Category:Spacecraft life support systems
Pages in category "Spacecraft life support systems"
The following 9 pages are in this category, out of 9 total. This list may not reflect recent changes (learn more).
The following 9 pages are in this category, out of 9 total. This list may not reflect recent changes (learn more).
1. Space toilet – A space toilet, or zero gravity toilet, is a toilet that can be used in a weightless environment. In the absence of weight, the collection and retention of liquid and solid waste is directed by use of air flow, since the air used to direct the waste is returned to the cabin, it is filtered beforehand to control odor and cleanse bacteria. In older systems, waste water is vented into space, more modern systems expose solid waste to vacuum pressures to kill bacteria, which prevents odor problems and kills pathogens. When humans travel into space, the absence of gravity causes fluids to distribute uniformly around their bodies and their kidneys detect the fluid movement and a physiological reaction causes the humans to need to relieve themselves within two hours of departure from Earth. As a result, the toilet has been the first device activated on shuttle flights. There are four parts in a space toilet, the liquid waste vacuum tube, the vacuum chamber, the waste storage drawers. The liquid waste vacuum tube is a 2 to 3-foot long rubber or plastic hose that is attached to the vacuum chamber, at the end of the tube there is a detachable urine receptacle, which come in different versions for male and female astronauts. The male urine receptacle is a plastic funnel two to three inches in width and about four inches deep, a male astronaut urinates directly into the funnel from a distance of two or three inches away. The female funnel is oval and is two inches by four wide at the rim. Near the funnels rim are small holes or slits that allow air movement to prevent excessive suction, the vacuum chamber is a cylinder about 1-foot deep and six inches wide with clips on the rim where waste collection bags may be attached and a fan that provides suction. Urine is pumped into and stored in waste storage drawers, solid waste is stored in a detachable bag made of a special fabric that lets gas escape, a feature that allows the fan at the back of the vacuum chamber to pull the waste into the bag. When the astronaut is finished, he or she then twists the bag, samples of urine and solid waste are frozen and taken to Earth for testing. The toilet used on the Space Shuttle is called the Waste Collection System, in addition to air flow, it also uses rotating fans to distribute solid waste for in-flight storage. Solid waste is distributed in a container which is then exposed to vacuum to dry the waste. Liquid waste is vented to space, during STS-46, one of the fans malfunctioned, and crew member Claude Nicollier was required to perform in-flight maintenance. An earlier, complete failure, on the eight-day STS-3 test flight, forced its crew to use a fecal containment device for waste elimination. There are two toilets on the International Space Station, located in the Zvezda and Tranquility modules and they use a fan-driven suction system similar to the Space Shuttle WCS. Liquid waste is collected in 20-litre containers, solid waste is collected in individual micro-perforated bags which are stored in an aluminum container
2. Primary Life Support System – The PLSS is generally worn like a backpack. When used in a microgravity environment, a propulsion system is generally needed for safety and control. Some of the water was used to remove excess heat from the astronauts breathing air. The PLSS also contained a radio transceiver and antenna for communications, PLSS controls were provided in the Remote Control Unit mounted on the astronauts chest. Oxygen and water were rechargeable for multiple EVAs from the environmental control system. An emergency backup was provided in case the system failed, by a separate unit called the Oxygen Purge System, mounted on top of the PLSS. The OPS maintained suit pressure and removed carbon dioxide, heat and water vapor through a continuous, when activated, the OPS provided oxygen to a separate inlet on the pressure suit, once a vent valve on a separate suit outlet was manually opened. The OPS provided a maximum of about 30 minutes of oxygen for breathing and cooling. This could be extended to 75 to 90 minutes with a buddy system hose that used the other astronauts functional PLSS for cooling and this allowed the vent valve to be partly closed to decrease the oxygen flow rate. The PLSS was 26 inches high,18 inches wide, and 10 inches deep and it was tested in space for the first time by Russell Schweickart in a stand-up EVA in Earth orbit on Apollo 9. His PLSS weighed 84 pounds on Earth, which translated to a weight of only 14 lb on the Moon, the OPS weighed 41 pounds on Earth. The OPS was also used as a backup on tethered in-space EVAs where a spacecraft provided oxygen to the astronaut through an umbilical hose, similar systems have been used by Space Shuttle astronauts, and are currently used by International Space Station crews. The Primary Life Support System for the EMU suit used on the Space Shuttle and it is mounted to the back of the Hard Upper Torso assembly. Oxygen, carbon dioxide and water vapor are drawn from the extremities of the suit by the Liquid Cooling and Ventilation Garment or LCVG, when gas enters the PLSS, activated charcoal removes odors and lithium hydroxide removes carbon dioxide. Next, the gas passes through a fan which maintains a flow rate of about six feet per minute. A sublimator then condenses water vapor, which is removed by a slurper, the removed water is stored and used to supplement the water supply used in the LCVG. The sublimator also cools the remaining oxygen to about 55 °F, a flow sensor monitors the flow rate. Extra oxygen is added to the flow from a tank as necessary
