Author Topic: NASA - Cassini updates  (Read 191130 times)

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Re: NASA - Cassini updates
« Reply #20 on: 02/01/2008 04:34 AM »
Cassini Finds Rhythm in Saturn's Rings

Order can be found in the most unexpected places, as demonstrated by our neighbor three planets down. Two of Saturn's rings have been found by NASA's Cassini spacecraft to contain orderly lines of densely grouped, boulder-size icy particles that extend outward across the rings like ripples from a rock dropped in a calm pond.

"Imagine going to a town that stretches from San Francisco to Los Angeles and seeing buildings spaced the same distance apart on every block," said Cassini radio science team member Essam Marouf of San Jose State University, San Jose, Calif. "All of these groups of particles within the rings are very close together, and the space between them is extremely small, only 100 to 250 meters (320 feet to 820 feet) wide, depending on where they are in the ring."

Normally, the distances between particles change with their velocity. In the case of Saturn's rings, the distances between these ring particles stay relatively equal even though their velocities may change. This type of pattern is completely new, according to Marouf.

"This particular feature is the smallest and most detailed of anything seen in Saturn's rings so far," Marouf said. "In the chaotic environment of the rings, to find such regularity in the most cramped areas is nothing short of amazing." The regular structure can only be found in locations where particles are densely packed together, such as the B ring and the innermost part of the A ring.  

The unexpected pattern within Saturn's rings may give scientists some new ideas of what to expect from other similar planets and solar systems.

The pattern was detected when the radio on board the Cassini spacecraft sent out three signals toward Earth. The signals crossed the Saturn's rings, and their frequencies were separated by scattering from the ring particles. Once the signals were captured by Earth-based antennas of NASA's Deep Space Network, Cassini scientists saw a regular pattern in the received signal frequencies.

"The signals showed that the particle groups were arranged in an unexpectedly regular formation that had 'rhythm within the rings of Saturn,'" said Marouf. "Each particle is in its own orbit, and sometimes they collide and move apart as their velocities change. As a result, you have particles bunched together into dense groups that extend across the ring in harmony with each other."

The pattern of particles is described as an enormously extended natural diffraction grating. A diffraction grating has parallel lines like a picket fence; when light hits this fence, it separates according to wavelength, from ultraviolet to infrared light.

The same thing happened when Cassini's radio signals hit the fencelike pattern of ring particles. The signals, sent out in 2005, were meant to capture a complete view of the rings.

This research appears as a cover story in the Dec. 28 issue of Geophysical Research Letters.

Written by: Diya Chacko

Media Relations Contact: Carolina Martinez

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Re: NASA - Cassini updates
« Reply #21 on: 02/13/2008 05:13 PM »
Saturn's orange moon Titan has hundreds of times more liquid hydrocarbons than all the known oil and natural gas reserves on Earth, according to new Cassini data. The hydrocarbons rain from the sky, collecting in vast deposits that form lakes and dunes.

More at:
http://www.esa.int/SPECIALS/Cassini-Huygens/SEMCSUUHJCF_0.html

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Re: NASA - Cassini updates
« Reply #22 on: 02/19/2008 05:51 PM »
Cassini finds mingling moons may share a dark past  Saturn's moons
 
19 February 2008

Despite the incredible diversity of Saturn’s icy moons, theirs is a story of great interaction. Some are pock-marked, some seemingly dirty, others pristine, one spongy, one two-faced, some still spewing with activity and some seeming to be captured from the far reaches of the solar system. Yet many of them have a common thread - black ‘stuff’ coating their surfaces.


http://www.esa.int/esaCP/SEMMNOVHJCF_index_0.html


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Re: NASA - Cassini updates
« Reply #23 on: 03/06/2008 07:34 PM »
NEWS RELEASE: 2008-039                                                             March 6, 2008

Saturn's Moon Rhea Also May Have Rings

PASADENA, Calif. -- NASA's Cassini spacecraft has found evidence of material orbiting Rhea, Saturn's second largest moon. This is the first time rings may have been found around a moon.

A broad debris disk and at least one ring appear to have been detected by a suite of six instruments on Cassini specifically designed to study the atmospheres and particles around Saturn and its moons.

