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Kepler va in orbita a cercare un'altra Terra


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E' iniziata la caccia al pianeta gemello della Terra. Sta infatti per raggiungere la rampa di lancio, in Florida, il telescopio della Nasa Kepler. Verrà mandato in orbita il 5 marzo, e allora, salvo imprevisti, prenderà il via una delle missioni più affascinanti della storia dell'astronautica: la ricerca di pianeti simili al nostro che orbitano intorno ad altre stelle. In realtà, gli astronomi ne hanno già individuati 340, ma nessuno di essi ha caratteristiche simili alla Terra e soprattutto su nessuno di essi vi può essere la vita così come noi la conosciamo.

 

 

 

 

 

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Sono troppo grandi (il più piccolo è stato trovato dal telescopio spaziale Corot e ha una dimensione di circa due volte la Terra, ma la sua temperatura superficiale è di oltre 1.000°C), oppure sono gassosi o troppo vicini o troppo lontani dalla loro stella per permettere di avere condizioni ideali alla vita. "Kepler invece, si propone di scovare tra le stelle della nostra galassia pianeti rocciosi che orbitano intorno a stelle simili al nostro Sole in un'area ritenuta abitabile. Gli astronomi definiscono "abitabile" una fascia di spazio intorno ad una stella dove la temperatura sia tale da permette all'acqua di scorrere liquida, in quanto quest'ultima è ritenuta indispensabile per originare e mantenere la vita", spiega Jon Morse, direttore della divisione di astrofisica della Nasa. La Terra si trova proprio all'interno della fascia di abitabilità del nostro sistema solare.

 

Il telescopio Kepler getterà il suo occhio tra le stelle per circa 4 anni, scandagliandone grosso modo 100.000, nella regione della Via Lattea nota come Cigno-Lira. Il telescopio infatti, deve puntare il proprio occhio in una regione che sia opposta a quella in cui si trova il Sole, altrimenti rischierebbe di rovinarsi e la regione scelta, che possiede tali caratteristiche, sembra avere anche una concentrazione di stelle simili alle nostre molto elevata. Si ipotizza che a varie distanze dalle proprie stelle-madri siano centinaia i pianeti con dimensioni terrestri. Da uno studio statistico realizzato dalla Nasa risulta che se pianeti di tipo terrestre fossero abbondanti in fasce abitabili, Kepler ne scoprirebbe a dozzine.

 

Al termine della sua missione potrebbe dare una risposta significativa alla domanda che già si posero gli antichi greci: "Ci sono altri mondi abitabili o il nostro è un'eccezione?".

 

Ma come farà a scoprire tali pianeti? Kepler è stato costruito appositamente per rilevare la periodica diminuzione di luce di un astro che un pianeta extrasolare - che si trova tra la Terra e la sua stella - produce quando gli passa di fronte. La sensibilità delle sue ottiche è tale che il telescopio è in grado di misurare variazioni di luminosità di 20 parti su un milione. Per ottenere una simile risoluzione gli ingegneri della Nasa hanno costruito la più potente macchina fotografica mai lanciata nello spazio: ha una capacità di 95 megapixel (si pensi che le macchine fotografiche professionali non superano i 15 megapixel). "Se Kepler dovesse guardare alla Terra di notte sarebbe in grado di rilevare la diminuzione di luce che una persona produce passando davanti ad una veranda illuminata", dice James Fanson, responsabile del Progetto Kepler.

 

Erano anni che gli astronomi aspettavano il lancio di questa missione perché dalla terra è impossibile, al momento, poter sperare di osservare la diminuzione di luce prodotta da pianeti terrestri quando passano di fronte ad una stella. Kepler invece, potrà farci sognare scoprendo pianeti gemelli della Terra.

 

 

http://www.repubblica.it/2009/02/sezioni/s...erca-terra.html

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La Nasa ha lanciato il telescopio Kepler, alla ricerca di pianeti simili alla Terra fuori dal sistema solare. Il vettore Delta 2 e' partito dalla base militare di Cap Canaveral (Florida), alle 22:49 (le 4:49 ora italiana), in condizioni meteo quasi perfette. Keplero e' stato messo in orbita con successo 62 minuti dopo il lancio dalla base militare di Cape Canaveral. Il distacco del terzo stadio del vettore Delta 2 si e' verificato a 721,53 km d'altitudine.

