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Welcome to Space Manufacturing

During the early years of spaceflight only nation states had the resources to develop and fly spacecraft. Both the U.S. space program and Soviet space program were operated using mainly military pilots as astronauts. During this period, no commercial space launches were available to private operators, and no private organization was able to offer space launches. In the 1980s, the European Space Agency created Arianespace, the world's first commercial space transportation company, and, following the Challenger disaster, the American government deregulated the American space transportation market as well. In the 1990s the Russian government sold their majority stake in RSC Energia to private investors (although it has recently renationalized the Russian space sector in 2013–2014. These events for the first time allowed private organizations to purchase, develop and offer space launch services; beginning the period of private spaceflight in the late-1980s and early-1990s.

Space manufacturing is the production of manufactured goods in an environment outside a planetary atmosphere. Typically this includes conditions of microgravity and hard vacuum. Manufacturing in space has several potential advantages over Earth-based industry.
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img credit: spacex

1.The unique environment can allow for industrial processes that cannot be readily reproduced on Earth.
2.Raw materials could be lifted to orbit from other bodies within the solar system and processed at a low expense compared to the cost of lifting materials into orbit from Earth.
3.Potentially hazardous processes can be performed in space with minimal risk to the environment of the Earth or other planets.

The space environment is expected to be beneficial for production of a variety of products. Once the heavy capitalization costs of assembling the mining and manufacturing facilities is paid, the production will need to be economically profitable in order to become self-sustaining and beneficial to society. The most significant cost is overcoming the energy hurdle for boosting materials into orbit. Once this barrier is significantly reduced in cost per kilogram, the entry price for space manufacturing can make it much more attractive to entrepreneurs.
Economic requirements of space manufacturing imply a need to collect the requisite raw materials at a minimum energy cost. The economical movement of material in space is directly related to the delta-v, or change in velocity required to move from the mining sites to the manufacturing plants. Near-Earth asteroids, Phobos, Deimos and the lunar surface have a much lower delta-v compared to launching the materials from the surface of the Earth to Earth orbit.

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During the Soyuz 6 mission of 1969, Russian astronauts performed the first welding experiments in space. Three different welding processes were tested using a hardware unit called Vulkan. The tests included welding aluminum, titanium, and stainless steel. The Skylab mission, launched in May 1973, served as a laboratory to perform various space manufacturing experiments. The station was equipped with a materials processing facility that included a multi-purpose electric furnace, a crystal growth chamber, and an electron beam gun. Among the experiments to be performed was research on molten metal processing; photographing the behavior of ignited materials in zero-gravity; crystal growth; processing of immiscible alloys; brazing of stainless steel tubes, electron beam welding, and the formation of spheres from molten metal. The crew spent a total of 32 man-hours on materials science and space manufacturing investigation during the mission. The Space Studies Institute began hosting a bi-annual Space Manufacturing Conference in 1977. Microgravity research in materials processing continued in 1983 using the Spacelab facility. This module has been carried into orbit 26 times aboard the Space Shuttle, as of 2002. In this role the shuttle served as an interim, short-duration research platform before the completion of the International Space Station. The Wake Shield Facility is deployed by the Space Shuttle's robotic arm. NASA image In February 1994 and September 1995, the Wake Shield Facility was carried into orbit by the Space Shuttle. This demonstration platform used the vacuum created in the orbital wake to manufacture thin films of gallium arsenide and aluminum gallium arsenide. On May 31, 2005, the recoverable, unmanned Foton-M2 laboratory was launched into orbit. Among the experiments were crystal growth and the behavior of molten-metal in weightlessness.

