![]() The occasional visibility of other plasma ions is not sufficient for imaging purposes. The most abundant ion in space plasma is the hydrogen ion-a bare proton with no excitable electrons to emit visible photons. These images are important because they challenge existing theories about the region. The first ever images of the heliosphere boundary, published in October 2009, were made by the ENA instruments aboard the IBEX and Cassini spacecraft. The IMAGE mission's three dedicated ENA cameras observed Earth's magnetosphere from 2000–2005 while the TWINS Mission, launched in 2008, provides stereo ENA imaging of Earth's magnetosphere using simultaneous imaging from two satellites. Cassini's ENA images of Saturn revealed a unique magnetosphere with complex interactions that have yet to be fully explained. Today, dedicated ENA instruments have provided detailed magnetospheric images from Venus, Mars, Jupiter, and Saturn. Īlthough ENAs were observed in space from the 1960s through 1980s, the first dedicated ENA camera was not flown until 1995 on the Swedish Astrid-1 satellite, to study Earth's magnetosphere wind. However, the development of dedicated ENA detectors entailed overcoming significant obstacles in both skepticism and technology. Ion detectors were co-opted for further ENA detection experiments in other low-ion regions. While some early efforts were made at detection, their signatures also explained inconsistent findings by ion detectors in regions of expected low-ion populations. The creation of ENAs by space plasma was predicted, but their discovery was both deliberate and serendipitous. The heliosphere's structure is due to the invisible interaction between the solar wind and cold gas from the local interstellar medium. The heliosphere protects the entire Solar System from the majority of cosmic rays but is so remote that only an imaging technique such as ENA imaging will reveal its properties. Geomagnetic weather systems have been late to benefit from the satellite imagery taken for granted in weather forecasting and space physics because their origins in magnetospheric plasma frequency present the added problem of invisibility. A deeper understanding of this region is important. This region of " space weather" is the site of geomagnetic storms that disrupt communications systems and pose radiation hazards to humans traveling in airplanes (if both altitude and latitude are high) or in orbiting spacecraft. Įarth's magnetosphere preserves Earth's atmosphere and protects life on Earth from cell-damaging radiation. ENA images are constructed from the detection of these energetic neutral atoms. These are called Energetic Neutral Atoms. ![]() Still moving very fast, they tend to travel mostly in a straight line, subject to gravity. Occasionally, charged particles within plasmas steal electrons from neutral atoms they run into, making them neutral and not subject to large-scale electromagnetic fields and waves. These charged particles can be redirected by magnetic fields for instance, Earth's magnetic field deflects these solar wind particles around the Earth. ![]() The space between solar systems is similar, but they come from other stars in our galaxy. The solar wind plasma is mostly composed of hydrogen, bare electrons and protons, along with some other kinds of nuclei, mostly helium. The solar wind is composed of plasma that is emitted from the Sun. The images were generated by the High Energy Neutral Atom (HENA) instrument present on the IMAGE spacecraft.Įnergetic 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. ENA images of the fluctuation of Earth's ring current during a geomagnetic storm that occurred during July 15–16, 2000. This page is shared under a CK-12 license and was authored, remixed, and/or curated by Melissa Alviar-Agnew, Henry Agnew, and Lance S.
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