 

 

http://www.ansa.it/site/notizie/awnplus/sc..._107330237.html

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A trouble-free countdown and nominal launch into clear skies sent NASA's Kepler mission to find planets outside our Solar System on its way March 6 from Cape Canaveral Air Force Station.

 

The 2,320-pound spacecraft, built by Ball Aerospace, was lifted into an Earth-trailing orbit by a United Launch Alliance Delta II from Cape Canaveral Air Force Station, Fla.

 

"With the successful launch we are now positioned to turn on the photometer and start collecting calibration data from our 95 megapixel camera," said John Troeltzsch, Ball Aerospace program manager. "That means we're one step closer to opening the dust cover and allowing the light from 4.5 million objects to pass through the telescope, which is a very rewarding place to be."

 

Kepler carries a single instrument: a 1.4 meter (4.6-foot) Schmidt telescope and a photometer so sensitive it can detect variations in light at 20 parts per million. Forty-two charge-coupled devices combine to produce the 95 million pixels referred to by Troeltzsch.

 

In a steady stare, Kepler will concentrate on 100,000 Sun-like stars amidst some 4.3 million in the Cygnus-Lyra region of the Milky Way. Its goal is to catch the faint "wink" of planets as they transit in front of their host star, causing its brightness to dim slightly.

 

Astronomers have discovered more than 300 planets orbiting stars outside the solar system, but none of these so-called exoplanets seen so far are the right distance from their host star to support life. Only a handful have been near Earth's size. With its superior optics, Kepler is likely to spot numerous exoplanets, but how many of them will be in a "habitable zone" -- the correct distance from their host star to have water and the potential for life -- is an open question.

 

The liftoff required the three-stage Delta II, flying in a 7925-10L configuration, to lift Kepler across the South Atlantic. The liquid-fueled Pratt & Whitney RS27A first stage was supplemented by nine Alliant Techsystem strap-on solid rockets. It was the 139th successful Delta II launch over the past 20 years. Kepler will require a 60 day telescope and instrument checkout before it can become operational.

 

The spacecraft, which stands 15.3 feet tall and is 9 feet in diameter, will slowly distance itself from Earth, reaching an operating position of 0.1 astronomical units -- about 9 million miles -- behind the planet.

 

At that distance Earth's gravitational tug won't upset its instruments and the planet itself won't occlude the telescope's view. It will keep drifting on its 3.5-year nominal mission, orbiting the sun every 373 days. It has sufficient fuel for six years.

 

http://www.aviationweek.com/aw/generic/sto...p;channel=space

 

 

 

kepler-NASA.jpg

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NASA's Kepler mission has taken its first images of the star-rich sky where it will soon begin hunting for planets like Earth.

 

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This image from NASA's Kepler mission shows the telescope's full field of view -- an expansive star-rich patch of sky in the constellations Cygnus and Lyra stretching across 100 square degrees, or the equivalent of two side-by-side dips of the Big Dipper.

 

A cluster of stars, called NGC 6791, and a star with a known planet, called TrES-2, are outlined. The cluster is eight billion years old, and located 13,000 light-years from Earth. It is called an open cluster because its stars are loosely bound and have started to spread out. TrES-2 is a hot Jupiter-like planet known to cross in front of, or transit, its star every 2.5 days. Kepler will hunt for transiting planets that are as small as Earth.

 

Image credit: NASA/Ames/JPL-Caltech

 

 

Articolo completo e altre immagini

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Planetary scientists are awaiting the first transmission of science data from NASA's Kepler planet-finding mission to arrive on June 18, after the spacecraft has spent more than a month staring at a stretch of sky in the Cygnus and Lyra constellations.

 

Kepler is seeking tiny variations in the light reaching its 1.4-meter (4.6-foot) Schmidt telescope. Science data collection started May 12, after a 60-day checkout period. Researchers at Ames Research Center in California are pleased with the calibration data collected, which revealed "hundreds" of variable stars and binary stars eclipsing each other.