"Until now, only planets were known to have rings, but now Rhea seems to have some family ties to its ringed parent Saturn," said Geraint Jones, a Cassini scientist and lead author on a paper that appears in the March 7 issue of the journal Science. Jones began this work while at the Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany, and is now at the Mullard Space Science Laboratory, University College, London.

Rhea is roughly 1,500 kilometers (950 miles) in diameter. The apparent debris disk measures several thousand miles from end to end. The particles that make up the disk and any embedded rings probably range from the size of small pebbles to boulders. An additional dust cloud may extend up to 5,900 kilometers (3,000 miles) from the moon's center, almost eight times the radius of Rhea.

"Like finding planets around other stars, and moons around asteroids, these findings are opening a new field of rings around moons," said Norbert Krupp, a scientist with Cassini's Magnetospheric Imaging Instrument from the Max Planck Institute for Solar System Research.

Since the discovery, Cassini scientists have carried out numerical simulations to determine if Rhea can maintain rings. The models show that Rhea's gravity field, in combination with its orbit around Saturn, could allow rings that form to remain in place for a very long time.

The discovery was a result of a Cassini close flyby of Rhea in November 2005, when instruments on the spacecraft observed the environment around the moon. Three instruments sampled dust directly. The existence of some debris was expected because a rain of dust constantly hits Saturn's moons, including Rhea, knocking particles into space around them. Other instruments' observations showed how the moon was interacting with Saturn's magnetosphere, and ruled out the possibility of an atmosphere.

Evidence for a debris disk in addition to this tenuous dust cloud came from a gradual drop on either side of Rhea in the number of electrons detected by two of Cassini's instruments. Material near Rhea appeared to be shielding Cassini from the usual rain of electrons. Cassini's Magnetospheric Imaging Instrument detected sharp, brief drops in electrons on both sides of the moon, suggesting the presence of rings within the disk of debris. The rings of Uranus were found in a similar fashion, by NASA's Kuiper Airborne Observatory in 1977, when light from a star blinked on and off as it passed behind Uranus' rings.

"Seeing almost the same signatures on either side of Rhea was the clincher," added Jones. "After ruling out many other possibilities, we said these are most likely rings. No one was expecting rings around a moon."

One possible explanation for these rings is that they are remnants from an asteroid or comet collision in Rhea's distant past. Such a collision may have pitched large quantities of gas and solid particles around Rhea. Once the gas dissipated, all that remained were the ring particles. Other moons of Saturn, such as Mimas, show evidence of a catastrophic collision that almost tore the moon apart.

"The diversity in our solar system never fails to amaze us," said Candy Hansen, co-author and Cassini scientist on the Ultraviolet Imaging Spectrograph at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Many years ago we thought Saturn was the only planet with rings. Now we may have a moon of Saturn that is a miniature version of its even more elaborately decorated parent."

These ring findings make Rhea a prime candidate for further study. Initial observations by the imaging team when Rhea was near the sun in the sky did not detect dust near the moon remotely. Additional observations are planned to look for the larger particles.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter was designed, developed and assembled at JPL. The Magnetospheric Imaging Instrument was designed, built and is operated by an international team led by the Applied Physics Laboratory of the Johns Hopkins University, Laurel, Md.

For information on the Cassini mission, visit: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov .


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Re: NASA - Cassini updates
« Reply #24 on: 03/07/2008 09:57 AM »
Saturn's moon Rhea may also have rings

7 March 2008
The Cassini spacecraft has found evidence of material orbiting Rhea, Saturn's second largest moon. This is the first time rings may have been found around a moon.

http://www.esa.int/esaCP/SEMY6NK26DF_index_0.html

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Re: NASA - Cassini updates
« Reply #25 on: 03/10/2008 06:31 PM »
RELEASE: 08-078

CASSINI SPACECRAFT TO DIVE INTO WATER PLUME OF SATURN MOON

PASADENA, Calif. - NASA's Cassini spacecraft will make an
unprecedented "in your face" flyby of Saturn's moon Enceladus on
Wed., March 12.

