This article is about the NASA instruments on Earth satellites. For the meteorological instruments on NASA's InSight Mars lander, see Temperature and Winds for InSight. For other uses of "Twins", see Twins (disambiguation).
Two Wide-Angle Imaging Neutral-Atom Spectrometers (TWINS) are a pair of NASA instruments aboard two United StatesNational Reconnaissance Office (NRO) satellites in Molniya orbits. TWINS was designed to provide stereo images of the Earth's ring current. The first instrument, TWINS-1, was launched aboard USA-184 on 28 June 2006. TWINS-2 followed aboard USA-200 on 13 March 2008.
TWINS
TWINS 1 and TWINS 2 in simultaneous Molniya orbits, obtain stereo images of the Earth's ring current, including signals from both trapped ions and precipitating ions.
Each instrument consists of an energetic neutral atom imager and a Lyman alpha detector. The ENA imager provides indirect remote sensing of the ring current ions, and the Lyman alpha detector gives a measure of the neutral hydrogen cloud about the Earth, known as the geocorona. The TWINS prime mission lasted two years, from 2008 to 2010, and has been followed by an extended mission which is ongoing.[1]
Launched as missions of opportunity (MoO) aboard classified, non-NASA U.S. government spacecraft, TWINS conducts stereoscopic imaging of Earth's magnetosphere. By imaging the charge exchange neutral atoms over a broad energy range (~1-100 keV) using two identical instruments on two widely spaced high-altitude, high-inclination spacecraft, TWINS enables the 3-dimensional visualization and the resolution of large scale structures and dynamics within the magnetosphere for the first time. In contrast to traditional space experiments, which make measurements at only one point in space, imaging experiments provide simultaneous viewing of different regions of the magnetosphere. Stereo imaging, as done by TWINS, takes the next step of producing 3-D images, and provides a leap ahead in our understanding of the global aspects of the terrestrial magnetosphere.
The ENA imagers observe energetic neutrals produced from the global magnetospheric ion population, over an energy range of 1 to 100 keV with high angular (4°) and time (about 1-minute) resolution. A Lyman-alpha geocoronal imager is used to monitor cold exospheric hydrogenatoms that produce ENAs from ions via charge exchange. Complementing these imagers are detectors that measure the local charged particle environment around the spacecraft. The offset in the orbital phases (apogees at different times) of TWINS 1 and TWINS 2 means that in addition to stereo ENA imaging for several hours twice per day, the two TWINS instruments also obtain essentially continuous magnetospheric observations. The TWINS instrumentation is essentially the same as the MENA instrument on the IMAGE spacecraft. This instrumentation consists of a neutral atom imager covering the ~1-100 keV energy range with 4° x 4° angular resolution and 1-minute time resolution, and a simple Lyman-alpha imager to monitor the geocorona.
TWINS provides stereo imaging of the Earth's magnetosphere, the region surrounding the planet controlled by its magnetic field and containing the Van Allen radiation belts and other energetic charged particles. TWINS enables three-dimensional global visualization of this region, leading to greatly enhanced understanding of the connections between different regions of the magnetosphere and their relation to the solar wind.[2]
Operation and storm eventsEdit
This is a first-light stereo ENA image of the terrestrial ring current obtained by TWINS on 15 June 2008 for 10 keV energy. Visible in each image are both low-altitude emissions (LAE) from precipitating ions, and high-altitude ring current emissions (RCE). For reference, the Earth's limb is drawn in, along with dipole magnetic field lines at four cardinal local times (noon=red, dusk=lavender, midnight, and dawn) and two L-values (L=4 and L=8).
Routine stereo imaging by TWINS began on 15 June 2008, during an extremely weak geomagnetic storm whose Dst index never fell below -40 nT, as compared to a nominal Dst of -100 nT for classification as a storm. During the TWINS prime mission (2008–2010), an extended and unprecedented solar minimum (from solar cycle 23) prevailed, bringing with it very calm magnetospheric conditions ranging from dead quiet to mildly disturbed. During this time period TWINS observed numerous weak storms, roughly once every 27 days (corresponding to the solar rotation period and triggered by solar corotating interaction regions (CIRs). The strongest storm (which was still very mild) observed by TWINS during its prime mission was on 22 July 2009, with Dst reaching a moderate -79 nT. Throughout these extended quiet conditions TWINS images contained ENA signals from both high-altitude (ring current) and low-altitude emission (LAE) regions.
The TWINS Mission of Opportunity maintains a library of selected storm events.[3]
^"Five Years of Stereo Imaging for NASA's TWINS". NASA. 24 June 2013. Retrieved 3 May 2018. This article incorporates text from this source, which is in the public domain.
^. NASA. 13 March 2008. Archived from the original on 16 April 2010. Retrieved 17 December 2010. This article incorporates text from this source, which is in the public domain.
