latest count of numbers of moons, see...
- 2010 December 14. NASA RELEASE 10-335: Cassini Spots Potential Ice Volcano On Saturn Moon. Excerpt: NASA's Cassini spacecraft has found possible ice volcanoes on Saturn's moon Titan that are similar in shape to those on Earth that spew molten rock…
…"This is the very best evidence, by far, for volcanic topography anywhere documented on an icy satellite," said Jeffrey Kargel, a planetary scientist at the University of Arizona, Tucson. "It's possible the mountains are tectonic in origin, but the interpretation of cryovolcano is a much simpler, more consistent explanation."...
- 2010 December 10. Venus Has a Moon? By Mike Simonsen, Discovery News. Excerpt: ...2002 VE68 used to be a run of the mill, potential impact threat Near Earth Object (NEO). But approximately 7,000 years ago it had a close encounter with Earth that kicked it into a new orbit.
It now occupies a place in orbit around the sun where at its closest it wanders inside the orbit of Mercury and at its furthest it reaches just outside the orbit of the Earth. It is now in a 1:1 orbital resonance with Venus…
An orbital resonance is when two orbiting bodies exert a regular, periodic gravitational influence on each other due to their orbital periods being related by a ratio of two small numbers...
...In the case of Venus and 2002 VE68, they both take the same time to orbit the sun once. They are in a 1:1 orbital resonance. So by definition, 2002 VE68 is considered a quasi-satellite of Venus.
- 2010 October 7. Titan's Atmosphere Could Produce Building Blocks of Life. By Nancy Atkinson, Universe Today. Excerpt: Saturn’s moon Titan has long been thought to be an analog of early Earth, and a recent experiment demonstrates that amino acids and nucleotide bases — which are the basic building blocks of life on Earth – could very easily be under production in Titan’s hazy atmosphere...
...Two recent exciting discoveries led the team to try and find out more about Titan’s atmosphere: first, the discovery of high energy oxygen ions flowing into Titan’s atmosphere, and second, that there are high heavy molecular ions in the atmosphere – neither of which were expected.
Working with a team in France, Sarah Horst [a graduate student from the University of Arizona] and her professor Roger Yelle filled a reaction chamber with Titan-like atmosphere, (a cold plasma consisting of nitrogen, methane and carbon monoxide), and infused radio-frequency radiation as an energy source.
... The molecules discovered in the aerosols include the five nucleotide bases used by life on Earth (cytosine, adenine, thymine, guanine and uracil) and the two smallest amino acids, glycine and alanine.
- 2010 October 5. Saturn’s Rings Formed from Large Moon’s Destruction. By Nancy Atkinson, Universe Today. Excerpt: The formation of Saturn‘s rings has been one of the classical if not eternal questions in astronomy...Robin Canup from the Southwest Research Institute has uncovered evidence that the rings came from a large, Titan-sized moon that was destroyed as it spiraled into a young Saturn.
…Canup’s new alternative theory is that a Titan-sized moon with a rocky core and an icy mantle spiraled into Saturn early in solar system history. Tidal forces ripped off part of the icy mantle, distributing it into what would become the rings. But the rocky core was made of more durable material that held together until it hit Saturn’s surface. “The end result is a pure ice ring,” Canup said in an article in Nature.
Over time the ring spreads out and its mass decreases, and icy moons are created. Due to changes in the evolving Saturn system, these “spawned” moons then spiraled outward rather than inward. In this way, ice rings and ice-enhanced inner moons originate as a primordial byproduct of the same process that produces Saturn’s regular satellite system, making the whole process simpler than if there were several events.
Canup studies formation events with detailed computer simulations, including studying how our own Moon formed.
