| Ultimi arrivi - Asteroids and Comets |
Itokawa-05.jpgOrbiting around Itokawa (2)67 visiteHayabusa is a technology demonstration spacecraft focusing on key technologies that are required for future large-scale sample and return missions, yet is also making new scientific observations and discoveries. The technology demonstration component of the mission consists of 5 goals:
1) ion engine propulsion in interplanetary cruise;
2) ion engine propulsion in combination with an Earth gravity assist;
3) autonomous guidance and navigation using optical measurements;
4) collection of surface samples in an ultra-low gravity environment and
5) the direct recovery of these samples on the ground after its return from interplanetary flight.
To date the Hayabusa project has accomplished these demonstrations up through
the third goal.Nov 22, 2005
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Itokawa-04.jpgOrbiting around Itokawa (1)59 visiteHayabusa arrived at its exploration target, near Earth asteroid Itokawa, on Sept., 12th, 2005 after having been propelled there via ion engines and an Earth swing-by. Since then, it has successfully performed orbital maneuvers, precisely keeping its position relative to Itokawa. The Hayabusa Project Team has made many discoveries while carrying out their ambitious scientific observations of Itokawa. This release summarizes and reports the major scientific and engineering achievements in advance of Hayabusa’s unprecedented and historic descent to the surfaceof Itokawa for sample collection middle to later this month (November 2005).Nov 22, 2005
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Itokawa-03.pngThe Southern Hemisphere of Itokawa59 visiteAfter reaching the sub-solar point, Hayabusa started to travel out of the ecliptic plane to observe the polar regions of Itokawa. This image shows the Southern Hemisphere
of Itokawa. Due to the low altitude and solar elevation angles, we can see detailed topography in the high-latitude regions. There are even some boulders on Muses-Sea, which looked very smooth in previous observations. Imagine one of these boulders flying in space. If it came to the Earth's vicinity, we would observe it as a tiny independent near-Earth asteroid. It has long been conjectured that meteorites are fragments of asteroids delivered to the Earth's surface, but it remains to be proven. The samples of Itokawa collected and returned by Hayabusa could provide the first direct evidence of the link between asteroids and meteorites.Nov 22, 2005
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Itokawa-3.jpgItokawa and Hayabusa's shadow60 visiteDi asteroidi dalla forma bizzarra ne abbiamo visti davvero molti, ma mai così curiosi quanto Itokawa. Questa immagine, che peraltro possiede una definizione davvero ottima, ci mostra l'ombra della Sonda Hayabusa che si staglia, perfettamente definita, sul versante di Itokawa illuminato dal Sole.
Ed ora, qualche informazione su Hayabusa direttamente dall'Agenzia Spaziale Giapponese:"HAYABUSA's return trip from Earth to Itokawa is 2 billion kilometres long. Needless to say, such a long journey requires a large amount of fuel. HAYABUSA is the first long-distance interplanetary probe to use an ion engine as its main propulsion device.
Traditionally, propulsion occurs when gas is emitted at high speed. Until now, the main form of propulsion has consisted of super-heated gases created by burning fuel with an oxidant. An ion engine, in contrast, gets thrust from ionized gas accelerated by electricity. Therefore, it can accelerate much faster than by traditional propulsion, and only requires a tenth of the fuel.".Nov 21, 2005
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Itokawa-2.jpgItokawa in natural colors59 visiteThis is the composite color image of Itokawa taken at September 12, 2005. This image composed of three images with different filters as red, green and blue. The irregular shape of this body is clearly seen and Hayabusa science observations started.
Hayabusa will approach Itokawa at a distance of 0,3 BKM from Earth. At this distance, even light takes about 17' to travel, so if Hayabusa needed an emergency instruction from Earth, it would not reach the probe in time. Therefore, Hayabusa is designed to pilot itself: to use the on-board camera and laser to read the asteroid's geography and judge when to approach it and where to land.