 

The spacecraft is staying in touch with controllers via the Deep Space Network, sending back health data that show it keeping a stable attitude except when its reaction wheels are desaturated every three days or so.

 

From its "drift-away" orbit around the sun, the spacecraft's photometer can detect variations in light as small as 20 parts per million. The instrument will be able to register the flickers that occur when an extrasolar planet passes in front of its star.

 

Once the science data start coming down, scientists expect to begin finding many stars like the one designated TrES-2, which has a so-called "Hot Jupiter" planet crossing in front of it every 2.5 days. But it probably will take years to isolate much smaller Earth-like planets orbiting their stars in the "habitable zone" where water can be in its liquid state. Finding those stars is the objective of the mission.

 

www.aviationweek.com

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NASA's Kepler Spies Changing Phases on a Distant World

 

Exoplanet orbiting close to its sun.

NASA's new exoplanet-hunting Kepler space telescope has detected the atmosphere of a known giant gas planet, demonstrating the telescope's extraordinary scientific capabilities. The discovery will be published Friday, Aug. 7, in the journal Science.

 

The find is based on a relatively short 10 days of test data collected before the official start of science operations. Kepler was launched March 6, 2009, from Cape Canaveral Air Force Station in Florida. The observation demonstrates the extremely high precision of the measurements made by the telescope, even before its calibration and data analysis software were finished.

 

"As NASA's first exoplanets mission, Kepler has made a dramatic entrance on the planet-hunting scene," said Jon Morse, director of the Science Mission Directorate's Astrophysics Division at NASA Headquarters in Washington. "Detecting this planet's atmosphere in just the first 10 days of data is only a taste of things to come. The planet hunt is on!"

 

Kepler team members say these new data indicate the mission is indeed capable of finding Earth-like planets, if they exist. Kepler will spend the next three-and-a-half years searching for planets as small as Earth, including those that orbit stars in a warm zone where there could be water. It will do this by looking for periodic dips in the brightness of stars, which occur when orbiting planets transit, or cross in front of, the stars.

 

"When the light curves from tens of thousands of stars were shown to the Kepler science team, everyone was awed; no one had ever seen such exquisitely detailed measurements of the light variations of so many different types of stars," said William Borucki, the principal science investigator and lead author of the paper.

 

The observations were collected from a planet called HAT-P-7, known to transit a star located about 1,000 light years from Earth. The planet orbits the star in just 2.2 days and is 26 times closer than Earth is to the sun. Its orbit, combined with a mass somewhat larger than the planet Jupiter, classifies this planet as a "hot Jupiter." It is so close to its star, the planet is as hot as the glowing red heating element on a stove.

 

The Kepler measurements show the transit from the previously detected HAT-P-7. However, these new measurements are so precise, they also show a smooth rise and fall of the light between transits caused by the changing phases of the planet, similar to those of our moon. This is a combination of both the light emitted from the planet and the light reflected off the planet. The smooth rise and fall of light is also punctuated by a small drop in light, called an occultation, exactly halfway between each transit. An occultation happens when a planet passes behind a star.

 

The new Kepler data can be used to study this hot Jupiter in unprecedented detail. The depth of the occultation and the shape and amplitude of the light curve show the planet has an atmosphere with a day-side temperature of about 4,310 degrees Fahrenheit. Little of this heat is carried to the cool night side. The occultation time compared to the main transit time shows the planet has a circular orbit. The discovery of light from this planet confirms the predictions by researchers and theoretical models that the emission would be detectable by Kepler.

 

This new discovery also demonstrates Kepler has the precision to find Earth-size planets. The observed brightness variation is just one and a half times what is expected for a transit caused by an Earth-sized planet. Although this is already the highest precision ever obtained for an observation of this star, Kepler will be even more precise after analysis software being developed for the mission is completed.

 

"This early result shows the Kepler detection system is performing right on the mark," said David Koch, deputy principal investigator of NASA's Ames Research Center at Moffett Field, Calif. "It bodes well for Kepler's prospects to be able to detect Earth-size planets."

 

Kepler is a NASA Discovery mission. Ames is responsible for the ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., manages the Kepler mission development. Ball Aerospace and Technologies Corp. of Boulder, Colo., is responsible for developing the Kepler flight system and supporting mission operations.

