- September 22, 2008. The
Bone-Dry Moon Might be Damp. Written by G. Jeffrey Taylor, Hawai'i Institute of
Geophysics and Planetology. Excerpt: Detailed analysis
of the first lunar samples collected by Apollo 11 astronauts
in 1969 revealed no evidence that lunar magmas contained
even a smidgeon of water. Analysis of samples returned
by subsequent missions did not contradict this important
observation. It became a tenant of lunar science that
the Moon is bone dry.
...Recent analyses of lunar volcanic glasses suggest
that a smidgeon, maybe even a mega-smidgeon, of water
is present. Alberto Saal and his colleagues at Brown
University, the Carnegie Institution of Washington,
and Case Western Reserve University have measured volatile
elements in lunar volcanic glass beads, using ion microprobe
capabilities not available until a few years ago. They
measured OH- (hydroxyl) anions (which are fragments
of the H2O) molecule). All the measurements (of OH-,
sulfur, fluorine, and chlorine) had higher concentrations
in the center of the 276-micrometer beads, and decreased
progressively towards the surface. This is a classic
diffusion profile, suggesting that these elements were
present in the droplets of magma when erupted, but
began to be lost to the surrounding volcanic gases.
Saal and his colleagues calculated how much of these
volatiles were present upon eruption. They concluded
that the lunar magmas contained about 745 parts per
million of water, similar to the amount in magmas produced
at mid-ocean ridges on Earth. The results imply that
the region of the lunar interior that melted to make
the magmas contained about the same amount as in the
Earth's depleted upper mantle, which is way more than
a smidgeon. This may have implications for the origin
of the Moon. It certainly will spark new research on
lunar volatiles--and lots of arguments!
...The Importance of Water in the Moon
Besides possibly overturning a long-held tenant of
lunar science that proclaims that the Moon is bone
dry, the discovery of water in lunar samples has
implications for the conditions existing during lunar
formation. It is particularly important for understanding
how and when Earth obtained its water. Understanding
how much water there was initially in the Moon is
pertinent to understanding delivery of water to the
inner Solar System and to unraveling the details
of lunar formation. The amount of water in the Moon
also would have affected the compositions, movement,
eruption, and crystallization of lunar magmas, depending
on how much water resided in the Moon.
- 2008 August. The
changing face of Titan. By Ralph
D. Lorenz, Physics Today, page 34. Excerpt:
...The discovery of a significant atmosphere sets Titan
apart from the other satellites in the solar system.
Indeed, the atmosphere makes it more planetlike than
many planets.... With our scientific appetites whetted
by the prospect of surface liquids—perhaps even
a global ocean—Titan
was a prime target of the international Cassini–Huygens
mission.....
Possibly the greatest surprise from Cassini so far
is how Earth-like Titan's landscape is. The pictures
from the Huygens probe5 show terrain that looks familiar—hills
cut by a dendritic network of river channels....
Radar and near-IR images from orbit have shown larger
channels, complete with meanders like terrestrial rivers,
in other locations....
Besides Earth, Titan is the only place in the solar
system today where rain falls to the surface. But in
Titan's exotic environment, the balance between surface
tension and aerodynamic forces on a falling drop of
liquid methane allows the drops to be gigantic—about
1 cm in diameter, rather than the roughly 6-mm drops
that fall on Earth. Moreover, in Titan's thick atmosphere
and low gravity, those drops fall at only 1.6 m/s (compared
with 10 m/s on Earth), more like fluffy snowflakes
do on Earth....
Nevertheless, seasonally changing solar heating appears
to be the origin of Titan's longest-monitored change,
that of the haze in the stratosphere. Even in the 1970s,
it was known that Titan's overall brightness changed
over the years, and by different amounts at blue and
yellow wavelengths.... As Titan goes
around the Sun, its two hemispheres are presented to
Earth by varying amounts, and their intrinsic brightness
changes, most visibly at blue wavelengths, as the seasons
wax and wane.... The stratospheric haze may also be
connected with a recently observed extensive cloud
over the north pole, presently just emerging from winter.
That cloud, perhaps largely composed of ethane, may
be connected with one of Titan's most appealing landforms—lakes....
Not all of Titan's surface is wet. Indeed, some 20%
of it, all at low latitudes, is covered with giant
sand dunes....
A striking feature of the dunes is that they are longitudinal
in form, lining up along the mean transport direction.
Such dunes form on Earth when the wind blows in two
predominant nonparallel directions.... On Titan, whether
the alternating wind regime is due to the gravitational
tide or to seasons remains to be determined....
- 2008 July 30. NASA RELEASE: 08-193. NASA CONFIRMS
LIQUID LAKE ON SATURN MOON. Excerpt: PASADENA, Calif.
-- NASA scientists have concluded that at least one
of the large lakes observed on Saturn's moon Titan
contains liquid hydrocarbons, and have positively identified
the presence of ethane. This makes Titan the only body
in our solar system beyond Earth known to have liquid
on its surface. Scientists made the discovery using
data from an instrument aboard the Cassini spacecraft.
...hundreds of dark lake-like features are present.
...Ethane and several other simple hydrocarbons have
been identified in Titan's atmosphere, which consists
of 95 percent nitrogen, with methane making up the
other 5 percent. Ethane and other hydrocarbons are
products from atmospheric chemistry caused by the breakdown
of methane by sunlight.
...More information on the Cassini-Huygens mission.
- 2008 April 15. NASA
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.
..."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.
...Unlike Earth, Titan's lakes, rivers and rain are
composed of methane and ethane, and temperatures reach
a chilly minus 290 degrees Fahrenheit.
...More information on the Cassini-Huygens
mission.
- 2008 March 26, RELEASE:
08-089. CASSINI TASTES ORGANIC MATERIAL AT SATURN'S
GEYSER MO ON. Excerpt:
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. "...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'
brew is like carbonated water with an essence of natural
gas," said Waite. ..."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."