- 2010. October 5. Warm ‘Perrier’ Ocean Could be Powering Enceladus’ Geysers. By Nancy Atkinson, Universe Today. Excerpt: Bottled water companies take note: an exotic form of warm, bubbly mineral water could be what feeds the mysterious jets spraying from the south polar region of Saturn‘s moon Enceladus. A new model of the sub-surface ocean explains how the small moon could be so cryo-volcanically active. The Cassini spacecraft has detected sodium and potassium salts, as well as carbonates in the water vapor plumes spewing from the moon, which indicates a liquid, bubbly subsurface ocean.
…What we think is going on is that Enceladus has a subsurface ocean where water, heat and chemicals are stored before they erupt,” said Dennis Matson, a NASA planetary scientist from JPL. There is an ice crust, many tens of kilometers thick. The ocean is gas rich, — and previous researchers dubbed such an ocean as a ‘Perrier’ ocean -– which basically “pops the cap” of the ice crust.
…Finding the sodium in the icy grains in the plume is huge piece of evidence pointing to a subsurface ocean. Previously, Earth-based observations did not detect salts in the plume, and so scientists didn’t think a liquid ocean was possible. But infrared observations with an instrument on Cassini found the particles in the plumes include water ice, and substantial amounts of sodium and potassium salts and carbonates, as well as organics.
- 2010 October 6. Eris and Pluto: Two Peas in a Pod. By Nancy Atkinson, Universe Today. Excerpt: …Eris and Pluto have a lot in common. Eris appears to have a frozen surface, predominantly covered in nitrogen ice and methane, just like Pluto.
The scientists integrated two years of work conducted in Northern Arizona University’s new ice research laboratory, in addition to astronomical observations of Eris from the Multiple Mirror Telescope Observatory from Mount Hopkins, Ariz., and of Pluto from Steward Observatory from Kitt Peak, Ariz.
…NAU’s ice lab grew optically clear ice samples of methane, nitrogen, argon, methane-nitrogen mixtures, and methane-argon mixtures in a vacuum chamber at temperatures as low as minus 390 degrees Fahrenheit to simulate the planets’ cold surfaces. Light passed through the samples revealed the “chemical fingerprints” of molecules and atoms, which were compared to telescopic observations of sunlight reflected from the surfaces of Eris and Pluto.
“By combining the astronomical data and laboratory data, we found about 90 percent of Eris’s icy surface is made up of nitrogen ice and about 10 percent is made up of methane ice, which is not all that different from Pluto,” said David Cornelison, coauthor and physicist at Missouri State University.
- 2010 October 4. Titan-ic Tsunami Causing Crack in Titan's C Ring. Universe Today. Excerpt: Saturn’s rings have several gaps, most of which are caused by small moons shepherding ring debris into breaks in the rocky rings. But one gap may be caused by gravitational perturbations from Saturn’s largest moon, Titan, sending tsunami-like waves up to 3 kilometers (2 miles) high in the C ring. This causes one region of the ring to spin like a warped, uneven vinyl record on a turntable.
…The gap in the middle of the C ring has been known since Voyager 1 flew by Saturn in the 1980, and it appeared there was a 15 km-wide gap. But when Cassini arrived in 2004 and began observations, the gap was only 2 km (1.5 miles) and sometimes it wasn’t there at all.
…Nicholson and Cassini Deputy Project Scientist Linda Spilker said the same types of processes seen in Saturn’s rings could also explain what is seen in disks of debris around other stars, with the theory that there are gaps forming in the disks associated with the formation of planets. “Saturn provides a wonderful natural laboratory of how protoplanetary nebula may evolve,” said Spilker.
- 2010 September 15. NASA RELEASE 10-223: NASA's Lunar Spacecraft Completes Exploration Mission Phase. Excerpt: WASHINGTON -- NASA's Lunar Reconnaissance Orbiter, or LRO, will complete the exploration phase of its mission on Sept. 16, after a number of successes that transformed our understanding of Earth's nearest neighbor.
