Portal:Space

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Introduction

A right-handed three-dimensional Cartesian coordinate system used to indicate positions in space.

Space is the boundless three-dimensional extent in which objects and events have relative position and direction. Physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of a boundless four-dimensional continuum known as spacetime. The concept of space is considered to be of fundamental importance to an understanding of the physical universe. However, disagreement continues between philosophers over whether it is itself an entity, a relationship between entities, or part of a conceptual framework.

Debates concerning the nature, essence and the mode of existence of space date back to antiquity; namely, to treatises like the Timaeus of Plato, or Socrates in his reflections on what the Greeks called khôra (i.e. "space"), or in the Physics of Aristotle (Book IV, Delta) in the definition of topos (i.e. place), or in the later "geometrical conception of place" as "space qua extension" in the Discourse on Place (Qawl fi al-Makan) of the 11th-century Arab polymath Alhazen. Many of these classical philosophical questions were discussed in the Renaissance and then reformulated in the 17th century, particularly during the early development of classical mechanics. In Isaac Newton's view, space was absolute—in the sense that it existed permanently and independently of whether there was any matter in the space. Other natural philosophers, notably Gottfried Leibniz, thought instead that space was in fact a collection of relations between objects, given by their distance and direction from one another. In the 18th century, the philosopher and theologian George Berkeley attempted to refute the "visibility of spatial depth" in his Essay Towards a New Theory of Vision. Later, the metaphysician Immanuel Kant said that the concepts of space and time are not empirical ones derived from experiences of the outside world—they are elements of an already given systematic framework that humans possess and use to structure all experiences. Kant referred to the experience of "space" in his Critique of Pure Reason as being a subjective "pure a priori form of intuition".

Selected general articles

Saturn V rocket, used for the American manned lunar landing missions
Space exploration is the discovery and exploration of celestial structures in outer space by means of evolving and growing space technology. While the study of space is carried out mainly by astronomers with telescopes, the physical exploration of space is conducted both by unmanned robotic space probes and human spaceflight.

While the observation of objects in space, known as astronomy, predates reliable recorded history, it was the development of large and relatively efficient rockets during the mid-twentieth century that allowed physical space exploration to become a reality. Common rationales for exploring space include advancing scientific research, national prestige, uniting different nations, ensuring the future survival of humanity, and developing military and strategic advantages against other countries. Read more...
The environment of space is lethal without appropriate protection: the greatest threat in the vacuum of space derives from the lack of oxygen and pressure, although temperature and radiation also pose risks. The effects of space exposure can result in ebullism, hypoxia, hypocapnia, and decompression sickness. In addition to these, there is also cellular mutation and destruction from high energy photons and sub-atomic particles that are present in the surroundings. Decompression is a serious concern during the extra-vehicular activities (EVAs) of astronauts. Current EMU designs take this and other issues into consideration, and have evolved over time. A key challenge has been the competing interests of increasing astronaut mobility (which is reduced by high-pressure EMUs, analogous to the difficulty of deforming an inflated balloon relative to a deflated one) and minimising decompression risk. Investigators have considered pressurizing a separate head unit to the regular 71 kPa (10.3 psi) cabin pressure as opposed to the current whole-EMU pressure of 29.6 kPa (4.3 psi). In such a design, pressurization of the torso could be achieved mechanically, avoiding mobility reduction associated with pneumatic pressurization. Read more...
The survival of some microorganisms exposed to outer space has been studied using both simulated facilities and low Earth orbit exposures. Bacteria were some of the first organisms investigated, when in 1960 a Russian satellite carried Escherichia coli, Staphylococcus, and Enterobacter aerogenes into orbit. A large number of microorganisms have been selected for exposure experiments since, as listed in the table below.

Experiments of the adaption of microbes in space have yielded unpredictable results. While sometimes the microorganism may weaken, they can also increase in their disease-causing potency. Read more...
Porous chondrite interplanetary dust particle.