The International Space Station (ISS) is a space station (habitable artificial satellite) in low Earth orbit. The ISS programme is a joint project between five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA (Japan), ESA (Europe), and CSA (Canada). The ownership and use of the space station is established by intergovernmental treaties and agreements. The ISS serves as a microgravity and space environment research laboratory in which crew members conduct experiments in biology, human biology, physics, astronomy, meteorology, and other fields. The station is suited for the testing of spacecraft systems and equipment required for missions to the Moon and Mars. The ISS maintains an orbit with an average altitude of 400 kilometres (250 mi) by means of reboost manoeuvres using the engines of the Zvezda module or visiting spacecraft. It circles the Earth in roughly 92 minutes and completes 15.5 orbits per day. The station is divided into two sections, the Russian Orbital Segment (ROS), which is operated by Russia, and the United States Orbital Segment (USOS), which is shared by many nations. As of January 2018, operations of the US segment were funded until 2025.Roscosmos has endorsed the continued operation of ISS through 2024,but has proposed using elements of the Russian segment to construct a new Russian space station called OPSEK.
The first ISS component was launched in 1998, with the first long-term residents arriving on 2 November 2000. Since then, the station has been continuously occupied for 18 years and 291 days. This is the longest continuous human presence in low Earth orbit, having surpassed the previous record of 9 years and 357 days held by Mir. The latest major pressurised module was fitted in 2011, with an experimental inflatable space habitat added in 2016. As of December 2018, the station is expected to operate until 2030.
Development and assembly of the station continues, with several major new Russian elements scheduled for launch starting in 2020. The ISS is the largest human-made body in low Earth orbit and can often be seen with the naked eye from Earth. The ISS consists of pressurised habitation modules, structural trusses, solar arrays, radiators, docking ports, experiment bays and robotic arms. Major ISS modules have been launched by Russian Proton and Soyuz rockets and US Space Shuttles.
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The ISS is the ninth space station to be inhabited by crews, following the Soviet and later Russian Salyut, Almaz, and Mir stations as well as Skylab from the US. The station is serviced by a variety of visiting spacecraft: the Russian Soyuz and Progress, the US Dragon and Cygnus, the Japanese H-II Transfer Vehicle, and the European Automated Transfer Vehicle. The Dragon spacecraft allows the return of pressurised cargo to Earth (downmass), which is used for example to repatriate scientific experiments for further analysis. The Soyuz return capsule has minimal downmass capability next to the astronauts.
The ISS has been visited by astronauts, cosmonauts and space tourists from 18 different nations. As of 14 March 2019, 236 people from 18 countries had visited the space station, many of them multiple times. The United States sent 149 people, Russia sent 47, nine were Japanese, eight were Canadian, five were Italian, four were French, three were German, and there were one each from Belgium, Brazil, Denmark, Kazakhstan, Malaysia, the Netherlands, South Africa, South Korea, Spain, Sweden, and the United Kingdom.
Salyut 1 was the first space station of any kind, launched into low Earth orbit by the Soviet Union on April 19, 1971. The International Space Station is currently the only fully functional space station, with continuous inhabitance since the year 2000.

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Purpose

The ISS was originally intended to be a laboratory, observatory, and factory while providing transportation, maintenance, and a low Earth orbit staging base for possible future missions to the Moon, Mars, and asteroids. However, not all of the uses envisioned in the initial Memorandum of Understanding between NASA and Roskosmos have come to fruition. In the 2010 United States National Space Policy, the ISS was given additional roles of serving commercial, diplomatic and educational purposes.

Scientific research

The ISS provides a platform to conduct scientific research, with power, data, cooling, and crew available to support experiments. Small uncrewed spacecraft can also provide platforms for experiments, especially those involving zero gravity and exposure to space, but space stations offer a long-term environment where studies can be performed potentially for decades, combined with ready access by human researchers. The ISS simplifies individual experiments by allowing groups of experiments to share the same launches and crew time. Research is conducted in a wide variety of fields, including astrobiology, astronomy, physical sciences, materials science, space weather, meteorology, and human research including space medicine and the life sciences. Scientists on Earth have timely access to the data and can suggest experimental modifications to the crew. If follow-on experiments are necessary, the routinely scheduled launches of resupply craft allows new hardware to be launched with relative ease. Crews fly expeditions of several months' duration, providing approximately 160 person-hours per week of labour with a crew of 6. However, a considerable amount of crew time is taken up by station maintenance.
Perhaps the most notable ISS experiment is the Alpha Magnetic Spectrometer (AMS), which is intended to detect dark matter and answer other fundamental questions about our universe and is as important as the Hubble Space Telescope according to NASA. Currently docked on station, it could not have been easily accommodated on a free flying satellite platform because of its power and bandwidth needs. On 3 April 2013, scientists reported that hints of dark matter may have been detected by the AMS. According to the scientists, "The first results from the space-borne Alpha Magnetic Spectrometer confirm an unexplained excess of high-energy positrons in Earth-bound cosmic rays." The space environment is hostile to life. Unprotected presence in space is characterised by an intense radiation field (consisting primarily of protons and other subatomic charged particles from the solar wind, in addition to cosmic rays), high vacuum, extreme temperatures, and microgravity. Some simple forms of life called extremophiles, as well as small invertebrates called tardigrades can survive in this environment in an extremely dry state through desiccation.
The space environment is hostile to life. Unprotected presence in space is characterised by an intense radiation field (consisting primarily of protons and other subatomic charged particles from the solar wind, in addition to cosmic rays), high vacuum, extreme temperatures, and microgravity. Some simple forms of life called extremophiles, as well as small invertebrates called tardigrades can survive in this environment in an extremely dry state through desiccation. Medical research improves knowledge about the effects of long-term space exposure on the human body, including muscle atrophy, bone loss, and fluid shift. This data will be used to determine whether high duration human spaceflight and space colonisation are feasible. As of 2006, data on bone loss and muscular atrophy suggest that there would be a significant risk of fractures and movement problems if astronauts landed on a planet after a lengthy interplanetary cruise, such as the six-month interval required to travel to Mars.

