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Earth and Moon from Cassini Options
thar
Posted: Sunday, April 23, 2017 8:01:14 AM

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As you may know know, the Cassini probe which has been orbiting Saturn is being sent in close inside its rings before being crashed into the planet.

If you are feeling big-headed this morning, or even overwhelmed, here is an image to put this in perspective - Earth seen from Cassini from between Saturn's rings.





But more interesting than that, you can see the Moon as well.
I like the way it puts it in perspective, as normally everything with the moon is not to scale.

You may have to zoom in. Faint and to the left, for those with bad eyes like me!

Or already cropped and zoomed (but not as much fun!)




Sorry if it's big. But sort of the point! Whistle
Jyrkkä Jätkä
Posted: Sunday, April 23, 2017 10:50:36 AM

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Thanks, thar! Impressive.



In the beginning there was nothing, which exploded.
FounDit
Posted: Sunday, April 23, 2017 11:04:34 AM

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Beautifully fascinating. Thanks, thar.

A great many people will think they are thinking when they are merely rearranging their prejudices. ~ William James ~
Ashwin Joshi
Posted: Sunday, April 23, 2017 11:16:50 AM

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Wow thar! What an interesting thread you have started? Planets and stars have always fascinated me.

Cassini probe is a joint venture of NASA and 18 European countries.

The spacecraft launched on October 15, 1997, aboard a Titan IVB/Centaur and entered orbit around Saturn on July 1, 2004, after an interplanetary voyage that included flybys of Earth, Venus, and Jupiter. On December 25, 2004, Huygens separated from the orbiter, and it landed on Saturn's moon Titan on January 14, 2005. It successfully returned data to Earth, using the orbiter as a relay. This was the first landing ever accomplished in the outer Solar System. Sixteen European countries and the United States make up the team responsible for designing, building, flying and collecting data from the Cassini orbiter and Huygens probe. The mission is managed by NASA's Jet Propulsion Laboratory in the United States, where the orbiter was assembled. Huygens was developed by the European Space Research and Technology Centre. The Centre's prime contractor, Aérospatiale of France (now Thales Alenia Space), assembled the probe with equipment and instruments supplied by many European countries (Huygens' batteries and two scientific instruments by the United States). The Italian Space Agency (ASI) provided the Cassini orbiter's high-gain radio antenna, with the incorporation of a low-gain antenna (to ensure telecommunications with the Earth for the entire duration of the mission), a compact and lightweight radar, which also uses the high-gain antenna and serves as a synthetic aperture radar, a radar altimeter, a radiometer, the radio science subsystem (RSS), the visible channel portion VIMS-V of VIMS spectrometer.The VIMS infrared counterpart was provided by NASA, as well as Main Electronic Assembly, which includes electronic subassemblies provided by CNES of France.

Cassini travelled as much distance and with such a speed as an ant would travel around the earth 60 times.

The following link will take you to mind-boggling facts about Cassini.

https://saturn.jpl.nasa.gov/mission/saturn-tour/where-is-cassini-now/




Artistic impressions abound, but the pics uploaded by thar and I, are the real ones.

This following is an actual pic of the probe Cassini.






Me Gathering Pebbles at The Seashore.-Aj
Tanav Joshi
Posted: Sunday, April 23, 2017 1:01:09 PM

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AshDancing win is my grandfather
and Iam very thankfulApplause to him as he has entered my account in this forumApplause as he asked me to join this forumto learn many exeptionalvocabulary grammar ,science and culture.
almo 1
Posted: Monday, April 24, 2017 10:54:01 AM
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Drag0nspeaker
Posted: Monday, April 24, 2017 10:54:52 AM

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Hello Tanav!

Welcome to the forum.
Have fun.


Wyrd bið ful aræd - bull!
almo 1
Posted: Monday, April 24, 2017 3:19:42 PM
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Location: Fussa, Tokyo, Japan

Hi, Joshis!



SPECIAL FORCE rapped by Hannah Joshi



SPECIAL FORCE



Joshi is a formal way of saying "girl" in grade/middle/high school and college in Japan. Hannah was in Japanese school, so her pseudonym is Hannah Joshi.


