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Ørsted (satellite)
Ørsted is an Earth science satellite launched in 1999 to study the Earth's geomagnetic field. It is Denmark's first satellite, named after Hans Christian Ørsted (1777–1851), a Danish physicist and professor at the University of Copenhagen, who discovered electromagnetism in 1820. Objectives The spacecraft's primary science objectives are to perform highly accurate and sensitive measurements of the geomagnetic field and to perform global monitoring of the high energy charged particle environment. Instruments The instrumentation consisted of two magnetometers ( proton precession and fluxgate), a star imager for attitude determination, a solid-state charged particle detector package, and a GPS receiver. The Science Instrument Team is responsible for the design of the instruments, while the Science Team is responsible for the science mission planning and international science participation. The science data obtained during the planned one-year mission will be used to derive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth Observation
Earth observation (EO) is the gathering of information about the physical, chemical, and biosphere, biological systems of the planet Earth. It can be performed via remote sensing, remote-sensing technologies (Earth observation satellites) or through direct-contact sensors in ground-based or airborne platforms (such as weather stations and weather balloons, for example). According to the Group on Earth Observations (GEO), the concept encompasses both "space-based or remotely-sensed data, as well as ground-based or In situ#Earth and atmospheric sciences, in situ data". Earth observation is used to monitor and assess the status of and changes in natural environment, natural and built environments. Terminology In Europe, ''Earth observation'' has often been used to refer to satellite-based remote sensing, but the term is also used to refer to any form of observations of the Earth system, including in situ and airborne observations, for example. The GEO, which has over 100 member coun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proton Magnetometer
A proton magnetometer, also known as a proton precession magnetometer (PPM), uses the principle of Earth's field NMR, Earth's field nuclear magnetic resonance (EFNMR) to measure very small variations in the Earth's magnetic field, allowing ferrous objects on land and at sea to be detected. It is used in land-based archaeology to map the positions of demolished walls and buildings, and at sea to locate wrecked ships, sometimes for recreational diving. PPMs were once widely used in mineral exploration. They have largely been superseded by Magnetometer#Overhauser effect magnetometer, Overhauser effect magnetometers and alkali vapour (Magnetometer#Caesium vapour magnetometer, caesium, rubidium, and Magnetometer#Potassium vapour magnetometer, potassium) or helium magnetometers, which sample faster and are more sensitive. Principles of operation A direct current flowing in a solenoid creates a strong magnetic field around a hydrogen-rich fluid (kerosine and decane are popular; wat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GPS Receiver
A satellite navigation (satnav) device or GPS device is a device that uses satellites of the Global Positioning System (GPS) or similar global navigation satellite systems (GNSS). A satnav device can determine the user's geographic coordinates and may display the geographical position on a map and offer routing directions (as in turn-by-turn navigation). , four GNSS systems are operational: the original United States' GPS, the European Union's Galileo, Russia's GLONASS, and China's BeiDou Navigation Satellite System. The Indian Regional Navigation Satellite System (IRNSS) will follow and Japan's Quasi-Zenith Satellite System ( QZSS) scheduled for 2023 will augment the accuracy of a number of GNSS. A satellite navigation device can retrieve location and time information from one or more GNSS systems in all weather conditions, anywhere on or near the Earth's surface. Satnav reception requires an unobstructed line of sight to four or more GNSS satellites, and is subject t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Particle
Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. They are generally produced in the process of alpha decay but may also be produced in different ways. Alpha particles are named after the first letter in the Greek alphabet, α. The symbol for the alpha particle is α or α2+. Because they are identical to helium nuclei, they are also sometimes written as He2+ or 2+ indicating a helium ion with a +2 charge (missing its two electrons). Once the ion gains electrons from its environment, the alpha particle becomes a normal (electrically neutral) helium atom . Alpha particles have a net spin of zero. When produced in standard alpha radioactive decay, alpha particles generally have a kinetic energy of about 5 MeV and a velocity in the vicinity of 4% of the speed of light. They are a highly ionizing form of particle radiation, with low penetration depth (stopped b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proton
A proton is a stable subatomic particle, symbol , Hydron (chemistry), H+, or 1H+ with a positive electric charge of +1 ''e'' (elementary charge). Its mass is slightly less than the mass of a neutron and approximately times the mass of an electron (the proton-to-electron mass ratio). Protons and neutrons, each with a mass of approximately one Dalton (unit), dalton, are jointly referred to as ''nucleons'' (particles present in atomic nuclei). One or more protons are present in the Atomic nucleus, nucleus of every atom. They provide the attractive electrostatic central force which binds the atomic electrons. The number of protons in the nucleus is the defining property of an element, and is referred to as the atomic number (represented by the symbol ''Z''). Since each chemical element, element is identified by the number of protons in its nucleus, each element has its own atomic number, which determines the number of atomic electrons and consequently the chemical characteristi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electron