The spacecraft, orchestrating its closest approach to date, will skirt
along the edges of huge Old-Faithful-like geysers erupting from giant
fractures on the south pole of Enceladus. Cassini will sample
scientifically valuable water-ice, dust and gas in the plume.

The source of the geysers is of great interest to scientists who think
liquid water, perhaps even an ocean, may exist in the area. While
flying through the edge of the plumes, Cassini will be approximately
120 miles from the surface. At closest approach to Enceladus, Cassini
will be only 30 miles from the moon.

"This daring flyby requires exquisite technical finesse, but it has
the potential to revolutionize our knowledge of the geysers of
Enceladus. The Cassini mission team is eager to see the scientific
results, and so am I," said Alan Stern, associate administrator of
NASA's Science Mission Directorate, Washington.

Scientists and mission personnel studying the anatomy of the plumes
have found that flying at these close distances poses little threat
to Cassini because, despite the high speed of Cassini, the plume
particles are small. The spacecraft routinely crosses regions made up
of dust-size particles in its orbit around Saturn.

Cassini's cameras will take a back seat on this flyby as the main
focus turns to the spacecraft's particle analyzers that will study
the composition of the plumes. The cameras will image Enceladus on
the way in and out, between the observations of the particle
analyzers.

Images will reveal northern regions of the moon previously not
captured by Cassini. The analyzers will "sniff and taste" the plume.
Information on the density, size, composition and speed of the gas
and the particles will be collected.

"There are two types of particles coming from Enceladus, one pure
water-ice, the other water-ice mixed with other stuff," said Sascha
Kempf, deputy principal investigator for Cassini's Cosmic Dust
Analyzer at the Max Planck Institute for Nuclear Physics in
Heidelberg, Germany. "We think the clean water-ice particles are
being bounced off the surface and the dirty water-ice particles are
coming from inside the moon. This flyby will show us whether this
concept is right or wrong."

In 2005, Cassini's multiple instruments discovered that this icy
outpost is gushing water vapor geysers out to a distance of three
times the radius of Enceladus. The moon is only 310 miles in
diameter, but despite its petite size, its one of the most
scientifically compelling bodies in our solar system. The icy water
particles are roughly one ten-thousandth of an inch, or about the
width of a human hair. The particles and gas escape the surface at
jet speed at approximately 800 miles per hour. The eruptions appear
to be continuous, refreshing the surface and generating an enormous
halo of fine ice dust around Enceladus, which supplies material to
one of Saturn's rings, the E-ring.

Several gases, including water vapor, carbon dioxide, methane, perhaps
a little ammonia and either carbon monoxide or nitrogen gas make up
the gaseous envelope of the plume.

"We want to know if there is a difference in composition of gases
coming from the plume versus the material surrounding the moon. This
may help answer the question of how the plume formed," said Hunter
Waite, principal investigator for Cassini's Ion and Neutral Mass
Spectrometer at the Southwest Research Institute, San Antonio.

This is the first of four Cassini flybys of Enceladus this year. In
June, Cassini completes its prime mission, a four-year tour of
Saturn. Cassini's next flyby of Enceladus is planned for August, well
into Cassini's proposed extended mission. Cassini will perform seven
Enceladus flybys in its extended mission. If this encounter proves
safe, future passes may bring the spacecraft even closer than this
one. How close Cassini will be allowed to approach will be determined
based on data from this flyby.

The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency and the Italian Space Agency. JPL manages the
Cassini-Huygens mission for NASA's Science Mission Directorate. The
Cassini orbiter was designed, developed and assembled at JPL.

For images and more information about the Cassini mission and the
Enceladus flyby, visit:

http://www.nasa.gov/cassini


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Re: NASA - Cassini updates
« Reply #26 on: 03/12/2008 09:09 PM »
The flyby has been performed! What mysteries are just on the verge of being thrown into the light? Wow, this week there's too many news!