Free fall

Gravity at the altitude of the ISS is approximately 90% as strong as at Earth's surface, but objects in orbit are in a continuous state of freefall, resulting in an apparent state of weightlessness. This perceived weightlessness is disturbed by five separate effects:
1.Drag from the residual atmosphere.
2.Vibration from the movements of mechanical systems and the crew.
3.Actuation of the on-board attitude control moment gyroscopes.
4.Thruster firings for attitude or orbital changes.
5.Gravity-gradient effects, also known as tidal effects.
6.Items at different locations within the ISS would, if not attached to the station, follow slightly different orbits. Being mechanically interconnected these items experience small forces that keep the station moving as a rigid body.
The study of materials science is an important ISS research activity, with the objective of reaping economic benefits through the improvement of techniques used on the ground. Other areas of interest include the effect of the low gravity environment on combustion, through the study of the efficiency of burning and control of emissions and pollutants. These findings may improve current knowledge about energy production, and lead to economic and environmental benefits. Future plans are for the researchers aboard the ISS to examine aerosols, ozone, water vapour, and oxides in Earth's atmosphere, as well as cosmic rays, cosmic dust, antimatter, and dark matter in the universe.

Education & Cultural Outreach

Amateur Radio on the ISS (ARISS) is a volunteer programme which encourages students worldwide to pursue careers in science, technology, engineering and mathematics through amateur radio communications opportunities with the ISS crew. ARISS is an international working group, consisting of delegations from nine countries including several countries in Europe as well as Japan, Russia, Canada, and the United States. In areas where radio equipment cannot be used, speakerphones connect students to ground stations which then connect the calls to the station.

Manufacturing

Since the International Space Station is a multi-national collaborative project, the components for in-orbit assembly were manufactured in various countries around the world. Beginning in the mid 1990s, the U.S. components Destiny, Unity, the Integrated Truss Structure, and the solar arrays were fabricated at the Marshall Space Flight Center and the Michoud Assembly Facility. These modules were delivered to the Operations and Checkout Building and the Space Station Processing Facility for final assembly and processing for launch. The Russian modules, including Zarya and Zvezda, were manufactured at the Khrunichev State Research and Production Space Center in Moscow. Zvezda was initially manufactured in 1985 as a component for Mir-2, but was never launched and instead became the ISS Service Module. The European Space Agency Columbus module was manufactured at the European Space Research and Technology Centre (ESTEC) in the Netherlands, along with many other contractors throughout Europe. The other ESA-built modules - Harmony, Tranquility, the Leonardo MPLM, and the Cupola - were initially manufactured at the Thales Alenia Space factory located at the Cannes Mandelieu Space Center. The structural steel hulls of the modules were transported by aircraft to the Kennedy Space Center SSPF for launch processing. The Japanese Experiment Module Kibo, was fabricated in various technology manufacturing facilities in Japan, at the NASDA (now JAXA) Tanegashima Space Center, and the Institute of Space and Astronautical Science. The Kibo module was transported by ship and flown by aircraft to the KSC Space Station Processing Facility. The Mobile Servicing System, consisting of the Canadarm-2 and the Dextre grapple fixture, was manufactured at various factories in Canada and the United States under contract by the Canadian Space Agency. The mobile base system, a connecting framework for Canadarm-2 mounted on rails, was built by Northrop Grumman. The Canadarm-2 and Dextre were built by MDA Space Missions.

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Space Station-Blue Print

The ISS is a third generation modular space station. Modular stations can allow modules to be added to or removed from the existing structure, allowing greater flexibility. Below is a diagram of major station components. The blue areas are pressurised sections accessible by the crew without using spacesuits. The station's unpressurised superstructure is indicated in red. Other unpressurised components are yellow. Note that the Unity node joins directly to the Destiny laboratory. For clarity, they are shown apart.

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Orbit

The ISS is maintained in a nearly circular orbit with a minimum mean altitude of 330 km (205 mi) and a maximum of 410 km (255 mi), in the centre of the thermosphere, at an inclination of 51.6 degrees to Earth's equator, necessary to ensure that Russian Soyuz and Progress spacecraft launched from the Baikonur Cosmodrome may be safely launched to reach the station. Spent rocket stages must be dropped into uninhabited areas and this limits the directions rockets can be launched from the spaceport. It travels at an average speed of 27,724 kilometres per hour (17,227 mph), and completes 15.54 orbits per day (93 minutes per orbit). The station's altitude was allowed to fall around the time of each NASA shuttle flight to permit heavier loads to be transferred to the station. After the retirement of the shuttle, the nominal orbit of the space station was raised in altitude. Other, more frequent supply ships do not require this adjustment as they are substantially higher performance vehicles. Orbital boosting can be performed by the station's two main engines on the Zvezda service module, or Russian or European spacecraft docked to Zvezda's aft port. The ATV is constructed with the possibility of adding a second docking port to its aft end, allowing other craft to dock and boost the station. It takes approximately two orbits (three hours) for the boost to a higher altitude to be completed. Maintaining ISS altitude uses about 7.5 tonnes of chemical fuel per annum at an annual cost of about $210 million. Orbits of the ISS, shown in April 2013 The Russian Orbital Segment contains the Data Management System, which handles Guidance, Navigation and Control (ROS GNC) for the entire station. Initially, Zarya, the first module of the station, controlled the station until a short time after the Russian service module Zvezda docked and was transferred control. Zvezda contains the ESA built DMS-R Data Management System. Using two fault-tolerant computers (FTC), Zvezda computes the station's position and orbital trajectory using redundant Earth horizon sensors, Solar horizon sensors as well as Sun and star trackers. The FTCs each contain three identical processing units working in parallel and provide advanced fault-masking by majority voting.

