Space environment is a branch of astronautics, aerospace engineering and space physics that seeks to understand and address conditions existing in space that affect the design and operation of spacecraft. A related subject, space weather, deals with dynamic processes in the solar-terrestrial system that can give rise to effects on spacecraft, but that can also affect the atmosphere, ionosphere and geomagnetic field, giving rise to several other kinds of effects on human technologies.
Astronautics is the theory and practice of navigation beyond Earth's atmosphere.
Aerospace engineering is the primary field of engineering concerned with the development of aircraft and spacecraft. It has two major and overlapping branches: aeronautical engineering and astronautical engineering. Avionics engineering is similar, but deals with the electronics side of aerospace engineering.
Space physics is the study of plasmas as they occur naturally in the Earth's upper atmosphere (aeronomy) and within the Solar System. As such, it encompasses a far-ranging number of topics, such as heliophysics which includes the solar physics of the Sun: the solar wind, planetary magnetospheres and ionospheres, auroras, cosmic rays, and synchrotron radiation. Space physics is a fundamental part of the study of space weather and has important implications in not only to understanding the universe, but also for practical everyday life, including the operations of communications and weather satellites.
Effects on spacecraft can arise from radiation, space debris and meteoroid impact, upper atmospheric drag and spacecraft electrostatic charging.
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes:
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 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.
A meteoroid is a small rocky or metallic body in outer space.
Radiation in space usually comes from three main sources: (i) the Van Allen radiation belts; (ii) solar proton events and solar energetic particles; and (iii) galactic cosmic rays. For long duration missions, the high doses of radiation can damage electronic components and solar cells. A major concern is also radiation-induced "single-event effects" such as single event upset. Manned missions usually avoid the radiation belts and the international space station is at an altitude well below the most severe regions of the radiation belts. During solar energetic events (solar flares and coronal mass ejections) particles can be accelerated to very high energies and can reach the Earth in times as short as 30 minutes (but usually take some hours). These particles are mainly protons and heavier ions that can cause radiation damage, disruption to logic circuits and even hazards to astronauts. Manned missions to return to the Moon or to travel to Mars will have to deal with the major problems presented by solar particle events to radiation safety, in addition to the important contribution to doses from the low-level background cosmic rays. In near-Earth orbits, the Earth's geomagnetic field screens spacecraft from a large part of these hazards - a process called geomagnetic shielding. Space debris and meteoroids can impact spacecraft at high speeds, causing mechanical or electrical damage. The average speed of space debris is 10 km/s while the average speed of meteoroids is much greater. For example, the meteoroids associated with the Perseid meteor shower travel at an average speed of 58 km/s. Mechanical damage from debris impacts have been studied through space missions including LDEF, which had over 20,000 documented impacts through its 5.7 year mission. Electrical anomalies associated with impact events include ESA's Olympus spacecraft, which lost attitude control during the 1993 Perseid meteor shower. A similar event occurred with the Landsat 5 spacecraft during the 2009 Perseid meteor shower.
A single event upset (SEU) is a change of state caused by one single ionizing particle striking a sensitive node in a micro-electronic device, such as in a microprocessor, semiconductor memory, or power transistors. The state change is a result of the free charge created by ionization in or close to an important node of a logic element. The error in device output or operation caused as a result of the strike is called an SEU or a soft error.
The Perseids are a prolific meteor shower associated with the comet Swift–Tuttle. The meteors are called the Perseids because the point from which they appear to hail lies in the constellation Perseus.
Landsat 5 was a low Earth orbit satellite launched on March 1, 1984 to collect imagery of the surface of Earth. A continuation of the Landsat Program, Landsat 5 was jointly managed by the U.S. Geological Survey (USGS) and the National Aeronautics and Space Administration (NASA). Data from Landsat 5 was collected and distributed from the USGS's Center for Earth Resources Observation and Science (EROS).
Spacecraft electrostatic charging is caused by the hot plasma environment around the Earth. The plasma encountered in the region of the geostationary orbit becomes heated during geomagnetic substorms caused by disturbances in the solar wind. "Hot" electrons (with energies in the kilo-electron volt range) collect on surfaces of spacecraft and can establish electrostatic potentials of the order of kilovolts. As a result, discharges can occur and are known to be the source of many spacecraft anomalies.