- March 20, 2008. NASA
RELEASE: 08-085. CASSINI SPACECRAFT FINDS OCEAN MAY
EXIST BENEATH TITAN'S CRUST. Excerpt:
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.
- 2008 Mar 20. CASSINI
SPACECRAFT FINDS OCEAN MAY EXIST BENEATH TITAN'S
CRUST. NASA news RELEASE :
08-085. 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.
- 2008 Mar 19. A
BRIEF ENCELADUS SHOWER. NASA Astrobiology
Magazine. NASA's Cassini spacecraft performed a daring
flyby of Saturn's moon Enceladus on March 12, flying
about 15 kilometers per second (32,000 mph) through
icy water geyser-like jets. The spacecraft snatched
up precious samples that might point to a water ocean
or organics inside the little moon.
- 2008 Mar 6. SATURN'S
MOON RHEA ALSO MAY HAVE RINGS.
NASA Cassini mission news. 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.
- 2007 Dec 13. Return
to Europa: A closer look is possible. Washington University News. "We've learned
a lot about Europa in the past few years," says
William B. McKinnon, professor of earth and planetary
sciences at Washington University in St. Louis. "Before
we were almost sure that there was an ocean, but now
the scientific community has come to a consensus that
there most certainly is an ocean. We're ready to take
the next step and explore that ocean and the ice shell
that overlays it. We have a number of new discoveries
and techniques that can help us do that."
- 3 April 2007. Two
Views of the Moon's Composition ---
There is a striking dichotomy in
estimates of the abundance of refractory elements
in the Moon. Written by G. Jeffrey Taylor, Hawai'i
Institute of Geophysics and Planetology. Estimates
of the chemical composition of the bulk (entire)
Moon fall into two drastically different categories.
One group of estimates claims that the Moon is
enriched in refractory elements (those that boil
at high temperatures, such as calcium and aluminum)
by about 50% compared to Earth. The other group
claims that the abundances of refractory elements
are the same in the Earth and Moon....
- 3 January 2007: Another
meteor shower, another bunch of lunar impacts...
[Science@NASA] Excerpt: "On Dec.
14, 2006, we observed at least five Geminid meteors
hitting the Moon," reports Bill Cooke of NASA's
Meteoroid Environment Office in Huntsville, AL. Each
impact caused an explosion ranging in power from
50 to 125 lbs of TNT and a flash of light as bright
as a 7th-to-9th magnitude star. The explosions occurred
while Earth and Moon were passing through a cloud
of debris following near-Earth asteroid 3200 Phaethon.
This happens every year in mid-December and gives
rise to the annual Geminid meteor shower: Streaks
of light fly across the sky as rocky chips of Phaethon
hit Earth's atmosphere. It's a beautiful display.
The same chips hit the Moon, of course, but on the
Moon there is no atmosphere to intercept them. Instead,
they hit the ground. "We saw about one explosion
per hour," says Cooke. How does a meteoroid
explode? "This isn't the kind of explosion we
experience on Earth," explains Cooke. The Moon
has no oxygen to support fire or combustion, but
in this case no oxygen is required: Geminid meteoroids
hit the ground traveling 35 km/s (78,000 mph). "At
that speed, even a pebble can blast a crater several
feet wide," says Cooke. "The flash of light
comes from rocks and soil made so hot by impact that
they suddenly glow."
- 3 January 2007. New
Evidence of Liquid Methane on Saturn's Moon.
NY Times. By JOHN NOBLE WILFORD. As
scientists predicted but have had a hard time proving,
the surface of Titan, Saturn's largest moon, appears
to be dotted with an abundance of lakes of liquid
methane. The lakes are more intriguing evidence
of the active phenomena at play on the only moon
in the solar system that has a dense atmosphere.
...a radar survey of Titan's high northern latitudes
by the Cassini spacecraft, which has been orbiting
Saturn and its retinue of satellites since July
2004 ...detected more than 75 dark patches in the
landscape toward Titan's northern polar region.
The patches, they said, indicated smooth surfaces
in an otherwise rugged topography, suggesting lake
beds either partly dry or filled with liquid.
These smooth surfaces, more or less circular and
ranging in diameter from 2 to 40 miles, are associated
with channels that appear to have been formed by
flowing liquids, presumably tributaries to the
lakes. Methane exists in Titan's atmosphere and,
in the extreme cold of high latitudes, is expected
to rain on the surface and be present as liquids
in subsurface reservoirs. The discovery team concluded
that the radar images, made on a close pass of
the moon in July, "provide definitive evidence
for the presence of lakes on the surface of Titan." ...Dr.
Ellen R. Stofan said that the lake depressions
could be volcanic craters or sinkholes....
- 9 Nov 2006. Is
the Moon Still Alive? NASA Science
News. Conventional wisdom says the Moon is dead.
Conventional wisdom may be wrong. Today in the journal
Nature, a team of NASA-supported scientists announced
evidence for fresh geologic activity on the Moon.
- 8 November 2006. Recent
Gas Escape from the Moon. By G. Jeffrey Taylor,
Hawai'i Institute of Geophysics and Planetology. Excerpt:
Gases may have escaped from the Moon as recently
as a million years ago, implying that the lunar
interior is not as lethargic as conventional wisdom
dictates. The Moon is generally thought to be geologically
inactive, ...The youngest returned igneous rocks
are about 3 billion years old, although crater
counting suggest some lava flows as young as a
billion years. However, Peter Schultz (Brown University),
Matthew Staid (Planetary Sciences Institute, Tucson),
and Carl Pieters (Brown University) report an
array of data that indicate that the Moon may be
active enough inside to occasionally spew puffs
of gases that blow off the fine-grained, busted
up surface materials known as the regolith. The
researchers studied a feature called the Ina structure,
a depression containing numerous steep-sided hills,
located in a mare region known as Lacus Felicitatis.
