View Full Version : [Space]Sonda Stardust ritorna sulla terra
duchetto
14-01-2006, 01:21
ROMA - Appuntamento domenica con i primi campioni di povere di cometa mai arrivati sulla Terra. Insieme ad essi, con la sonda americana Stardust arriveranno anche i primi campioni di polvere interstellare provenienti dalla galassia, forse liberati dall'esplosione di una supernova e arrivati nel Sistema Solare.
Le polveri, raccolte dalla cometa Wild-2, saranno anche i primi campioni portati sulla Terra da un corpo roccioso del Sistema Solare, subito dopo i campioni di rocce lunari riportati dalle missioni Apollo.
E' un materiale unico e antichissimo, nel quale i ricercatori sperano di trovare informazioni preziose per ricostruire la storia del Sistema Solare all'epoca della sua formazione, 4,5 miliardi di anni fa. Dalla polvere interstellare, il primo materiale giunto a Terra dalla Via Lattea, si attendono invece informazioni importanti sui processi che avvengono all'interno di stelle distanti, come supernovae, giganti rosse o stelle di neutroni, che generano polveri ma anche elementi importanti per la vita, come carbonio, azoto e ossigeno.
Ad aspettare di esaminare le polveri della cometa ci sono decine di ricercatori, fra i quali il gruppo italiano coordinato all'Istituto Nazionale di Astrofisica (INAF) presso l'Osservatorio di Capodimonte, e al quale partecipano università Parthenope di Napoli e Osservatorio di Catania-INAF. Ma sono tantissimi anche gli appassionati (fra i quali numerosi astrofili italiani) che si preparano ad andare a caccia di granelli di polvere interstellare (difficilissima da individuare a causa delle dimensioni) utilizzando il "microscopio virtuale" messo a disposizione dalla NASA su Internet. Lanciata il 7 febbraio 1999 e costata 212 milioni di dollari, Stardust ha catturato la polvere della cometa Wild-2 il 2 gennaio 2004.
Durante l'incontro ravvicinato che l'ha portata a soli 241 chilometri dalla cometa, la sonda ha catturato le polveri imprigionandole in un disco di aerogel, una sostanza a base di silicio, dall'aspetto lattiginoso, molto spugnosa e 100 volte più leggera dell'acqua. Durante il suo lungo viaggio ha poi orientato il suo Stardust Interstellar Dust Collector (SIDC) verso il fascio di polveri che attraversa il Sistema Solare alla velocità di circa 20 chilometri al secondo e in questo modo ha catturato anche materiale proveniente da stelle molto lontane, forse liberato 10 milioni di anni fa con l'esplosione di una supernova. Con questo carico prezioso Stardust farà il suo ingresso nell'atmosfera domenica 15 gennaio, alla velocità maggiore mai raggiunta da un veicolo costruito dall'uomo (circa 46.000 chilometri orari).
A circa 32 chilometri dal suolo, la sonda rallenterà dispiegando un paracadute. A tre chilometri da terra il paracadute sarà rilasciato e quindi la capsula si poserà al suolo, in corrispondenza di una base dell'esercito nello Utah che ha le dimensioni della Valle d'Aosta, e potrà essere recuperata da un elicottero. Quindi il suo carico prezioso sarà trasportato presso il Johnson Space Center a Houston, dove l'aerogel sarà prelevato dalla capsula in un ambiente sterile in modo da ridurre al minimo il rischio di contaminazioni.
Metti uno spazio nel titolo... :D
Ho aggiunto il thread all'indice delle discussioni:
http://www.hwupgrade.it/forum/showthread.php?t=851766
:)
Per chi è interessato c'e' un progetto simile a SETI@home, chiamato STARDUST@home, per l'analisi distribuita dell'aerogel
link (http://www.berkeley.edu/news/media/releases/2006/01/10_dust.shtml)
Frank1962
15-01-2006, 12:13
è arrivata ;)
Welcome home, Stardust!
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: January 15, 2006
Wrapping up a seven-year, 2.9-billion-mile space odyssey, NASA's Stardust comet sample return vehicle plunged back to Earth early Sunday, slamming into the atmosphere above the western United States at nearly 30,000 mph before floating to a gentle parachute touchdown in Utah.
Radar tracking did not initially indicate a successful deployment of the craft's stabilizing drogue parachute, raising fears of a repeat of the 2004 crash of a similar spacecraft carrying samples of the solar wind.