Ashwin Joshi
Posted: Monday, May 01, 2017 7:57:37 AM

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Hahahahaa..........Thanks almo1.

Me Gathering Pebbles at The Seashore.-Aj
Listening . . .
Posted: Saturday, May 13, 2017 1:55:18 PM

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Love the pictures, Thar! Thank you for sharing. Question: is it just me or does the moon look too far away from the earth from this distance? Think
thar
Posted: Sunday, May 14, 2017 7:01:08 AM

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That's why I like it - I think most images push it closer to make a simpler diagram!

I don't know the positions of all the players from this angle - they must be side-on or the Sun would blind - but there must be enough sunlight to reflect out to Saturn...
the likelihood of catching them 'square' side-on (at the right angle to see the maximum separation) is small - so I think the distance must actually be shortened ..Think




Ashwin Joshi
Posted: Sunday, May 14, 2017 12:00:21 PM

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Whatever, A thought of peeping into the space is sufficient to raise goosebumps.

Me Gathering Pebbles at The Seashore.-Aj
thar
Posted: Sunday, May 14, 2017 3:04:26 PM

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Very true.

Got another image, which I think shows better what a big technological leap it was to go to the Moon and return safely.

It is far more than just getting into orbit - it is going a lot further.
The Moon looks big in the sky, but only because we notice it, and only in that small section of sky that we see at any one time.
And the diagrams showing the phases etc show it far too close, for convenience.
The Moon is very big, as moons go - but it is still very small and very far away for us humans and our clunky rockets!

In fact you need two scales to show all three levels - ISS, Hubble, Mir etc, GPS satellites, and the Moon.




https://upload.wikimedia.org/wikipedia/commons/8/82/Orbitalaltitudes.jpg


TMe
Posted: Monday, May 15, 2017 11:15:29 AM

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Traveiing at a speed of 76000 mph Cassini will dash into atmosphere of gorgeous Saturn on 15 Sep 17.



NASA’s Cassini spacecraft faces one last perilous adventure around Saturn.

Cassini swings past Saturn’s mega moon Titan early Saturday for a gravity-assisted, orbit-tweaking nudge.

“That last kiss goodbye,” as project manager Earl Maize calls it, will push Cassini onto a path no spacecraft has gone before — into the gap between Saturn and its rings. It’s treacherous territory. A particle from the rings — even as small as a speck of sand — could cripple Cassini, given its velocity.

Cassini will make its first pass through the relatively narrow gap Wednesday. Twenty-two crossings are planned, about one a week, until September, when Cassini goes in and never comes out, vaporizing in Saturn’s atmosphere.

Launched in 1997, Cassini reached Saturn in 2004 and has been exploring it from orbit ever since. Its European traveling companion, Huygens, landed on Titan in 2005. Cassini’s fuel tank is practically empty, so with little left to lose, NASA has opted for a risky, but science-rich grand finale.

“What a spectacular end to a spectacular mission,” said Jim Green, NASA’s planetary science division director. “I feel a little sad in many ways that Cassini’s discoveries will end. But I’m also quite optimistic that we’re going to discover some new and really exciting science as we probe the region we’ve never probed before.”

There’s no turning back once Cassini flies past Titan, Maize said. The spacecraft on Wednesday will hurtle through the 1,900-km-wide gap between Saturn’s atmosphere and its rings, at a breakneck 113,000-plus kph.

From a navigation standpoint, “this is an easy shot,” Maize said. The operation will be run from NASA’s Jet Propulsion Laboratory in Pasadena, California. The concern is whether computer models of Saturn’s rings are accurate. On a few of the crossings, Cassini is “kind of flirting with the edge of where we think it’s safe,” he noted.

For at least the first trip through the gap, Cassini’s big dish antenna will face forward to shield the science instruments from any ring particles that might be lurking there. A couple instruments will provide a quick rundown on the dust situation.

Scientists anticipate lots of lightweight impacts, since the spacecraft will be going through extremely small material, more like smoke than distinct particles. Material from the innermost D ring — which is slowly extending into Saturn — should be diffuse enough “that we should be fine,” Maize said.