Cosmic dust, also called extraterrestrial dust or space dust, is dust which exists in outer space, or has fallen on Earth. Most cosmic dust particles are between a few molecules to 0.1 µm in size. Cosmic dust can be further distinguished by its astronomical location: intergalactic dust, interstellar dust, interplanetary dust (such as in the zodiacal cloud) and circumplanetary dust (such as in a planetary ring).

In the Solar System, interplanetary dust causes the zodiacal light. Solar System dust includes comet dust, asteroidal dust, dust from the Kuiper belt, and interstellar dust passing through the Solar System. Thousands of tons of cosmic dust are estimated to reach the Earth's surface every year, with each grain having a mass between 10⁻¹⁶ kg (0.1 pg) and 10⁻⁴ kg (100 mg). The density of the dust cloud through which the Earth is traveling is approximately 10⁻⁶/m³. Read more...
Astronaut Marsha Ivins demonstrates the effects of zero-G on her hair in space

Venturing into the environment of space can have negative effects on the human body. Significant adverse effects of long-term weightlessness include muscle atrophy and deterioration of the skeleton (spaceflight osteopenia). Other significant effects include a slowing of cardiovascular system functions, decreased production of red blood cells, balance disorders, eyesight disorders and a weakening of the immune system. Additional symptoms include fluid redistribution (causing the "moon-face" appearance typical in pictures of astronauts experiencing weightlessness), loss of body mass, nasal congestion, sleep disturbance, and excess flatulence.

The engineering problems associated with leaving Earth and developing space propulsion systems have been examined for over a century, and millions of man-hours of research have been spent on them. In recent years there has been an increase in research on the issue of how humans can survive and work in space for extended and possibly indefinite periods of time. This question requires input from the physical and biological sciences and has now become the greatest challenge (other than funding) facing human space exploration. A fundamental step in overcoming this challenge is trying to understand the effects and impact of long-term space travel on the human body. Read more...
Space Shuttle Challenger disintegrates 73 seconds after its 1986 launch resulting in the death of all seven crew members.

This article lists verifiable spaceflight-related accidents and incidents resulting in fatality or near-fatality during flight or training for manned space missions, and testing, assembly, preparation or flight of manned and unmanned spacecraft. Not included are accidents or incidents associated with intercontinental ballistic missile (ICBM) tests, unmanned space flights not resulting in fatality or serious injury, or Soviet or German rocket-powered aircraft projects of World War II. Also not included are alleged unreported Soviet space accidents, which are considered fringe theories by a majority of historians.

, there have been 18 astronaut and cosmonaut fatalities during spaceflight. Astronauts have also died while training for space missions, such as the Apollo 1 launch pad fire which killed an entire crew of three. There have also been some non-astronaut fatalities during spaceflight-related activities. Read more...
Food aboard the Space Shuttle served on a tray. Note the use of magnets, springs, and Velcro to hold the cutlery and food packets to the tray

Space food is a type of food product created and processed for consumption by astronauts in outer space. The food has specific requirements of providing balanced nutrition for individuals working in space, while being easy and safe to store, prepare and consume in the machinery-filled weightless environments of manned spacecraft.

In recent years, space food has been used by various nations engaging on space programs as a way to share and show off their cultural identity and facilitate intercultural communication. Although astronauts consume a wide variety of foods and beverages in space, the initial idea from The Man in Space Committee of the Space Science Board in 1963 was to supply astronauts with a formula diet that would supply all the needed vitamins and nutrients. Read more...
Space warfare is combat that takes place in outer space. The scope of space warfare therefore includes ground-to-space warfare, such as attacking satellites from the Earth, as well as space-to-space warfare, such as satellites attacking satellites.

In the early 1960s the U.S. military produced a film called Space and National Security which depicted space warfare. Read more...
A 1990 artist rendering of Space Station Freedom, a project that eventually evolved into the International Space Station

Space architecture, in its simplest definition, is the theory and practice of designing and building inhabited environments in outer space.