... photographs taken from orbit during the Apollo
15 mission ... Clementine spacecraft ... in 1994,
returning images in several wavelengths, ...tell
us ... important information about the maturity
of the surface--how long the surface has been exposed
to solar wind and micrometeorite bombardment, or "space
weathering." ...Schultz and colleagues suggest
that the regolith or pyroclastic layer was blown
away by the sudden release of pressurized gases.
The subdued ejecta surrounding the structure indicates
that the process was not as energetic as an impact,
consistent with a gas eruption. Which gases is
unknown, but they must have come from deep within
the Moon, and collected beneath the surface until
their pressure built up enough to suddenly burp
out, blowing regolith around, a rare case of wind
on the airless Moon. ...Perhaps astronauts will
visit Ina someday, examining its fluffy deposits
and rugged underlying rock. It might not, however,
be such a great place to establish a lunar base.
Imagine sitting in your habitat, working on some
samples you collected ..., when the habitat shakes
and your view of the outside is obscured by regolith
being lifted by gases spewing from the interior
of the not-so-burnt-out cinder!
- 17 October 2006 Cassini
Views Dione, a Frigid Ice World (Source: Jet
Propulsion Laboratory) Image: Speeding
toward pale, icy Dione, Cassini's view is enriched
by the tranquil gold and blue hues of Saturn in
the distance. Image: http://photojournal.jpl.nasa.gov/catalog/PIA07744
Image info: http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=1790
See also http://photojournal.jpl.nasa.gov/catalog/PIA06162
- 8 August 2006. Scientists
Chip Away at Mysteries of the Moon. By KENNETH
CHANG, NY Times. Excerpt: The Moon
is slightly squashed, as if someone had held it
at the poles between thumb and forefinger and squeezed,
flattening it around its equatorial midsection.
That is not surprising. The Moon spins, and the
outward centrifugal force should indeed have generated
a bulge as the molten magma of a young moon cooled
to solid rock eons ago. ...But as far back as 1799,
the mathematician Pierre-Simon Laplace noticed
a back-and-forth wobbling because of the Moon's
deformed shape. Although the flattening was slight
- the Moon's width, 2,159 miles, is about 2.5 miles
greater than its pole-to-pole height - it was still
greater than would be expected for its current
rotation period of 27 days 7 hours 43 minutes and
11.5 seconds.
"The puzzle had been the Moon was too flat," said
Maria T. Zuber, a professor of geophysics and planetary
sciences at the Massachusetts Institute of Technology.
Space probes of the 1960's and 1970's found a second
deformity of the Moon: it is slightly elongated
along the Moon-Earth axis. That is, if the Moon
were sliced in half along its equator, the cross-section
would not be a circle, but more like a football,
with one of the narrow ends pointing toward Earth.
But no one could come up with a completely convincing
explanation for the Moon's current shape. ..."Quite
a lot of the darned thing is still quite mysterious," said
Kimmo Innanen, a professor of astronomy at York
University in Toronto. In the current issue of
Science, Dr. Zuber, with Jack Wisdom and Ian Garrick-Bethell,
say they have a possible answer to the problem
of the Moon's shape. Actually, they say they have
several. What Laplace did not know is that the
Moon is moving away from Earth and slowing down.
Years of bouncing laser beams off mirrors left
on the lunar surface by the Apollo astronauts show
that each year the Moon is another 1.5 inches farther
from Earth....
- 9 June 2006 Earth
Science Picture of the Day (EPOD) shows evidence
that the Moon's distance from Earth varies.
- 10 April 2006 - In
Search of Water, NASA Spacecraft to Hit the Moon. NASA
today announced that a small spacecraft, to be
developed by a team at NASA Ames, has been selected
to travel to the moon to look for precious water
ice at the lunar south pole. The name of the mission
is LCROSS, short for Lunar CRater Observation and
Sensing Satellite. LCROSS is a secondary payload:
It will hitch a ride to the moon onboard the same
rocket as the Lunar Reconnaissance Orbiter (LRO)
satellite due to launch from the Kennedy Space
Center in October 2008. "The LCROSS mission
gives the agency an excellent opportunity to answer
the question about water ice on the moon," says
Daniel Andrews of NASA Ames, whose team proposed
LCROSS.
- 1 November 2005. Persistent
Astronomers Find Pluto Has Two More Moons.
By KENNETH CHANG. NY Times. Excerpt:
Astronomers using NASA's Hubble Space Telescope
announced yesterday that they had spotted two small
moons circling Pluto. That gives Pluto, the smallest
of the nine planets, a total of three moons, or
more than four of the other planets....Pluto's
largest moon, Charon, was discovered in 1978. Hubble
spotted the second and third moons on May 15 and
May 18. For now they are known only as S/2005 P1
and S/2005 P2. S/2005 P1, estimated to orbit 40,000
miles from Pluto, is up to 100 miles wide. P2 is
likely 10 to 15 percent smaller and about 30,000
miles from Pluto.... Astronomers believe that Charon
formed in the aftermath of a collision between
a large meteor and Pluto. ...the new moons also
formed out of that collision and that there could
be more. ....Another possibility is that the two
moons were originally part of the Kuiper Belt,
the ring of small icy bodies beyond Neptune, and
were captured by Pluto's gravitational pull.