If the models are wrong and Cassini is clobbered by BB-size material, it still will end up exactly where NASA is aiming for on Sept. 15 — at Saturn. The space agency wants to keep the 6.7-meter-high, 4-meter-wide spacecraft away from Titan and its lakes of liquid methane and from the ice-encrusted moon Enceladus and its underground ocean and spouting geysers. It doesn’t want to shower contaminating wreckage onto these worlds that might harbor life.

This last leg of Cassini’s 20-year, $3.27 billion voyage should allow scientists to measure the mass of the multiple rings — shedding light on how old they are and how they formed — and also to determine the composition of the countless ring particles. First spotted by Galileo in 1610, the rings are believed to be 99 percent ice; the remaining 1 percent is a mystery, said project scientist Linda Spilker. A cosmic dust analyzer on Cassini will scoop up ring particles and analyze them.

“Imagine the pictures we’re going to get back of Saturn’s rings,” Spilker said.

Cassini will have the best views ever of Saturn’s poles, as it skims its surface. Near mission’s end, Spilker said, “we’re act ually going to dip our toe” into Saturn’s atmosphere, sending back measurements until the last possible moment.

All this is on top of a science mission that already has rewritten the textbooks on the Saturnian system.

“But the best is still yet to come — perhaps,” Maize said at a news conference in early April. “But we are certainly going to provide more excitement.”



For Scientists Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause Applause



Deliberate practice of one hour is worth ten hours of normal practice.
thar
Posted: Monday, May 15, 2017 1:03:13 PM

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You've seen the pictures, you've read the words - now listen to the audio of what the probe did actually find:

This is Cassini passing through a faint ring...

https://youtu.be/MXmAuaomZQQ

While this is the 'gap' inside the rings.

https://youtu.be/XITah0sxFFQ


It is surprising the Cassini scientists by being so quiet...Shhh Think

Quote:
Cassini Finds 'The Big Empty' Close to Saturn


As NASA's Cassini spacecraft prepares to shoot the narrow gap between Saturn and its rings for the second time in its Grand Finale, Cassini engineers are delighted, while ring scientists are puzzled, that the region appears to be relatively dust-free. This assessment is based on data Cassini collected during its first dive through the region on April 26.

With this information in hand, the Cassini team will now move forward with its preferred plan of science observations.

"The region between the rings and Saturn is 'the big empty,' apparently," said Cassini Project Manager Earl Maize of NASA's Jet Propulsion Laboratory in Pasadena, California. "Cassini will stay the course, while the scientists work on the mystery of why the dust level is much lower than expected."

A dustier environment in the gap might have meant the spacecraft's saucer-shaped main antenna would be needed as a shield during most future dives through the ring plane. This would have forced changes to how and when Cassini's instruments would be able to make observations. Fortunately, it appears that the "plan B" option is no longer needed. (There are 21 dives remaining. Four of them pass through the innermost fringes of Saturn's rings, necessitating that the antenna be used as a shield on those orbits.)

Based on images from Cassini, models of the ring particle environment in the approximately 1,200-mile-wide (2,000-kilometer-wide) region between Saturn and its rings suggested the area would not have large particles that would pose a danger to the spacecraft.

But because no spacecraft had ever passed through the region before, Cassini engineers oriented the spacecraft so that its 13-foot-wide (4-meter-wide) antenna pointed in the direction of oncoming ring particles, shielding its delicate instruments as a protective measure during its April 26 dive.

Cassini's Radio and Plasma Wave Science (RPWS) instrument was one of two science instruments with sensors that poke out from the protective shield of the antenna (the other being Cassini's magnetometer). RPWS detected the hits of hundreds of ring particles per second when it crossed the ring plane just outside of Saturn's main rings, but only detected a few pings on April 26.

When RPWS data are converted to an audio format, dust particles hitting the instrument's antennas sound like pops and cracks, covering up the usual whistles and squeaks of waves in the charged particle environment that the instrument is designed to detect. The RPWS team expected to hear a lot of pops and cracks on crossing the ring plane inside the gap, but instead, the whistles and squeaks came through surprisingly clearly on April 26.