The architectural approach to spacecraft design addresses the total built environment. It is mainly based on the field of engineering (especially aerospace engineering), but also involves diverse disciplines such as physiology, psychology, and sociology. Like architecture on Earth, the attempt is to go beyond the component elements and systems and gain a broad understanding of the issues that affect design success. Much space architecture work has been in designing concepts for orbital space stations and lunar and Martian exploration ships and surface bases for the world's space agencies, chiefly NASA. Read more...
Hubble Deep Field (full mosaic) released by NASA on January 15, 1996. Credit: R. Williams (STScI), the Hubble Deep Field Team and NASA.
Space law is the body of law governing space-related activities, encompassing both international and domestic agreements, rules, and principles. Parameters of space law include space exploration, liability for damage, weapons use, rescue efforts, environmental preservation, information sharing, new technologies, and ethics. Other fields of law, such as administrative law, intellectual property law, arms control law, insurance law, environmental law, criminal law, and commercial law, are also integrated within space law.

The origins of space law date can be traced back to 1919, with international law recognizing each country's sovereignty over the airspace directly above their territory, later reinforced at the Chicago Convention in 1954. The onset of domestic space programs during the Cold War propelled the official creation of international space policy (i.e. the International Geophysical Year) initiated by the International Council of Scientific Unions. The Soviet Union's 1957 launch of the world's first artificial satellite, Sputnik 1, directly spurred the United States Congress to pass the Space Act, thus creating the National Aeronautics and Space Administration (NASA). Because space exploration required crossing transnational boundaries, it was during this era where space law became a field independent from traditional aerospace law. Read more...
Space neuroscience is the scientific study of the central nervous system (CNS) functions during spaceflight. Living systems can integrate the inputs from the senses to navigate in their environment and to coordinate posture, locomotion, and eye movements. Gravity has a fundamental role in controlling these functions. In weightlessness during spaceflight, integrating the sensory inputs and coordinating motor responses is harder to do because gravity is no longer sensed during free-fall. For example, the otolith organs of the vestibular system no longer signal head tilt relative to gravity when standing. However, they can still sense head translation during body motion. Ambiguities and changes in how the gravitational input is processed can lead to potential errors in perception, which affects spatial orientation and mental representation. Dysfunctions of the vestibular system are common during and immediately after spaceflight, such as space motion sickness in orbit and balance disorders after return to Earth.

Adaptation to weightlessness involves not just the Sensory-motor coupling functions, but some autonomic nervous system functions as well. Sleep disorders and orthostatic intolerance are also common during and after spaceflight. There is no hydrostatic pressure in a weightless environment. As a result, the redistribution of body fluids toward the upper body causes a decrease in leg volume, which may affect muscle viscosity and compliance. An increase in intracranial pressure may also be responsible for a decrease in near visual acuity. In addition, muscle mass and strength both decrease as a result of the reduced loading in weightlessness. Moreover, approximately 70% of astronauts experience space motion sickness to some degree during the first days. The drugs commonly used to combat motion sickness, such as scopolamine and promethazine, have soporific effects. These factors can lead to chronic fatigue. The challenge of integrative space medicine and physiology is to investigate the adaptation of the human body to spaceflight as a whole, and not just as the sum of body parts because all body functions are connected and interact with each other. Read more...
Notes on a map written with a felt-tip pen by Michael Collins while in orbit around the Moon

Several instruments have been used to write in outer space, including different types of pencils and pens. Some of them have been unmodified versions of conventional writing instruments; others have been invented specifically to counter the problems with writing in space conditions.

A common urban legend states that, faced with the fact that ball-point pens would not write in zero-gravity, NASA spent a large amount of money to develop a pen that would write in the conditions experienced during spaceflight (the result purportedly being the Fisher Space Pen), while the Soviet Union took the simpler and cheaper route of just using pencils. The Fisher Space Pen was developed independently by a private organization in the 1960s. Read more...
NASA astronaut Catherine Coleman plays a flute aboard the International Space Station in 2011.

