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  • richardmitnick 10:05 am on February 21, 2019 Permalink | Reply
    Tags: , , , , , , Geocorona, ,   

    From European Space Agency via Manu Garcia, a friend from IAC: “The limits of the Earth’s atmosphere” 

    From Manu Garcia, a friend from IAC.

    The universe around us.
    Astronomy, everything you wanted to know about our local universe and never dared to ask.

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    From European Space Agency

    20 February, 2019

    Igor Baliukin
    Space Research Institute
    Russian Academy of Science
    Moscow, Russia
    Email: igor.baliukin@gmail.com

    Jean-Loup Bertaux
    Former principal investigator of SWAN
    Laboratoire Atmospheres Milieux, Observations Spatiales (LATMOS)
    Université de Versailles-Saint-Quentin-en-Yvelines, France
    Email: jean-loup.bertaux@latmos.ipsl.fr

    Bernhard Fleck
    SOHO project scientist
    European Space Agency
    Email: bfleck@esa.nascom.nasa.gov

    Markus Bauer
    ESA Science Program Communication Officer
    Tel: +31 71 565 6799
    Mob: +31 61 594 3 954
    Email: markus.bauer@esa.int

    Earth’s atmosphere reaches the Moon and beyond.
    The extent of land geocorona. Where the atmosphere of the Earth merges with outer space, there is a cloud of hydrogen atoms called geocorona. A recent discovery based on observations of the Solar and Heliospheric Observatory ESA / NASA SOHO shows that geocorona extends far beyond the orbit of the Moon, reaching up to 630 000 km above the surface of the Earth, or 50 times the diameter of our planet. Note: The illustration is not to scale. Credit: ESA.

    The most distant region of our atmosphere extends beyond the lunar orbit, up to twice the distance to our natural satellite.

    Thanks to data collected by the Solar and Heliospheric Observatory (SOHO) of ESA / NASA, a recent discovery shows that the gas layer that surrounds the Earth has a radius of 630,000 km, 50 times the diameter of our planet.


    “The moon orbits inside the Earth’s atmosphere,” says Igor Baliukin, the Russian Space Research Institute and lead author of the paper presenting the results.

    “We were not aware of it until we recover the observations made over two decades ago by SOHO.”

    In the region where the atmosphere merges into the outer space, there is a cloud of hydrogen atoms called “geocorona”. One of the satellite instruments, SWAN [no image available], used its sensors to track the signing of hydrogen and accurately detect how far the limit of the geocorona arrived.

    These observations could be made only at certain times of the year when the Earth and its geocorona were visible instrument.

    In the planets with their exosferas hydrogen, water vapor often seen near the surface. This is what happens on Earth, Mars and Venus.

    Jean-Loup Bertaux as, former principal investigator and co-author SWAN explains: “This is particularly interesting when we look for planets with possible water deposits beyond our solar system.”

    The first telescope on the Moon, deployed in 1972 by the Apollo astronauts 16 mission captured an image reminiscent of Earth wrapped in geocorona bright ultraviolet light.

    “At that time, the astronauts on the lunar surface did not know that they were actually immersed in the outermost layers of the geocorona” says Jean-Loup.

    The Sun interacts with the hydrogen atoms through a specific wavelength of the ultraviolet spectrum, called Lyman alpha, these atoms can absorb and emit. As this type of light is absorbed by Earth’s atmosphere, it can only be observed from space.

    With its cell uptake of hydrogen, the SWAN instrument could measure light selectively Lyman alpha geocorona and discard the hydrogen atoms located in interplanetary space.

    The new study has revealed that sunlight compresses the hydrogen atoms in the geocorona of the day side of the Earth, while producing a denser region on the night side. Hydrogen daytime region of higher density remains rather low, with only 70 atoms per cubic centimeter to 60,000 kilometers from the earth’s surface, and about 0.2 atoms at the distance of the Moon.

    “On Earth we would call it empty, so this extra source of hydrogen is not enough to provide space exploration,” Igor added.

    The good news is that these particles do not pose a threat to space travelers of future manned missions to orbit the moon.

    “There is also ultraviolet radiation associated -we recalls Jean-Loup geocorona Bertaux- since the hydrogen atoms are dispersed in all directions, but the impact on astronauts in orbit would be minimal mole compared to the main radiation source : the Sun”.