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Mission controls

The components of the ISS are operated and monitored by their respective space agencies at mission control centres across the globe, including: Roscosmos's Mission Control Center at Korolyov, Moscow Oblast, controls the Russian Orbital Segment which handles Guidance, Navigation and Control for the entire Station,in addition to individual Soyuz and Progress missions. ESA's ATV Control Centre, at the Toulouse Space Centre (CST) in Toulouse, France, controls flights of the uncrewed European Automated Transfer Vehicle. JAXA's JEM Control Center and HTV Control Center at Tsukuba Space Center (TKSC) are responsible for operating the Kibō complex and all flights of the White Stork HTV Cargo spacecraft, respectively. NASA's Mission Control Center at Lyndon B. Johnson Space Center in Houston, Texas, serves as the primary control facility for the United States segment of the ISS. NASA's Payload Operations and Integration Center at Marshall Space Flight Center in Huntsville, Alabama, coordinates payload operations in the USOS. ESA's Columbus Control Centre at the German Aerospace Center in Oberpfaffenhofen, Germany, manages the European Columbus research laboratory. CSA's MSS Control at Saint-Hubert, Quebec, Canada, controls and monitors the Mobile Servicing System, or Canadarm2.

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Life Aboard

Crew activities
A typical day for the crew begins with a wake-up at 06:00, followed by post-sleep activities and a morning inspection of the station. The crew then eats breakfast and takes part in a daily planning conference with Mission Control before starting work at around 08:10. The first scheduled exercise of the day follows, after which the crew continues work until 13:05. Following a one-hour lunch break, the afternoon consists of more exercise and work before the crew carries out its pre-sleep activities beginning at 19:30, including dinner and a crew conference. The scheduled sleep period begins at 21:30. In general, the crew works ten hours per day on a weekday, and five hours on Saturdays, with the rest of the time their own for relaxation or work catch-up.
The time zone used aboard the ISS is Coordinated Universal Time (UTC). The windows are covered at night hours to give the impression of darkness because the station experiences 16 sunrises and sunsets per day. During visiting Space Shuttle missions, the ISS crew mostly follows the shuttle's Mission Elapsed Time (MET), which is a flexible time zone based on the launch time of the shuttle mission.
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The station provides crew quarters for each member of the expedition's crew, with two 'sleep stations' in the Zvezda and four more installed in Harmony. The USOS quarters are private, approximately person-sized soundproof booths. The ROS crew quarters include a small window, but provide less ventilation and sound proofing. A crew member can sleep in a crew quarter in a tethered sleeping bag, listen to music, use a laptop, and store personal items in a large drawer or in nets attached to the module's walls. The module also provides a reading lamp, a shelf and a desktop. Visiting crews have no allocated sleep module, and attach a sleeping bag to an available space on a wall. It is possible to sleep floating freely through the station, but this is generally avoided because of the possibility of bumping into sensitive equipment. It is important that crew accommodations be well ventilated; otherwise, astronauts can wake up oxygen-deprived and gasping for air, because a bubble of their own exhaled carbon dioxide has formed around their heads. During various station activities and crew rest times, the lights in the ISS can be dimmed, switched off, and color temperatures adjusted.

Life Support

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Food

On the USOS, most of the food aboard is vacuum sealed in plastic bags; cans are rare because they are heavy and expensive to transport. Preserved food is not highly regarded by the crew and taste is reduced in microgravity,so efforts are taken to make the food more palatable, including using more spices than in regular cooking. The crew looks forward to the arrival of any ships from Earth as they bring fresh fruit and vegetables. Care is taken that foods do not create crumbs, and liquid condiments are preferred over solid to avoid contaminating station equipment. Each crew member has individual food packages and cooks them using the on-board galley. The galley features two food warmers, a refrigerator which was added in November 2008, and a water dispenser that provides both heated and unheated water. Drinks are provided as dehydrated powder that is mixed with water before consumption. Drinks and soups are sipped from plastic bags with straws, while solid food is eaten with a knife and fork attached to a tray with magnets to prevent them from floating away. Any food that floats away, including crumbs, must be collected to prevent it from clogging the station's air filters and other equipment.

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Hygiene | Toilet

Showers on space stations were introduced in the early 1970s on Skylab and Salyut 3. By Salyut 6, in the early 1980s, the crew complained of the complexity of showering in space, which was a monthly activity. The ISS does not feature a shower; instead, crewmembers wash using a water jet and wet wipes, with soap dispensed from a toothpaste tube-like container. Crews are also provided with rinseless shampoo and edible toothpaste to save water.

