NASA’s Cassini spacecraft successfully completed its Oct. 1 flyby of Saturn’s moon Enceladus and its jets of water vapor and ice. At its closest approach, the spacecraft flew approximately 62 miles (100 kilometers) above the moon’s surface. The close approach was designed to give some of Cassini’s instruments, including the ion and neutral mass spectrometer, the chance to “taste” the jets themselves.

At a higher vantage point during the encounter, Cassini’s high-resolution camera captured pictures of the jets emanating from the moon’s south polar region. The latest raw images of Enceladus are online at: http://saturn.jpl.nasa.gov/photos/raw/ .

The images of the surface include previously seen leading-hemisphere terrain. However, during this encounter, multi-spectral imaging of these terrains extended farther into the ultraviolet region of the electromagnetic spectrum than had previously been achieved at this resolution. By looking at the surface at ultraviolet wavelengths, scientists can better detect the difference between surface materials and shadows than they can at visible wavelengths, where icy materials are highly reflective and shadows are washed out. With both ultraviolet and visible images of the same terrain available to them, scientists will better understand how the surface coverage of icy particles coming from the vents and plumes changes with terrain type and age.

Cassini’s next pass of this fascinating moon will be Oct. 19, when the spacecraft flies by at an altitude of approximately 765 miles (1231 kilometers).

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.
The Ion and Neutral Mass Spectrometer science team is based at the Southwest Research Institute, San Antonio, Texas.

More…

Because the moon is tidally locked (meaning the same side always faces Earth), it was not until 1959 that the farside was first imaged by the Soviet Luna 3 spacecraft (hence the Russian names for prominent farside features, such as Mare Moscoviense). And what a surprise -­ unlike the widespread maria on the nearside, basaltic volcanism was restricted to a relatively few, smaller regions on the farside, and the battered highlands crust dominated. A different world from what we saw from Earth.

Of course, the cause of the farside/nearside asymmetry is an interesting scientific question. Past studies have shown that the crust on the farside is thicker, likely making it more difficult for magmas to erupt on the surface, limiting the amount of farside mare basalts. Why is the farside crust thicker? That is still up for debate, and in fact several presentations at this week’s Lunar and Planetary Science Conference attempt to answer this question.

The Clementine mission obtained beautiful mosaics with the sun high in the sky (low phase angles), but did not have the opportunity to observe the farside at sun angles favorable for seeing surface topography. This WAC mosaic provides the most complete look at the morphology of the farside to date, and will provide a valuable resource for the scientific community. And it’s simply a spectacular sight!

The Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC) is a push-frame camera that captures seven color bands (321, 360, 415, 566, 604, 643, and 689 nm) with a 57-km swath (105-km swath in monochrome mode) from a 50 km orbit. One of the primary objectives of LROC is to provide a global 100 m/pixel monochrome (643 nm) base map with incidence angles between 55°-70° at the equator, lighting that is favorable for morphological interpretations. Each month, the WAC provides nearly complete coverage of the Moon under unique lighting. As an added bonus, the orbit-to-orbit image overlap provides stereo coverage. Reducing all these stereo images into a global topographic map is a big job, and is being led by LROC Team Members from the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR). Several preliminary WAC topographic products have appeared in LROC featured images over the past year (Orientale basin, Sinus Iridum). For a sneak preview of the WAC global DEM with the WAC global mosaic, view a rotating composite moon (70 MB video from ASU’s LROC website). The WAC topographic dataset will be completed and released later this year.

The global mosaic released today is comprised of over 15,000 WAC images acquired between November 2009 and February 2011. The non-polar images were map projected onto the GLD100 shape model (WAC derived 100 m/pixel DTM), while polar images were map projected on the LOLA shape model. In addition, the LOLA derived crossover corrected ephemeris, and an improved camera pointing, provide accurate positioning (better than 100 m) of each WAC image.