 

fonte: NASA.gov

 

La Nasa ha diffuso i primi risultati della sonda Kepler, incaricata di cercare e trovare nella nostra galassia un pianeta simile al nostro dove è possibile lo sviluppo di forme di vita. Il primo pianeta osservato si chiama HAT-P-7, un pianeta extrasolare già noto, il quale orbita intorno ad una stella che dista 1000 anni luce da noi. Il pianeta, che ha una massa un po' più grande di Giove, è molto vicino al suo sole, per l'esattezza 26 volte più vicino di quanto la nostra Terra dista dal nostro Sole. E' così vicino che tutto il pianeta è praticamente rovente. HAT-P-7 impiega 2,2 giorni (terrestri) a compiere un'intera orbita intorno alla sua stella. Le misurazioni di Kepler spiccano per la loro precisione e riescono ad individuare anche leggere fluttuazioni della luce causate dalle variazioni di fase del pianeta (in maniera simile alle nostre fasi lunari). Si tratta di una combinazione della luce emessa dal pianeta e quella da lui riflessa. Dai dati ricevuti da Kepler è possibile studiare HAT-P-7 con un'accuratezza senza precedenti. Ad esempio la profondità dell'occultazione e la forma ed ampiezza della curva mostra che il pianeta ha un'atmosfera con una temperatura durante il giorno di circa 4310 gradi Fahrenheit (2376,666 °C). Eppure il lato notturno è piuttosto "fresco". Il tempo di occultazione confrontato con il tempo totale di transito mostra inoltre che il pianeta ha un'Orbita circolare.

Il primo pianeta osservato quindi non sembra essere in grado di ospitare la vita perchè troppo vicino al prorpio sole, ma i risultati ottenuti indicano che la sonda è dotata di notevoli capacità e gli scienziati sono fiduciosi riguardo il lavoro futuro della sonda.

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Perdonatemi, ma non era stato trovato un pianeta simile alla Terra orbitante attorno a una stella più piccola del sole a 20 anni luce da qui?

 

ne trovano parecchi, ma ci sono migliaia di fattori da tener conto per poter comparare un altro pianeta con il nostro, come ad esempio la distanza pianeta/stella, presenza di satelliti, composizione atmosferica ecc ecc

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La mia opinione personale è che altri pianeti come la Terra esistano. Quanto a trovarli, ci vorrà del tempo: lasciamo il povero Kepler lavorare.

 

Quoto intruder, nell'Universo, che è immenso, possibile che ci sia un solo pianeta favorevole alla vita?

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Ultime da Kepler ....

 

NASA'S Kepler Discovers its Smallest 'Habitable Zone' Planets to Date ....

NASA's Kepler mission has discovered two new planetary systems that include three super-Earth-size planets in the "habitable zone," the range of distance from a star where the surface temperature of an orbiting planet might be suitable for liquid water.
The Kepler-62 system has five planets; 62b, 62c, 62d, 62e and 62f.

The Kepler-69 system has two planets; 69b and 69c.

Kepler-62e, 62f and 69c are the super-Earth-sized planets.

 

Fonte .... http://www.nasa.gov/home/hqnews/2013/apr/HQ_13-112_Kepler_62_finding.html

 

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Kepler-62f with 62e as Morning Star ....

 

The artist's concept depicts NASA's Kepler misssion's smallest habitable zone planet. Seen in the foreground is Kepler-62f, a super-Earth-size planet in the habitable zone of a star smaller and cooler than the sun, located about 1,200 light-years from Earth in the constellation Lyra.

Kepler-62f orbits it's host star every 267 days and is roughly 40 percent larger than Earth in size. The size of Kepler-62f is known, but its mass and composition are not. However, based on previous exoplanet discoveries of similar size that are rocky, scientists are able to determine its mass by association.

Much like our solar system, Kepler-62 is home to two habitable zone worlds. The small shining object seen to the right of Kepler-62f is Kepler-62e. Orbiting on the inner edge of the habitable zone, Kepler-62e is roughly 60 percent larger than Earth.

Image credit: NASA Ames/JPL-Caltech

 

Edited by TT-1 Pinto
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