Life-support system

Last updated

Apollo portable life support system Apollo portable life support system.jpg
Apollo portable life support system

A life-support system is the combination of equipment that allows survival in an environment or situation that would not support that life in its absence. It is generally applied to systems supporting human life in situations where the outside environment is hostile, such as outer space or underwater, or medical situations where the health of the person is compromised to the extent that the risk of death would be high without the function of the equipment. [1]

Contents

In human spaceflight, a life-support system is a group of devices that allow a human being to survive in outer space. US government space agency NASA, [2] and private spaceflight companies use the phrase "environmental control and life-support system" or the acronym ECLSS when describing these systems. [3] The life-support system may supply air, water and food. It must also maintain the correct body temperature, an acceptable pressure on the body and deal with the body's waste products. Shielding against harmful external influences such as radiation and micro-meteorites may also be necessary. Components of the life-support system are life-critical, and are designed and constructed using safety engineering techniques.

In underwater diving, the breathing apparatus is considered to be life support equipment, and a saturation diving system is considered a life-support system – the personnel who are responsible for operating it are called life support technicians. The concept can also be extended to submarines, crewed submersibles and atmospheric diving suits, where the breathing gas requires treatment to remain respirable, and the occupants are isolated from the outside ambient pressure and temperature.

Medical life-support systems include heart-lung machines, medical ventilators and dialysis equipment.

Human physiological and metabolic needs

A crewmember of typical size requires approximately 5 kilograms (11 lb) of food, water, and oxygen per day to perform standard activities on a space mission, and outputs a similar amount in the form of waste solids, waste liquids, and carbon dioxide. [4] The mass breakdown of these metabolic parameters is as follows: 0.84 kg (1.9 lb) of oxygen, 0.62 kg (1.4 lb) of food, and 3.54 kg (7.8 lb) of water consumed, converted through the body's physiological processes to 0.11 kg (3.9 oz) of solid wastes, 3.89 kg (8.6 lb) of liquid wastes, and 1.00 kg (2.20 lb) of carbon dioxide produced. These levels can vary due to activity level of a specific mission assignment, but must obey the principle of mass balance. Actual water use during space missions is typically double the given value, mainly due to non-biological use (e.g. showering). Additionally, the volume and variety of waste products varies with mission duration to include hair, finger nails, skin flaking, and other biological wastes in missions exceeding one week in length. Other environmental considerations such as radiation, gravity, noise, vibration, and lighting also factor into human physiological response in outer space, though not with the more immediate effect that the metabolic parameters have.

Atmosphere

Outer space life-support systems maintain atmospheres composed, at a minimum, of oxygen, water vapor and carbon dioxide. The partial pressure of each component gas adds to the overall barometric pressure.

However, the elimination of diluent gases substantially increases fire risks, especially in ground operations when for structural reasons the total cabin pressure must exceed the external atmospheric pressure; see Apollo 1. Furthermore, oxygen toxicity becomes a factor at high oxygen concentrations. For this reason, most modern crewed spacecraft use conventional air (nitrogen/oxygen) atmospheres and use pure oxygen only in pressure suits during extravehicular activity where acceptable suit flexibility mandates the lowest inflation pressure possible.

Water

Water is consumed by crew members for drinking, cleaning activities, EVA thermal control, and emergency uses. It must be stored, used, and reclaimed (from waste water and exhaled water vapor) efficiently since no on-site sources currently exist for the environments reached in the course of human space exploration. Future lunar missions may utilize water sourced from polar ices; Mars missions may utilize water from the atmosphere or ice deposits.

Food

All space missions to date have used supplied food. Life-support systems could include a plant cultivation system which allows food to be grown within buildings or vessels. This would also regenerate water and oxygen. However, no such system has flown in outer space as yet. Such a system could be designed so that it reuses most (otherwise lost) nutrients. This is done, for example, by composting toilets which reintegrate waste material (excrement) back into the system, allowing the nutrients to be taken up by the food crops. The food coming from the crops is then consumed again by the system's users and the cycle continues. The logistics and area requirements involved however have been prohibitive in implementing such a system to date.

Gravity

Depending on the length of the mission, astronauts may need artificial gravity to reduce the effects of space adaptation syndrome, body fluid redistribution, and loss of bone and muscle mass. Two methods of generating artificial weight in outer space exist.

Linear acceleration

If a spacecraft's engines could produce thrust continuously on the outbound trip with a thrust level equal to the mass of the ship, it would continuously accelerate at the rate of 32.2 feet per second (9.8 m/s) per second, and the crew would experience a pull toward the ship's aft bulkhead at normal Earth gravity (one g). The effect is proportional to the rate of acceleration. When the ship reaches the halfway point, it would turn around and produce thrust in the retrograde direction to slow down.