But finally, right on time, the Stardust main parachute unfurled at an altitude of about 10,000 feet above the Utah Test and Training Range, sparking wild cheers and applause among flight controllers as the craft's rate of descent abruptly slowed.
"Appears to be under a good chute," a controller said over NASA's audio loop. "All stations, main chute is open, we're coming down slowly," project manager Tom Duxbury told the team.
A few moments later, the ground team picked up a UHF locator beacon broadcast from the descending craft and at 5:10 a.m. EST (1010 GMT), radar indicated touchdown on the UTTR salf flats.
"All stations, we have touchdown," Duxbury said, prompting another round of cheers back at the Jet Propulsion Laboratory in Pasadena, Calif.
A helicopter recovery team at the landing site immediately took off and began searching for the capsule. But the craft drifted northeast of its entry ground track while descending under the main parachute and the searchers did not immediately spot it in the pre-dawn darkness.
But finally, at 5:54 a.m., the craft was located, prompting yet another round of cheers and applause.
"All stations, we can report (the search team) has located the capsule," Duxbury reported. The search team later reported the capsule appeared to be intact.
If all goes well, the spacecraft will be airlifted back to a clean room, its precious comet samples removed and flown to the Johnson Space Center in Houston where an international team of scientists is standing by to begin an exhaustive analysis.
The Stardust probe began its seven-your voyage Feb. 7, 1999, with a flawless launch from the Cape Canaveral Air Station in Florida atop a Boeing Delta 2 rocket.
The target of the mission was comet Wild 2, which spent virtually its entire life in the outer solar system. In 1974, however, the comet made a close flyby of Jupiter, which deflected it into a different orbit that has since carried it around the sun only a handful of times. Compared to other short-period comets, Wild-2 is believed to be relatively pristine, providing an unprecedented window on the birth of the solar system.
After a velocity-boosting Earth flyby in 2001, Stardust finally caught up with the comet on Jan. 2, 2004. Just before closest approach, a two-sided 14-inch-wide dust collector shaped like a tennis racket was extended into the dust stream surrounding the comet. Cells on the back side of collector were used earlier in the flight to collect interstellar dust grains.
Along with successfully collecting samples, the spacecraft's navigation camera snapped 72 photos of Wild-2's frozen nucleus as the spacecraft made its final approach.
The goal of the ambitious mission is to answer long-standing questions about the cloud of dusty debris that coalesced to form the solar system and whether comets helped seed planet Earth with water and the organic building blocks of life.
"The science that's going to come out of this, that's going to tell us about the early formation of our solar system, the role that comets have played in the formation of Earth and ourselves, that will unfold over the next few years," Duxbury told reporters earlier. "The science that this project is returning will be unprecedented."
Goldrake_xyz
15-01-2006, 18:44
L'articolo completo : http://stardust.jpl.nasa.gov/home/index.html
http://stardust.jpl.nasa.gov/images/140999main_return-vogel-023.jpg
deggungombo
16-01-2006, 03:14
Per chi è interessato c'e' un progetto simile a SETI@home, chiamato STARDUST@home, per l'analisi distribuita dell'aerogel
link (http://www.berkeley.edu/news/media/releases/2006/01/10_dust.shtml)
grande....lo stavo giusto cercando... :) :fagiano:
Cosmic paydirt with Stardust
UNIVERSITY OF WASHINGTON NEWS RELEASE
Posted: January 18, 2006
Scientists at the Johnson Space Center in Houston were excited and awed Tuesday by what they saw when the sample-return canister from the Stardust spacecraft was opened.
"It exceeds all expectations," said Donald Brownlee, a University of Washington astronomy professor who is principal investigator, or lead scientist, for Stardust. "It's a huge success. We can see lots of impacts. There are big ones, there are small ones."
Stardust returned to Earth in a spectacular re-entry early Sunday after a 7-year mission to collect particles from comet Wild 2 and samples of interstellar dust streaming into our solar system from other parts of the galaxy. The comet dates from the formation of the solar system 4.6 billion years ago.
Brownlee calculated there might be more than a million microscopic specks of dust embedded in Stardust's aerogel collector. Aerogel, a remarkable material that is as much as 99.9 percent empty space, greatly reduced the stress of impact on the particles, he said. The carrot-shaped tracks of much larger particles are visible in the aerogel from several feet away, Brownlee said, and in some of the tracks the black comet dust is visible at the end of the track. One track, he said, "is almost large enough to put your little finger into it."