- 31 October 2005. NASA RELEASE: 05-351. NASA's
Hubble Reveals Possible New Moons Around Pluto. Using
NASA's Hubble Space Telescope to view the ninth
planet in our solar system, astronomers discovered
Pluto may have not one, but three moons.If confirmed,
the discovery of the two new moons could offer
insights into the nature and evolution of the Pluto
system; Kuiper Belt Objects with satellite systems;
and the early Kuiper Belt. ...The team plans to
make follow-up Hubble observations in February
to confirm the newly discovered objects are truly
Pluto's moons. Only after confirmation will the
International Astronomical Union consider names
for S/2005 P1 and S/2005 P2. The Hubble's Advanced
Camera for Surveys observed the two new candidate
moons on May 15, 2005. The candidates are roughly
5,000 times fainter than Pluto. Three days later,
Hubble looked at Pluto again. The two objects were
still there and appeared to be moving in orbit
around Pluto.Photos at http://hubblesite.org/newscenter/newsdesk/archive/releases/2005/19/ See
also: background info http://www.boulder.swri.edu/plutomoons/ For
detailed information and images about this research
on the Web, visit: http://hubblesite.org/news/2005/19
- 30 August 2005. Cassini
Finds Enceladus Tiger Stripes Are Really Cubs. The
Cassini spacecraft discovered the long, cracked
features dubbed "tiger stripes"
on Saturn's icy moon Enceladus are very young.
They are between 10 and 1,000 years old. These
findings support previous results showing the moon's
southern pole is active. The pole had episodes
of geologic activity as recently as 10 years ago.
These cracked features are approximately 80 miles
long, spaced about 25 miles apart and run roughly
parallel to each another. The cracks act like vents.
They spew vapor and fine ice water particles that
have become ice crystals. This crystallization
process can help scientists pin down the age of
the features.
- 29 July 2005. NASA News Release: 05-207. CASSINI
FINDS AN ACTIVE, WATERY WORLD AT SATURN'S ENCELADUS. Saturn's
tiny icy moon Enceladus, which ought to be cold
and dead, instead displays evidence for active
ice volcanism. NASA's Cassini spacecraft has found
a huge cloud of water vapor over the moon's south
pole, and warm fractures where evaporating ice
probably supplies the vapor cloud. Cassini has
also confirmed Enceladus is the major source of
Saturn's largest ring, the E-ring."Enceladus
is the smallest body so far found that seems to
have active volcanism," said Dr. Torrence
Johnson, Cassini imaging-team member at NASA's
Jet Propulsion Laboratory, Pasadena, Calif. "Enceladus'
localized water vapor atmosphere is reminiscent
of comets. 'Warm spots' in its icy and cracked
surface are probably the result of heat from tidal
energy like the volcanoes on Jupiter's moon Io.
And its geologically young surface of water ice,
softened by heat from below, resembles areas on
Jupiter's moons, Europa and Ganymede," Johnson
added...The fact the atmosphere persists on this
low-gravity world, instead of instantly escaping
into space, suggests the moon is geologically active
enough to replenish the water vapor at a slow continuous
rate...Images show the south pole has an even younger
and more fractured appearance than the rest of
Enceladus, complete with icy boulders the size
of large houses and long, bluish cracks or faults
dubbed "tiger stripes."
- 29 February 2005. NASA News Release: 05-059 NASA'S
CASSINI CONTINUES MAKING NEW SATURN DISCOVERIES NASA's
Cassini spacecraft continues making new and exciting
discoveries. The findings include wandering and
rubble-pile moons; new and clumpy Saturn rings;
splintering storms and a dynamic magnetosphere. "For
the last seven months it has been a nonstop, science-packed
mission. It has been a whirlwind, and already we
have many new results," said Dr. Dennis Matson,
Cassini project scientist at NASA's Jet Propulsion
Laboratory, Pasadena, Calif.
- 25 February 2005. Rainbows
on Titan. NASA Science News. Saturn's
moon Titan is wet, according to the ESA's Huygens
probe, but Titan's "water" is not like
Earth's.
When the European Space Agency's Huygens probe
visited Saturn's moon Titan last month, the probe
parachuted through humid clouds. It photographed
river channels and beaches and things that look
like islands. Finally, descending through swirling
fog, Huygens landed in mud. To make a long story
short, Titan is wet.
- 16 February 2005. Cassini's
Radar Spots Giant Crater on Titan. A
giant impact crater the size of Iowa was spotted
on Saturn's moon Titan by NASA's Cassini radar
instrument during Tuesday's Titan flyby.
- 15 January 2005. Craft
on Titan Finds Tantalizing Signs of Liquid.
By JOHN NOBLE WILFORD . NY Times. DARMSTADT,
Germany, Jan. 14 - A European spacecraft... Huygens...
plunged through the murky atmosphere of Saturn's
moon Titan on Friday and successfully came to rest
on a bizarre landscape never before explored. Astronomers
expressed joy at achieving the first landing on
another planet's moon, particularly Titan, the
only moon in the solar system with substantial
atmosphere.... The first pictures from the spacecraft,,
did nothing to undermine the reputation of Titan
as a strange place. One showed what appeared to
be deep channels leading to the shoreline of a
dark, flat surface, possibly a lake of liquid methane. "Clearly
there is liquid matter flowing on the surface of
Titan," said Dr. Martin G. Tomasko of the
University of Arizona, an imaging specialist for
the mission. That possibility has tantalized scientists,
who say Titan may resemble Earth early in its development
and could give clues to the origin of life here.
- 7 January 2005. NASA Press Release: 2005-005. Saturn's
Moon Iapetus Shows a Bulging Waistline. Images
returned by NASA's Cassini spacecraft cameras during
a New Year's Eve flyby of Saturn's moon Iapetus
(eye-APP-eh-tuss) show startling surface features
that are fueling heated scientific discussions
about their origin. One of these features is a
long narrow ridge that lies almost exactly on the
equator of Iapetus, bisects its entire dark hemisphere
and reaches 20 kilometers high (12 miles). It extends
over 1,300 kilometers (808 miles) from side to
side, along its midsection. No other moon in the
solar system has such a striking geological feature.
In places, the ridge is comprised of mountains.
In height, they rival Olympus Mons on Mars, approximately
three times the height of Mt. Everest, which is
surprising for such a small body as Iapetus. Mars
is nearly five times the size of Iapetus. Images
from the flyby are available at http://saturn.jpl.nasa.gov, http://www.nasa.gov/cassini and http://ciclops.org.
