on Earth
Thinkness - 0.48 cm, 13 layers
Atmosphere - 0.29 atm of pure oxygen
Volume - .125 to .153 m3
Component of the EMU
Major parts:
- Maximum Absorption Garment (MAG) - collects urine produced by the astronaut
- Liquid Cooling and Ventilation Garment (LCVG) - removes excess body heat produced by the astronaut during spacewalks
- EMU Electrical Harness (EEH) - provides connections for communications and bio-instruments
- Communications Carrier Assembly (CCA) - contains microphones and earphones for communications
- Lower Torso Assembly (LTA) - lower half of the EMU including pants, knee and ankle joints, boots and lower waist
- Hard Upper Torso (HUT) - hard fiberglass shell that supports several structures including the arms, torso, helmet, life-support backpack and control module
- Arms
- Gloves - outer and inner gloves
- Helmet
- Extravehicular Visor Assembly (EVA) - protects the astronaut from bright sunlight
- In-suit Drink Bag (IDB) - provides drinking water for the astronaut during the spacewalk
- Primary Life Support Subsystem (PLSS) - provides oxygen, power, carbon dioxide removal, cooling water, radio equipment and warning system
- Secondary Oxygen Pack (SOP) - provides emergency oxygen supply
- Display and Control Module (DCM) - displays and controls to run the PLSS
Accessories:
- Servicing and Cooling Umbilical (SCU) - provides connections to the spacecraft's oxygen, power, communication and water lines
- Airlock Adapter Plate (AAP) - holds the EMU pieces while the astronaut is suiting up
- Helmet Lights and Camera - provide additional lighting and cameras for ground control monitoring
- Sleeve-mounted Mirrors and Checklists - help astronauts see gauges on the DCM and remind them of spacewalk procedures
Maximum Absorption Garment (MAG)
Spacewalking take long hours. During that time, their bodies produce urine.
Astronauts cannot simply go inside the spacecraft and use the toilet as it takes too much time to pressurize and depressurize both the spacesuits and the spacecraft.
So each spacewalking astronauts wear a large , absorbant diaper to collect urine and feces while in the spacesuit.
The MAG is disposed when the spacewalk is over.
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Liquid Cooling and Ventilation Garment (LCVG)
LCVG is a set of Nylon tricot and spandex "long underwear" that is laced with thin plastic tubes.
Cool water, which comes from the spacesuit's backpack unit or from the spacecraft through an umbilical cord, flows through these tubes to remove the heat produced by the astronaut.
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EMU Electrical Harness (EEH)
EEH is a set of communications wires and bioinstruments that is worn by the astronaut inside the suit.
It provides connections to the radio and bioinstruments in the suit's backpack.
Communication and monitoring of the astronaut's vital signs (e.g. respiration rate, heart rate, temperature) are allowed.
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Communications Carrier Assembly (CCA)
The CCA is a fabric cap worn by the astronaut. Microphones and speakers are contained for use with the radio. It allows hands-free radio communications within the suit.
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Lower Torso Assembly (LTA)
The LTA is a one-piece unit that contains the lower half of the EMU, including pants, knee and ankle joints, boots and lower waist.
A metal connect ring is used in LTA to fit to the upper half of the EMU.
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Hard Upper Torso (HUT)
The HUT is a hard fibreglass shell in the shape of a vest.
It supports several structures including the arms, lower torso, helmet, life-support backpack and control module.
A mini-tool carrier can also be held. Pieces click into the HUT through quick-connect rings.
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Arms
Arms unit contain shoulder, upper arm and elbow joint bearings so that the astronaut can move his or her arms in many directions.
Quick connect rings are used tho fit arms unit into the HUT.
The arm units come in various sizes so that the EMU can be fitted to different astronauts.
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Gloves
Gloves have wrist bearings to ease the movement. Quickconnect rings are fitted into the arms.
The gloves have rubberized fingertips to help astronauts grip things.
Astronauts also wear fine-fabric gloves inside the outer glove unit for comfort.
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Helmet
The helmet is made of clear, impact-resistant, polycarbonate plastic, and fits to the HUT by a quick-connect ring.
The helmet is padded in the rear for comfort, because the helmet remains fixed rather than rotating with the astronaut's head.
It has a purge valve to remove carbon dioxide if the backup oxygen supply must be used.
In the helmet, oxygen flows from behind the astronaut's head, over the head and down the face.
The inside of the helmet is treated with an anti-fog compound prior to the spacewalk.
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Extravehicular Visor Assembly (EVA)
The EVA fits over the helmet. It consist of the following main pieces:
- A metallic-gold-covered visor to filter sunlight
- A clear, impact resistant cover for thermal and impact protection
- Adjustable blinders to block sunlight
- Four head lamps
- A TV camera
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In-suit Drink Bag (IDB)
Astronauts working in a spacecraft need water.
So the spacesuit has the IDB, which is a plastic pouch mounted inside the HUT.
The IDB can hold 1.9 liters of water and has a small tube, a straw, that is positioned next to the astronaut's mouth.
There is also a slot in the helmet for a rice-paper-covered fruit and cereal bar that the astronaut can eat if he or she gets hungry during the spacewalk.
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Primary Life-Support Subsystem (PLSS)
The PLSS is the backpack worn by the astronaut.
It contains the oxygen tanks (0.54 kg at 518 atm tank pressure), carbon dioxide scrubbers/filters, cooling water (4.6 kg), radio, electrical power, ventilating fans and warning systems.
Oxygen flows into the suit behind the astronauts' head and out of the suit at the feet and elbows.
Once inside the PLSS, the air flow enters a charcoal cartridge, to remove odors, and then the carbon dioxide scrubber cartridage.
The gas flow through a fan, and then to a sublimator that removes water vapour and returns it to the cooling-water supply.
The temperature of the air flow is maintained at 12.8 degrees Celsius.
The temperature, pressure and air flow can be adjusted through controls on the DCM.
The PLSS provides up to seven hours of oxygen supply and carbon dioxide removal.
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Secondary Oxygen Pack (SOP)
The SOP is an emergency oxygen supply, it has two oxygen tanks that contain a total of 1.2 kg at 408 atm tank pressure.
The oxygen supply turns on automatically once the oxygen pressure in the suit drops below 0.23 atm.
This is enough oxygen for 30 minutes, which is sufficient time to get a crewmember back inside the spacecraft.
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Display and Control Mdule (DCM)
The DCM is mounted on the chest, it contains all of the switches, gauges, valves and LCD display necessary to operate the PLSS.
The DCM can be seen by astronaut, sometimes with the aid of a sleeve-mounted mirror.
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Servicing and Cooling Umbilical (SCU)
The SCU is an umbilical cord containing tubes for cooling water, electrical wires for power and tubes for oxygen.
The SCU is used to provide water, power and oxygen to the EMU while the astronaut is in the airlock preparing for the spacewalk.
This helps conserve the EMU's expendable supplies until the astronaut actually leaves the spacecraft.
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Airlock Adapter Plate (AAP)
The AAP is a frame mounted to the wall of the airlock that helps hold the EMU pieces while the astronaut is suiting up.
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Helmet Lights and Caemra
These devices are mounted on the EVA, which fits over the helmet.
It aims at helping the astronauts and ground controllers see into dark areas.
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Sleeve-mounted Mirrors and Checklists
These devices fit over the sleeves of the EMU.
The mirrors help the astronauts see the DCM displays and see behind them.
The checklists help them remember procedures over the course of a spacewalk.
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The Jobs of a Typical Spacesuit The Current Spacesuit