Music in space is music played in or broadcast from a spacecraft in outer space. According to the Smithsonian Institution, the first musical instruments played in outer space were an 8-note Hohner "Little Lady" harmonica and a handful of small bells carried by American astronauts Wally Schirra and Thomas P. Stafford aboard Gemini 6A. Upon achieving a space rendezvous in Earth orbit with their sister ship Gemini 7 in December 1965, Schirra and Stafford played a rendition of "Jingle Bells" over the radio after jokingly claiming to have seen an unidentified flying object piloted by Santa Claus. The instruments had been smuggled on-board without NASA's knowledge, leading Mission Control director Elliot See to exclaim "You're too much" to Schirra after the song. The harmonica was donated to the Smithsonian by Schirra in 1967, with his note that it "...plays quite well".

In the 1970s music tape cassettes were brought to the American space station Skylab, while Soviet cosmonauts Aleksandr Laveikin and Yuri Romanenko brought a guitar to the space station Mir in 1987. Musical instruments must be checked for gases they may emit before being taken aboard the confined environment of a space station. As of 2003, instruments that have been aboard the International Space Station include a flute, a keyboard guitar, a saxophone, and a didgeridoo. Read more...
Zinnia flower floating inside ISS, Earth in the background

Plants in space is about plants in outer space. In the late 20th and 21st century, plants were often taken into space in low Earth orbit to be grown in a weightless but pressurized controlled environment, sometimes called space gardens. In the context of human spaceflight, they can be consumed as food and/or provide a refreshing atmosphere. Plants can metabolize carbon dioxide in the air to produce valuable oxygen, and can help control cabin humidity. Growing plants in space may provide a psychological benefit to human spaceflight crews. Usually the plants were part of studies or technical development to further develop space gardens or conduct science experiments. To date plants taken into space have had mostly scientific interest, with only limited contributions to the functionality of the spacecraft, however the Apollo Moon tree project was more or less forestry inspired mission and the trees part of a country's bicentennial celebration

The first challenge in growing plants in space is how to get plants to grow without gravity. This runs into difficulties regarding the effects of gravity on root development, providing appropriate types of lighting, and other challenges. In particular, the nutrient supply to root as well as the nutrient biogeochemical cycles, and the microbiological interactions in soil-based substrates are particularly complex, but have been shown to make possible space farming in hypo- and micro-gravity. Read more...
Expedition 30 in a Christmas time crew photo, 25 December 2011

Christmas on the International Space Station covers the celebration of Christmas on the International Space Station. Christmas is celebrated each year by the International Space Station crew, their families, and ground-staff. Crew are given time off duty according to their respective culture, religion/faith and ethnicity. The Russian Orthodox Church celebrates Christmas according to the Julian calendar, whilst the Catholic Church and the various Protestant denominations use the Gregorian calendar so the crew may celebrate Christmas more than once on the station choosing between 25 December or 6, 7 or 19 January.

Expedition One arrived on the ISS on 2 November 2000, celebrating their first Christmas on board the station later that year. Other celebrations included Expedition 30, with the arrival of Donald Pettit, Oleg Kononenko, and André Kuipers. The station has been continuously occupied since 2000, so every Christmas has been experienced by a crew. The holiday is popular enough that one of the traditions that has developed is having a Christmas dinner. Read more...
Space burials launch cremated remains out of the atmosphere.
Space burial refers to the blasting of cremated remains into outer space. Missions may go into orbit around the Earth, to other planetary bodies (such as the Moon), or into deep space.

The cremated remains are not actually scattered in space, and thus do not contribute to space debris. Instead, the ashes remain sealed inside their spacecraft until the spacecraft either: re-enters the Earth's atmosphere and burns up upon re-entry (Earth orbit missions); reaches its final, extraterrestrial destination (e.g. the Moon); or escapes the solar system (deep space missions). To a lesser extent, suborbital flights provide the opportunity to briefly fly ashes into space and return them back to Earth for recovery. Only a sample of remains is launched so as to make the service affordable. Read more...
Corrosion in space is the corrosion of materials occurring in outer space. Instead of moisture and oxygen acting as the primary corrosion causes, the materials exposed to outer space are subjected to vacuum, bombardment by ultraviolet and X-rays, and high-energy charged particles (mostly electrons and protons from solar wind). In the upper layers of the atmosphere (between 90–800 km), the atmospheric atoms, ions, and free radicals, most notably atomic oxygen, play a major role. The concentration of atomic oxygen depends on altitude and solar activity, as the bursts of ultraviolet radiation cause photodissociation of molecular oxygen. Between 160 and 560 km, the atmosphere consists of about 90% atomic oxygen. Read more...
Space tourist Mark Shuttleworth