Rotation

Alternatively, if the ship's cabin is designed with a large cylindrical wall, or with a long beam extending another cabin section or counterweight, spinning it at an appropriate speed will cause centrifugal force to simulate the effect of gravity. If ω is the angular velocity of the ship's spin, then the acceleration at a radius r is:

Notice the magnitude of this effect varies with the radius of rotation, which crewmembers might find inconvenient depending on the cabin design. Also, the effects of Coriolis force (a force imparted at right angles to motion within the cabin) must be dealt with. And there is concern that rotation could aggravate the effects of vestibular disruption.

Space vehicle systems

Gemini, Mercury, and Apollo

American Mercury, Gemini and Apollo spacecraft contained 100% oxygen atmospheres, suitable for short duration missions, to minimize weight and complexity. [5]

Space Shuttle

The Space Shuttle was the first American spacecraft to have an Earth-like atmospheric mixture, comprising 22% oxygen and 78% nitrogen. [5] For the Space Shuttle, NASA includes in the ECLSS category systems that provide both life support for the crew and environmental control for payloads. The Shuttle Reference Manual contains ECLSS sections on: Crew Compartment Cabin Pressurization, Cabin Air Revitalization, Water Coolant Loop System, Active Thermal Control System, Supply and Waste Water, Waste Collection System, Waste Water Tank, Airlock Support, Extravehicular Mobility Units, Crew Altitude Protection System, and Radioisotope Thermoelectric Generator Cooling and Gaseous Nitrogen Purge for Payloads. [6]

Soyuz

The life-support system on the Soyuz spacecraft is called the Kompleks Sredstv Obespecheniya Zhiznideyatelnosti (KSOZh) (Russian : Комплекс Средств Обеспечения Жизнедеятельности (KCOЖ)).[ citation needed ] Vostok, Voshkod and Soyuz contained air-like mixtures at approximately 101kPa (14.7 psi). [5] The life support system provides a nitrogen/oxygen atmosphere at sea level partial pressures. The atmosphere is then regenerated through KO2 cylinders, which absorb most of the CO2 and water produced by the crew biologically and regenerates the oxygen, the LiOH cylinders then absorb the leftover CO2. [7]

Plug and play

The Paragon Space Development Corporation is developing a plug and play ECLSS called commercial crew transport-air revitalization system (CCT-ARS) [8] for future spacecraft partially paid for using NASA's Commercial Crew Development (CCDev) funding. [9]

The CCT-ARS provides seven primary spacecraft life support functions in a highly integrated and reliable system: Air temperature control, Humidity removal, Carbon dioxide removal, Trace contaminant removal, Post-fire atmospheric recovery, Air filtration, and Cabin air circulation. [10]

Space station systems

Space station systems include technology that enables humans to live in outer space for a prolonged period of time. Such technology includes filtration systems for human waste disposal and air production.

Skylab

Skylab used 72% oxygen and 28% nitrogen at a total pressure of 5 psi.[ citation needed ]

Salyut and Mir

The Salyut and Mir space stations contained an air-like Oxygen and Nitrogen mixture at approximately sea-level pressures of 93.1 kPa (13.5psi) to 129 kPa (18.8 psi) with an Oxygen content of 21% to 40%. [5]

Bigelow commercial space station

The life-support system for the Bigelow Commercial Space Station is being designed by Bigelow Aerospace in Las Vegas, Nevada. The space station will be constructed of habitable Sundancer and BA 330 expandable spacecraft modules. As of October 2010, "human-in-the-loop testing of the environmental control and life-support system (ECLSS)" for Sundancer has begun. [11]

Natural systems

Natural LSS like the Biosphere 2 in Arizona have been tested for future space travel or colonization. These systems are also known as closed ecological systems. They have the advantage of using solar energy as primary energy only and being independent from logistical support with fuel. Natural systems have the highest degree of efficiency due to integration of multiple functions. They also provide the proper ambience for humans which is necessary for a longer stay in outer space.

Underwater and saturation diving habitats

Underwater habitats and surface saturation accommodation facilities provide life-support for their occupants over periods of days to weeks. The occupants are constrained from immediate return to surface atmospheric pressure by decompression obligations of up to several weeks.

The life support system of a surface saturation accommodation facility provides breathing gas and other services to support life for the personnel under pressure. It includes the following components: [12] Underwater habitats differ in that the ambient external pressure is the same as internal pressure, so some engineering problems are simplified.