Iapetus is a two-toned moon. The leading hemisphere
is as dark as a freshly-tarred street, and the
white, trailing hemisphere resembles freshly-fallen
snow. The flyby images, which revealed a region
of Iapetus never before seen, show feathery-looking
black streaks at the boundary between dark and
bright hemispheres that indicate dark material
has fallen onto Iapetus. Opinions differ as to
whether this dark material originated from within
or outside Iapetus.
- 2 December 2004. JPL
Press Release. Cassini
Shows Before And After Look At Saturn's Moon
Titan. Cassini's second close flyby
of Titan completes a 'before' and 'after' look
at the fuzzy moon and provides the first direct
evidence of changing weather patterns in the
skies over Titan. In images obtained less than
two months ago, the Titan skies were cloud free,
except for a patch of clouds observed over the
moon's south pole. In images taken Monday, Dec.
13, during Cassini's second close flyby of Titan,
several extensive patches of clouds have formed.
Images show that Cassini has found Titan's upper
atmosphere to consist of a surprising number
of layers of haze.
- 15 December 2004. New
Clouds Add to Titan's Mystery. Using
adaptive optics on the Gemini North and Keck II
telescopes on Mauna Kea, Hawai'i, a U.S. team has
discovered a new phenomenon in the atmosphere of
Saturn's largest moon Titan. Unlike previous observations
showing storms at the south pole, these new images
reveal atmospheric disturbances at Titan's temperate
mid latitudes-about halfway between the equator
and the poles. Explaining the unexpected activity
has proven difficult, and the team speculates that
the storms could be driven by anything from short-term
surface events to shifts in global wind patterns.
- 10 December 2004. Composition
of the Moon's Crust. Written by Linda M. V.
Martel, Hawai'i Institute of Geophysics and Planetology. In
1997, PSRD first reported on the trailblazing efforts
to map the abundance and distribution of titanium
and iron on the entire lunar surface based on Clementine
orbital remote sensing data [see PSRD article: Moonbeams
and Elements]. Researchers calibrated the remote
sensing data with the best ground-truth standards
available: lunar soil and rock samples. Since the
initial mapping, planetary scientists have been
striving to improve the calibration of the remote
sensing data to correct for over or under estimates
of the global concentrations of primary elements.
This work is important because it prevents us from
getting erroneous ideas about the Moon's composition
and origin. New calibrations to Lunar Prospector
and Clementine data by Jeff Gillis (previously
at Washington University in St. Louis and now at
the University of Hawai'i), Brad Jolliff, and Randy
Korotev (both at Washington University in St. Louis)
have resulted in updated global maps for thorium
(Th), potassium (K), and iron oxide (FeO) that
are more consistent with the compositions of lunar
samples and lunar meteorites, and allow a better
understanding of the Moon's formation and evolution.
- 5 November 2004. Radar Image Shows Titan's Surface
Live and in Color. Saturn's moon Titan
shows a sharp contrast between its smooth and rough
edges in a new false-color radar image. Titan's surface
lies beneath a thick coat of hazy clouds, but Cassini's
radar instrument can peer through to show finer surface
features. Scientists have added color to emphasize
finer details on Titan, as shown in the image. This
image can be viewed at: http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini
- 31 October 2004. New Lunar Meteorite Provides its
Lunar Address and Some Clues about Early Bombardment
of the Moon. A newly discovered meteorite
from the Moon provides a detailed record of its history,
allowing scientists to make a reasonable guess about
where it came from on the Moon and to test ideas
for the timing of early impact bombardment.
Full story and a PDF link at: http://www.psrd.hawaii.edu/Oct04/SaU169.html
- 5 July 2004. New
Mineral Proves an Old Idea about Space Weathering
--- A newly discovered
vapor-deposited iron silicide in a lunar
meteorite has been named hapkeite. Written
by Linda M. V. Martel - Hawai'i Institute
of Geophysics and Planetology. Discovered
in a lunar meteorite, a new mineral
named hapkeite honors the scientist,
Bruce Hapke (Emeritis Professor at University
of Pittsburg), who nearly 30 years ago
predicted the importance of vaporization
as one of the processes in space weathering.
The new iron silicide mineral (Fe2Si)
was announced by the research team of
Mahesh Anand (formerly at the University
of Tennessee, Knoxville and now at the
Natural History Museum, London), Larry
Taylor (University of Tennessee, Knoxville),
Mikhail Nazarov (Vernadsky Institute
of Geochemistry and Analytical Chemistry,
Moscow), Jinfu Shu, Ho-kwang Mao, and
Russell Hemley (Carnegie Institution
of Washington). This mineral likely
formed by impact vaporization of the
lunar soil and subsequent condensation
of the iron and silicon into tiny metal
grains. The researchers conclude that
Fe-Si phases are more common in the
lunar soil than previously thought.
It is nanophase-sized Fe0, these Fe-Si
phases, and other space weathering products
that profoundly affect the optical properties
of the lunar soil at visible and near
infrared wavelengths and must be taken
into account when interpreting remote
sensing data of the Moon.
- 2 July 2004 Cassini
Exposes Puzzles About Ingredients In Saturn's Rings -- Just
two days after the Cassini spacecraft entered Saturn
orbit, preliminary science results are already
beginning to show a complex and fascinating planetary
system. ... One early result intriguing scientists
concerns Saturn's Cassini Division, the large gap
between the A and B rings. While Saturn's rings
are almost exclusively composed of water ice, new
findings show the Cassini Division contains relatively
more "dirt"
than ice. Further, the particles between the rings
seem remarkably similar to the dark material that
scientists saw on Saturn's moon, Phoebe. These
dark particles refuel the theory that the rings
might be the remnants of a moon. The F ring was
also found to contain more dirt.