Space tourism is space travel for recreational, leisure or business purposes. There are several different types of space tourism, including orbital, suborbital and lunar space tourism. To date, orbital space tourism has been performed only by the Russian Space Agency. Work also continues towards developing suborbital space tourism vehicles. This is being done by aerospace companies like Blue Origin and Virgin Galactic. In addition, SpaceX (an aerospace manufacturer) announced in 2018 that it is planning on sending two space tourists on a free-return trajectory around the Moon on the upper stage of SpaceX's BFR rocket, known as the Big Falcon Spaceship (BFS).

During the period from 2001 to 2009, the publicized price for flights brokered by Space Adventures to the International Space Station aboard a Russian Soyuz spacecraft was in the range of US$20–40 million. 7 space tourists made 8 space flights during this time. Some space tourists have signed contracts with third parties to conduct certain research activities while in orbit. By 2007, space tourism was thought to be one of the earliest markets that would emerge for commercial spaceflight. Space Adventures is the only company that has sent paying passengers to space. In conjunction with the Federal Space Agency of the Russian Federation and Rocket and Space Corporation Energia, Space Adventures facilitated the flights for all of the world's first private space explorers. The first three participants paid in excess of $20 million (USD) each for their 10-day visit to the ISS. Read more...
A computer-generated image representing space debris as could be seen from high Earth orbit. The two main debris fields are the ring of objects in geosynchronous Earth orbit (GEO) and the cloud of objects in low Earth orbit (LEO).

Initially, the term space debris referred to the natural debris found in the solar system: asteroids, comets, and meteoroids. However, with the 1979 beginning of the NASA Orbital Debris Program, the term also refers to the debris (alt. space waste or space garbage) from the mass of defunct, artificially created objects in space, especially Earth orbit. These include old satellites and spent rocket stages, as well as the fragments from their disintegration and collisions.

As of December 2016, five satellite collisions have generated space debris. Space debris is also known as orbital debris, space junk, space waste, space trash, space litter or space garbage. Read more...
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. Read more...
An astronaut asleep in the microgravity of Earth orbit-continual free-fall around the earth, inside the pressurized module Harmony node of the International Space Station in 2007

Sleeping in space requires that astronauts sleep in a crew cabin, a small room about the size of a shower stall. They lie in a sleeping bag which is strapped to the wall. Astronauts have reported having nightmares, dreams, and snoring while sleeping in space.

Sleeping and crew accommodations need to be well ventilated; otherwise, astronauts can wake up oxygen-deprived and gasping for air, because a bubble of their own exhaled carbon dioxide had formed around their heads. Brain cells are extremely sensitive to a lack of oxygen and brain cells can start dying less than 5 minutes after their oxygen supply disappears; the result is that brain hypoxia can rapidly cause severe brain damage or even death. A decrease of oxygen to the brain can cause dementia and brain damage, as well as a host of other symptoms. Read more...
ORS-2

:This article is about Space-based radar as space radio station (in line to article 1.64, ITU RR) and should not be confused with the radiolocation-satellite service in the meaning of a radiocommunication service in line to articles 1.19 and 1.49 (ITU RR).

Space-based radar refers to space-borne radar systems that may have any of a variety of purposes. A number of earth-observing radar satellites, such as RADARSAT, have employed synthetic aperture radar (SAR) to obtain terrain and land-cover information about the Earth. Read more...
Space Shuttle Endeavour appears to straddle the stratosphere and mesosphere in this photo. The troposphere, which contains clouds appears orange in this photo.