As part of the March 2011 PDS release, the LROC team posted the global map in ten regional tiles. Eight of the tiles are equirectangular projections that encompass 60° latitude by 90° longitude. In addition, two polar stereographic projections are available for each pole from ±60° to the pole. These reduced data records (RDR) products will be available for download on March 15, 2011. As the mission progresses, and our knowledge of the lunar photometric function increases, improved and new mosaics will be released! Work your way around the moon with these six orthographic projections constructed from WAC mosaics. The nearside view linked below is different from that released on 21 February.

More..

The work on the International Space Station will be the focus of the U.S. human space program for the next decade and it will be the first step in preparation for future manned flights to Mars, the head of NASA said.

“ISS is an anchor for the future of human space exploration and major component of our current human space program,” NASA Administrator Charles Bolden said at the International Space Station and Mars Conference at George Washington University on Wednesday.

“Over at least next ten years, we will continue collaboration with other nations in order to live and work together in space and perform researches and technology demonstrations,” Bolden said.

The NASA chief stressed the importance of the ISS as the most realistic model to test life support and other technologies that would ensure successful human exploration of the deep space.

“A journey to Mars will require robot systems, ensuring the crew stays healthy and safe. The station [ISS] is the start of this journey,” he said.

Bolden confirmed that a U.S. delegation will travel to Russia on April 12-15 to discuss the extension of ISS service life and future joint projects in space exploration, including the development of a nuclear-powered spaceship.

In a major space policy speech at Kennedy Space Center on April 15, 2010, U.S. President Barack Obama predicted a manned Mars mission to orbit the planet by the mid-2030s, followed by a landing.

The U.S. Congress has approved manned missions to the Moon, followed by asteroid exploration in 2025 and a trip to Mars in the 2030s.

Bring a filter if you plan on drinking water from the moon. Water ice recently discovered in dust at the bottom of a crater near the moon’s south pole is accompanied by metallic elements like mercury, magnesium, calcium, and even a bit of silver. Now you can add sodium to the mix, according to Dr. Rosemary Killen of NASA’s Goddard Space Flight Center in Greenbelt, Md.

Recent discoveries of significant deposits of water on the moon were surprising because our moon has had a tough life. Intense asteroid bombardments in its youth, coupled with its weak gravity and the Sun’s powerful radiation, have left the moon with almost no atmosphere. This rendered the lunar surface barren and dry, compared to Earth.

However, due to the moon’s orientation to the Sun, scientists theorized that deep craters at the lunar poles would be in permanent shadow and thus extremely cold, and able to trap volatile material like water as ice if such material were somehow transported there, perhaps by comet impacts or chemical reactions with hydrogen, a major component of the solar wind.

The October 9, 2009 impact of NASA’s Lunar CRater Observation and Sensing Satellite (LCROSS) spacecraft into the permanently shadowed region of the Cabeus crater confirmed that a surprisingly large amount of water ice exists in this region, along with small amounts of many other elements, including metallic ones.

LCROSS was launched June 18, 2009 as a companion mission to NASA’s Lunar Reconnaissance Orbiter, or LRO, from NASA’s Kennedy Space Center in Florida. After separating from LRO, the LCROSS spacecraft held onto the spent Centaur upper stage rocket of the launch vehicle, executed a lunar swingby, and entered into a series of long looping orbits around Earth.

After traveling approximately 113 days and nearly 5.6 million miles (9 million km), the Centaur and LCROSS separated on final approach to the moon. Moving faster than most rifle bullets, the Centaur impacted the lunar surface with LCROSS and LRO watching using their onboard instruments. Approximately four minutes of data were collected by LCROSS before the spacecraft itself impacted the lunar surface.

Killen and her team observed the LCROSS impacts with the National Solar Observatory’s McMath-Pierce solar telescope at the Kitt Peak National Observatory, Tucson, Ariz. They were the only team able to see the results of the impacts from the ground.

The impacts vaporized volatile material from the bottom of Cabeus crater, including water and sodium. After the vapor plume rose about 800 meters (around 2,600 feet) – high enough to clear the shadow from the crater rim — sunlight stimulated the sodium atoms, causing them to emit their signature yellow-orange glow. A high-resolution Echelle spectrometer attached to the telescope detected this unique glow. The instrument separates light into its component colors to identify materials by the characteristic colors they emit when energized by radiation or other events in space.