Plasma is one of the four fundamental states of matter, and was first described by chemist Irving Langmuir in the 1920s. Plasma can be artificially generated by heating or subjecting a neutral gas to a strong electromagnetic field to the point where an ionized gaseous substance becomes increasingly electrically conductive, and long-range electromagnetic fields dominate the behaviour of the matter.
A substorm, sometimes referred to as a magnetospheric substorm or an auroral substorm, is a brief disturbance in the Earth's magnetosphere that causes energy to be released from the "tail" of the magnetosphere and injected into the high latitude ionosphere. Visually, a substorm is seen as a sudden brightening and increased movement of auroral arcs. Substorms were first described in qualitative terms by Kristian Birkeland which he called polar elementary storms. Sydney Chapman used the term substorm about 1960 which is now the standard term. The morphology of aurora during a substorm was first described by Syun-Ichi Akasofu in 1964 using data collected during the International Geophysical Year.
Solutions devised by scientists and engineers include, but are not limited to, spacecraft shielding, special "hardening" of electronic systems, various collision detection systems. Evaluation of effects during spacecraft design includes application of various models of the environment, including radiation belt models, spacecraft-plasma interaction models and atmospheric models to predict drag effects encountered in lower orbits and during reentery.
The field often overlaps with the disciplines of astrophysics, atmospheric science, space physics, and geophysics, albeit usually with an emphasis on application.
Astrophysics is the branch of astronomy that employs the principles of physics and chemistry "to ascertain the nature of the astronomical objects, rather than their positions or motions in space". Among the objects studied are the Sun, other stars, galaxies, extrasolar planets, the interstellar medium and the cosmic microwave background. Emissions from these objects are examined across all parts of the electromagnetic spectrum, and the properties examined include luminosity, density, temperature, and chemical composition. Because astrophysics is a very broad subject, astrophysicists apply concepts and methods from many disciplines of physics, including mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics.
Geophysics is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis. The term geophysics sometimes refers only to the geological applications: Earth's shape; its gravitational and magnetic fields; its internal structure and composition; its dynamics and their surface expression in plate tectonics, the generation of magmas, volcanism and rock formation. However, modern geophysics organizations use a broader definition that includes the water cycle including snow and ice; fluid dynamics of the oceans and the atmosphere; electricity and magnetism in the ionosphere and magnetosphere and solar-terrestrial relations; and analogous problems associated with the Moon and other planets.
The United States government maintains a Space Weather Prediction Center at Boulder, Colorado. The Space Weather Prediction Center (SWPC) is part of the National Oceanic and Atmospheric Administration (NOAA). SWPC is one of the National Weather Service's (NWS) National Centers for Environmental Prediction (NCEP).
The Space Weather Prediction Center (SWPC), named the Space Environment Center (SEC) until 2007, is a laboratory and service center of the US National Weather Service (NWS), part of the National Oceanic and Atmospheric Administration (NOAA), located in Boulder, Colorado. SWPC continually monitors and forecasts Earth's space environment, providing solar-terrestrial information. SWPC is the official source of space weather alerts and warnings for the United States.
Boulder is the home rule municipality that is the county seat and the most populous municipality of Boulder County, Colorado, United States. It is the state's 11th most populous municipality; Boulder is located at the base of the foothills of the Rocky Mountains at an elevation of 5,430 feet (1,655 m) above sea level. The city is 25 miles (40 km) northwest of Denver.
The National Oceanic and Atmospheric Administration is an American scientific agency within the United States Department of Commerce that focuses on the conditions of the oceans, major waterways, and the atmosphere.
Space weather effects on Earth can include ionospheric storms, temporary decreases in ozone densities, disruption to radio communication, to GPS signals and submarine positioning. Some scientists also theorize links between sunspot activity and ice ages.
The Leonids are a prolific meteor shower associated with the comet Tempel–Tuttle. The Leonids get their name from the location of their radiant in the constellation Leo: the meteors appear to radiate from that point in the sky. Their proper Greek name should be Leontids, but the word was initially constructed as a Greek/Latin hybrid and it has been used since. They peak in the month of November.
The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma consists of mostly electrons, protons and alpha particles with kinetic energy between 0.5 and 10 keV. Embedded within the solar-wind plasma is the interplanetary magnetic field. The solar wind varies in density, temperature and speed over time and over solar latitude and longitude. Its particles can escape the Sun's gravity because of their high energy resulting from the high temperature of the corona, which in turn is a result of the coronal magnetic field.