- 23 June 2004 NASA RELEASE: 04-202 CASSINI
OPENS A COSMIC TIME CAPSULE
Like a woolly mammoth
trapped in Arctic ice, Saturn's small
moon Phoebe may be a frozen artifact
of a bygone era, some four billion years
ago. The finding is suggested by new
data from the Cassini spacecraft.
- 23 June 2004. Cassini high resolution image
of Saturn's moon Phoebe
- 19 August 2003. Mars
Profiler (from Sky and Telescope Skywatchers
bulletin). To compare what you see
on Mars with a map, you need to know which side
of the planet you're looking at. The Mars Profiler
(javascript utility) tells you that and more, for
any date and time.
- 19 August 2003. Observing
Mars's moons article from Sky and Telescopes. Phobos
(mag 10.5 max) and Deimos (mag 11.6 max). Instructions
for how to make an occulting bar on an eyepiece,
as well as a "Martian Moons" javascript
utility to show optimal observing times.
- 19 August 2003. Storm
Watch on Mars (from Sky and Telescope Skywatchers
bulletin). If events of the past
30 years are an indication, there's a good chance
that the Martian landscape may soon be cloaked
by a major dust storm. Discover what to see on
the red planet even if a dust storm is raging:
- 19 August 2003. Plots
showing distance and apparent size of Mars by
Joe Macke [joe01@--- azmackes.net]17 August 2003. Images
and movies of Mars from ToUcam webcam taken
from back yard by Howard C. Anderson [handy13@--
mindspring.com]
- 3 July 2003. A
simply staggering image of Mars by the passing
Moon. Though some image enhancements
were made for clarifying the original digital file,
the basic material is original.
- 3 July 2003 Mars Express Earth-Moon
image. On the night of July
3, the Mars Express spacecraft was pointed backwards
to obtain a view of the Earth-Moon system from
a distance of 8 million kilometres while on its
way to Mars. See...Image.
Also has image of spectrum of Earth, with indicators
that there may be life on Earth. See also...Article.
- 20 December 2002. Image
of Uranus and 7 of it's moons in ESO press
release
- 18 December 2002. Full
Moon Effect on Behavior Minimal, Studies Say
John Roach for National
Geographic News.
- 18 December 2002, Clouds discovered on Saturn's
moon Titan PASADENA, Calif.- Teams
of astronomers at the California Institute of
Technology (Caltech) and at the University of
California, Berkeley, have discovered methane
clouds near the south pole of Titan, resolving
a fierce debate about whether clouds exist amid
the haze of the moon's atmosphere. http://pr.caltech.edu/media/Press_Releases/PR12323.html
- 9 December 2002. Featherweight Jupiter Moon is
Likely a Jumble of Pieces -- http://galileo.jpl.nasa.gov/news/display.cfm?News_ID=3919 -- NASA's
Galileo spacecraft continues to deliver surprises
with the discovery that Jupiter's potato-shaped inner
moon, named Amalthea, appears to have a very low
density, indicating it is full of holes.
"The density is unexpectedly low," said Dr. John
D. Anderson, an astronomer at NASA's Jet Propulsion
Laboratory, Pasadena, Calif. "Amalthea is apparently
a loosely packed pile of rubble."
- 6 December 2002.
Mountains on Io at Sunset -- Galileo spacecraft
image of mountains on Io from February 2000.
The image was taken when the Sun was low in the
sky, [revealing a] low scarp, roughly 250 meters
(820 feet) high, .... Mongibello Mons, the jagged
ridge at the left of the image, rises 7 kilometers
(23,000 feet) above the plains of Io, higher
than any mountain in North America. Full
article.
- 31 October 2002 -- Galileo's Last Rendezvous --
By Monica Bobra http://SkyandTelescope.com/news/current/article_780_1.asp-- Next
September (2003) the spacecraft will plunge directly
into the Jovian atmosphere. But Galileo should provide
one more burst of science data before making a final
orbit around Jupiter. Next week it will sweep past
Amalthea (Jupiter's innermost large satellite), race
through the planet's ring, and experience its most
intense magnetic and radiation environment to date.
It will glide 160 kilometers above Amalthea's surface
on November 5th 2002 at 6:19 Universal Time.
- 11 October 2002 DRY ICE SEEN ON SURFACE OF ARIEL
--http://sse.jpl.nasa.gov/news/display.cfm?News_ID=3448-- Planetary
scientists have discovered carbon dioxide ice on
the surface of Ariel, one of the moons of the planet
Uranus. ... The distribution of Ariel's dry ice revealed
an additional curiosity. Just as Earth's Moon always
shows the same face to the Earth, Ariel always shows
the same face to Uranus. Each of these moons has
a leading side and a trailing side as they orbit
their respective planet. The leading side received
more bombardment by meteors, just as a car's front
windshield is struck by more insects than the rear
window. Grundy and his collegues observed both leading
and trailing sides of Ariel, but dry ice only appeared
on the trailing side. A possible explanation for
the dry ice being on the trailing hemisphere only
is that the dry ice was originally distributed uniformly
over the surface, but over time was buried or destroyed
by the more intense bombardment of meteors on the
leading hemisphere.
- 17 April 2002 -- Hubble Hunts Down Binary
Objects at the Fringe of Our Solar System -- http://oposite.stsci.edu/pubinfo/pr/2002/04/ The
Hubble Space Telescope is hot on the trail of
a puzzling new class of solar system object that
might be called a Pluto "mini-me." Together,
these objects are 5,000 times less massive than
Pluto and Charon. Like Pluto and Charon, these
dim and fleeting objects travel in pairs in the
frigid, mysterious outer realm of the solar system
called the Kuiper Belt, a long-hypothesized "junkyard" of
countless icy bodies left over from the solar
system's formation.
