| Planetary Surface Exploration Mobility Unit Version 1 | |
|---|---|
 | |
| Name | Planetary Surface Exploration Mobility Unit Version 1 (PSEMU-01) |
| Manufacturers | ACT (Pressure Suit Assembly, Long-range Life Support System) and RIGID HVAC (Liquid Cooling Unit) |
| Missions | Ceres I |
| Function | Orbital Extra-vehicular activity (EVA), and Terrestrial EVA |
| Operating Pressure | 14.7 psi (101.3 kPa) |
| Pressure Suit Mass | 13.5 kg |
| Total EVA Suit Mass | 25 kg |
| Life Support | 6 hours |
The Planetary Surface Exploration Mobility Unit (PSEMU) is a class of spacesuit used in Ceres missions. These spacesuits are optimized for the vastly different atmospheric conditions the Ceres crew will endure either in the vacuum of space or during the terrestrial extra-vehicular activity (EVA).
The Planetary Surface Exploration Mobility Unit Version 1 (PSEMU-01) consists of a Pressure Suit Assembly (PSA) and a Long-range Life Support System (LoLSS). The PSEMU-01 was the spacesuit used on Ceres I.
Requirements
When exploring other planets, astronauts need a special suit to protect them from the potentially harsh environments they encounter. A spacesuit must perform several important functions to keep its wearer safe and comfortable. It provides a stable internal pressure, allows for mobility, and supplies breathable oxygen while eliminating carbon dioxide. It also regulates temperature and has a communication system for the astronaut to stay connected with their spacecraft and fellow astronauts.
Pressure Suit Assembly
One important function is providing a stable internal pressure. The suit’s pressure during terrestrial EVA is 14,7 psi (1 standard atmosphere) it can be less than Earth’s atmosphere, but that requires a lengthy process to avoid decompression sickness. Running the suit at higher pressure can result in lower mobility. The high mobility of the PSEMU-01 is achieved through careful joint design. The suit maintains a constant internal volume through a combination of mechanical counterpressure and convoluted joints. These joints allow the wearer to bend their arms without changing the internal volume of the suit. The spacesuit also needs to shield against harmful ultraviolet radiation and protect against micrometeoroids traveling at high speeds. A puncture-resistant Thermal Micrometeoroid material is used as the outermost layer of the suit.
Long-range Life Support System
The LoLSS consists out of a communications system, an oxygen system and a liquid cooling system and a rechargeable battery. The complete system consists of several separate modules. The Communications System, power for the Oxygen Filtration and Conservation System and a remote control for the Liquid Cooling System are carried in pouches on the front of the torso attached to the External Carrying System (ECS). The backpack contains a Rechargeable Power Supply Unit (RPSU) and the Liquid Cooling System (LCS) which connects directly to the Liquid Cooling Garment (LCG) the astronauts wear underneath the suit.
Communications System
Communications are provided via a cap worn over the head, which includes earphones and a microphone and a integrated Full Duplex radio system.
Oxygen Filtration and Conservation System
The suit is equipped with a sophisticated Oxygen Filtration and Conservation System (OFCS) that filters out carbon dioxide and replenishes the suit with fresh, breathable oxygen. The system is designed to be highly efficient, conserving oxygen and minimizing the amount of carbon dioxide that needs to be expelled. A fan circulates oxygen through the helmet.
Liquid Cooling System
The LCS helps regulate the temperature inside the suit, which is particularly important when operating in extreme temperature conditions on the surface of a planet. The LCS is one of the key technologies that enables astronauts to explore and conduct research on planetary surfaces. The system works in conjunction with the LCG.
Liquid Cooling Garment
The first piece of a spacesuit that the astronauts put on is the LCG. A stretchy body suit with plastic tubing which circulate water to cool the astronaut minimizing sweating and fogging of the suit helmet. Around 16 meters of tubes are sewn into a tight fitting garment that covers the entire body except for the feet, hands and head. While exerting energy the astronauts body heat warms up the water in the LCG. Water is pumped from the LCG to the LCS in the backpack, where the circulating water is cooled to a constant comfortable by a miniature refrigeration system. The astronauts can control the temperature with a remote control carried on the front of the suit.
Helmet
The helmet is made of two types of strong plastic to keep the pressure of the suit contained. The main body of the helmet is made of High Impact Polystyrene (HIPS) for its durability and impact resistance. The visor is made of Polyethylene Terephthalate Glycol (PETG) because of its impact and chemical resistance and good optical clarity. Outside of the clear visor is a protective sun visor with a special orange coating that protect the astronaut from harmful radiation. The helmet houses the OFCS that provides the astronaut with oxygen which is powered through the 12 pin connector on the front.
Gloves
Possible the most complex sub-assembly of the PSEMU-01, the gloves are the astronauts direct interface with their tools and environment. The gloves are mode of many layers of insulation materials and durable fabrics for pressurization, warmth and protection. The fingertips are made from silicone with a finger print like ridges for grip and feature coated aluminum nails for added dexterity. The fingers have flexible joints so the astronauts can handle tools and the inside of the fingers and palms have dotted silicon structure to help with grip. The index fingers of the gloves have an integrated LED assembly powered by a battery pack on the back.
Boots
The boots are integrated into the pants assembly for optimum protection, it ensures the protective layers around the lower legs never have to be separated from the PSEMU. The soles of the boot assembly need ribs to increase thermal insulation qualities, to provide lateral and torsional rigidity, and to provide traction on the ground surface.
External Carrying System
The ECS is an external harness that is completely separate from the PSEMU, it has attachment points for one backpack, a front pack and side pouches. The front and back pack are connected using a robust quick release system designed by Austrialpin. These connectors are easy to connect and disconnect and can stand up to 18 kN (1835 kilograms) of force before disassembling involuntarily.