Great video of the flyby's observations in the blog: http://blogs.nasa.gov/cm/blog/Enceladus%20Flyby
http://blogs.nasa.gov/cm/blog/Enceladus%20Flyby/1000811main_61En_movie_h264.mov
-DaviD-

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Re: NASA - Cassini updates
« Reply #27 on: 03/14/2008 11:29 AM »

News about the flyby: http://www.nasa.gov/mission_pages/cassini/media/cassini-20080313.html

Apparently, while the CDA (Cosmic Dust Analyzer, see the thread in the general section) wasn't able to record any data during closest approach because of a software glitch, it did before and after, so the instrument wasn't rendered useless after all.

"During Cassini's closest approach, two instruments were collecting data--the Cosmic Dust Analyzer and the Ion and Neutral Mass Spectrometer. An unexplained software hiccup with Cassini's Cosmic Dust Analyzer instrument prevented it from collecting any data during closest approach, although the instrument did get data before and after the approach. During the flyby, the instrument was switching between two versions of software programs. The new version was designed to increase the ability to count particle hits by several hundred hits per second. The other four fields and particles instruments on the spacecraft, in addition to the ion and neutral mass spectrometer, did capture all of their data, which will complement the overall composition studies and elucidate the unique plume environment of Enceladus. "

-DaviD-

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Re: NASA - Cassini updates
« Reply #28 on: 03/20/2008 09:20 PM »
MEDIA ADVISORY: M08-061

NASA TO RELEASE NEW DETAILS FROM CLOSE FLYBY OF SATURN MOON

WASHINGTON - NASA will hold a news conference at 2 p.m. EDT,
Wednesday, March 26, to present new clues on the composition of the
icy plumes jetting off the surface of Saturn's moon Enceladus. The
findings were obtained March 12 during the closest flyby of the moon
by the Cassini spacecraft. The briefing will take place in the NASA
Headquarters television studio, 300 E St., S.W., Washington, and will
be carried live on NASA Television.

Participants in the press conference will be:
- Hunter Waite, Southwest Research Institute, San Antonio, principal
investigator, Ion and Neutral Mass Spectrometer
- John Spencer, Southwest Research Institute, Boulder, Colo.,
co-investigator, Composite Infrared Spectrometer
- Larry Esposito, University of Colorado, Boulder, principal
investigator, Ultraviolet Imaging Spectrograph
- Carolyn Porco, Space Science Institute, Boulder, team leader,
Imaging Science Subsystem

Participating NASA centers will provide question-and-answer capability
for reporters.

For NASA TV streaming video, scheduling and downlink information,
visit:

http://www.nasa.gov/ntv

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Re: NASA - Cassini updates
« Reply #29 on: 03/20/2008 09:20 PM »
RELEASE: 08-085

CASSINI SPACECRAFT FINDS OCEAN MAY EXIST BENEATH TITAN'S CRUST

PASADENA, Calif. - NASA's Cassini spacecraft has discovered evidence
that points to the existence of an underground ocean of water and
ammonia on Saturn's moon Titan. The findings made using radar
measurements of Titan's rotation will appear in the March 21 issue of
the journal Science.

"With its organic dunes, lakes, channels and mountains, Titan has one
of the most varied, active and Earth-like surfaces in the solar
system," said Ralph Lorenz, lead author of the paper and Cassini
radar scientist at the Johns Hopkins Applied Physics Laboratory in
Laurel, Md., "Now we see changes in the way Titan rotates, giving us
a window into Titan's interior beneath the surface."

Members of the mission's science team used Cassini's Synthetic
Aperture Radar to collect imaging data during 19 separate passes over
Titan between October 2005 and May 2007. The radar can see through
Titan's dense, methane-rich atmospheric haze, detailing
never-before-seen surface features and establishing their locations
on the moon's surface.

Using data from the radar's early observations, the scientists and
radar engineers established the locations of 50 unique landmarks on
Titan's surface. They then searched for these same lakes, canyons and
mountains in the reams of data returned by Cassini in its later
flybys of Titan. They found prominent surface features had shifted
from their expected positions by up to 19 miles. A systematic
displacement of surface features would be difficult to explain unless
the moon's icy crust was decoupled from its core by an internal
ocean, making it easier for the crust to move.