Underwater habitats balance internal pressure with the ambient external pressure, allowing the occupants free access to the ambient environment within a specific depth range, while saturation divers accommodated in surface systems are transferred under pressure to the working depth in a closed diving bell

The life support system for the bell provides and monitors the main supply of breathing gas, and the control station monitors the deployment and communications with the divers. Primary gas supply, power and communications to the bell are through a bell umbilical, made up from a number of hoses and electrical cables twisted together and deployed as a unit. [13] This is extended to the divers through the diver umbilicals. [12]

The accommodation life support system maintains the chamber environment within the acceptable range for health and comfort of the occupants. Temperature, humidity, breathing gas quality sanitation systems and equipment function are monitored and controlled. [13]

Experimental life-support systems

MELiSSA

Micro-Ecological Life Support System Alternative (MELiSSA) is a European Space Agency led initiative, conceived as a micro-organisms and higher plants based ecosystem intended as a tool to gain understanding of the behaviour of artificial ecosystems, and for the development of the technology for a future regenerative life-support system for long term crewed space missions.

CyBLiSS

CyBLiSS ("Cyanobacterium-Based Life Support Systems") is a concept developed by researchers from several space agencies (NASA, the German Aerospace Center and the Italian Space Agency) which would use cyanobacteria to process resources available on Mars directly into useful products, and into substrates[ clarification needed ] for other key organisms of Bioregenerative life support system (BLSS). [14] The goal is to make future human-occupied outposts on Mars as independent of Earth as possible (explorers living "off the land"), to reduce mission costs and increase safety. Even though developed independently, CyBLiSS would be complementary to other BLSS projects (such as MELiSSA) as it can connect them to materials found on Mars, thereby making them sustainable and expandable there. Instead of relying on a closed loop, new elements found on site can be brought into the system.

See also

Footnotes

  1. "Definition of LIFE-SUPPORT SYSTEM". www.merriam-webster.com. Retrieved 14 June 2023.
  2. NASA, 2008
  3. Barry 2000.
  4. Sulzman & Genin 1994.
  5. 1 2 3 4 Davis, Johnson & Stepanek 2008.
  6. NASA-HSF
  7. "Habitation module of Soyuz spacecraft". www.russianspaceweb.com. Retrieved 15 May 2024.
  8. Paragon Projects
  9. NASA 2010
  10. Paragon Press Release
  11. Bigelow Volunteers
  12. 1 2 Crawford, J. (2016). "8.5.1 Helium recovery systems". Offshore Installation Practice (revised ed.). Butterworth-Heinemann. pp. 150–155. ISBN   9781483163192.
  13. 1 2 Staff, US Navy (2006). "15". US Navy Diving Manual, 6th revision. United States: US Naval Sea Systems Command. Retrieved 15 June 2008.
  14. Verseux, Cyprien; Baqué, Mickael; Lehto, Kirsi; de Vera, Jean-Pierre P.; Rothschild, Lynn J.; Billi, Daniela (3 August 2015). "Sustainable life support on Mars – the potential roles of cyanobacteria". International Journal of Astrobiology. 15 (1): 65–92. Bibcode:2016IJAsB..15...65V. doi: 10.1017/S147355041500021X .

Related Research Articles

<span class="mw-page-title-main">Apollo 1</span> Planned United States spaceflight destroyed by accidental fire (1967)

Apollo 1, initially designated AS-204, was planned to be the first crewed mission of the Apollo program, the American undertaking to land the first man on the Moon. It was planned to launch on February 21, 1967, as the first low Earth orbital test of the Apollo command and service module. The mission never flew; a cabin fire during a launch rehearsal test at Cape Kennedy Air Force Station Launch Complex 34 on January 27 killed all three crew members—Command Pilot Gus Grissom, Senior Pilot Ed White, and Pilot Roger B. Chaffee—and destroyed the command module (CM). The name Apollo 1, chosen by the crew, was made official by NASA in their honor after the fire.

<span class="mw-page-title-main">Interplanetary spaceflight</span> Crewed or uncrewed travel between stars or planets

Interplanetary spaceflight or interplanetary travel is the crewed or uncrewed travel between stars and planets, usually within a single planetary system. In practice, spaceflights of this type are confined to travel between the planets of the Solar System. Uncrewed space probes have flown to all the observed planets in the Solar System as well as to dwarf planets Pluto and Ceres, and several asteroids. Orbiters and landers return more information than fly-by missions. Crewed flights have landed on the Moon and have been planned, from time to time, for Mars, Venus and Mercury. While many scientists appreciate the knowledge value that uncrewed flights provide, the value of crewed missions is more controversial. Science fiction writers propose a number of benefits, including the mining of asteroids, access to solar power, and room for colonization in the event of an Earth catastrophe.