    The bad news is that the Earth’s future geocorona could interfere with astronomical observations near the moon.

    As Jean-Loup warns: “Space telescopes that observe the sky in ultraviolet wavelengths to study the chemical composition of stars and galaxies have to take this into account.”

    The power of files.
    Print Artist Solar and Heliospheric Observatory ESA / NASA SOHO, with the Sun seen by the extreme ultraviolet telescope satellite images on September 14 , 1999. Credit: Spacecraft: ESA / Medialab ATG; Sun: ESA / NASA SOHO, CC BY-SA 3.0 IGO

    Launched in December 1995, the space observatory SOHO has more than two decades studying the sun, from inside its core to the outer corona and solar wind. The satellite orbits in the first Lagrange point (L1), about 1.5 million kilometers from Earth toward the sun.

    LaGrange Points map. NASA

    Its position is perfect to watch the geocorona from outside. The SWAN instrument SOHO captured images of the Earth and its atmosphere on three occasions between 1996 and 1998.

    The team of researchers from Jean-Loup and Igor in Russia decided to recover this data set from the files for analysis. These unique of all the geocorona from SOHO views are now shedding new light on Earth’s atmosphere.

    “It is often possible to take advantage of archived data many years and do new science with them -constata Bernhard Fleck, SOHO Project Scientist of ESA-. This finding underscores the value of some data collected over 20 years and the outstanding performance of SOHO “.

    More information:
    The article ” SWAN / SOHO Lyman-alpha mapping: the Hydrogen geocorona extends well beyond the Moon .” I Baliukin et al, is accepted for publication in Journal of Geophysical Research: Space Physics.

    See the full article here .

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 11:48 am on January 22, 2018 Permalink | Reply
    Tags: , , Geocorona, Lyman Alpha Imaging Camera U Tokyo, The PROCYON spacecraft NAOJ/ESA, Tracing the Path of Gas Atoms from Earth to the Final Frontier   

    From Eos: “Tracing the Path of Gas Atoms from Earth to the Final Frontier” 

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    Sarah Witman

    Scientists capture the first complete image of Earth’s luminous geocorona and prove its ecliptic north–south symmetry.

    An image of the geocorona, a luminous halo formed by photons released by hydrogen atoms in the outermost layer of Earth’s atmosphere. Credit: Rikkyo University.

    The outermost layer of Earth’s atmosphere, called the outer exosphere, is almost entirely made up of hydrogen. These hydrogen atoms scatter photons, producing a luminous halo called the geocorona. Observing the precise shape of the geocorona would shed light on the last phase of an important geophysical process: the escape of hydrogen atoms from Earth into interplanetary space.

    The exosphere has been observed from within—distances of less than 64,000 kilometers—extensively. But, from the outside looking in, past space missions have been able to observe the geocorona only from far greater distances. For example, Mariner 5 caught a glimpse from roughly 240,000 kilometers out, and Apollo 16 observed it from the Moon—about 380,000 kilometers away.

    In a recent study, Kameda et al. [Geophysical Research Letters] used the Lyman Alpha Imaging Camera on board the Proximate Object Close Flyby with Optical Navigation (PROCYON ) spacecraft to observe Earth’s geocorona from the greatest distance yet: more than 15 million kilometers away.

    LAICA flight model (image credit: U Tokyo.)

    The PROCYON spacecraft and comet 67P/Churumov-Gerasiment (Conceptual Image). Credit: NAOJ/ESA/Go Miyazaki.

    The camera was able to capture the first image of the entire geocorona, stretching more than 240,000 kilometers: 38 times the length of Earth’s radius. (In comparison, partial images captured by past observation revealed roughly 100,000 kilometers, or less than 16 times the length of Earth’s radius.)

    In addition to this comprehensive image—which proved the ecliptic north–south symmetry of the geocorona for the first time—the team used a mathematical model to determine the distribution of the geocoronal emission’s intensity. From this model, they found that the production of hot hydrogen in the magnetized plasmasphere (a layer of dense plasma surrounding Earth) is likely not the main process involved in shaping the outer exosphere, although it may still be involved somehow.

    This study is a step forward in the geophysical and space sciences and the first successful attempt since the 1970s era Apollo mission to paint a picture of the outermost reaches of Earth’s atmosphere.

    See the full article here .

    Please help promote STEM in your local schools.

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    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

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