LRO completed a one-year exploration mission in a polar orbit approximately 31 miles above the moon's surface. It produced a comprehensive map of the lunar surface in unprecedented detail; searched for resources and safe landing sites for potential future missions to the moon; and measured lunar temperatures and radiation levels.
The LRO team will continue to send data gathered during the last year to the Planetary Data System, which archives and distributes scientific information from NASA planetary missions, astronomical observations and laboratory measurements.
By the time LRO achieves full mission success in March, and its data is processed and released to the scientific community, it will have sent more information to the Planetary Data System than all other previous planetary missions combined. During its new phase of discovery, LRO will continue to map the moon for two to four more years.
...Results from the mission include: new observations of the Apollo landing sites; indications that permanently shadowed and nearby regions may harbor water and hydrogen; observations that large areas in the permanently shadowed regions are colder than Pluto; detailed information about lunar terrain; and the first evidence of a globally distributed population of thrust faults that indicates the moon has recently contracted and may still be shrinking.
- 2010 June 14. RELEASE: 10-144. Research Suggests Water Content of Moon Interior Underestimated. Excerpt: WASHINGTON -- NASA-funded scientists estimate from recent research that the volume of water molecules locked inside minerals in the moon's interior could exceed the amount of water in the Great Lakes here on Earth.
…"For over 40 years we thought the moon was dry," said Francis McCubbin of Carnegie and lead author of the report published in Monday's Online Early Edition of the Proceedings of the National Academy of Sciences. "In our study we looked at hydroxyl, a compound with an oxygen atom bound with hydrogen, and apatite, a water-bearing mineral in the assemblage of minerals we examined in two Apollo samples and a lunar meteorite."
…Previous studies found evidence of water both on the lunar surface and inside the moon by using respectively, remote sensing data from the Indian spacecraft Chandrayaan-1 and other lunar sample analysis. Carnegie researchers looked within crystalline rocks called KREEP (K for potassium; REE, for rare Earth elements; and P for phosphorus). These rocks are a component of some lunar impact melt and basaltic rocks.
…"It is gratifying to see this proof of the hydroxyl contents in lunar apatite," said lunar scientist Bradley Jolliff of Washington University in St. Louis. "The concentrations are very low and, accordingly, they have been until recently nearly impossible to detect. We can now finally begin to consider the implications - and the origin - of water in the interior of the moon."
- 2010 March 1. RELEASE : 10-055. NASA Radar Finds Ice Deposits at Moon's North Pole; Additional Evidence of Water Activity on Moon. Excerpt: WASHINGTON -- Using data from a NASA radar that flew aboard India's Chandrayaan-1 spacecraft, scientists have detected ice deposits near the moon's north pole. NASA's Mini-SAR instrument, a lightweight, synthetic aperture radar, found more than 40 small craters with water ice. The craters range in size from 1 to 9 miles (2 to15 km) in diameter. Although the total amount of ice depends on its thickness in each crater, it's estimated there could be at least 1.3 trillion pounds (600 million metric tons) of water ice.
"The emerging picture from the multiple measurements and resulting data of the instruments on lunar missions indicates that water creation, migration, deposition and retention are occurring on the moon," said Paul Spudis, principal investigator of the Mini-SAR experiment at the Lunar and Planetary Institute in Houston....
During the past year, the Mini-SAR mapped the moon's permanently-shadowed polar craters that aren't visible from Earth. The radar uses the polarization properties of reflected radio waves to characterize surface properties. Results from the mapping showed deposits having radar characteristics similar to ice.
"After analyzing the data, our science team determined a strong indication of water ice, a finding which will give future missions a new target to further explore and exploit," said Jason Crusan, program executive for the Mini-RF Program for NASA's Space Operations Mission Directorate in Washington....
