#stereo-b

An international science team says NASAs Fermi Gamma-ray Space Telescope has observed high-energy light from solar eruptions located on the far side of the sun, which should block direct light from these events. This apparent paradox is providing solar scientists with a unique tool for exploring how charged particles are accelerated to nearly the speed of light and move across the sun during solar flares. Fermi has seen gamma rays from the Earth-facing side of the sun, but the emission is produced by streams of particles blasted out of solar flares on the far side These particles must travel some 300,000 miles within about five minutes of the eruption to produce this light. Fermi has doubled the number of these rare events, called behind-the-limb flares, since it began scanning the sky in 2008. Its Large Area Telescope (LAT) has captured gamma rays with energies reaching 3 billion electron volts, some 30 times greater than the most energetic light previously associated with these "hidden" flares. Thanks to NASAs Solar Terrestrial Relations Observatory (STEREO) spacecraft, which were monitoring the solar far side when the eruptions occurred, the Fermi events mark the first time scientists have direct imaging of beyond-the-limb solar flares associated with high-energy gamma rays. The hidden flares occurred Oct. 11, 2013, and Jan. 6 and Sept. 1, 2014. All three events were associated with fast coronal mass ejections (CMEs), where billion-ton clouds of solar plasma were launched into space. The CME from the most recent event was moving at nearly 5 million miles an hour as it left the sun. Researchers suspect particles accelerated at the leading edge of the CMEs were responsible for the gamma-ray emission. Large magnetic field structures can connect the acceleration site with distant part of the solar surface. Because charged particles must remain attached to magnetic field lines, the research team thinks particles accelerated as the CME traveled to the sun’s visible side along magnetic field lines connecting both locations. As the particles impacted the surface, they generated gamma-ray emission through a variety of processes. One prominent mechanism is thought to be proton collisions that result in a particle called a pion, which quickly decays into gamma rays.

LA NASA RITROVA UNA NAVICELLA PERDUTA

L’agenzia spaziale statunitense ristabilisce il contatto con una navicella persa nel 2014, Stereo-B, che serve a studiare i flussi di energia che provengono dal Sole. A volte ritornano. Navicelle e relative missioni credute ormai compromesse possono riapparire anche dopo anni. Purché si continui a mantenere aperte le orecchie per sentirle. È successo alla Nasa, che ha appena annunciato di aver…

NASA heeft het contact hersteld met een zonnesatelliet die twee jaar lang stil is gebleven. Het gaat om de STEREO-tweelingsondes (Solar Terrestrial Relations Observatory) die in 2006 gelanceerd zijn om de zon in de gaten te houden. De ene ruimtesonde, STEREO A, draait voor de aarde uit rond de zon, terwijl de andere (STEREO-B) juist achter ons aan loopt. De ruimtesondes zijn geprogrammeerd om iedere dag contact te maken met de aarde en om zichzelf te rebooten als 72 uur lang geen contact is geweest. De missie zou eigenlijk twee jaar duren, maar is steeds verlengd. Dat is op zich natuurlijk goed nieuws, maar dat betekent wél dat beide sondes drie maanden per jaar aan de achterkant van de zon staan – buiten communicatiebereik. De betrokken technici hebben op 1 oktober 2014 een systeem getest om die lange stilte te mitigeren, maar vervolgens reageerde STEREO-B niet meer. Vermoedelijk is de ruimtesonde per ongeluk gaan roteren, waardoor zijn antenne niet meer op de aarde stond gericht én de zonnepanelen niet altijd op de zon stonden gericht! Iets soortgelijks heeft recent de Japanse ruimtetelescoop Hitomi aan een vroegtijdig einde gebracht. STEREO-B leek dus te zijn gedoemd, maar op 21 augustus j.l. werd plotseling contact gelegd. De volgende stap is het diagnosticeren van het probleem en proberen de boel weer onder controle te brengen.

https://youtu.be/evNC5KkGr0o

Bron: New Scientist

Nasa : une sonde retrouvée dans l’espace - #Cmr #Cameroun #Team237 #Team216 #Kebetu #Team241 #Team229 #Team221 #Team261 #Team224 #Team212

Perdu dans l’espace depuis près de deux ans et hors de portée des radars de la NASA, le satellite STEREO-B a finalement rétabli les liaisons avec l’agence spatiale, qui a ainsi pu le retrouvé. 

            Perdu dans l’immensité intersidéral depuis deux ans et sans aucun moyen d’entrer en contact avec la Terre,           c’est le périple qu’a connu STEREO-B, un satellite de la Nasa mis en orbite…

Spacecraft in solar orbit regains contact with Earth

This image shows our sun’s far side. It was obtained by the STEREO probes on Feb. 2, 2011 at 23:56 UT. Image courtesy NASA.

A probe launched by NASA in 2006 has resumed communication with the agency after nearly 23 months of silence.

The STEREO-B spacecraft, which orbits the sun, lost contact with Earth on Oct. 1, 2014.

The Deep Space Network reestablished the link with STEREO-B at 6:21 pm EDT on…

NASA has found a spacecraft that's been lost for two years

NASA is reporting that one of the Solar Terrestrial Relations Observatories, known as the STEREO-B spacecraft, has made contact after two years of silence.

NASA re-establishes contact with Sun-observing STEREO-B spacecraft

Artist’s concept of the STEREO-B spacecraft. Image Credit: NASA

After nearly two years of silence, NASA has finally picked up a signal from its wayward STEREO-B probe designed to study the Sun. Contact was lost on October 1, 2014, during a test of the spacecraft’s command loss timer, when the probe was on the other side of the Sun. (more…)