<span class="mw-page-title-main">Human spaceflight</span> Spaceflight with a crew or passengers

Human spaceflight is spaceflight with a crew or passengers aboard a spacecraft, often with the spacecraft being operated directly by the onboard human crew. Spacecraft can also be remotely operated from ground stations on Earth, or autonomously, without any direct human involvement. People trained for spaceflight are called astronauts, cosmonauts (Russian), or taikonauts (Chinese); and non-professionals are referred to as spaceflight participants or spacefarers.

<span class="mw-page-title-main">Space suit</span> Garment worn to keep a human alive in the harsh environment of outer space

A space suit is an environmental suit used for protection from the harsh environment of outer space, mainly from its vacuum as a highly specialized pressure suit, but also its temperature extremes, as well as radiation and micrometeoroids. Basic space suits are worn as a safety precaution inside spacecrafts in case of loss of cabin pressure. For extravehicular activity (EVA) more complex space suits are worn, featuring a portable life support system.

<span class="mw-page-title-main">Spaceflight</span> Flight into or through outer space

Spaceflight is an application of astronautics to fly objects, usually spacecraft, into or through outer space, either with or without humans on board. Most spaceflight is uncrewed and conducted mainly with spacecraft such as satellites in orbit around Earth, but also includes space probes for flights beyond Earth orbit. Such spaceflights operate either by telerobotic or autonomous control. The first spaceflights began in the 1950s with the launches of the Soviet Sputnik satellites and American Explorer and Vanguard missions. Human spaceflight programs include the Soyuz, Shenzhou, the past Apollo Moon landing and the Space Shuttle programs. Other current spaceflight are conducted to the International Space Station and to China's Tiangong Space Station.

<span class="mw-page-title-main">Airlock</span> Compartment for transfer between environments with different atmospheres

An airlock is a room or compartment which permits passage between environments of differing atmospheric pressure or composition, while minimizing the changing of pressure or composition between the differing environments.

<i>Quest</i> Joint Airlock Primary airlock for the International Space Station

The Quest Joint Airlock is the primary airlock for the International Space Station. Quest was designed to host spacewalks with both Extravehicular Mobility Unit (EMU) spacesuits and Orlan space suits. The airlock was launched on STS-104 on July 14, 2001.

<span class="mw-page-title-main">Space capsule</span> Type of spacecraft

A space capsule is a spacecraft designed to transport cargo, scientific experiments, and/or astronauts to and from space. Capsules are distinguished from other spacecraft by the ability to survive reentry and return a payload to the Earth's surface from orbit or sub-orbit, and are distinguished from other types of recoverable spacecraft by their blunt shape, not having wings and often containing little fuel other than what is necessary for a safe return. Capsule-based crewed spacecraft such as Soyuz or Orion are often supported by a service or adapter module, and sometimes augmented with an extra module for extended space operations. Capsules make up the majority of crewed spacecraft designs, although one crewed spaceplane, the Space Shuttle, has flown in orbit.

<span class="mw-page-title-main">Space medicine</span> For health conditions encountered during spaceflight

Space Medicine is a subspecialty of Emergency Medicine which evolved from the Aerospace Medicine specialty. Space Medicine is dedicated to the prevention and treatment of medical conditions that would limit success in space operations. Space medicine focuses specifically on prevention, acute care, emergency medicine, wilderness medicine, hyper/hypobaric medicine in order to provide medical care of astronauts and spaceflight participants. The spaceflight environment poses many unique stressors to the human body, including G forces, microgravity, unusual atmospheres such as low pressure or high carbon dioxide, and space radiation. Space medicine applies space physiology, preventive medicine, primary care, emergency medicine, acute care medicine, austere medicine, public health, and toxicology to prevent and treat medical problems in space. This expertise is additionally used to inform vehicle systems design to minimize the risk to human health and performance while meeting mission objectives.

<span class="mw-page-title-main">Orbiting Frog Otolith</span> NASA space program which sent frogs into orbit

The Orbiting Frog Otolith (OFO) was a NASA space program which sent two bullfrogs into orbit on November 9, 1970, for the study of weightlessness. The name, derived through common use, was a functional description of the biological experiment carried by the satellite. Otolith referred to the frog's inner ear balance mechanism.