The spectrometer views the sky through a narrow slit to separate the colors, so the team had to make assumptions about the shape and temperature of the plume to estimate the total amount of sodium liberated by the impacts. Using a computer model of the impact and other data on the impacts from instruments on LCROSS and LRO to guide their assumptions, the team calculated that about one to two kilograms (about 2.2 to 4.4 pounds) of sodium were released. “This is one to two percent of the amount of water released by the impacts,” said Killen. “Our oceans have a comparable sodium to water ratio – about one percent.” (The amount of sodium derived from the observations depends on the assumed temperature of the vapor.)

This much sodium raises the question: where did it all come from? Sodium atoms from comet impacts could bounce across the lunar surface until they landed in the permanently shadowed regions, where they would get “cold trapped” — frozen in place. The solar wind carries small amounts of sodium, which could become embedded in the lunar surface, and it might also liberate sodium from lunar rocks, which are about 0.4 percent sodium. Sodium is also liberated from lunar rocks by meteoroid impacts. (The LCROSS impacts didn’t have enough energy to vaporize rock, so it’s unlikely the sodium vapor plume simply came from rocks at the impact site, according to Killen.)

“Two percent sodium to water is consistent with the amount of sodium in comets, so perhaps the bulk of the sodium and water came from comet impacts,” said Killen. She makes it clear that this is just speculation at this point, and that it’s possible they came from a different source or even a variety of sources, including cold-trapped lunar volatiles and solar-wind-induced chemistry. Better evidence for a cometary origin would come from an analysis of the hydrogen isotopes in lunar water, according to Killen.

Isotopes are versions of an element with different weights, or masses. For example, a deuterium atom is a heavier version of a common hydrogen atom because it has an extra particle – a neutron – in its nucleus at the center. Deuterium can be substituted for the regular form of hydrogen in a water molecule, but it is much less common than hydrogen, and its concentration varies in objects across the solar system. If the deuterium to hydrogen ratio in lunar water is similar to the ratio in comets, it would suggest the water came from comet impacts. Since comets as “dirty snowballs” carry many other materials, it would imply that much of the sodium and other volatiles came from comets as well.

The team plans to shed light on the origin of lunar water and other volatiles using data from the upcoming Lunar Atmosphere and Dust Environment Explorer (LADEE) mission, scheduled to be launched in May, 2013. The mission will orbit the moon and observe its tenuous atmosphere (technically called an exosphere, because it is so thin, atoms rarely collide with each other above the surface).

The research was funded by NASA’s Dynamic Response of the Environment At the Moon (DREAM) project. “This discovery highlights a particular value of the DREAM program – we can rapidly support missions like the LCROSS impact with additional observations and analysis,” said Dr. William Farrell of NASA Goddard, lead of the DREAM institute.

The McMath-Pierce telescope is operated by the National Solar Observatory, which is funded by the National Science Foundation and managed by the Association of Universities for Research in Astronomy. Killen’s paper on this research was published in Geophysical Research Letters in December 2010.

More…

State-of-the-art seismological techniques applied to Apollo-era data suggest our moon has a core similar to Earth’s.

Uncovering details about the lunar core is critical for developing accurate models of the moon’s formation. The data sheds light on the evolution of a lunar dynamo — a natural process by which our moon may have generated and maintained its own strong magnetic field.

The team’s findings suggest the moon possesses a solid, iron-rich inner core with a radius of nearly 150 miles and a fluid, primarily liquid-iron outer core with a radius of roughly 205 miles. Where it differs from Earth is a partially molten boundary layer around the core estimated to have a radius of nearly 300 miles. The research indicates the core contains a small percentage of light elements such as sulfur, echoing new seismology research on Earth that suggests the presence of light elements — such as sulfur and oxygen — in a layer around our own core.

The researchers used extensive data gathered during the Apollo-era moon missions. The Apollo Passive Seismic Experiment consisted of four seismometers deployed between 1969 and 1972, which recorded continuous lunar seismic activity until late-1977.