The exploration of small Solar System Bodies will contribute to improve our understanding of the Earth itself and it will also ead us to a more comprehensive interpretation of the constituents and potential resources that these celestial objects may have.Nov 21, 2005
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Itokawa~0.jpgClosing on Itokawa59 visiteItokawa: un asteroide che sembra contraddire tutto quanto viene dato per acquisito nel campo delle forme esteriori e dei rilievi superficiali dei corpi (teoricamente) esposti a pesantissimi azioni di impatto sin dagli albori della loro esistenza. Pensate a 433-Eros, oppure a Ceres, o Dactyl o a qualsiasi altro corpo similare che abbiamo avuto occasione di vedere da distanza ravvicinata. Forse il solo asteroide AnneFrank non sembra presentare una particolare craterizzazione (ma le immagini, di cattiva qualità, non possono essere considerate definitorie) e quindi si viene a porre nel novero delle rarità. Tuttavia, quello che vediamo adesso, è ben più che un'eccezione e molto di più di un'Anomalìa: Itokawa NON ha alcun cratere superficiale visibile e le sue forme, spigolose ed a tratti aguzze, costituiscono una novità assoluta per i Ricercatori e gli Studiosi di Scienze Planetarie.
Original caption:"Where are the craters on asteroid Itokawa? No one knows. The Japanese robot probe Hayabusa recently approached the Earth-crossing asteroid and is returning pictures showing a surface unlike any other Solar System body yet photographed -- a surface possibly devoid of craters. One possibility for the lack of common circular indentations is that asteroid Itokawa is a rubble pile -- a bunch of rocks and ice chunks only loosely held together by a small amount of gravity. If so, craters might be filled in whenever the asteroid gets jiggled by a passing planet -- Earth in this case. Alternatively, surface particles may become electrically charged by the Sun, levitate in the microgravity field, and move to fill in craters. Over the weekend, Hayabusa lowered itself to the surface of the strange asteroid in an effort to study the unusual body and collect surface samples that could be returned to Earth in 2007".Nov 21, 2005
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Itokawa.jpgHayabusa's "shadow"!59 visiteWhat's that unusual looking spot on asteroid Itokawa? It's the shadow of the robot spacecraft Hayabusa that took the image. Japan's Hayabusa Mission arrived at the asteroid in early September and has been imaging and maneuvering around the floating space mountain ever since. The above picture was taken earlier this month (November 2005).
Asteroid Itokawa spans about 300 mt.
One scientific goal of the Hayabusa mission is to determine out how much ice, rock and trace elements reside on the asteroid's surface, which should give indications about how asteroids and planets formed in the early Solar System. A can-sized robot MINERVA that was scheduled to hop around the asteroid's surface has not, so far, functioned as hoped. Later this month, Hayabusa is scheduled to descend to asteroid Itokawa and collect surface samples in a return capsule. In December, Hayabusa will fire its rockets toward Earth and drop the return capsule down to Earth's Australian outback in 2007 June.Nov 16, 2005
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Itokawa.gifAsteroid "Itokawa": a new "shooting" against a Celestial Body59 visiteJapan's JAXA Space Agency launched the Hayabusa Mission to rendezvous with asteroid Itokawa. Last week, the small robotic Hayabusa spacecraft arrived at asteroid Itokawa and stationed only 20 Km away. Although a long term goal is to find out how much ice, rock and trace elements reside on the asteroid's surface, a shorter term goal is to determine the mass of the asteroid by measuring the attraction of the drifting Hayabusa spacecraft. During the next few months, Hayabusa will also image and map asteroid Itokawa. The above time-lapse image sequence was taken by Hayabusa upon final approach, showing the general oblong shape of the asteroid. In November, a small coffee-can sized robot dubbed MINERVA is scheduled for release and is expected to hop around the asteroid taking pictures. Also in November, Hayabusa will fire pellets into asteroid Itokawa and collect some of the debris in a return capsule. In December, Hayabusa will fire its rockets toward Earth and drop the return capsule in June 2007.Set 19, 2005
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Tempel1-ZZ-ZI.jpgA few seconds before the "Space-Fireworks"57 visiteDa "NASA - Picture of the Day" del 15 Settembre 2005:"Approaching the nucleus of comet Tempel 1 at 10 Km/sec., the Deep Impact probe's targeting camera recorded a truly dramatic series of images. Successive pictures improve in resolution and have been composited here at a scale of 5 mt per pixel - including images taken within a few meters of the surface moments before the July 4th impact. Analyzing the resulting cloud of debris, researchers are directly exploring the makeup of a comet, a primordial chunk of Solar System material. Described as a recipe for primordial soup, the list of Tempel 1's ingredients - tiny grains of silicates, iron compounds, complex hydrocarbons and clay and carbonates thought to require liquid water to form - might be more appropriate for a cosmic souffle, as the nucleus is apparently porous and fluffy.