- 12 March 2002 Once
Upon a Water Planet
- 12 February 2002 -- The
Real Lord of the Rings. "After
all this time we're still not sure about the
origin of Saturn's rings," says Jeff Cuzzi,
a planetary scientist at the NASA Ames Research
Center. Astronomers once thought that Saturn's
rings formed when Saturn did: 4.8 billion years
ago as the Sun and planets coalesced from a
swirling cloud of interstellar gas. "But lately," Cuzzi
says, "there's a growing awareness that Saturn's
rings can't be so old."
- 8 February 2002 Possible
Locations for Life on Europa -- A
professor from the University of Arizona believes
that Jupiter's moon Europa might not only sustain
life, but actually foster it in various habitable "niches".
Through its combination of liquid water, active
tidal forces, and periodic surface exposure,
the moon might encourage life faster than a
cold, arid place like Mars. Microbes have been
discovered on Earth which stay dormant for
millions of years and then spring to life when
the ice around them thaws.
- 15 January 2002 -- FAREWELL, IO; GALILEO PAYING
LAST VISIT TO A RESTLESS MOON- ftp://ftp.hq.nasa.gov/pub/pao/pressrel/2002/02-010.txt -- NASA's
Galileo orbiter will dart past Jupiter's moon Io
on Thursday in the veteran spacecraft's last and
closest flyby of any of the giant planet's four major
moons. Io's volcanoes have presented many surprises
... Scientists hope this week's encounter will reveal
how several regions of Io have changed over the years. "Galileo's
days are numbered now, so it's especially exciting
to visit Io one last time," said Dr. Eilene Theilig,
Galileo project manager at NASA's Jet Propulsion
Laboratory (JPL), Pasadena, Calif. RELEASE: 02-10
- 10 December 2001 -- Jupiter's Io Generates
Power and Noise, But No Magnetic Field -- http://www.jpl.nasa.gov/releases/2001/release_2001_240.html -- As
[Galileo] flew near Io's poles in August and
October, the density of charged particles it
was passing through suddenly increased about
tenfold when the spacecraft crossed the path
of a magnetic-field connection between Io and
Jupiter, reported Dr. Donald Gurnett of the University
of Iowa, Iowa City. The waves, indicating the
density, travel in a plasma of charged particles,
and would be silent to the ear, but Iowa researchers
converted them to sound waves to make the patterns
audible. Audio clips are available online at
http://www.jpl.nasa.gov/videos/io .
- 5 December 2001 What makes Europa pink? Does Europa's
rosy glow betray a flourishing colony of bugs? -- http://www.eurekalert.org/pub_releases/2001-12/ns-wme120501.php --
New Scientist article
- Solar
System Websites
- 29 November 2001 -- Ocean Inside
Jupiter's Moon Callisto May Have Cushioned
Big Impact -- http://www.jpl.nasa.gov/releases/2001/release_2001_230.html -- A
recent image from NASA's Galileo spacecraft
adds evidence to a theory that Callisto,
the outermost of Jupiter's four large
moons, may hold an underground ocean.
The image shows a part of Callisto's
surface directly opposite from the Valhalla
basin where Callisto was punched by a
major collision. The opposition point
shows no effect from the impact. Points
opposite major impact features on some
similar-size worlds, such as Mercury
and Earth's Moon, show lumpy terrain
attributed to seismic shocks from the
distant impacts.
- 27 November 2001 -- New Images Catch
Jupiter's Moon Io in Action http://www.jpl.nasa.gov/galileo/news/release/press011127.html JPL
Press Release #2001-228
- 8 November 2001 -- Europa's Ice Crust
Is Deeper Than 3 Kilometers, UA Scientists
Find -- JPL
Press Release
- 26 September 2001 -- Spacecraft at
Io Sees and Sniffs Tallest Volcanic Plume -- Jupiter's
moon Io has pulled a surprise on NASA's
Galileo spacecraft, hurling up the tallest
volcanic plume ever seen, which arose from
a previously unknown volcano. ... Adding
to the surprise, for the first time a Galileo
instrument has caught particles freshly
released from an eruption, giving scientists
a direct sample of Io material to analyze. "This
was totally unexpected," said the leader
of that experiment, Dr. Louis Frank of
the University of Iowa, Iowa City. "We've
had wonderful images and other remote sensing
of the volcanoes on Io before, but we've
never caught the hot breath from one of
them until now. Galileo smelled the volcano's
strong breath and survived." JPL
Press Release #2001-192
- 16 August 2001 Moon making made easy--Mars-sized
mass implicated by new model for Moon's violent
birth. http://www.nature.com/nsu/010816/010816-14.html Nature
- 22 August 2001 GALILEO FLYBY REVEALS CALLISTO'S
BIZARRE LANDSCAPE -- A spiky
landscape of bright ice and dark dust shows
signs of slow but active erosion on the surface
of Jupiter's moon Callisto in new images
from NASA's Galileo spacecraft. RELEASE:
01-174.
- 8 January 2001, 10 additional moons
discovered around Jupiter BY JEFF FOUST
SPACEFLIGHT NOW http://spaceflightnow.com/news/n0101/08jovianmoons/
- 14 December 2000 Satellite Footprints
Seen in Jupiter Aurora http://oposite.stsci.edu/pubinfo/pr/2000/38/
- 4 November 2000 Europa's lifelines -- http://www.newscientist.com/news/news.jsp?id=ns226331 --
The cracks in Europa's icy crust are where
life is most likely to be found on the Jovian
moon,.... (New Scientist)
- 15 September 2000 Legal
Loopholes Help Man Sell the Moon.
- 25 July 2000 (space.com) http://www.space.com/businesstechnology/moon_companies_000724.html -- Companies
Who Plan to Profit from the Moon--including
efforts by SpaceDev, Idealab, TransOrbital
and LunaCorp.
