 | This article needs additional citations for verification .(June 2017) |
A heliospheric imager is a wide-field camera that is designed to image the solar wind in interplanetary space, far from the Sun itself.
| | This article needs additional citations for verification .(June 2017) |
A heliospheric imager is a wide-field camera that is designed to image the solar wind in interplanetary space, far from the Sun itself.
The solar wind is composed of plasma and contains both ions and free electrons. The electrons, in particular, scatter incident sunlight via Thomson scattering, and clouds of plasma can therefore be photographed using visible light. Heliospheric imagers are simple in principle – they are simple visible light cameras placed inside deep optical baffles. However, the solar wind features are extremely faint – as little as 0.1% of the brightness of the background starfield and zodiacal light – and therefore heliospheric imager data require extensive post-processing to remove these backgrounds.
Heliospheric imagers are generally flown in space because the Earth's atmosphere itself interferes with the signal even at night. Terrestrial features such as clouds, aircraft, moonlight, small variations in dust and moisture content of the air column, and even high altitude airglow and aurora, can obscure the desired solar wind signal. Instruments flown to date include the Solar Mass Ejection Imager (SMEI [1] ) flown on a USAF satellite in high polar orbit, and the HI imagers that formed part of the SECCHI instrument suite [2] on board NASA's twin STEREO spacecraft in deep space. The concept was first demonstrated in the 1980s via detailed post-processing of photometer data from the two HELIOS spacecraft flown in the 1970s.
The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between 0.5 and 10 keV. The composition of the solar wind plasma also includes a mixture of materials found in the solar plasma: trace amounts of heavy ions and atomic nuclei such as C, N, O, Ne, Mg, Si, S, and Fe. There are also rarer traces of some other nuclei and isotopes such as P, Ti, Cr, 54Fe and 56Fe, and 58Ni, 60Ni, and 62Ni. Superposed with 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.
Voyager 1 is a space probe launched by NASA on September 5, 1977, as part of the Voyager program to study the outer Solar System and interstellar space beyond the Sun's heliosphere. Launched 16 days after its twin, Voyager 2, Voyager 1 has been operating for 44 years, 7 months and 1 day as of April 7, 2022 UTC [refresh], and still communicates with the Deep Space Network to receive routine commands and to transmit data to Earth. Real-time distance and velocity data is provided by NASA and JPL. At a distance of 155.8 AU from Earth as of January 21, 2022, it is the most distant artificial object from Earth.
Ulysses was a robotic space probe whose primary mission was to orbit the Sun and study it at all latitudes. It was launched in 1990 and made three "fast latitude scans" of the Sun in 1994/1995, 2000/2001, and 2007/2008. In addition, the probe studied several comets. Ulysses was a joint venture of the European Space Agency (ESA) and the United States' National Aeronautics and Space Administration, under leadership of ESA with participation from Canada's National Research Council. Ulysses is also the last spacecraft launched from Space Shuttle. The last day for mission operations on Ulysses was 30 June 2009.
Giotto was a European robotic spacecraft mission from the European Space Agency. The spacecraft flew by and studied Halley's Comet and in doing so became the first spacecraft to make close up observations of a comet. On 13 March 1986, the spacecraft succeeded in approaching Halley's nucleus at a distance of 596 kilometers. It was named after the Early Italian Renaissance painter Giotto di Bondone. He had observed Halley's Comet in 1301 and was inspired to depict it as the star of Bethlehem in his painting Adoration of the Magi in the Scrovegni Chapel.
A coronal mass ejection (CME) is a significant release of plasma and accompanying magnetic field from the Sun's corona into the solar wind. CMEs are often associated with solar flares and other forms of solar activity, but a broadly accepted theoretical understanding of these relationships has not been established.
Venus Express (VEX) was the first Venus exploration mission of the European Space Agency (ESA). Launched in November 2005, it arrived at Venus in April 2006 and began continuously sending back science data from its polar orbit around Venus. Equipped with seven scientific instruments, the main objective of the mission was the long term observation of the Venusian atmosphere. The observation over such long periods of time had never been done in previous missions to Venus, and was key to a better understanding of the atmospheric dynamics. It was hoped that such studies can contribute to an understanding of atmospheric dynamics in general, while also contributing to an understanding of climate change on Earth. ESA concluded the mission in December 2014.
Deep Space Climate Observatory is a National Oceanic and Atmospheric Administration (NOAA) space weather, space climate, and Earth observation satellite. It was launched by SpaceX on a Falcon 9 v1.1 launch vehicle on 11 February 2015, from Cape Canaveral. This is NOAA's first operational deep space satellite and became its primary system of warning Earth in the event of solar magnetic storms.