- 2009 Nov 25. New
Findings On Alan Hills Meteorite Point to Microbial
Life. by Nancy Atkinson, Universe
Today. Scientists caused quite a
stir in 1996 when they announced a meteorite had
been found in Antarctica that might contain evidence
for microscopic fossils of Martian bacteria. While
subsequent studies of the now famous Alan Hills Meteorite
shot down theories that the Mars rock held fossilized
alien life, both sides debated the issue and the
meteorite is still being studied. Now, Craig Covault
in Spaceflightnow.com reports that a new look at
ALH84001 provides "evidence
that supports the existence of life on the surface
of Mars, or in subsurface water pools, early in the
planet's history." Covault says we can expect
a public announcement by NASA Headquarters within
a few days.
...The new findings were reported in the November
issue of the respected journal Geochimica et Cosmochimica
Acta, the journal of the Geochemical and Meteoritic
Society. The authors include Kathie Thomas-Keprta,
Simon Clement, David McKay (who led the original
team), Everett Gibson and Susan Wentworth, all of
the Johnson Space Center.
Covault said the new work centers on what is called
magnetic bacteria that on Earth, and Mars as well,
leave distinctively-shaped remnants in the rock.
These features test with a high chemical purity more
like a biological feature than geological.
- 2009 Nov 13. NASA
RELEASE: 09-265. NASA'S LCROSS IMPACTS CONFIRM
WATER IN LUNAR CRATER. Excerpt:
MOFFETT FIELD, Calif. -- Preliminary data from NASA's
Lunar Crater Observation and Sensing Satellite, or
LCROSS, indicates the mission successfully uncovered
water in a permanently shadowed lunar crater. The
LCROSS spacecraft and a companion rocket stage made
twin impacts in the Cabeus crater Oct. 9 that created
a plume of material from the bottom of a crater that
has not seen sunlight in billions of years. ...Since
the impacts, the LCROSS science team has been analyzing
the huge amount of data the spacecraft collected.
The team concentrated on data from the satellite's
spectrometers, which provide the most definitive
information about the presence of water. ..."We
are ecstatic," said Anthony Colaprete, LCROSS
project scientist and principal investigator at NASA's
Ames Research Center in Moffett Field, Calif. "Multiple
lines of evidence show water was present in both
the high angle vapor plume and the ejecta curtain
created by the LCROSS Centaur impact. The concentration
and distribution of water and other substances requires
further analysis, but it is safe to say Cabeus holds
water." The team took the known near-infrared
spectral signatures of water and other materials
and compared them to the impact spectra the LCROSS
near infrared spectrometer collected. "We were
able to match the spectra from LCROSS data only when
we inserted the spectra for water," Colaprete
said. "No other reasonable combination of other
compounds that we tried matched the observations.
The possibility of contamination from the Centaur
also was ruled out."
...For information about LCROSS, visit: http://www.nasa.gov/lcross
- 2009 Sep 24. NASA
RELEASE : 09-222. NASA Instruments Reveal Water
Molecules on Lunar Surface. Excerpt: WASHINGTON -- NASA scientists have
discovered water molecules in the polar regions of
the moon. Instruments aboard three separate spacecraft
revealed water molecules in amounts that are greater
than predicted, but still relatively small. Hydroxyl,
a molecule consisting of one oxygen atom and one
hydrogen atom, also was found in the lunar soil....
...The confirmation of elevated water molecules and
hydroxyl at these concentrations in the moon's polar
regions raises new questions about its origin and effect
on the mineralogy of the moon. Answers to these questions
will be studied and debated for years to come.
"Water ice on the moon has been something of a
holy grail for lunar scientists for a very long time," said
Jim Green, director of the Planetary Science Division
at NASA Headquarters in Washington. "This surprising
finding has come about through the ingenuity, perseverance
and international cooperation between NASA and the
India Space Research Organization."...
- 2009 Sep 21. NASA
RELEASE: 09-217. CASSINI REVEALS NEW RING QUIRKS,
SHADOWS DURING SATURN EQUINOX. Excerpt:
NASA scientists are marveling over the extent of
ruffles and dust clouds revealed in the rings of
Saturn during the planet's equinox last month. Scientists
once thought the rings were almost completely flat,
but new images reveal the heights of some newly discovered
bumps in the rings are as high as the Rocky Mountains.