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Docking

All Russian spacecraft and self-propelled modules are able to rendezvous and dock to the space station without human intervention using the Kurs radar docking system from over 200 kilometres away. The European ATV uses star sensors and GPS to determine its intercept course. When it catches up it uses laser equipment to optically recognize Zvezda, along with the Kurs system for redundancy. Crew supervise these craft, but do not intervene except to send abort commands in emergencies. Progress and ATV supply craft can remain at the ISS for six months,allowing great flexibility in crew time for loading and unloading of supplies and trash. From the initial station programs, the Russians pursued an automated docking methodology that used the crew in override or monitoring roles. Although the initial development costs were high, the system has become very reliable with standardisations that provide significant cost benefits in repetitive operations. An automated approach could also allow assembly of modules orbiting other worlds prior to crew arrival. Soyuz spacecraft used for crew rotation also serve as lifeboats for emergency evacuation; they are replaced every six months and were used after the Columbia disaster to return stranded crew from the ISS. Expeditions require, on average, 2,722 kg of supplies, and as of 9 March 2011, crews had consumed a total of around 22,000 meals. Soyuz crew rotation flights and Progress resupply flights visit the station on average two and three times respectively each year, with the ATV and HTV planned to visit annually from 2010 onwards. Other vehicles berth instead of docking. The Japanese H-II Transfer Vehicle parks itself in progressively closer orbits to the station, and then awaits 'approach' commands from the crew, until it is close enough for a robotic arm to grapple and berth the vehicle to the USOS. Berthed craft can transfer International Standard Payload Racks. Japanese spacecraft berth for one to two months. The berthing Cygnus and Dragon are contracted to fly cargo to the station under the Commercial Resupply Services program. From 26 February 2011 to 7 March 2011 four of the governmental partners (United States, ESA, Japan and Russia) had their spacecraft (NASA Shuttle, ATV, HTV, Progress and Soyuz) docked at the ISS, the only time this has happened to date. On 25 May 2012, SpaceX delivered the first commercial cargo with a Dragon spacecraft.

Orbital debris threats

The low altitudes at which the ISS orbits are also home to a variety of space debris,including spent rocket stages, defunct satellites, explosion fragments (including materials from anti-satellite weapon tests), paint flakes, slag from solid rocket motors, and coolant released by US-A nuclear-powered satellites. These objects, in addition to natural micrometeoroids, are a significant threat. Objects large enough to destroy the station can be tracked, and are not as dangerous as smaller debris. Objects too small to be detected by optical and radar instruments, from approximately 1 cm down to microscopic size, number in the trillions. Despite their small size, some of these objects are a threat because of their kinetic energy and direction in relation to the station. Spacewalking crew in spacesuits are also at risk of suit damage and consequent exposure to vacuum.
Ballistic panels, also called micrometeorite shielding, are incorporated into the station to protect pressurised sections and critical systems. The type and thickness of these panels depend on their predicted exposure to damage. The station's shields and structure have different designs on the ROS and the USOS. On the USOS, Whipple shields are used.
The US segment modules consist of an inner layer made from 1.5 cm thick aluminum, a 10 cm thick intermediate layers of Kevlar and Nextel, and an outer layer of stainless steel, which causes objects to shatter into a cloud before hitting the hull, thereby spreading the energy of impact. On the ROS, a carbon plastic honeycomb screen is spaced from the hull, an aluminium honeycomb screen is spaced from that, with a screen-vacuum thermal insulation covering, and glass cloth over the top.
Example of risk management: A NASA model showing areas at high risk from impact for the International Space Station. Space debris is tracked remotely from the ground, and the station crew can be notified. If necessary, thrusters on the Russian Orbital Segment can alter the station's orbital altitude, avoiding the debris. These Debris Avoidance Manoeuvres (DAMs) are not uncommon, taking place if computational models show the debris will approach within a certain threat distance. Ten DAMs had been performed by the end of 2009. Usually, an increase in orbital velocity of the order of 1 m/s is used to raise the orbit by one or two kilometres. If necessary, the altitude can also be lowered, although such a maneuver wastes propellant. If a threat from orbital debris is identified too late for a DAM to be safely conducted, the station crew close all the hatches aboard the station and retreat into their Soyuz spacecraft in order to be able to evacuate in the event the station was seriously damaged by the debris. This partial station evacuation has occurred on 13 March 2009, 28 June 2011, 24 March 2012 and 16 June 2015.