The mesosphere (/ˈmɛsoʊsfɪər/; from Greek mesos "middle" ) is the layer of the Earth's atmosphere that is directly above the stratosphere and directly below the thermosphere. In the mesosphere, temperature decreases as the altitude increases. This characteristic is used to define its limits: it begins at the top of the stratosphere (sometimes called the stratopause), and ends at the mesopause, which is the coldest part of Earth's atmosphere with temperatures below −143 °C (−225 °F; 130 K). The exact upper and lower boundaries of the mesosphere vary with latitude and with season (higher in winter and at the tropics, lower in summer and at the poles), but the lower boundary is usually located at heights from 50 to 65 kilometres (164,000 to 213,000 ft; 31 to 40 mi) above the Earth's surface and the upper boundary (mesopause) is usually around 85 to 100 kilometres (53 to 62 mi).

The stratosphere, mesosphere and lowest part of the thermosphere are collectively referred to as the "middle atmosphere", which spans heights from approximately 10 kilometres (33,000 ft; 6.2 mi) to 100 kilometres (62 mi; 330,000 ft). The mesopause, at an altitude of 80–90 km (50–56 mi), separates the mesosphere from the thermosphere—the second-outermost layer of the Earth's atmosphere. This is also around the same altitude as the turbopause, below which different chemical species are well mixed due to turbulent eddies. Above this level the atmosphere becomes non-uniform; the scale heights of different chemical species differ by their molecular masses. Read more...
Artist's conception of a colony on the Moon

Space colonization (also called space settlement, or extraterrestrial colonization) is permanent human habitation off the planet Earth.

Many arguments have been made for and against space colonization. The two most common in favor of colonization are survival of human civilization and the biosphere in the event of a planetary-scale disaster (natural or man-made), and the availability of additional resources in space that could enable expansion of human society. The most common objections to colonization include concerns that the commodification of the cosmos may be likely to enhance the interests of the already powerful, including major economic and military institutions, and to exacerbate pre-existing detrimental processes such as wars, economic inequality, and environmental degradation. Read more...
Zero Gravity Toilet on the International Space Station in the Zvezda Service Module

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, and any solids are compressed and stored for removal upon landing. More modern systems expose solid waste to vacuum pressures to kill bacteria, which prevents odor problems and kills pathogens. Read more...
LGM-118A Peacekeeper MIRVs re-entering Earth's atmosphere.

Space weapons are weapons used in space warfare. They include weapons that can attack space systems in orbit (i.e. anti-satellite weapons), attack targets on the earth from space or disable missiles travelling through space. In the course of the militarisation of space, such weapons were developed mainly by the contesting superpowers during the Cold War, and some remain under development today. Space weapons are also a central theme in military science fiction and sci-fi video games. Read more...
Space pioneer Miss Baker, a squirrel monkey, rode a Jupiter IRBM into space in 1959.

Non-human animals in space originally served to test the survivability of spaceflight, before human spaceflights were attempted. Later, other non-human animals were flown to investigate various biological processes and the effects microgravity and space flight might have on them. Bioastronautics is an area of bioengineering research which spans the study and support of life in space. To date, seven national space programs have flown animals into space: the Soviet Union, the United States, France, Argentina, China, Japan and Iran.

A wide variety of non-human animals have been launched into space, including monkeys, dogs, tortoises, and insects. The United States launched flights containing monkeys and primates primarily between 1948-1961 with one flight in 1969 and one in 1985. France launched two monkey-carrying flights in 1967. The Soviet Union and Russia launched monkeys between 1983 and 1996. During the 1950s and 1960s, the Soviet space program used a number of dogs for sub-orbital and orbital space flights. Two tortoises and a variety of insects were the first inhabitants of Earth to circle the Moon, on the 1968 Zond 5 mission. Read more...
Aurora australis observed by Discovery, May 1991

Space weather is a branch of space physics and aeronomy, or heliophysics, concerned with the time varying conditions within the Solar System, including the solar wind, emphasizing the space surrounding the Earth, including conditions in the magnetosphere, ionosphere, thermosphere, and exosphere. Space weather is distinct from the terrestrial weather of the Earth's atmosphere (troposphere and stratosphere). The term space weather was first used in the 1950s and came into common usage in the 1990s. Read more...
Human spaceflight (also referred to as crewed spaceflight or manned spaceflight) is space travel with a crew or passengers aboard the spacecraft. Spacecraft carrying people may be operated directly, by human crew, or it may be either remotely operated from ground stations on Earth or be autonomous, able to carry out a specific mission with no human involvement.