- 25 August 2000 GALILEO EVIDENCE POINTS
TO POSSIBLE WATER WORLD UNDER EUROPA'S
ICY CRUST (NASA Press Release ftp://ftp.hq.nasa.gov/pub/pao/pressrel/2000/00-131.txt
- 24 August 2000 The
slowing of Earth's period of rotation due
to tidal effects of the Moon (Dome-L posting)
- 01 June 2000 New
Images Reveal Io's Fiery Nature By
Josh Chamot -- WASHINGTON
Æ New images of Jupiter's moon Io, taken
by NASA's Galileo probes, reveal more than
100 volcanic peaks and basins -- some of
which are deeper than the Grand Canyon
-- with lava hotter than any found on Earth.
- 18 May 1999 Discovery
of Uranus' 18th moon -- news story
from U. of Arizona
- 16 March 1999 LUNAR DATA SUPPORT IDEA
THAT COLLISION SPLIT EARTH, MOON --NASA
Press Release -- Lunar Prospector
- 21 October 1998; Jet Propulsion Laboratory,
Pasadena, CA; NASA PRESS RELEASE: 98-192;
JUPITER'S MOON CALLISTO MAY HIDE SALTY OCEAN; ftp://ftp.hq.nasa.gov/pub/pao/pressrel/1998/98-192.txt --Jupiter's
second largest moon, Callisto, may have a
liquid ocean tucked under its icy, cratered
crust, according to scientists studying data
gathered by NASA's Galileo spacecraft.
TOP
- April, 2004. Johnson, Torrence V. A Look
at the Galilean Satellites After the Galileo
Mission. From volcanic
eruptions hotter than those typically found on
Earth to ocean sandwiches with water trapped
between ice layers, the Galileo mission revealed
fascinating phenomena on Jupiter's four largest
moons. Physics Today. Also available online
at http://www.physicstoday.org/vol-57/iss-4/p77.shtml but
for AGU members only.
- April, 2004. Canup, Robin M. Origin of Terrestrial
Planets and the Earth-Moon System. Increasingly
sophisticated simulations show how the four solid
planets could have emerged through collisions
and accretion. One late, giant collision with
Earth is the likely origin of the Moon. Physics
Today. Also available online at http://www.physicstoday.org/vol-57/iss-4/p56.shtml but
for AGU members only.
- May-June 2002. Jupiter's
Moons and the Longitude Problem, by Robert
Mentzer, Mercury Magazine, pp. 34-39.
- May, 2001, Sky & Telescope Magazine page
41, Galileo's Closest Look at Io, by
John Spencer.
- March-April, 2001, Mercury Magazine, On
the Hunt for Modern Moons Moons, by William
Schomaker.
- March-April, 2001, Mercury Magazine, The
Historic Hunt for Moons, by William Sheehan.
- 2000, February -- Raising Lunar Prospects by
Robert Irion, Astronomy Magazine, p. 44. During
its 19-month mission, Lunar Prospector exposed the
Moon's mysteries at a bargain-basement price.
- May 1999 Sky & Telescope magazine, page
26, Callisto's Rarefied Wisps, "...Calliso,
Jupiter's second-largest moon, has a thin atmosphere
of carbon dioxide... All four of Jupiter's largest
moons are now known to have atmospheres--Europa and
Ganymede each have thin envelopes of oxygen, while
Io is surrounded by sulfur dioxide.
- Sep 1998, Astronomy Magazine, Deconstructing
the Moon, Ray Jayawardhana, p.
40. On how the Moon formed.
TOP
Books
- Greenberg, Richard, Unmasking Europa: The
Search for Life on Jupiter's Ocean Moon. A Close
Look at Europa . . . And How Big Science Gets
Done . . .
University of Arizona, Lunar and Planetary Laboratory,
Tucson. In Unmasking Europa, Richard Greenberg tells
the story of how he and his team of researchers came
to believe that the surface of Europa is in fact
a crust so thin that it can barely hide an ocean
of liquid water below. He shows how the ocean is
warmed by the friction of tidal movements in this
small moon as it orbits around immense Jupiter. The
implications of this interpretation-which includes
the idea that there are active intermittent openings
from the liquid ocean to the frozen surface-are immense.
The warmth, the chemistry, and the connections from
ocean to surface provide the conditions necessary
for the existence of life, even at this relatively
remote locale in our solar system, far beyond what's
normally thought of as its 'habitable zone.' NY,
Springer, 2008.
- Kluger, Jeffery, Journey Beyond Selene,
Simon & Schuster Trade pub., 1999. Historical information
on the known moons of the solar system (up to 1999).
- Montgomery, Scott L., The Moon and Western
Imagination, University of Arizona Press,
1999. A collection of history, fable and reserach
about the Moon.
- Siy, Alexandria, Footprints on the Moon,
Charlebridge Publishing, 2001.
TOP
About Galileo...
TOP
On tides
and slowing of Earth's rotation...
Real image of the Earth-Moon system showing accurate size
and distance scalehttp://themis.asu.edu/latest/themis_em.html
Paper
Plate Moon Finder
For younger children construct
moon phases out of Oreo cookies. Given the current
phase of the moon, they could then tell me as what shape
it would appear in the near future. For pictures, check
out In upcoming weeks they will look for the moon and
draw its shape. --Chuck Bueter
TOP |
A series of images captured by Cassini
2008 August 30 and received on Earth 2008 August
31:
Cassini's Images
of Saturn
18 October 2006
F-Ring
dynamism
22 February 2006
Enceladus
15 December 2005
Prometheus,
Pandora, and F ring
16 November 2005
Pandora
color close-up
27 October 2005
Ripples
in F ring
5 October 2005
Prometheus
and gore in F ring
5 September 2005
Pandora
and F ring
23 February 2005
Mimas
+ Saturn
17 February 2005
Prometheus,
Epimetheus, Saturn's shadow
8 February 2005
Mimas
+ rings
16 December 2004
Mimas
TOP
|