The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up quark, up and down quark, down quarks. Electrons are extremely lightweight particles that orbit the positively charged atomic nucleus, nucleus of atoms. Their negative charge is balanced by the positive charge of protons in the nucleus, giving atoms their overall electric charge#Charge neutrality, neutral charge. Ordinary matter is composed of atoms, each consisting of a positively charged nucleus surrounded by a number of orbiting electrons equal to the number of protons. The configuration and energy levels of these orbiting electrons determine the chemical properties of an atom. Electrons are bound to the nucleus to different degrees. The outermost or valence electron, valence electrons are the least tightly bound and are responsible for th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Flux
In electromagnetism, electric flux is the total electric field that crosses a given surface. The electric flux through a closed surface is directly proportional to the total charge contained within that surface. The electric field E can exert a force on an electric charge at any point in space. The electric field is the gradient of the electric potential. Overview An electric charge, such as a single electron in space, has an electric field surrounding it. In pictorial form, this electric field is shown as "lines of flux" being radiated from a dot (the charge). These are called Gauss lines. Note that field lines are a graphic illustration of field strength and direction and have no physical meaning as isolated lines. The density of these lines corresponds to the electric field strength, which could also be called the electric flux density: the number of "lines" per unit area. Electric flux is directly proportional to the total number of electric field lines going through a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Danish Space Research Institute
Danish Space Research Institute (DSRI) (Danish language, Danish: ''Dansk Rumforskningsinstitut'', short ''DRI'' or ''DRKI'') was the space agency of Denmark from 1966 to 2005. It was a Danish sector research institute formed in 1966 under the Danish Ministry for Education and Research, later the Danish Ministry of Science Technology and Innovation.Brian Harvey - ''Europe's space programme: to Ariane and beyond (2003) - Page 149 (Google Books Link 2010) Denmark was a founding member of the European Space Agency (ESA) in 1975 and launched the satellite ''Oersted'' in 1999. ''Europe's space programme: to Ariane and beyond'', notes the DRI had budget in excess of 2.6 million Euros supporting a staff of 40 people, wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star Tracker
A star tracker is an optical device that measures the positions of stars using photocells or a camera. As the positions of many stars have been measured by astronomers to a high degree of accuracy, a star tracker on a satellite or spacecraft may be used to determine the orientation (or attitude) of the spacecraft with respect to the stars. In order to do this, the star tracker must obtain an image of the stars, measure their apparent position in the reference frame of the spacecraft, and identify the stars so their position can be compared with their known absolute position from a star catalog. A star tracker may include a processor to identify stars by comparing the pattern of observed stars with the known pattern of stars in the sky. History In the 1950s and early 1960s, star trackers were an important part of early long-range ballistic missiles and cruise missiles, in the era when inertial navigation systems (INS) were not sufficiently accurate for intercontinental ranges. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geomagnetic Field
Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from the Sun. The magnetic field is generated by electric currents due to the motion of convection currents of a mixture of molten iron and nickel in Earth's outer core: these convection currents are caused by heat escaping from the core, a natural process called a geodynamo. The magnitude of Earth's magnetic field at its surface ranges from . As an approximation, it is represented by a field of a magnetic dipole currently tilted at an angle of about 11° with respect to Earth's rotational axis, as if there were an enormous bar magnet placed at that angle through the center of Earth. The North geomagnetic pole (Ellesmere Island, Nunavut, Canada) actually represents the South pole of Earth's magnetic field, and conversely the South geomagnetic pole correspon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geomagnetic Storm
A geomagnetic storm, also known as a magnetic storm, is a temporary disturbance of the Earth's magnetosphere that is driven by interactions between the magnetosphere and large-scale transient Plasma (physics), plasma and magnetic field structures that originate on or near the Sun. The structures that produce geomagnetic storms include interplanetary coronal mass ejections (CME) and corotating interaction regions (CIR). The former often originate from solar active regions, while the latter originate at the boundary between high- and low-speed streams of solar wind. The frequency of geomagnetic storms increases and decreases with the sunspot cycle. During solar maximum, solar maxima, geomagnetic storms occur more often, with the majority driven by CMEs. When these structures reach Earth, 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 th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aurora
An aurora ( aurorae or auroras), also commonly known as the northern lights (aurora borealis) or southern lights (aurora australis), is a natural light display in Earth's sky, predominantly observed in high-latitude regions (around the Arctic and Antarctic). Auroras display dynamic patterns of radiant lights that appear as curtains, rays, spirals or dynamic flickers covering the entire sky. Auroras are the result of disturbances in the Earth's magnetosphere caused by enhanced speeds of solar wind from coronal holes and coronal mass ejections. These disturbances alter the trajectories of charged particles in the magnetospheric plasma. These particles, mainly electrons and protons, precipitate into the upper atmosphere ( thermosphere/exosphere). The resulting ionization and excitation of atmospheric constituents emit light of varying color and complexity. The form of the aurora, occurring within bands around both polar regions, is also dependent on the amount of acceler ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