The first human spaceflight was launched by the Soviet Union on 12 April 1961 as a part of the Vostok program, with cosmonaut Yuri Gagarin aboard. Humans have been continuously present in space for 18 years and 46 days on the International Space Station. All early human spaceflight was crewed, where at least some of the passengers acted to carry out tasks of piloting or operating the spacecraft. After 2015, several human-capable spacecraft are being explicitly designed with the ability to operate autonomously. Read more...
The Hubble Space Telescope, one of the Great Observatories

A space telescope or space observatory is an instrument located in outer space to observe distant planets, galaxies and other astronomical objects. Space telescopes avoid many of the problems of ground-based observatories, such as light pollution and distortion of electromagnetic radiation (scintillation). In addition, ultraviolet frequencies, X-rays and gamma rays are blocked by the Earth's atmosphere, so they can only be observed from space.

Theorized by Lyman Spitzer in 1946, the first operational space telescopes were the American Orbiting Astronomical Observatory OAO-2 launched in 1968 and the Soviet Orion 1 ultraviolet telescope aboard space station Salyut 1 in 1971. Read more...
STS-116 mission specialists, NASA astronaut Robert Curbeam and ESA astronaut Christer Fuglesang perform extravehicular activity (EVA) during construction of the International Space Station

Locomotion in space includes any variety of actions or methods used to move one's body through an environment with microgravity conditions. Locomotion in these conditions is different from locomotion in Earth's gravity. There are many factors that contribute to these differences, and they are crucial when researching long-term survival of humans in space. Read more...
NASA's Phoenix Mars Lander

In archaeology, space archaeology is the research-based study of various human-made items found in space, their interpretation as clues to the adventures mankind has experienced in space, and their preservation as cultural heritage.

It includes launch complexes on Earth, orbital debris, satellites, and objects and structures on other celestial bodies such as Mars. It also includes the applied field of cultural resource which evaluates the significance of space sites and objects in terms of national and international preservation laws. Cultural resource looks at what, how and why these artifacts of our recent history should be preserved for future generations. Read more...
A Russian Orthodox priest blesses the Soyuz rocket for ISS Expedition 31
Astronauts, cosmonauts, and spaceflight participants have observed their religions while in space; sometimes publicly, sometimes privately. Religious adherence in outer space poses unique challenges and opportunities for practitioners. Space travelers have reported profound changes in the way they view their faith related to the overview effect, while some secular groups have criticized the use of government spacecraft for religious activities by astronauts. Read more...
The interface between the Earth's surface and outer space. The Kármán line at an altitude of 100 km (62 mi) is shown. The layers of the atmosphere are drawn to scale, whereas objects within them, such as the International Space Station, are not.

Outer space, or just space, is the expanse that exists beyond the Earth and between celestial bodies. Outer space is not completely empty—it is a hard vacuum containing a low density of particles, predominantly a plasma of hydrogen and helium as well as electromagnetic radiation, magnetic fields, neutrinos, dust, and cosmic rays. The baseline temperature, as set by the background radiation from the Big Bang, is 2.7 kelvins (−270.45 °C; −454.81 °F). The plasma between galaxies accounts for about half of the baryonic (ordinary) matter in the universe; it has a number density of less than one hydrogen atom per cubic metre and a temperature of millions of kelvins; local concentrations of this plasma have condensed into stars and galaxies. Studies indicate that 90% of the mass in most galaxies is in an unknown form, called dark matter, which interacts with other matter through gravitational but not electromagnetic forces. Observations suggest that the majority of the mass-energy in the observable universe is a poorly understood vacuum energy of space, which astronomers label dark energy. Intergalactic space takes up most of the volume of the Universe, but even galaxies and star systems consist almost entirely of empty space.