Scientists will search the aerogel grid for dust samples, and more than 65,000 people have signed up to help in a project called Stardust@home, in which their home computers will examine images of tiny sections of the aerogel grid looking for dust particles.
The Johnson Space Center will be the curator of the Stardust samples, and as many as 150 scientists worldwide are waiting to study them.
"Stardust is a phenomenal success," Brownlee said.
Stardust probe loaded with primordial debris
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: January 19, 2006
NASA's Stardust probe returned to Earth last weekend loaded with primordial debris from an ancient comet, researchers said today, providing an unprecedented glimpse into the birth of the solar system 4.6 billion years ago.
Now inside an ultra clean room at the Johnson Space Center in Houston, the Stardust sample return canister has been opened up to give scientists their first glimpse inside.
"It exceeded all of our grandest expectations," said principal investigator Don Brownlee. "There are many things you can worry about on a mission like this and it's a magic moment when basically everything in this project, including the comet, came through.
"The spacecraft had to perform as it was designed to do. We didn't know about the comet, we have no control over nature, but the comet produced the samples that we wanted and the samples were of a nature that they could be collected."
The Stardust probe began its seven-your voyage Feb. 7, 1999, with a flawless launch from the Cape Canaveral Air Station in Florida atop a Boeing Delta 2 rocket.
The target of the mission was comet Wild 2, which spent virtually its entire life in the outer solar system. In 1974, however, the comet made a close flyby of Jupiter, which deflected it into a different orbit that has since carried it around the sun only a handful of times. Compared to other short-period comets, Wild-2 is believed to be relatively pristine, providing an unprecedented window on the birth of the solar system.
After a velocity-boosting Earth flyby in 2001, Stardust finally caught up with the comet on Jan. 2, 2004. Just before closest approach, a two-sided 14-inch-wide dust collector shaped like a tennis racket was extended into the dust stream surrounding the comet. Cells on the back side of collector were used earlier in the flight to collect interstellar dust grains.
Along with successfully collecting samples, the spacecraft's navigation camera snapped 72 photos of Wild-2's frozen nucleus as the spacecraft made its final approach.
The goal of the ambitious mission is to answer long-standing questions about the cloud of dusty debris that coalesced to form the solar system and whether comets helped seed planet Earth with water and the organic building blocks of life.
Wrapping up its seven-year, 2.9-billion-mile space odyssey, the Stardust sample return vehicle plunged back to Earth early Sunday, slamming into the atmosphere above the western United States at nearly 30,000 mph before floating to a gentle, parachute landing in Utah. The canister was collected, flown to Houston and opened two days later.
The comet fragments were captured in a material called aerogel, an ultra low-density glass-like substance sometimes referred to as "frozen smoke." Particles hitting aerogel at high speeds burrow into the material leaving a cone-shaped track behind.
"I had warned the team we might not be able to see tracks with the naked eye and not to be disappointed," Brownlee said. He need not have worried. The aerogel features numerous easy-to-see tracks, including at least one large enough to poke a finger in.
"The prediction was that we would get a dozen particles larger than human hair size and one particle a little bit larger than a millimeter," Brownlee said. "I think we've probably got that. ... We were totally overwhelmed by the ability to actually see this stuff so straight forwardly. ... Just looking at it, you can see hundreds and hundreds of tracks."
He said investigators now expect to find more than a million particles larger than one-millionth of a meter across.
"At this point in time, we're absolutely thrilled," Brownlee said. "All the things that can go wrong in space or scientifically, none of the bad things happened and it really exceeded our wildest expectations."
More than 150 scientists around the world will study the comet fragments to specify their bulk composition, mineralogy, petrology, spectroscopic properties and whatever organic compounds might be found.
Brownlee said Stardust cost American taxpayers some $200 million over the past decade, adding with a laugh, "the way I like to look at it, it's the same cost as a well-paid baseball player over a 10-year period."
He said "the fundamental result of this is knowledge. Right now, you go to new astronomy textbooks and they have pictures of the comet we took two years ago. So our mission has already changed the concept of comets. We now have samples from the very edge of the solar system.
"NASA's launching a Pluto mission right now and it's kind of an interesting link," he said. "New Horizons is going to Pluto. We have a sample right now here in Houston of a body that formed in the same collection of bodies that Pluto is a member of, the Kuiper belt. We have samples from the edge of the solar system. "For all the ideas and theories people might have, we have some real ground truth, we have actual samples of the materials the solar system was formed from." Initial scientific results from the Stardust mission are expected to be presented in March.
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