Energetic neutral atom

Energetic Neutral Atom (ENA) imaging is a technology used to create global images of otherwise invisible phenomena in the <a href="/facts/Magnetospheres/BXzgPoPy">magnetospheres</a> of planets and throughout the <a href="/facts/Heliosphere/Yc9ToWbA">heliosphere</a>.
<a href="/facts/Charged_particle/2zqBJGse">Charged particles</a>— <a href="/facts/Proton/clCjepXP">protons</a>, <a href="/facts/Electron/L0KBo5cW">electrons</a>, and various <a href="/facts/Atomic_nucleus/orpIm5Xl">nuclei</a>— emitted from <a href="/facts/Solar_wind/BvuB3dT8">solar wind</a> are the basis of the <a href="/facts/Interstellar_medium/mokU0WEz">interstellar medium</a>. These charged particles have the ability to be redirected by <a href="/facts/Magnetic_field/Ta8Ev588">magnetic fields</a> such as the magnetic field surrounding the <a href="/facts/Earth/HLLmDfj0">Earth</a>. Occasionally charged particles within the <a href="/facts/Plasma_(physics)/1d3btMVU">plasma</a> of the solar wind will collide with neutral <a href="/facts/Atom/FoQ4kGN5">atoms</a>. This collision results in the previously charged particle becoming a neutrally charged atom. Due to the loss of <a href="/facts/Electric_charge/xxsBfmlB">charge</a>, the atom no longer experiences <a href="/facts/Magnetism/eo75vApl">magnetic attraction</a> while maintaining its <a href="/facts/Gravitational_attraction/bqAN7DdQ">gravitational attraction</a> and <a href="/facts/Velocity/Q3o1LVDe">velocity</a>. These atoms are Energetic Neutral Atoms and the detection of these atoms can be reconstructed to build ENA images.
Earth's magnetosphere preserves its <a href="/facts/Atmosphere/oUpLaGRF">atmosphere</a> and protects life on Earth from cell-damaging <a href="/facts/Radiation/RwMocyeq">radiation</a>. This region of "<a href="/facts/Space_weather/FfwUCv2G">space weather</a>" is the site of <a href="/facts/Geomagnetic_storms/4rD8DSlm">geomagnetic storms</a> that disrupt communications systems and pose <a href="/facts/Radiation/RwMocyeq">radiation</a> hazards to humans traveling in airplanes (at high altitude and latitude) or in orbiting spacecraft. <a href="/facts/Geomagnetic/73G36wmx">Geomagnetic</a> weather systems have been late to benefit from the <a href="/facts/Satellite/PTX8c68t">satellite</a> imagery taken for granted in <a href="/facts/Weather_forecasting/nzqyMFCa">weather forecasting</a> and <a href="/facts/Space_physics/TfenH2xr">space physics</a> because their origins in <a href="/facts/Magnetosphere/BXzgPoPy">magnetospheric</a> <a href="/facts/Plasma_(physics)/1d3btMVU">plasma</a> frequency present the added problem of invisibility.
The heliosphere shields the <a href="/facts/Solar_System/QIcLSazQ">Solar System</a> from the majority of <a href="/facts/Cosmic_rays/uxCVdTKd">cosmic rays</a>, but is so remote that only an imaging technique such as ENA imaging will reveal its properties. The heliosphere's structure is due to the interaction between the solar wind and cold gas from the local <a href="/facts/Interstellar_medium/mokU0WEz">interstellar medium</a>.
The creation of ENAs by <a href="/facts/Space_plasma/lnUR4gHd">space plasma</a> was predicted, but their discovery was both deliberate and serendipitous. While some early efforts were made at detection, their signatures also explained inconsistent findings by ion detectors in regions of expected low-ion populations. Ion detectors were co-opted for further ENA detection experiments in other low-ion regions. However, the development of dedicated ENA detectors entailed overcoming significant obstacles in both skepticism and technology.
Although ENAs were observed in space from the 1960s through the 1980s, the first dedicated ENA camera was not flown until 1995 on the <a href="/facts/Astrid_(satellite)/BazBuANj">Swedish Astrid-1 satellite</a>, to study Earth's magnetosphere wind.
Today, dedicated ENA instruments have provided detailed magnetospheric images from <a href="/facts/Venus/pADnueP6">Venus</a>, <a href="/facts/Mars/AQGtVvz0">Mars</a>, <a href="/facts/Jupiter/95m7XjMT">Jupiter</a>, and <a href="/facts/Saturn/D54LcGJ9">Saturn</a>. <a href="/facts/Cassini%E2%80%93Huygens/PWknrDeY">Cassini</a>'s ENA images of Saturn revealed a unique magnetosphere with complex interactions that have yet to be fully explained. The <a href="/facts/IMAGE_(spacecraft)/fY9DudpT">IMAGE</a> mission's three dedicated ENA cameras observed Earth's magnetosphere from 2000–2005 while the <a href="/facts/NASA_TWINS_Mission/4su16Yca">TWINS Mission</a>, launched in 2008, provides stereo ENA imaging of Earth's magnetosphere using simultaneous imaging from two satellites.
The first ever images of the heliosphere boundary, published in October 2009, were made by the ENA instruments aboard the <a href="/facts/Interstellar_Boundary_Explorer/BruTvy7H">IBEX</a> and Cassini spacecraft, and challenge existing theories about the heliosphere region.

Energetic neutral atom open-in-new

Energetic neutral atom