Advanced Composition Explorer is a NASA Explorer program satellite and space exploration mission to study matter comprising energetic particles from the solar wind, the interplanetary medium, and other sources.
IMAGE is a NASA Medium Explorer mission that studied the global response of the Earth's magnetosphere to changes in the solar wind. It was believed lost but as of August 2018 might be recoverable. It was launched 25 March 2000, at 20:34:43.929 UTC, by a Delta II launch vehicle from Vandenberg Air Force Base on a two-year mission. Almost six years later, it unexpectedly ceased operations in December 2005 during its extended mission and was declared lost. The spacecraft was part of NASA's Sun-Earth Connections Program, and its data has been used in over 400 research articles published in peer-reviewed journals. It had special cameras that provided various breakthroughs in understanding the dynamics of plasma around the Earth. The principal investigator was Jim Burch of the Southwest Research Institute.
The heliosphere is the magnetosphere, astrosphere and outermost atmospheric layer of the Sun. It takes the shape of a vast, bubble-like region of space. In plasma physics terms, it is the cavity formed by the Sun in the surrounding interstellar medium. The "bubble" of the heliosphere is continuously "inflated" by plasma originating from the Sun, known as the solar wind. Outside the heliosphere, this solar plasma gives way to the interstellar plasma permeating the Milky Way. As part of the interplanetary magnetic field, the heliosphere shields the Solar System from significant amounts of cosmic ionizing radiation; uncharged gamma rays are, however, not affected. Its name was likely coined by Alexander J. Dessler, who is credited with first use of the word in scientific literature in 1967. The scientific study of the heliosphere is heliophysics, which includes space weather and space climate.
The Solar Orbiter (SolO) is a Sun-observing satellite developed by the European Space Agency (ESA). SolO, designed to obtain detailed measurements of the inner heliosphere and the nascent solar wind, will also perform close observations of the polar regions of the Sun which is difficult to do from Earth. These observations are important in investigating how the Sun creates and controls its heliosphere.
STEREO is a solar observation mission. Two nearly identical spacecraft were launched in 2006 into orbits around the Sun that cause them to respectively pull farther ahead of and fall gradually behind the Earth. This enabled stereoscopic imaging of the Sun and solar phenomena, such as coronal mass ejections.
The Coriolis satellite is a Naval Research Laboratory (NRL) and Air Force Research Laboratory (AFRL) Earth and space observation satellite launched from Vandenberg Air Force Base, on 2003-01-06 at 14:19 GMT.
Comet McNaught, also known as the Great Comet of 2007 and given the designation C/2006 P1, is a non-periodic comet discovered on 7 August 2006 by British-Australian astronomer Robert H. McNaught using the Uppsala Southern Schmidt Telescope. It was the brightest comet in over 40 years, and was easily visible to the naked eye for observers in the Southern Hemisphere in January and February 2007.
A comet tail—and coma—are features visible in comets when they are illuminated by the Sun and may become visible from Earth when a comet passes through the inner Solar System. As a comet approaches the inner Solar System, solar radiation causes the volatile materials within the comet to vaporize and stream out of the nucleus, carrying dust away with them. Separate tails are formed of dust and gases, becoming visible through different phenomena; the dust reflects sunlight directly and the gases glow from ionisation. Most comets are too faint to be visible without the aid of a telescope, but a few each decade become bright enough to be visible to the naked eye.
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.
The Heliophysics Science Division of the Goddard Space Flight Center (NASA) conducts research on the Sun, its extended Solar System environment, and interactions of Earth, other planets, small bodies, and interstellar gas with the heliosphere. Division research also encompasses geospace—Earth's uppermost atmosphere, the ionosphere, and the magnetosphere—and the changing environmental conditions throughout the coupled heliosphere.
Solar phenomena are the natural phenomena occurring within the outer atmosphere of the Sun. These phenomena take many forms, including solar wind, radio wave flux, solar flares, coronal mass ejections, coronal heating and sunspots.
Vigil, formerly known as Lagrange, is a planned solar weather mission by the European Space Agency (ESA). It envisions two spacecraft to be positioned at Lagrangian points L1 and L5.
Janet G. Luhmann is an American physicist and senior fellow of the Space Sciences Laboratory of the University of California, Berkeley. She has made major contributions to a wide range of topics in planetary, solar, magnetospheric, and heliospheric physics. She is the principal investigator of the IMPACT instrument suite on the twin-spacecraft STEREO mission. IMPACT stands for In-situ Measurements of Particles and Coronal mass ejection (CME) Transients. It consists of a, "suite of seven instruments that samples the 3-D distribution of solar wind plasma electrons, the characteristics of the solar energetic particle (SEP) ions and electrons, and the local vector magnetic field."
 | This article related to the Sun is a stub. You can help Wikipedia by expanding it. |