"We believe that about 62 miles beneath the ice and organic-rich
surface is an internal ocean of liquid water mixed with ammonia,"
said Bryan Stiles of NASA's Jet Propulsion Laboratory (JPL) in,
Pasadena, Calif. Stiles also is a contributing author to the paper.

The study of Titan is a major goal of the Cassini-Huygens mission
because it may preserve, in deep-freeze, many of the chemical
compounds that preceded life on Earth. Titan is the only moon in the
solar system that possesses a dense atmosphere. The moon's atmosphere
is 1.5 times denser than Earth's. Titan is the largest of Saturn's
moons, bigger than the planet Mercury.

"The combination of an organic-rich environment and liquid water is
very appealing to astrobiologists," Lorenz said. "Further study of
Titan's rotation will let us understand the watery interior better,
and because the spin of the crust and the winds in the atmosphere are
linked, we might see seasonal variation in the spin in the next few
years."

Cassini scientists will not have long to wait before another go at
Titan. On March 25, just prior to its closest approach at an altitude
of 620 miles, Cassini will employ its Ion and Neutral Mass
Spectrometer to examine Titan's upper atmosphere. Immediately after
closest approach, the spacecraft's Visual and Infrared Mapping
Spectrometer will capture high-resolution images of Titan's southeast
quadrant.

The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency and the Italian Space Agency. The mission is
managed by JPL, a division of the California Institute of Technology
in Pasadena. The Cassini orbiter also was designed, developed and
assembled at JPL.

For information about Cassini visit:

http://www.nasa.gov/cassini/

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Re: NASA - Cassini updates
« Reply #30 on: 03/25/2008 12:51 PM »
Cassini has discovered evidence that points to the existence of an underground ocean of water and ammonia on Saturn's moon Titan. The findings were made using radar measurements of Titan's rotation.


Read more at:

http://www.esa.int/SPECIALS/Cassini-Huygens/SEM52QQ03EF_0.html

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Re: NASA - Cassini updates
« Reply #31 on: 03/26/2008 06:26 PM »
RELEASE: 08-089

CASSINI TASTES ORGANIC MATERIAL AT SATURN'S GEYSER MOON

PASADENA, Calif. -- NASA's Cassini spacecraft tasted and sampled a
surprising organic brew erupting in geyser-like fashion from Saturn's
moon Enceladus during a close flyby on March 12. Scientists are
amazed that this tiny moon is so active, "hot" and brimming with
water vapor and organic chemicals.

New heat maps of the surface show higher temperatures than previously
known in the south polar region, with hot tracks running the length
of giant fissures. Additionally, scientists say the organics "taste
and smell" like some of those found in a comet. The jets themselves
harmlessly peppered Cassini, exerting measurable torque on the
spacecraft, and providing an indirect measure of the plume density.

"A completely unexpected surprise is that the chemistry of Enceladus,
what's coming out from inside, resembles that of a comet," said
Hunter Waite, principal investigator for the Cassini Ion and Neutral
Mass Spectrometer at the Southwest Research Institute in San Antonio.
"To have primordial material coming out from inside a Saturn moon
raises many questions on the formation of the Saturn system."

"Enceladus is by no means a comet. Comets have tails and orbit the
sun, and Enceladus' activity is powered by internal heat while comet
activity is powered by sunlight. Enceladus' brew is like carbonated
water with an essence of natural gas," said Waite.

The Ion and Neutral Mass Spectrometer saw a much higher density of
volatile gases, water vapor, carbon dioxide and carbon monoxide, as
well as organic materials, some 20 times denser than expected. This
dramatic increase in density was evident as the spacecraft flew over
the area of the plumes.

New high-resolution heat maps of the south pole by Cassini's Composite
Infrared Spectrometer show that the so-called tiger stripes, giant
fissures that are the source of the geysers, are warm along almost
their entire lengths, and reveal other warm fissures nearby. These
more precise new measurements reveal temperatures of at least minus
135 degrees Fahrenheit. That is 63 degrees Fahrenheit warmer than
previously seen and 200 degrees Fahrenheit warmer than other regions
of the moon. The warmest regions along the tiger stripes correspond
to two of the jet locations seen in Cassini images.