Radar-trackable objects, including debris, with distinct ring of geostationary satellites

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End of mission

According to the Outer Space Treaty, the United States and Russia are legally responsible for all modules they have launched. Natural orbital decay with random reentry (as with Skylab), boosting the station to a higher altitude (which would delay reentry), and a controlled targeted de-orbit to a remote ocean area were considered as ISS disposal options. As of late 2010, the preferred plan is to use a slightly modified Progress spacecraft to de-orbit the ISS. This plan was seen as the simplest, cheapest and with the highest margin.
The Orbital Piloted Assembly and Experiment Complex (OPSEK) was previously intended to be constructed of modules from the Russian Orbital Segment after the ISS is decommissioned. The modules under consideration for removal from the current ISS included the Multipurpose Laboratory Module (Nauka), currently scheduled to be launched in November 2019, and the other new Russian modules that are planned to be attached to Nauka. These newly launched modules would still be well within their useful lives in 2020 or 2024.
At the end of 2011, the Exploration Gateway Platform concept also proposed using leftover USOS hardware and 'Zvezda 2' [sic] as a refuelling depot and service station located at one of the Earth-Moon Lagrange points. However, the entire USOS was not designed for disassembly and will be discarded. In February 2015, Roscosmos announced that it would remain a part of the ISS programme until 2024.
Nine months earlier—in response to US sanctions against Russia over the annexation of Crimea—Russian Deputy Prime Minister Dmitry Rogozin had stated that Russia would reject a US request to prolong the orbiting station's use beyond 2020, and would only supply rocket engines to the US for non-military satellite launches. On 28 March 2015, Russian sources announced that Roscosmos and NASA had agreed to collaborate on the development of a replacement for the current ISS. Igor Komarov, the head of Russia's Roscosmos, made the announcement with NASA administrator Charles Bolden at his side. In a statement provided to SpaceNews on 28 March, NASA spokesman David Weaver said the agency appreciated the Russian commitment to extending the ISS, but did not confirm any plans for a future space station.[353] On 30 September 2015, Boeing's contract with NASA as prime contractor for the ISS was extended to 30 September 2020.
Part of Boeing's services under the contract will relate to extending the station's primary structural hardware past 2020 to the end of 2028. Regarding extending the ISS, on 15 November 2016 General Director Vladimir Solntsev of RSC Energia stated "Maybe the ISS will receive continued resources. Today we discussed the possibility of using the station until 2028," with discussion to continue under the new presidential administration. There have also been suggestions that the station could be converted to commercial operations after it is retired by government entities. In July 2018, the Space Frontier Act of 2018 was intended to extend operations of the ISS to 2030. This bill was unanimously approved in the Senate, but failed to pass in the U.S. House. In September 2018, the Leading Human Spaceflight Act was introduced with the intent to extend operations of the ISS to 2030, and was confirmed in December 2018.

Cost

The ISS has been described as the most expensive single item ever constructed. In 2010 the cost was expected to be $150 billion. This includes NASA's budget of $58.7 billion (inflation-unadjusted) for the station from 1985 to 2015 ($72.4 billion in 2010 dollars),
Russia's $12 billion,
Europe's $5 billion,
Japan's $5 billion,
Canada's $2 billion,
and the cost of 36 shuttle flights to build the station;
estimated at $1.4 billion each, or $50.4 billion in total.
Assuming 20,000 person-days of use from 2000 to 2015 by two- to six-person crews, each person-day would cost $7.5 million, less than half the inflation-adjusted $19.6 million ($5.5 million before inflation) per person-day of Skylab.

Sightings from Earth

Naked eye

The ISS is visible to the naked eye as a slow-moving, bright white dot because of reflected sunlight, and can be seen in the hours after sunset and before sunrise, when the station remains sunlit but the ground and sky are dark. The ISS takes about 10 minutes to pass from one horizon to another, and will only be visible part of that time because of moving into or out of the Earth's shadow. Because of the size of its reflective surface area, the ISS is the brightest artificial object in the sky, excluding flares, with an approximate maximum magnitude of −4 when overhead (similar to Venus). The ISS, like many satellites including the Iridium constellation, can also produce flares of up to 8 or 16 times the brightness of Venus as sunlight glints off reflective surfaces. The ISS is also visible in broad daylight, albeit with a great deal more difficulty. Tools are provided by a number of websites such as Heavens-Above (see Live viewing below) as well as smartphone applications that use orbital data and the observer's longitude and latitude to indicate when the ISS will be visible (weather permitting), where the station will appear to rise, the altitude above the horizon it will reach and the duration of the pass before the station disappears either by setting below the horizon or entering into Earth's shadow. In November 2012 NASA launched its "Spot the Station" service, which sends people text and email alerts when the station is due to fly above their town. The station is visible from 95% of the inhabited land on Earth, but is not visible from extreme northern or southern latitudes.

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There are several unique differences between the properties of materials in space compared to the same materials on the Earth. These differences can be exploited to produce unique or improved manufacturing techniques. The microgravity environment allows control of convection in liquids or gasses, and the elimination of sedimentation. Diffusion becomes the primary means of material mixing, allowing otherwise immiscible materials to be intermixed. The environment allows enhanced growth of larger, higher-quality crystals in solution. The ultraclean vacuum of space allows the creation of very pure materials and objects. The use of vapor deposition can be used to build up materials layer by layer, free from defects.
Surface tension causes liquids in microgravity to form perfectly round spheres. This can cause problems when trying to pump liquids through a conduit, but it is very useful when perfect spheres of consistent size are needed for an application. Space can provide readily available extremes of heat and cold. Sunlight can be focused to concentrate enough heat to melt the materials, while objects kept in perpetual shade are exposed to temperatures close to absolute zero. The temperature gradient can be exploited to produce strong, glassy materials.