“We applied tried and true methodologies from terrestrial seismology to this legacy data set to present the first-ever direct detection of the moon’s core,” said Renee Weber, lead researcher and space scientist at NASA’s Marshall Space Flight Center in Huntsville, Ala.

In addition to Weber, the team consisted of scientists from Marshall; Arizona State University; the University of California at Santa Cruz; and the Institut de Physique du Globe de Paris in France. Their findings are published in the online edition of the journal Science.

The team also analyzed Apollo lunar seismograms using array processing, techniques that identify and distinguish signal sources of moonquakes and other seismic activity. The researchers identified how and where seismic waves passed through or were reflected by elements of the moon’s interior, signifying the composition and state of layer interfaces at varying depths.

Although sophisticated satellite imaging missions to the moon made significant contributions to the study of its history and topography, the deep interior of Earth’s sole natural satellite remained a subject of speculation and conjecture since the Apollo era. Researchers previously had inferred the existence of a core, based on indirect estimates of the moon’s interior properties, but many disagreed about its radius, state and composition.

A primary limitation to past lunar seismic studies was the wash of “noise” caused by overlapping signals bouncing repeatedly off structures in the moon’s fractionated crust. To mitigate this challenge, Weber and the team employed an approach called seismogram stacking, or the digital partitioning of signals. Stacking improved the signal-to-noise ratio and enabled the researchers to more clearly track the path and behavior of each unique signal as it passed through the lunar interior.

“We hope to continue working with the Apollo seismic data to further refine our estimates of core properties and characterize lunar signals as clearly as possible to aid in the interpretation of data returned from future missions,” Weber said.

More…

Christmas Eve, 1968. As one of the most turbulent, tragic years in American history drew to a close, millions around the world were watching and listening as the Apollo 8 astronauts — Frank Borman, Jim Lovell and Bill Anders — became the first humans to orbit another world.

As their command module floated above the lunar surface, the astronauts beamed back images of the moon and Earth and took turns reading from the book of Genesis, closing with a wish for everyone “on the good Earth.”

“We were told that on Christmas Eve we would have the largest audience that had ever listened to a human voice,” recalled Borman during 40th anniversary celebrations in 2008. “And the only instructions that we got from NASA was to do something appropriate.”

“The first ten verses of Genesis is the foundation of many of the world’s religions, not just the Christian religion,” added Lovell. “There are more people in other religions than the Christian religion around the world, and so this would be appropriate to that and so that’s how it came to pass.”

The mission was also famous for the iconic “Earthrise” image, snapped by Anders, which would give humankind a new perspective on their home planet. Anders has said that despite all the training and preparation for an exploration of the moon, the astronauts ended up discovering Earth.

The Apollo 8 astronauts got where they were that Christmas Eve because of a bold, improvisational call by NASA. With the clock ticking on President Kennedy’s challenge to land on the moon by decade’s end, delays with the lunar module were threatening to slow the Apollo program. So NASA decided to change mission plans and send the Apollo 8 crew all the way to the moon without a lunar module on the first manned flight of the massive Saturn V rocket.

The crew rocketed into orbit on December 21, and after circling the moon 10 times on Christmas Eve, it was time to come home. On Christmas morning, mission control waited anxiously for word that Apollo 8′s engine burn to leave lunar orbit had worked. They soon got confirmation when Lovell radioed, “Roger, please be informed there is a Santa Claus.”

The crew splashed down in the Pacific on December 27. A lunar landing was still months away, but for the first time ever, men from Earth had visited the moon and returned home safely.

More…

NASA’s Mars Exploration Rover Opportunity has visited and photographed two craters informally named for the spacecraft that carried men to the moon 41 years ago this week.