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This article is about the NASA instruments on Earth satellites For the meteorological instruments on NASA s InSight Mars lander see Temperature and Winds for InSight For other uses of Twins see Twins disambiguation Two Wide Angle Imaging Neutral Atom Spectrometers TWINS are a pair of NASA instruments aboard two United States National Reconnaissance Office NRO satellites in Molniya orbits TWINS was designed to provide stereo images of the Earth s ring current The first instrument TWINS 1 was launched aboard USA 184 on 28 June 2006 TWINS 2 followed aboard USA 200 on 13 March 2008 TWINSTWINS 1 and TWINS 2 in simultaneous Molniya orbits obtain stereo images of the Earth s ring current including signals from both trapped ions and precipitating ions OperatorNASAInstrument typeSpectrometerFunctionMagnetosphericMission duration2 years planned Websitehttp twins swri edu index jspPropertiesNumber launched2Host spacecraftSpacecraftUSA 184USA 200OperatorNROOrbitMolniyaEach instrument consists of an energetic neutral atom imager and a Lyman alpha detector The ENA imager provides indirect remote sensing of the ring current ions and the Lyman alpha detector gives a measure of the neutral hydrogen cloud about the Earth known as the geocorona The TWINS prime mission lasted two years from 2008 to 2010 and has been followed by an extended mission which is ongoing 1 Contents 1 Mission 2 Operation and storm events 3 Instruments 4 See also 5 References 6 External linksMission EditLaunched as missions of opportunity MoO aboard classified non NASA U S government spacecraft TWINS conducts stereoscopic imaging of Earth s magnetosphere By imaging the charge exchange neutral atoms over a broad energy range 1 100 keV using two identical instruments on two widely spaced high altitude high inclination spacecraft TWINS enables the 3 dimensional visualization and the resolution of large scale structures and dynamics within the magnetosphere for the first time In contrast to traditional space experiments which make measurements at only one point in space imaging experiments provide simultaneous viewing of different regions of the magnetosphere Stereo imaging as done by TWINS takes the next step of producing 3 D images and provides a leap ahead in our understanding of the global aspects of the terrestrial magnetosphere The ENA imagers observe energetic neutrals produced from the global magnetospheric ion population over an energy range of 1 to 100 keV with high angular 4 and time about 1 minute resolution A Lyman alpha geocoronal imager is used to monitor cold exospheric hydrogen atoms that produce ENAs from ions via charge exchange Complementing these imagers are detectors that measure the local charged particle environment around the spacecraft The offset in the orbital phases apogees at different times of TWINS 1 and TWINS 2 means that in addition to stereo ENA imaging for several hours twice per day the two TWINS instruments also obtain essentially continuous magnetospheric observations The TWINS instrumentation is essentially the same as the MENA instrument on the IMAGE spacecraft This instrumentation consists of a neutral atom imager covering the 1 100 keV energy range with 4 x 4 angular resolution and 1 minute time resolution and a simple Lyman alpha imager to monitor the geocorona TWINS provides stereo imaging of the Earth s magnetosphere the region surrounding the planet controlled by its magnetic field and containing the Van Allen radiation belts and other energetic charged particles TWINS enables three dimensional global visualization of this region leading to greatly enhanced understanding of the connections between different regions of the magnetosphere and their relation to the solar wind 2 Operation and storm events Edit This is a first light stereo ENA image of the terrestrial ring current obtained by TWINS on 15 June 2008 for 10 keV energy Visible in each image are both low altitude emissions LAE from precipitating ions and high altitude ring current emissions RCE For reference the Earth s limb is drawn in along with dipole magnetic field lines at four cardinal local times noon red dusk lavender midnight and dawn and two L values L 4 and L 8 Routine stereo imaging by TWINS began on 15 June 2008 during an extremely weak geomagnetic storm whose Dst index never fell below 40 nT as compared to a nominal Dst of 100 nT for classification as a storm During the TWINS prime mission 2008 2010 an extended and unprecedented solar minimum from solar cycle 23 prevailed bringing with it very calm magnetospheric conditions ranging from dead quiet to mildly disturbed During this time period TWINS observed numerous weak storms roughly once every 27 days corresponding to the solar rotation period and triggered by solar corotating interaction regions CIRs The strongest storm which was still very mild observed by TWINS during its prime mission was on 22 July 2009 with Dst reaching a moderate 79 nT Throughout these extended quiet conditions TWINS images contained ENA signals from both high altitude ring current and low altitude emission LAE regions The TWINS Mission of Opportunity maintains a library of selected storm events 3 Instruments EditName Launch name Spacecraft Launch date UTC Launch site Rocket Orbit RemarksTWINS 1 TWINS A USA 184 28 June 200603 30 00 VAFB SLC 6 Delta IV M 4 2 1 138 39 210 km 707 24 364 mi x 63 2 4 TWINS 2 TWINS B USA 200 13 March 200810 02 VAFB SLC 3E Atlas V 411 1 652 38 702 km 1 027 24 048 mi x 63 4 5 See also Edit Spaceflight portalSTEREO Two spacecraft launched into heliocentric orbit in 2006 to provide stereographic imagery of the Sun List of heliophysics missions Temperature and Winds for InSight TWINS sensor package on InSight Mars lander References Edit Five Years of Stereo Imaging for NASA s TWINS NASA 24 June 2013 Retrieved 3 May 2018 This article incorporates text from this source which is in the public domain Missions TWINS A and B NASA Science NASA 13 March 2008 Archived from the original on 16 April 2010 Retrieved 17 December 2010 This article incorporates text from this source which is in the public domain TWINS Geomagnetic Storm Catalog McDowell Jonathan Satellite Catalog Jonathan s Space Report Retrieved 30 May 2011 Orbit Data USA 200 Heavens Above Retrieved 30 May 2011 External links EditTWINS official site TWINS Archived 12 October 2020 at the Wayback Machine SwRI version LAD LAD TWINS instrument Retrieved from https en wikipedia org w index php title TWINS amp oldid 1143678384, wikipedia, wiki, book, books, library,