For most manufacturing applications, specific material requirements must be satisfied. Mineral ores need to be refined to extract specific metals, and volatile organic compounds will need to be purified. Ideally these raw materials are delivered to the processing site in an economical manner, where time to arrival, propulsion energy expenditure, and extraction costs are factored into the planning process. Minerals can be obtained from asteroids, the lunar surface, or a planetary body. Volatiles could potentially be obtained from a comet, carbonaceous chondrite or "C-Type" asteroids, or the moons of Mars or other planets. It may also prove possible to extract hydrogen in the form of water ice or hydrated minerals from cold traps on the poles of the Moon. Another potential source of raw materials, at least in the short term, is recycled orbiting satellites and other man-made objects in space. Some consideration was given to the use of the Space Shuttle external fuel tanks for this purpose, but NASA determined that the potential benefits were outweighed by the increased risk to crew and vehicle
Unless the materials processing and the manufacturing sites are co-located with the resource extraction facilities, the raw materials will need to be moved about the solar system. There are several proposed means of providing propulsion for this material, including solar sails, electric sails, magnetic sails, electric ion thrusters, or mass drivers (this last method uses a sequence of electromagnets mounted in a line to accelerate a conducting material). At the materials processing facility, the incoming materials will need to be captured by some means. Maneuvering rockets attached to the load can park the content in a matching orbit. Alternatively, if the load is moving at a low delta-v relative to the destination, then it can be captured by means of a mass catcher. This could consist of a large, flexible net or inflatable structure that would transfer the momentum of the mass to the larger facility. Once in place, the materials can be moved into place by mechanical means or by means of small thrusters. Materials can be used for manufacturing either in their raw form, or by processing them to extract the constituent elements. Processing techniques include various chemical, thermal, electrolytic, and magnetic methods for separation. In the near term, relatively straightforward methods can be used to extract aluminum, iron, oxygen, and silicon from lunar and asteroidal sources. Less concentrated elements will likely require more advanced processing facilities, which may have to wait until a space manufacturing infrastructure is fully developed.
Some of the chemical processes will require a source of hydrogen for the production of water and acid mixtures. Hydrogen gas can also be used to extract oxygen from the lunar regolith, although the process is not very efficient. clarification needed][citation needed] So a readily available source of useful volatiles is a positive factor in the development of space manufacturing. Alternatively, oxygen can be liberated from the lunar regolith without reusing any imported materials by heating the regolith to 2,500 C in a vacuum. This was tested on Earth with lunar simulant in a vacuum chamber. As much as 20% of the sample was released as free oxygen. Eric Cardiff calls the remainder slag. This process is highly efficient in terms of imported materials used up per batch, but is not the most efficient process in energy per kilogram of oxygen. One proposed method of purifying asteroid materials is through the use of carbon monoxide (CO). Heating the material to 500 °F (260 °C) and exposing it to CO causes the metals to form gaseous carbonyls. This vapor can then be distilled to separate out the metal components, and the CO can then be recovered by another heating cycle. Thus an automated ship can scrape up loose surface materials from, say, the relatively nearby 4660 Nereus (in delta-v terms), process the ore using solar heating and CO, and eventually return with a load of almost pure metal. The economics of this process can potentially allow the material to be extracted at one-twentieth the cost of launching from Earth, but it would require a two-year round trip to return any mined ore.

Due to speed of light constraints on communication, manufacturing in space at a distant point of resource acquisition will either require completely autonomous robotics to perform the labor, or a human crew with all the accompanying habitat and safety requirements. If the plant is built in orbit around the Earth, or near a manned space habitat, however, telecheric devices can be used for certain tasks that require human intelligence and flexibility.
Solar power provides a readily available power source for thermal processing. Even with heat alone, simple thermally-fused materials can be used for basic construction of stable structures. Bulk soil from the Moon or asteroids has a very low water content, and when melted to form glassy materials is very durable. These simple, glassy solids can be used for the assembly of habitats on the surface of the Moon or elsewhere. The solar energy can be concentrated in the manufacturing area using an array of steerable mirrors.
The availability and favorable physical properties of metals will make them a major component of space manufacturing. Most of the metal handling techniques used on Earth can also be adopted for space manufacturing. A few of these techniques will need significant modifications due to the microgravity environment.
The production of hardened steel in space will introduce some new factors. Carbon only appears in small proportions in lunar surface materials and will need to be delivered from elsewhere. Waste materials carried by humans from the Earth is one possible source, as are comets. The water normally used to quench steel will also be in short supply, and require strong agitation.
Casting steel can be a difficult process in microgravity, requiring special heating and injection processes, or spin forming. Heating can be performed using sunlight combined with electrical heaters. The casting process would also need to be managed to avoid the formation of voids as the steel cools and shrinks.
Various metal-working techniques can be used to shape the metal into the desired form. The standard methods are casting, drawing, forging, machining, rolling, and welding. Both rolling and drawing metals require heating and subsequent cooling. Forging and extrusion can require powered presses, as gravity is not available. Electron beam welding has already been demonstrated on board the Skylab, and will probably be the method of choice in space. Machining operations can require precision tools which will need to be imported from the Earth for some duration.
New space manufacturing technologies are being studied at places such as Marshall's National Center for Advanced Manufacturing. The methods being investigated include coatings that can be sprayed on surfaces in space using a combination of heat and kinetic energy, and electron beam free form fabrication of parts. Approaches such as these, as well as examination of material properties that can be investigated in an orbiting laboratory, will be studied on the International Space Station by NASA and Made In Space, Inc.