Opportunity drove past “Yankee Clipper” crater on Nov. 4 and reached “Intrepid crater” on Nov. 9. For NASA’s Apollo 12, the second mission to put humans onto the moon, the command and service module was called Yankee Clipper, piloted by Dick Gordon, and the lunar module was named Intrepid, piloted by Alan Bean and commanded by the late Pete Conrad. The Intrepid landed on the moon with Bean and Conrad on Nov. 19, 1969, while Yankee Clipper orbited overhead. Their landing came a mere four months after Apollo 11′s first lunar landing.

This week, Bean wrote to the Mars Exploration Rover team: “I just talked with Dick Gordon about the wonderful honor you have bestowed upon our Apollo 12 spacecraft. Forty-one years ago today, we were approaching the moon in Yankee Clipper with Intrepid in tow. We were excited to have the opportunity to perform some important exploration of a place in the universe other than planet Earth where humans had not gone before. We were anxious to give it our best effort. You and your team have that same opportunity. Give it your best effort.”

Rover science team member James Rice, of NASA’s Goddard Space Flight Center, Greenbelt, Md., suggested using the Apollo 12 names. He was applying the rover team’s convention of using names of historic ships of exploration for the informal names of craters that Opportunity sees in the Meridian Planum region of Mars.

“The Apollo missions were so inspiring when I was young, I remember all the dates. When we were approaching these craters, I realized we were getting close to the Nov. 19 anniversary for Apollo 12,” Rice said. He sent Bean and Gordon photographs that Opportunity took of the two craters.

The images are available online at http://photojournal.jpl.nasa.gov/catalog/PIA13593 and http://photojournal.jpl.nasa.gov/catalog/PIA13596. Intrepid crater is about 20 meters (66 feet) in diameter. Yankee Clipper crater is about half that width.

After a two-day stop to photograph the rocks exposed at Intrepid, Opportunity continued on a long-term trek toward Endeavour crater, a highly eroded crater about 1,000 times wider than Intrepid. Endeavour’s name comes from the ship of James Cook’s first Pacific voyage.

During a drive of 116.9 meters (383.5 feet) on Nov. 14, Opportunity’s “odometer” passed 25 kilometers (15.53 miles). That is more than 40 times the driving-distance goal set for Opportunity to accomplish during its original three-month prime mission in 2004.

Mars Exploration Project Manager John Callas, of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., said, “Importantly, it’s not how far the rovers have gone but how much exploration and science discovery they have accomplished on behalf of all humankind.”

At the beginning of Opportunity’s mission, the rover landed inside “Eagle crater,” about the same size as Intrepid crater. The team’s name for that landing-site crater paid tribute to the lunar module of Apollo 11, the first human landing on the moon. Opportunity spent two months inside Eagle crater, where it found multiple lines of evidence for a wet environment in the area’s ancient past.

The rover team is checking regularly for Opportunity’s twin, Spirit, in case the increasing daily solar energy available at Spirit’s location enables the rover to reawaken and resume communication. No signal from Spirit has been received since March 22. Spring began last week in the southern hemisphere of Mars.

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rovers for the NASA Science Mission Directorate, Washington.

More…

Wispy clouds are illuminated by a bright quarter moon behind the tail of NASA’s Stratospheric Observatory for Infrared Astronomy, or SOFIA, flying observatory during telescope characterization testing in 2008. SOFIA will complement the Hubble, Spitzer, Herschel and James Webb space telescopes and major Earth-based telescopes. The mission, a joint program by NASA and DLR Deutsches Zentrum fur Luft- und Raumfahrt (German Aerospace Center), features a German-built 100-inch (2.5 meter) diameter far-infrared telescope weighing 20 tons mounted in the rear fuselage of a highly modified Boeing 747SP aircraft.

More…

Taking a long-weekend road trip, NASA’s Cassini spacecraft successfully glided near nine Saturnian moons, sending back a stream of raw images as mementos of its adrenaline-fueled expedition. The spacecraft sent back particularly intriguing images of the moons Dione and Rhea.

The Dione and Rhea pictures are the highest-resolution views yet of parts of their surfaces. The views of the southern part of Dione’s leading hemisphere (the part of the moon that faces forward in its orbit around Saturn) and the equatorial region of Rhea’s leading hemisphere are more detailed than the last time we saw these terrains with NASA’s Voyager spacecraft in the early 1980s.