Seen here, Tempel 1's nucleus is about 5 Km long, with the impact site between the two large craters near the bottom".Set 15, 2005
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Asteroids-Sylvia_compo680.jpg87 Sylvia and the Founders of Rome58 visiteDa "NASA - Picture of the Day" del 17 Agosto 2005:"Discovered in 1866, Main Belt Asteroid 87 Sylvia lies 3.5 AU from the Sun, between the orbits of Mars and Jupiter. Also shown in recent years to be one in a growing list of double asteroids, new observations during August and October 2004 made at the Paranal Observatory convincingly demonstrate that 87 Sylvia in fact has two moonlets - the first known triple asteroid system. At the center of this composite of the image data, potato-shaped 87 Sylvia itself is about 380 Km wide. The data show inner moon, Remus, orbiting Sylvia at a distance of about 710 Km once every 33 hours, while outer moon Romulus orbits at 1360 Km in 87,6 hours. Tiny Remus and Romulus are 7 and 18 Km across respectively. Because 87 Sylvia was named after Rhea Silvia, the mythical mother of the Founders of Rome, the discoverers proposed Romulus and Remus as fitting names for the two moonlets (...)".Ago 18, 2005
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Tenth_Planet-03.jpgThe 10th Planet? (3)56 visiteDa "NASA - Picture of the Day", del 1mo Agosto 2005:"Has a tenth planet been discovered? A newly discovered object, designated 2003 UB313 and located more than twice the distance of Pluto, is expected to be at least as large as Pluto and probably larger, given current measurements. 2003 UB313's dimness and highly tilted orbit (44°) prevented it from being discovered sooner. Many astronomers speculate that numerous other icy objects larger than Pluto likely exist in the Kuiper Belt of the far distant Solar System. If so, and if some are found closer in than 2003 UB313, it may be premature to call 2003 UB313 the tenth planet. Illustrated above is an artist's drawing showing what 2003 UB313 might look. The unusually bright star on the right is the Sun. Much of the world eagerly await the decision by the International Astronomical Union on whether 2003 UB313 will be designated a planet or given a name without subscripts".Ago 01, 2005
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Tenth_Planet-01.jpgThe 10th Planet? (2)59 visitePerchè escludere a priori, come fa la NASA, che il Decimo Pianeta abbia una superficie TOTALMENTE RIFLETTENTE?
Scusateci la provocazione, ma sarebbe sufficiente ipotizzare - per assurdo, se volete - che questo ipotetico Decimo Pianeta sia:
1) una sfera costituita prevalentemente di ghiaccio (un'eventualità tutt'altro che remota);
2) un corpo capace di emanare luce propria (una piccola stella?);
3) una sfera metallica (ossìa, per esempio, una gigantesca astronave che si trova "parcheggiata" ai confini del Sistema Solare).
Stupidaggini "Cosmiche"? Fantascienza di basso livello? Forse.
Ma se ci pensate (e se conoscete almeno un poco la storia del Sistema Solare e delle meccaniche - per lo più teoriche - che ci hanno permesso di stimarne le dimensioni complessive), l'ipotesi più improbabile (molto in voga negli anni '60/'70 ma poi ritenuta inverosimile ed abbandonata) è proprio quella che immagina il Decimo Pianeta come un corpo roccioso di dimensioni medio-grandi! Lug 31, 2005
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