NASA released the images Monday. ...On Aug. 11, sunlight
hit Saturn's rings exactly edge-on, performing a
celestial magic trick that made them all but disappear.
The spectacle occurs twice during each orbit Saturn
makes around the sun, which takes approximately 10,759
Earth days, or about 29.7 Earth years. Earth experiences
a similar equinox phenomenon twice a year; the autumnal
equinox will occur Sept. 22, when the sun will shine
directly over Earth's equator. ...The chunks of ice
that make up the main rings spread out 85,000 miles
from the center of Saturn, but they had been thought
to be only around 30 feet thick in the main rings,
known as A, B, C, and D.
...particles seemed to pile up in vertical formations
in each of the rings. Rippling corrugations -- previously
seen by Cassini to extend approximately 500 miles
in the innermost D ring -- appear to undulate out
to a total of 11,000 miles through the neighboring
C ring to the B ring.
The heights of some of the newly discovered bumps
are comparable to the elevations of the Rocky Mountains.
One ridge of icy ring particles, whipped up by the
gravitational pull of Saturn's moon Daphnis as it
travels through the plane of the rings, looms as
high as 2.5 miles. It is the tallest vertical wall
seen within the rings.
"We thought the plane of the rings was no taller
than two stories of a modern-day building and instead
we've come across walls more than two miles high," said
Carolyn Porco, Cassini imaging team leader at the
Space Science Institute in Boulder, Colo....
- 2009 Sep 17. NASA
Lunar Satellite Begins Detailed Mapping of Moon's
South Pole. NASA RELEASE: 09-215.
Excerpt: NASA reported Thursday that
its Lunar Reconnaissance Orbiter, or LRO, has successfully
completed its testing and calibration phase and entered
its mapping orbit of the moon. The spacecraft already
has made significant progress toward creating the
most detailed atlas of the moon's south pole to date.
Scientists released preliminary images and data from
LRO's seven instruments. "The
LRO mission already has begun to give us new data
that will lead to a vastly improved atlas of the
lunar south pole and advance our capability for human
exploration and scientific benefit," said Richard
Vondrak, LRO project scientist at NASA's Goddard
Space Flight Center in Greenbelt, Md. ...The south
pole of the moon is of great interest to explorers
because potential resources such as water ice or
hydrogen may exist there. Permanently shadowed polar
craters that are bitterly cold at their bottoms may
hold deposits of water ice or hydrogen from comet
impacts or the solar wind. The deposits may have
accumulated in these "cold-trap" regions
over billions of years. ...For more information about
LRO and to view the new images, visit: http://www.nasa.gov/lro
- 2009 July. Newly restored video from the Apollo 11
restoration effort: http://www.nasa.gov/multimedia/hd/apollo11.html
NASA's Apollo 40th anniversary Web sites: http://www.nasa.gov/apollo40th.
Easy access to various agency resources and multimedia
about the program and the history of human spaceflight,
including a gallery of Apollo multimedia features.
- 2009 July 16-24. Audio retrospective beginning at
6:32 a.m. CDT Thursday, 2009 July 16, two hours before
the spacecraft launched. The audio continues through
splashdown of the mission at 11:51 a.m. CDT Friday,
July 24, and recovery of the crew shortly afterward.
The Web stream features the communications between
the astronauts and ground teams,and commentary from
Mission Control at NASA's Johnson Space Center in Houston.
To listen to the replay, visit: http://www.nasa.gov/externalflash/apollo11_radio
For historical information about Apollo 11, visit:
- 2009 April. Journey
to Jupiter. National Geographic
video -- naked science series. Ganymede has a molten
- 2009 Apr 27. Prometheus
Creating Saturn Ring Streamers (APOD).