he option of 3D printing items in space holds many advantages over manufacturing situated on Earth. With 3D printing technologies, rather than exporting tools and equipment from Earth into space, astronauts have the option to manufacture needed items directly. On-demand patterns of manufacturing make long-distance space travel more feasible and self-sufficient as space excursions require less cargo. Mission safety is also improved.
The Made In Space, Inc. 3D printers, which launched in 2014 to the International Space Station, are designed specifically for a zero-gravity or micro-gravity environment. The effort was awarded the Phase III Small Business Innovation and Research Contract. The Additive Manufacturing Facility will be used by NASA to carry out repairs (including during emergency situations), upgrades, and installation. Made In Space lists the advantages of 3D printing as easy customization, minimal raw material waste, optimized parts, faster production time, integrated electronics, limited human interaction, and option to modify the printing process.
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The Refabricator experiment, under development by Firmamentum, a division of Tethers Unlimited, Inc. under a NASA Phase III Small Business Innovation Research contract, combines a recycling system and a 3D printer to perform demonstration of closed-cycle in-space manufacturing on the International Space Station (ISS). The Refabricator experiment, scheduled for launch to the ISS in early 2018, will process plastic feedstock through multiple printing and recycling cycles to evaluate how many times the plastic materials can be re-used in the microgravity environment before their polymers degrade to unacceptable levels.
Additionally, 3D printing in space can also account for the printing of meals. NASA's Advanced Food Technology program is currently investigating the possibility of printing food items in order to improve food quality, nutrient content, and variety.

There are thought to be a number of useful products that can potentially be manufactured in space and result in an economic benefit. Research and development is required to determine the best commodities to be produced, and to find efficient production methods. The following products are considered prospective early candidates:

1.Growth of protein crystals
2.Improved semiconductor wafers
3.Micro-encapsulation.

As the infrastructure is developed and the cost of assembly drops, some of the manufacturing capacity can be directed toward the development of expanded facilities in space, including larger scale manufacturing plants. These will likely require the use of lunar and asteroid materials, and so follow the development of mining bases.
Rock is the simplest product, and at minimum is useful for radiation shielding. It can also be subsequently processed to extract elements for various uses.
Water from lunar sources, Near Earth Asteroids or Martian moons is thought to be relatively cheap and simple to extract, and gives adequate performance for many manufacturing and material shipping purposes. Separation of water into hydrogen and oxygen can be easily performed in small scale, but some scientists.believe that this will not be performed on any large scale initially due to the large quantity of equipment and electrical energy needed to split water and liquify the resultant gases. Water used in steam rockets gives a specific impulse of about 190 seconds; less than half that of hydrogen/oxygen, but this is adequate for delta-v's that are found between Mars and Earth. Water is useful as a radiation shield and in many chemical processes.
Ceramics made from lunar or asteroid soil can be employed for a variety of manufacturing purposes. These uses include various thermal and electrical insulators, such as heat shields for payloads being delivered to the Earth's surface.
Metals can be used to assemble a variety of useful products, including sealed containers (such as tanks and pipes), mirrors for focusing sunlight, and thermal radiators. The use of metals for electrical devices would require insulators for the wires, so a flexible insulating material such as plastic or fiberglass will be needed.
A notable output of space manufacturing is expected to be solar panels. Expansive solar energy arrays can be constructed and assembled in space. As the structure does not need to support the loads that would be experienced on Earth, huge arrays can be assembled out of proportionately smaller amounts of material. The generated energy can then be used to power manufacturing facilities, habitats, spacecraft, lunar bases, and even beamed down to collectors on the Earth with microwaves.
Other possibilities for space manufacturing include propellants for spacecraft, some repair parts for spacecraft and space habitats, and, of course, larger factories. Ultimately, space manufacturing facilities can hypothetically become nearly self-sustaining, requiring only minimal imports from the Earth. The microgravity environment allows for new possibilities in construction on a massive scale, including megascale engineering. These future projects might potentially assemble space elevators, massive solar array farms, very high capacity spacecraft, and rotating habitats capable of sustaining populations of tens of thousands of people in Earth-like conditions.

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