"These spectacular new data will really help us understand what powers
the geysers. The surprisingly high temperatures make it more likely
that there's liquid water not far below the surface," said John
Spencer, Cassini scientist on the Composite Infrared Spectrometer
team at the Southwest Research Institute in Boulder, Colo.

Previous ultraviolet observations showed four jet sources, matching
the locations of the plumes seen in previous images. This indicates
that gas in the plume blasts off the surface into space, blending to
form the larger plume.

Images from previous observations show individual jets and mark places
from which they emanate. New images show how hot spot fractures are
related to other surface features. In future imaging observations,
scientists hope to see individual plume sources and investigate
differences among fractures.

"Enceladus has got warmth, water and organic chemicals, some of the
essential building blocks needed for life," said Dennis Matson,
Cassini project scientist at NASA's Jet Propulsion Laboratory in
Pasadena, Calif. "We have quite a recipe for life on our hands, but
we have yet to find the final ingredient, liquid water, but Enceladus
is only whetting our appetites for more."

At closest approach, Cassini was only 30 miles from Enceladus. When it
flew through the plumes it was 120 miles from the moon's surface.
Cassini's next flyby of Enceladus is in August.

The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency and the Italian Space Agency. The mission is
managed by JPL for NASA's Science Mission Directorate, Washington.

For images and more information, visit:

http://www.nasa.gov/cassini

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Re: NASA - Cassini updates
« Reply #32 on: 03/26/2008 07:10 PM »
This is huge... another moon to look really seriously at, to add to the Titan and Europa list (my list would run too long if we counted geologically interesting moons, I'm just referring to the best candidates for liquid water ;) )Still shuffling through the information, Cassini is simply wonderful.
-DaviD-

Offline Eerie

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Re: NASA - Cassini updates
« Reply #33 on: 03/26/2008 07:27 PM »
Quote
eeergo - 26/3/2008  3:10 PM

This is huge... another moon to look really seriously at, to add to the Titan and Europa list (my list would run too long if we counted geologically interesting moons, I'm just referring to the best candidates for liquid water ;) )Still shuffling through the information, Cassini is simply wonderful.

Meh, luquid water underground is boring. Give me liquid water on the surface any day...

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Re: NASA - Cassini updates
« Reply #34 on: 03/26/2008 10:55 PM »
The impressive result here is the beginnings of a rational understanding of how Saturn's moons "geology" functions.

Didn't think we'd learn this to much later missions. Cassini/Huygens is turning out to be a legendary mission in many ways.

It also has humorous notes - we're looking at the end of hydrocarbon fuels on Earth, at a time when a planetary-scale refinery has been discovered within our solar system. How ironic. We are even understanding how it works.

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Re: NASA - Cassini updates
« Reply #35 on: 03/27/2008 07:54 PM »

Quote
nobodyofconsequence - 27/3/2008  12:55 AMThe impressive result here is the beginnings of a rational understanding of how Saturn's moons "geology" functions.Didn't think we'd learn this to much later missions. Cassini/Huygens is turning out to be a legendary mission in many ways.It also has humorous notes - we're looking at the end of hydrocarbon fuels on Earth, at a time when a planetary-scale refinery has been discovered within our solar system. How ironic. We are even understanding how it works.

Agreed on those. :) There has been a media briefing update (kindly recorded by John44, now in Space-Multimedia) and here  it can be replayed.

-DaviD-

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Re: NASA - Cassini updates
« Reply #36 on: 04/06/2008 09:32 PM »
Interesting article by Planetary Society blogger Emily Lakdawalla about topographic features in Titan:

http://www.planetary.org/blog/article/00001385/
-DaviD-

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Re: NASA - Cassini updates
« Reply #37 on: 04/06/2008 10:11 PM »
Thanks eeergo, good stuff.

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Re: NASA - Cassini updates
« Reply #38 on: 04/06/2008 10:35 PM »
This is some fascinating science right here and no mistake :)

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Re: NASA - Cassini updates
« Reply #39 on: 04/15/2008 03:06 PM »
RELEASE: 08-098

NASA EXTENDS CASSINI'S GRAND TOUR OF SATURN

PASADENA, Calif. -- NASA is extending the international
Cassini-Huygens mission by two years. The historic spacecraft's
stunning discoveries and images have revolutionized our knowledge of
Saturn and its moons.

