I due satelliti gemelli STEREO (Solar TErrestrial RElations Observatory) sono stati lanciati ieri alle 20.52 ora della Florida del 25/10/2006, a bordo di un Delta II 7925-10L.
Per maggiori info:
http://stereo.gsfc.nasa.gov/
Missione poco nota ma molto interessante
Ecco il comunicato ufficiale della NASA
Oct. 25, 2006Erica Hupp
Headquarters, Washington
202-358-1237Rani Chohan/Lynn Chandler
Goddard Space Flight Center, Greenbelt, Md.
301-286-2483/2806RELEASE: 06-340
NASA’S FIRST 3-D SOLAR IMAGING MISSION SOARS INTO SPACE
NASA’s twin Solar Terrestrial Relations Observatories mission, known
as STEREO, successfully launched Wednesday at 8:52 p.m. EDT from Cape
Canaveral Air Force Station, Fla.STEREO’s nearly identical twin, golf cart-sized spacecraft will make
observations to help researchers construct the first-ever
three-dimensional views of the sun. The images will show the star’s
stormy environment and its effects on the inner solar system, vital
data for understanding how the sun creates space weather.“The stunning solar views the two observatories will send back to
Earth will help scientists get a better understanding of the sun and
its activity than we’ve ever been able to obtain from the ground or
any of our other missions,” said Nick Chrissotimos, STEREO project
manager at NASA’s Goddard Space Flight Center, Greenbelt, Md.The two observatories were launched on a Delta II rocket in a stacked
configuration and separated from the launch vehicle approximately 25
minutes after lift-off. After receiving the first signal from the
spacecraft approximately 63 minutes after launch, mission control
personnel at the Johns Hopkins University Applied Physics Laboratory
(APL), Laurel, Md., confirmed each observatory’s solar arrays
successfully deployed and were providing power. NASA’s Deep Space
Network antennas in Canberra, Australia received the initial radio
signals.During the next two weeks, mission managers at APL will ensure all
systems are properly working. For the next three months, the
observatories will fly from a point close to Earth to one that
extends just beyond the moon’s orbit.After about two months, STEREO’s orbits will be synchronized to
encounter the moon. The “A” observatory will use the moon’s gravity
to redirect it to an orbit “ahead” of Earth. The “B” observatory will
encounter the moon again for a second swing-by about one month later
to redirect its position “behind” Earth. STEREO is the first NASA
mission to use separate lunar swing-bys to place two observatories
into vastly different orbits around the sun.Just as the slight offset between human eyes provides depth
perception, this placement will allow the STEREO observatories to
obtain 3-D images of the sun. The arrangement also allows the two
spacecraft to take local particle and magnetic field measurements of
the solar wind as it flows by.During the observatories’ two-year mission, they will explore the
origin, evolution and interplanetary consequences of coronal mass
ejections, some of the most violent explosions in our solar system.
These billion-ton eruptions can produce spectacular aurora, disrupt
satellites, radio communications and Earth’s power systems. Energetic
particles associated with these solar eruptions permeate the entire
solar system and can be hazardous to spacecraft and astronauts.Better prediction of solar eruptions provides more warning time for
satellite and power grid operators to put their assets into a safe
mode to weather the storm. A better understanding of the nature of
these events will help engineers build better and more resilient
systems.“We’re becoming more and more reliant on space technologies in our
everyday lives and are hatching ambitious plans to explore our outer
space surroundings,” said Michael Kaiser, STEREO Project Scientist at
Goddard. “But nature has a mind of its own and STEREO is going to
help us figure out how to avoid those surprises the sun tends to
throw at us and our best-laid plans.”For more information about STEREO, visit:
Goddard manages the STEREO mission. The APL designed and built the
spacecraft. The laboratory will maintain command and control of the
observatories throughout the mission, while NASA tracks and receives
the data, determines the orbit of the satellites, and coordinates the
science results. Each observatory has 16 instruments, including
imaging telescopes and equipment to measure solar wind particles and
to perform radio astronomy.The STEREO mission includes significant international cooperation with
European partners in instrument development, data sharing and
analysis.-end-
Decimo anniversario del lancio.
C’è anche un video in 3D.
Come leggere le immagini di STEREO.
La sonda Stereo A è ancora attiva e si sta riavvicinando alla Terra. Dopo la partenza, più di 15 anni fa, ha orbitato attorno al Sole con un periodo (346 giorni) di qualche giorno in meno rispetto alla Terra.
Questa differenza si è accumulata nel tempo ed è quasi arrivata a un anno di sfasamento. Ora sta tornando verso la Terra praticamente dalla parte opposta dalla quale è partita.
Vista dalla Terra, era posizionata in un’orbita eliocentrica a pochi milioni di chilometri, piano piano si è allontanata fino a sparire dietro il Sole, poi è rispuntata dall’altro lato, e ora si sta riavvicinando di nuovo.
Qui c’è la posizione attuale:
https://stereo-ssc.nascom.nasa.gov/where.shtml
Mentre su quest’altro tool si può modificare la data per vedere la posizione passata o futura:
https://stereo-ssc.nascom.nasa.gov/cgi-bin/make_where_gif
Nel 2023 dovrebbe tornare a pochi milioni di km di distanza dalla Terra.
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Per l’occasione del passaggio ravvicinato di Stereo A, nel portale della missione è stata creata una nuova pagina apposita con la posizione delle sonde in L1, Stereo A, la Terra e la Luna. La grafica non è accattivante, ma fa vedere come passa molto vicino dopo essere stata a 300 milioni di km di distanza 10 anni fa.
https://stereo-ssc.nascom.nasa.gov/cgi-bin/make_ic_gif
Le 4 missioni in L1 sono quelle attive di cui seguivamo le notizie negli aggiornamenti dal sistema solare fino all’edizione di dicembre 2022, Soho, DSCOVR, ACE e Wind.
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La sonda è stata già agganciata con strumenti “amatoriali”.
https://twitter.com/coastal8049/status/1672777291561324545?t=usxXRGLniR5D-ZSCdX9WRw&s=19
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Questo è l’avvicinamento della sonda visto in un sistema di riferimento non inerziale:
https://twitter.com/coastal8049/status/1674284223967133696
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Non per tutti, ma possible 
Oggi c’è il passaggio ravvicinato.
Torna dopo 17 anni, è solo un evento mediatico, il passaggio non permette nessuna opportunità scientifica aggiuntiva.
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