- 2009 April 21. Electrically
Charged Particles Found in Enceladus' Plumes. Written by Nancy Atkinson, Universe
Today. Excerpt: A team of planetary scientists working
on the Cassini-Huygens mission has discovered tiny,
icy particles in the plume from Saturn's moon Enceladus
that offer a tantalizing glimpse of the interior of
this enigmatic world. The spectrometer on Cassini,
the Cassini Plasma Spectrometer (CAPS) discovered a
surprise: the ice particles are electrically charged.
Cassini has been exploring Saturn and its moons since
2004. Enceladus is 500 kilometers (300 miles) wide
and Cassini's suite of instruments has found the moon
to be active, with jets near its southern pole that
spew gas and water thousands of kilometers out into
space. During two particularly close flybys of the
moon in 2008, skimming only 52 and 25 km from the surface
at around 15 km per second (54,000 km per hour), the
CAPS instrument on the spacecraft was pointed to scoop
up gas as it zoomed through the plume.
- 2009 Apr 15. Jagged
Shadows May Indicate Saturn Ring Particles (APOD).
Also see http://planetary.org/blog/article/00001909/
- 2009 March 24. Cassini
Provides Virtual Flyover of Saturn's Moon Titan. News Release from Cassini Equinox
mission. Excerpt: ...new flyover maps show, for the
first time, the 3-D topography and height of the 1,200-meter
(4,000-foot) mountain tops, the north polar lake country,
the vast dunes more than 100 meters (300 feet) high
that crisscross the moon, and the thick flows that
may have oozed from possible ice volcanoes.
The topographic maps were made from stereo pairs of
radar images. They are available at saturn.jpl.nasa.gov and http://www.nasa.gov/cassini .
- 2008 December 15. Saturn's
Dynamic Moon Enceladus Shows More Signs of Activity. NASA
RELEASE : 08-325.
Excerpt: PASADENA, Calif. - The closer
scientists look at Saturn's small moon Enceladus,
the more they find evidence of an active world. The
most recent flybys of Enceladus made by NASA's Cassini
spacecraft have provided new signs of ongoing changes
on and around the moon. The latest high-resolution
images of Enceladus show signs that the south polar
surface changes over time.
Close views of the southern polar region, where jets
of water vapor and icy particles spew from vents within
the moon's distinctive "tiger stripe" fractures,
provide surprising evidence of Earth-like tectonics.
They yield new insight into what may be happening within
the fractures. The latest data on the plume -- the
huge cloud of vapor and particles fed by the jets that
extend into space -- show it varies over time and has
a far-reaching effect on Saturn's magnetosphere.
"Of all the geologic provinces in the Saturn system
that Cassini has explored, none has been more thrilling
or carries greater implications than the region at
the southernmost portion of Enceladus," said Carolyn
Porco, Cassini imaging team leader at the Space Science
Institute in Boulder, Colo.
...Images from recent close Enceladus flybys also have
bolstered an idea the Cassini imaging team has that
condensation from the jets erupting from the surface
may create ice plugs that close off old vents and force
new vents to open. The opening and clogging of vents
also corresponds with measurements indicating the plume
varies from month to month and year to year.
...Enceladus' output of ice and vapor dramatically
impacts the entire Saturnian system by supplying the
ring system with fresh material and loading ionized
gas from water vapor into Saturn's magnetosphere.
...With water vapor, organic compounds and excess heat
emerging from Enceladus' south polar terrain, scientists
are intrigued by the possibility of a liquid-water-rich
habitable zone beneath the moon's south pole....
- 2008 September 22. 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
...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
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
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
- 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."
- 2008 March 20. 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
- 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."
- 2007 June. Cryovolcanoes, Swiss Cheese, and the Walnut Moon. Science Fact article by Richard Lovett in Analog magazine. [Not online] Excerpt: ...One of the most useful things Cassini has done is to allow us to get a fairly precise spectrum of the particle size in each segment of the rings. That's done by observing what happens when the rings lie between the probe's radio antenna and a source of light or radio waves. [backscattering] ...ranging in size fro marbles to chunks the size of small houses. There is also a lot of dust.