3. ISS ECLSS – The Elektron system aboard Zvezda and a similar system in Destiny generate oxygen aboard the station. The crew has an option in the form of bottled oxygen. Carbon dioxide is removed from the air by the Russian Vozdukh system in Zvezda, lab module, and one CDRA in the U. S. Node 3 module. Other by-products of human metabolism, such as methane from the intestines, the ISS has two water recovery systems. Zvezda contains a recovery system that processes water vapor from the atmosphere that could be used for drinking in an emergency but is normally fed to the Elektron system to produce oxygen. The American segment has a Water Recovery System installed during STS-126 that can process water vapour collected from the atmosphere, the Water Recovery System was installed initially in Destiny on a temporary basis in November 2008 and moved into Tranquility in February 2010. The Water Recovery System consists of a Urine Processor Assembly and a Water Processor Assembly, the Urine Processor Assembly uses a low pressure vacuum distillation process that uses a centrifuge to compensate for the lack of gravity and thus aid in separating liquids and gasses. The Urine Processor Assembly is designed to handle a load of 9 kg/day, the water is then tested by onboard sensors and unacceptable water is cycled back through the water processor assembly. The Volatile Removal Assembly flew on STS-89 in January 1998 to demonstrate the Water Processor Assemblys catalytic reactor in microgravity, a Vapour Compression Distillation Flight Experiment flew, but was destroyed, in STS-107. The distillation assembly of the Urine Processor Assembly failed on November 21,2008, one of the three centrifuge speed sensors was reporting anomalous speeds, and high centrifuge motor current was observed. This was corrected by re-mounting the distillation assembly without several rubber vibration isolators, the distillation assembly failed again on December 28,2008 due to high motor current and was replaced on March 20,2009. Ultimately, during testing, one centrifuge speed sensor was found to be out of alignment. Several systems are used on board the ISS to maintain the spacecrafts atmosphere. Normal air pressure on the ISS is 101.3 kPa, Carbon dioxide and trace contaminants are removed by the Air Revitalisation System. The Air Revitalization System was flown to the station aboard STS-128 and was installed in the Japanese Experiment Module pressurised module. The system was scheduled to be transferred to Tranquility after it arrived and was installed during Space Shuttle Endeavour mission STS-130, the Oxygen Generating System is a NASA rack designed to electrolyse water from the Water Recovery System to produce oxygen and hydrogen. The oxygen is delivered to the atmosphere and the hydrogen is vented overboard. The unit is installed in the Destiny module, during one of the spacewalks conducted by STS-117 astronauts, a hydrogen vent valve required to begin using the system was installed
4. MELiSSA – Initiated in 1989, the design is inspired by a terrestrial ecosystem. Today MELiSSA is a made up of 30 organisations across Europe. Space missions involving humans require essential resources to sustain life, approximately 5 kg/day/person for metabolic consumables and 20 kg/day/person for hygiene water. The longer and further the missions are, the more difficult, mELiSSAs aim is to ideally create an artificially closed ecosystem to autonomously recycle the wastes to oxygen, water and food with only the input of energy to drive the process. The loop is made up of 4 compartments with the members at the centre. The compartments are, The liquefying compartment, This compartment is the point for all mission waste as well as the non-edible parts of the higher plant compartment. The compartments aim is to transform this waste to ammonium, H2, CO2, volatile fatty acids. For biosafety reasons and for optimum efficiency, the compartment operates in thermophilic conditions. The process of degradation in this compartment is carried out by proteolysis, saccharolysis and cellulolysis, the Photoheterotrophic Compartment, This compartment is responsible for the elimination of the terminal products of the liquefying compartment, mainly the volatile fatty acids. The compartment is composed of a mix of Nitrosomonas and Nitrobacter which oxidise NH4+ to NO2− and NO2− to NO3− respectively, as this compartment is a fixed bed reactor, the importance of the hydrodynamic factors is slightly more important as well as more complicated. The Photoautotophic Compartment, The fourth compartment is split into two parts, the algae compartment colonised by the cyanobacteria, Arthrospira platensis and the Higher Plant compartment and these compartments are essential for the regeneration of oxygen and the production of food. The conversion of waste elements to resources, which can be used by crewmembers can be achieved by two means, physiochemically or biologically, physiochemical processes such as the Sabatier reaction would result in high efficiencies however a large amount of energy is required in terms of temperature and pressure. Whereas biologically, using photosynthesis, efficiencies are lower, however ambient temperatures and pressures can be used, photosynthesis is the process whereby plants convert light energy into chemical energy of sugars and other organic compounds. The chemical reactions utilise carbon and water with the by-product of oxygen, MELiSSA is partly based on these photosynthetic reactions, recycling carbon dioxide into oxygen. Higher plants would be utilised to produce food for the crewmembers and it is akin to industrial processes, transforming raw materials into useful substances. However, one key difference is the objective to recycle near 100% of wastes. Achieving near 100% for the elements is of course theoretical. Further, an ecosystem is inherently dynamic, MELiSSA has to respond very quickly to changes in human behaviour