Outer space does not begin at a definite altitude above the Earth's surface. However, the Kármán line, an altitude of 100 km (62 mi) above sea level, is conventionally used as the start of outer space in space treaties and for aerospace records keeping. The framework for international space law was established by the Outer Space Treaty, which entered into force on 10 October 1967. This treaty precludes any claims of national sovereignty and permits all states to freely explore outer space. Despite the drafting of UN resolutions for the peaceful uses of outer space, anti-satellite weapons have been tested in Earth orbit. Read more...
The 2suit test in microgravity on The Universe series Sex in Space, September 13, 2008.

Sex in space is human sexual activity in the weightlessness of outer space. It presents difficulties for the performance of most sexual activities due to Newton's third law. According to the law, if the couple remain attached, their movements will counter each other. Consequently, their actions will not change their velocity unless they are affected by another, unattached, object. Some difficulty could occur due to drifting into other objects. If the couple have a combined velocity relative to other objects, collisions could occur. There have been suggestions that conception and pregnancy in off-Earth environments could be an issue.

, with NASA planning long-term missions for lunar settlements with goals to explore and colonize space, the topic has taken a respected place in life sciences. Scientist Stephen Hawking publicly concluded in 2006 that possibly human survival itself will depend on successfully contending with the extreme environments of space. Read more...
Tracy Caldwell Dyson viewing Earth from the ISS Cupola, 2010

Women of many nationalities have worked in space. The first woman in space, Soviet cosmonaut Valentina Tereshkova, flew in 1963. Space flight programs were slow to employ women, and only began to include them from the 1980s. Most women in space have been United States citizens, with missions on the Space Shuttle and on the International Space Station. Three countries maintain active space programs that include women: China, Russia, and the United States of America. In addition, a number of other countries — Canada, France, India, Iran, Italy, Japan, South Korea, and the United Kingdom — have sent women into orbit or space on Russian or US missions.

Women in space face many of the same challenges faced by men: physical difficulties posed by non-Earth conditions and psychological stresses of isolation and separation. Scientific studies on female amphibians and non-human mammals generally show no adverse effect from short space missions, although the effect of extended space travel on human female reproduction is not known. Read more...
Dan Burbank and Anton Shkaplerov participate in a medical contingency drill in the Destiny laboratory of the International Space Station. This drill gives crew members the opportunity to work as a team in resolving a simulated medical emergency on board the space station.

Space medicine is the practice of medicine on astronauts in outer space whereas astronautical hygiene is the application of science and technology to the prevention or control of exposure to the hazards that may cause astronaut ill health. Both these sciences work together to ensure that astronauts work in a safe environment. The main objective is to discover how well and for how long people can survive the extreme conditions in space, and how fast they can adapt to the Earth's environment after returning from their voyage. Medical consequences such as possible blindness and bone loss have been associated with human spaceflight.

In October 2015, the NASA Office of Inspector General issued a health hazards report related to space exploration, including a human mission to Mars. Read more...

Did you know...

... that Katherine Oppenheimer, the wife of physicist J. Robert Oppenheimer, was a cousin of German Field Marshal Wilhelm Keitel?
... that Marshal Lin Biao attempted to flee China from Qinhuangdao Shanhaiguan Airport, but was killed when his plane crashed in Mongolia?
... that in 2015, Taylor Swift's video for the single "Blank Space" became the fastest to reach one billion views on Vevo?
... that IRNSS-1G, successfully launched by ISRO in April, was the seventh and last satellite of the Indian Regional Navigation Satellite System?
... that prior to casting Andrea Martin as the female Ferengi Ishka on Star Trek: Deep Space Nine, David Livingston suggested Wallace Shawn in drag?
... that Bulgaria's first cosmonaut, Georgi Ivanov, safely returned to Earth despite a failing main engine and a damaged backup engine on his Soyuz 33 spacecraft?
... that Titian's painting of Venus and Adonis exists in "two-dog" and "three-dog" versions?
... that Adam Marshall was the first Catholic chaplain in the United States Navy, albeit unofficially?
... that the Martian wedge-shaped mound Abalos Mensa has been described as "an enigmatic wedge of material"?
... that the dunes of the Hagal dune field on Mars (detail pictured) look like dots and dashes, and are called the "Martian Morse Code"?