...being watched is Pan [20 km dia], ...inhabits the 300-kilometer-wide Encke Gap in the outer portion of the A ring. ..."Pan is master of this gap," says Carolyn Porco, head of the Cassini imaging team at the Space Science Institute in Boulder, Colorado. "It is the creator of clumps and the destroyer of clumps."
...pairs of bright streaks shaped like two-bladed propellers...are wannabe gaps. If the moonlets creating them [only about 100 meters dia] were larger, the blades would get longer and longer until eventually they would circle all the way around the ring.
...Enceladus's south pole...shows a pattern of distinctive bands that reminded early observers of tiger stripes. The surrounding area is particularly young...it's snowing...Enceladus's snow appears to be creating one of Saturn's rings. ...distinct jets...appeared to emanate from the tiger stripes. ...Enceladus is blasting out 360 kilograms of water vapor per second.... Enceladus lies in the heart of the mysterious E ring, which is so faint it wasn't discovered until 1979. The E ring is losing water at the rate of about a kilogram per second due to chemical reactions with sunlight and collisions between particles. Enceladus appears to be pumping out more than enough water to keep the ring supplied, indefinitely. ...[liquid] water pools that feed the geysers probably lie only a few dozen meters below the surface. ...One you have liquid water, you have the potential for living organisms....
...methane...at Titan temperatures, ...plays a similar role to water in the Earth's atmosphere: forming clouds...and precipitating as rain or snow. Methane rain and melting methane snow should scour the landscape like flowing water, before evaporating back into the atmosphere. ...paucity of craters means that Titan's surface...is geologically young. ...Lots and lots of lakes, up to 70 kilometers in diameter. The discovery made Titan the only body in the Solar System other than Earth appearing to have bodies of liquid at it's surface.
...The Cassini mission carried a second probe, called Huygens, which...parachuted to the surface [of Titan] on January 14, 2005. ...With an atmosphere four times as thick as Earth's...It took the probe two-and-a-half-hours to descend.... The landing site was close enough to one of the river deltas ... covered in rounded "rocks" of ice...one to six inches in diameter. This means that by the time they reached the landing site, the floods had slowed enough to leave bigger rocks behind, but were moving fast enough to scour smaller ones away: exactly what geologists see with earthly flash floods...."The most striking find," says [Larry] Soderblom, "is that a place I expected to be alien and un-earthlike turned out to resemble a modern textbook in geomorphology....
- 2007 April 3. 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....
- 2007 January 3. 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."
- 2007 January 3. 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....
- 2006 Nov 9. 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
- 2006 November 8. 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!
- 2006 October 17. 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
- 2006 August 8. 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
"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
- 2006 June 9. Earth
Science Picture of the Day (EPOD) shows evidence
that the Moon's distance from Earth varies.
- 2006 April 10. 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
- 2005 November 1. 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
- 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
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
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
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,
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@--
- 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
- 18 December 2002. Full
Moon Effect on Behavior Minimal, Studies Say
John Roach for National
- 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
- 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
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
- 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
- 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
- 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
- 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
- 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
- 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:
- 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
- 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.
- 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
- March-April, 2001, Mercury Magazine, On
the Hunt for Modern Moons Moons, by William
- 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.
- 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,
- 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.
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
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
GIF Animation of phases of the Moon:
A series of images captured by Cassini
2008 August 30 and received on Earth 2008 August
18 October 2006
22 February 2006
15 December 2005
Pandora, and F ring
16 November 2005
27 October 2005
in F ring
5 October 2005
and gore in F ring
5 September 2005
and F ring
23 February 2005
17 February 2005
Epimetheus, Saturn's shadow
8 February 2005
16 December 2004