<span class="mw-page-title-main">Paragon Space Development Corporation</span>

Paragon Space Development Corporation is an American company headquartered in Tucson, Arizona. Paragon is a provider of environmental controls for extreme and hazardous environments. They design, build, test and operate life-support systems and leading thermal-control products for astronauts, contaminated water divers, and other extreme environment explorers, as well as for uncrewed space and terrestrial applications.

Astronautical hygiene evaluates, and mitigates, hazards and health risks to those working in low-gravity environments. The discipline of astronautical hygiene includes such topics as the use and maintenance of life support systems, the risks of the extravehicular activity, the risks of exposure to chemicals or radiation, the characterization of hazards, human factor issues, and the development of risk management strategies. Astronautical hygiene works side by side with space medicine to ensure that astronauts are healthy and safe when working in space.

<span class="mw-page-title-main">Space architecture</span> Architecture of off-planet habitable structures

Space architecture is the theory and practice of designing and building inhabited environments in outer space. This mission statement for space architecture was developed in 2002 by participants in the 1st Space Architecture Symposium, organized at the World Space Congress in Houston, by the Aerospace Architecture Subcommittee, Design Engineering Technical Committee (DETC), American Institute of Aeronautics and Astronautics (AIAA).

<span class="mw-page-title-main">ISS ECLSS</span> Life support system for the International Space Station

The International Space Station (ISS) Environmental Control and Life Support System (ECLSS) is a life support system that provides or controls atmospheric pressure, fire detection and suppression, oxygen levels, proper ventilation, waste management and water supply. It was jointly designed and tested by NASA's Marshall Space Flight Center, UTC Aerospace Systems, Boeing, Lockheed Martin, and Honeywell, inc.

<span class="mw-page-title-main">George F. Bond</span> US Navy physician and diving medicine and saturation diving researcher

Captain George Foote Bond was a United States Navy physician who was known as a leader in the field of undersea and hyperbaric medicine and the "Father of Saturation Diving".

<span class="mw-page-title-main">European Service Module</span> Primary power and propulsion component of the Orion spacecraft

The European Service Module (ESM) is the service module component of the Orion spacecraft, serving as its primary power and propulsion component until it is discarded at the end of each mission. In January 2013, NASA announced that the European Space Agency (ESA) will contribute the service module for Artemis I, based on the ESA's Automated Transfer Vehicle (ATV). It was delivered by Airbus Defence and Space in Bremen, in northern Germany to NASA at the end of 2018. After approval of the first module, the ESA will provide the ESMs from Artemis II to Artemis VI.

<span class="mw-page-title-main">Mars habitat</span> Facility where humans could live on Mars

A Mars habitat is a hypothetical place where humans could live on Mars. Mars habitats would have to contend with surface conditions that include almost no oxygen in the air, extreme cold, low pressure, and high radiation. Alternatively, the habitat might be placed underground, which helps solve some problems but creates new difficulties.

<span class="mw-page-title-main">Mars suit</span> Space suit for the Martian surface

A Mars suit or Mars space suit is a space suit for EVAs on the planet Mars. Compared to a suit designed for space-walking in the near vacuum of low Earth orbit, Mars suits have a greater focus on actual walking and a need for abrasion resistance. Mars' surface gravity is 37.8% of Earth's, approximately 2.3 times that of the Moon, so weight is a significant concern, but there are fewer thermal demands compared to open space. At the surface the suits would contend with the atmosphere of Mars, which has a pressure of about 0.6 to 1 kilopascal. On the surface, radiation exposure is a concern, especially solar flare events, which can dramatically increase the amount of radiation over a short time.

<span class="mw-page-title-main">SpaceX CRS-22</span> 2021 American resupply spaceflight to the ISS

SpaceX CRS-22, also known as SpX-22, was a Commercial Resupply Services (CRS) mission to the International Space Station (ISS) that launched at 17:29:15 UTC on 3 June 2021. The mission is contracted by NASA and is flown by SpaceX using a Cargo Dragon 2. This is the second flight for SpaceX under NASA's CRS Phase 2 contract awarded in January 2016.

<span class="mw-page-title-main">Cygnus NG-15</span> 2021 American resupply spaceflight to the ISS

Cygnus NG-15, previously known as OA-15, was the fifteenth launch of the Northrop Grumman robotic resupply spacecraft Cygnus and its fourteenth flight to the International Space Station (ISS) under the Commercial Resupply Services (CRS) contract with NASA. The mission launched on 20 February 2021 at 17:36:50 UTC. This is the fourth launch of Cygnus under the CRS-2 contract.

References

Further reading