Cassini's mission originally had been scheduled to end in July 2008.
The newly-announced two-year extension will include 60 additional
orbits of Saturn and more flybys of its exotic moons. These will
include 26 flybys of Titan, seven of Enceladus, and one each of
Dione, Rhea and Helene. The extension also includes studies of
Saturn's rings, its complex magnetosphere, and the planet itself.

"This extension is not only exciting for the science community, but
for the world to continue to share in unlocking Saturn's secrets,"
said Jim Green, director, Planetary Science Division, NASA
Headquarters, Washington. "New discoveries are the hallmarks of its
success, along with the breathtaking images beamed back to Earth that
are simply mesmerizing."

"The spacecraft is performing exceptionally well and the team is
highly motivated, so we're excited at the prospect of another two
years," said Bob Mitchell, Cassini program manager at NASA's Jet
Propulsion Laboratory in Pasadena, Calif.

Based on findings from Cassini, scientists think liquid water may be
just beneath the surface of Saturn's moon, Enceladus. That's why the
small moon, only one-tenth the size of Titan and one-seventh the size
of Earth's moon, is one of the highest-priority targets for the
extended mission.

Cassini discovered geysers of water-ice jetting from the Enceladus'
surface. The geysers, which shoot out at a distance three times the
diameter of Enceladus, feed particles into Saturn's most expansive
ring. In the extended mission, the spacecraft may come as close as 15
miles from the moon's surface.

Cassini's observations of Saturn's largest moon, Titan, have given
scientists a glimpse of what Earth might have been like before life
evolved. They now believe Titan possesses many parallels to Earth,
including lakes, rivers, channels, dunes, rain, snow, clouds,
mountains and possibly volcanoes.

"When we designed the original tour, we really did not know what we
would find, especially at Enceladus and Titan," said Dennis Matson,
the JPL Cassini project scientist. "This extended tour is responding
to these new discoveries and giving us a chance to look for more."

Unlike Earth, Titan's lakes, rivers and rain are composed of methane
and ethane, and temperatures reach a chilly minus 290 degrees
Fahrenheit. Although Titan's dense atmosphere limits viewing the
surface, Cassini's high-resolution radar coverage and imaging by the
infrared spectrometer have given scientists a better look.

Other activities for Cassini scientists will include monitoring
seasons on Titan and Saturn, observing unique ring events, such as
the 2009 equinox when the sun will be in the plane of the rings, and
exploring new places within Saturn's magnetosphere.

Cassini has returned a daily stream of data from Saturn's system for
almost four years. Its travel scrapbook includes nearly 140,000
images and information gathered during 62 revolutions around Saturn,
43 flybys of Titan and 12 close flybys of the icy moons.

More than 10 years after launch and almost four years after entering
into orbit around Saturn, Cassini is a healthy and robust spacecraft.
Three of its science instruments have minor ailments, but the impact
on science-gathering is minimal. The spacecraft will have enough
propellant left after the extended mission to potentially allow a
third phase of operations. Data from the extended mission could lay
the groundwork for possible new missions to Titan and Enceladus.

Cassini launched Oct. 15, 1997, from Cape Canaveral, Fla., on a
seven-year journey to Saturn, traversing 2.2 billion miles. It is one
of the most scientifically capable spacecraft ever launched, with a
record 12 instruments on the orbiter and six more instruments on the
European Space Agency's Huygens probe, which piggybacked a ride to
Titan on Cassini. Cassini receives electrical power from three
radioisotope thermoelectric generators, which generate electricity
from heat produced by the natural decay of plutonium. The spacecraft
was captured into Saturn orbit in June 2004 and immediately began
returning data to Earth.

The Cassini-Huygens mission is a cooperative project between NASA, the
European Space Agency and the Italian Space Agency.

For more information on the Cassini-Huygens mission, visit:

http://www.nasa.gov/cassini

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