"It was a bit disorienting -- we weren't hearing what we expected to hear," said William Kurth, RPWS team lead at the University of Iowa, Iowa City. "I've listened to our data from the first dive several times and I can probably count on my hands the number of dust particle impacts I hear."


The team's analysis suggests Cassini only encountered a few particles as it crossed the gap -- none larger than those in smoke (about 1 micron across).

Cassini will next cross through the ring plane Tuesday, May 2, at 12:38 p.m. PDT (3:38 p.m. EDT) in a region very close to where it passed on the previous dive. During this orbit, in advance of the crossing, Cassini's cameras have been looking closely at the rings; in addition, the spacecraft has rotated (or "rolled") faster than engineers have ever allowed it to before, in order to calibrate the magnetometer. As with the first finale dive, Cassini will be out of contact during closest approach to Saturn, and is scheduled to transmit data from this dive on May 3.



Listening . . .
Posted: Tuesday, May 16, 2017 9:00:36 AM

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thar wrote:
That's why I like it - I think most images push it closer to make a simpler diagram!

I don't know the positions of all the players from this angle - they must be side-on or the Sun would blind - but there must be enough sunlight to reflect out to Saturn...
the likelihood of catching them 'square' side-on (at the right angle to see the maximum separation) is small - so I think the distance must actually be shortened ..Think






Interesting. Eye opening! I love it when I see OR HEAR Dancing something (anything!) from a new perspective. Thank you, Thar , Applause

ashwin wrote:
Whatever, A thought of peeping into the space is sufficient to raise goosebumps.


COMPLETELY agree! Shocking to me how this is missed by too many in the population of Earth! Speaking of which, I am SUPER excited to see the images the James Webb telescope sends us! This is the telescope developed to replace the Hubble. Think of the improvements in technology since the Hubble was built!! Launch is expected late 2018.

thar
Posted: Wednesday, May 31, 2017 7:26:25 AM

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Joined: 7/8/2010
Posts: 15,143
Neurons: 60,135
That is one heck of a bump:


Quote:


Saturn's icy, ocean-bearing moon Enceladus may have tipped over in the distant past, according to recent research from NASA's Cassini mission. Researchers with the mission found evidence that the moon's spin axis -- the line through the north and south poles -- has reoriented, possibly due to a collision with a smaller body, such as an asteroid.

Examining the moon's features, the team showed that Enceladus appears to have tipped away from its original axis by about 55 degrees -- more than halfway toward rolling completely onto its side. "We found a chain of low areas, or basins, that trace a belt across the moon's surface that we believe are the fossil remnants of an earlier, previous equator and poles," said Radwan Tajeddine, a Cassini imaging team associate at Cornell University, Ithaca, New York, and lead author of the paper.

The area around the icy moon's current south pole is a geologically active region where long, linear fractures referred to as tiger stripes slice across the surface. Tajeddine and colleagues speculate that an asteroid may have struck the region in the past when it was closer to the equator. "The geological activity in this terrain is unlikely to have been initiated by internal processes," he said. "We think that, in order to drive such a large reorientation of the moon, it's possible that an impact was behind the formation of this anomalous terrain."

In 2005, Cassini discovered that jets of water vapor and icy particles spray from the tiger stripe fractures -- evidence that an underground ocean is venting directly into space from beneath the active south polar terrain.

Whether it was caused by an impact or some other process, Tajeddine and colleagues think the disruption and creation of the tiger-stripe terrain caused some of Enceladus' mass to be redistributed, making the moon's rotation unsteady and wobbly. The rotation would have eventually stabilized, likely taking more than a million years. By the time the rotation settled down, the north-south axis would have reoriented to pass through different points on the surface -- a mechanism researchers call "true polar wander."

The polar wander idea helps to explain why Enceladus' modern-day north and south poles appear quite different. The south is active and geologically young, while the north is covered in craters and appears much older. The moon's original poles would have looked more alike before the event that caused Enceladus to tip over and relocate the disrupted tiger-stripe terrain to the moon's south polar region.

The results were published in the online edition of the journal Icarus on April 30, 2017.

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the mission for NASA's Science Mission Directorate, Washington. JPL designed, developed and assembled the Cassini orbiter.





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