A solar flare is a sudden flash of increased brightness on the Sun, usually observed near its surface and in close proximity to a sunspot group. Powerful flares are often, but not always, accompanied by a coronal mass ejection. Even the most powerful flares are barely detectable in the total solar irradiance.
A Van Allen radiation belt is a zone of energetic charged particles, most of which originate from the solar wind, that are captured by and held around a planet by that planet's magnetic field. Earth has two such belts and sometimes others may be temporarily created. The discovery of the belts is credited to James Van Allen, and as a result, Earth's belts are known as the Van Allen belts. Earth's two main belts extend from an altitude of about 640 to 58,000 km above the surface in which region radiation levels vary. Most of the particles that form the belts are thought to come from solar wind and other particles by cosmic rays. By trapping the solar wind, the magnetic field deflects those energetic particles and protects the atmosphere from destruction.
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 but conceptually related to the terrestrial weather of the atmosphere of Earth. The term space weather was first used in the 1950s and came into common usage in the 1990s. Similar to terrestrial climatology, the long term patterns of space weather comprise space climate.
A geomagnetic storm is a temporary disturbance of the Earth's magnetosphere caused by a solar wind shock wave and/or cloud of magnetic field that interacts with the Earth's magnetic field. The increase in the solar wind pressure initially compresses the magnetosphere. The solar wind's magnetic field interacts with the Earth's magnetic field and transfers an increased energy into the magnetosphere. Both interactions cause an increase in plasma movement through the magnetosphere and an increase in electric current in the magnetosphere and ionosphere.
A meteor shower is a celestial event in which a number of meteors are observed to radiate, or originate, from one point in the night sky. These meteors are caused by streams of cosmic debris called meteoroids entering Earth's atmosphere at extremely high speeds on parallel trajectories. Most meteors are smaller than a grain of sand, so almost all of them disintegrate and never hit the Earth's surface. Very intense or unusual meteor showers are known as meteor outbursts and meteor storms, which produce at least 1,000 meteors an hour, most notably from the Leonids. The Meteor Data Centre lists over 900 suspected meteor showers of which about 100 are well established. Several organizations point to viewing opportunities on the Internet.
A micrometeoroid is a tiny meteoroid; a small particle of rock in space, usually weighing less than a gram. A micrometeorite is such a particle that survives passage through the Earth's atmosphere and reaches the Earth's surface.
The Van Allen Probes, formerly known as the Radiation Belt Storm Probes, are two robotic spacecraft being used to study the Van Allen radiation belts that surround Earth. NASA is conducting the Van Allen Probes mission as part of the Living With a Star program. Understanding the radiation belt environment and its variability has important practical applications in the areas of spacecraft operations, spacecraft system design, mission planning and astronaut safety. The probes were launched on 30 August 2012.
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.
The health threats from cosmic rays is the danger posed by galactic cosmic rays (GCR) and solar energetic particles to astronauts on interplanetary missions or any missions that venture through the Van-Allen Belts or outside the Earth's magnetosphere. They are one of the greatest barriers standing in the way of plans for interplanetary travel by crewed spacecraft, but space radiation health risks also occur for missions in low Earth orbit such as the International Space Station (ISS).
Energetic neutral atom (ENA) imaging, often described as "seeing with atoms", is a technology used to create global images of otherwise invisible phenomena in the magnetospheres of planets and throughout the heliosphere, even to its outer boundary. This constitutes the far-flung edge of the solar system.
A solar proton event (SPE), or "proton storm", occurs when particles emitted by the Sun become accelerated either close to the Sun during a flare or in interplanetary space by CME shocks. The events can include other nuclei such as helium ions and HZE ions. These particles cause multiple effects. They can penetrate the Earth's magnetic field and cause ionization in the ionosphere. The effect is similar to auroral events, except that protons rather than electrons are involved. Energetic protons are a significant radiation hazard to spacecraft and astronauts.
Lagrange is a 2018 concept study for a solar weather mission by the European Space Agency (ESA). This is a British-led concept that envisions two spacecraft to be positioned at Lagrangian points L1 and L5.
Explorer 50, also known as IMP-J or IMP-8, was a NASA satellite launched to study the magnetosphere. It was the eighth and last in a series of the Interplanetary Monitoring Platform.