Of the five big icy moons of Saturn, Dione and Rhea are often considered a pair because they orbit close to each other, are darker than the others, and exhibit similar patterns of light reflecting off them. These new images, however, highlight the differences between these sister moons.

Both images show similar geographic regions on each satellite. However, scientists can identify differences in geological histories of the two bodies from differences in the numbers and sizes of visible craters on their surfaces. The number and size of craters on a body’s surface help indicate the age of that surface – the more craters there are and the larger they are, the older the surface is.

Rhea, for example, shows ancient, intense bombardments throughout this region. However, the same region of Dione is divided into distinct areas that exhibit variations in the number and size of preserved craters. In particular, while parts of Dione are heavily cratered like Rhea, there are other areas covered by relatively smooth plains. Those areas have many small craters, but few large impact scars, which indicates that they are geologically younger than the heavily cratered areas. The smooth plains must have been resurfaced at some point in Dione’s past — an event that seems to be missing from Rhea’s geological history on this side of the moon.

Images of the moon Mimas, captured just before it went into shadow behind Saturn, will be compared to thermal maps made earlier this year that showed an unexpected “Pac-Man” heat pattern.

Cassini also caught a picture of the tiny, 4-kilometer-wide (3-mile-wide) moon Pallene, in front of the planet Saturn, which is more than 120,000 kilometers (75,000 miles) wide at its equator.

Cassini’s elliptical orbital pattern around Saturn means it can target moons for flybys about once or twice a month. The flybys on this particular Cassini road trip were “non-targeted” flybys, meaning navigators did not refine Cassini’s path to fly over particular points on each moon.

Cassini’s long weekend started on Thursday, Oct. 14, at 5:07 p.m. UTC (9:07 a.m. PDT), when it passed by Saturn’s largest moon Titan at an altitude of 172,368 kilometers (107,104 miles) above the surface. Then came a whirlwind 21 hours in which Cassini flew by Polydeuces at 116,526 kilometers (72,406 miles), Mimas at 69,950 kilometers (43,465 miles), Pallene at 36,118 kilometers (22,443 miles), Telesto at 48,455 kilometers (30,109 miles), Methone at 105,868 kilometers (65,783 miles), Aegaeon at 96,754 kilometers (60,120 miles) and Dione at 31,710 kilometers (19,704 miles). Cassini’s last visit — Rhea at 38,752 kilometers (24,079 miles) – took place at 6:47 a.m. UTC on Oct. 17 (10:47 p.m. PDT on Oct. 16).

Scientists decided in advance which observations they wanted to make while the spacecraft was cruising past all the moons. They chose to obtain images of Titan, Mimas, Pallene, Dione and Rhea. They also obtained thermal scans of Mimas, Dione and Rhea.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory manages the project for NASA’s Science Mission Directorate in Washington. The Cassini orbiter was designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

More…

NASA’s Cassini spacecraft discovered a giant plume of water gushing from cracks in the surface near the south pole of Saturn’s moon Enceladus in 2005, indicating that there was a reservoir of water beneath the ice. Cassini data also suggest that the south polar has been continuously releasing about 13 billion watts of energy. But how does Enceladus stay warm enough to maintain liquid water underground?

In smaller moons like Enceladus, the cache of radioactive elements usually is not massive enough to produce significant heat for long. So, scientists have considered the role of tidal heating – the gravitational pull from Saturn as Enceladus orbits the planet – as a way to keep Enceladus warm enough for liquid water to remain under its surface.

Scientists with the Cassini team have compared a map of the gravitational tidal stress on the icy crust of Enceladus to a map of the warm zones created using Cassini’s composite infrared spectrometer instrument. Areas with the most stress should overlap the warmest zones on the CIRS map, but they don’t exactly match.

Terry Hurford, of NASA’s Goddard Space Flight Center, Greenbelt, Md., and his team believe the discrepancy can be resolved if Enceladus’ rotation rate is not uniform – if it wobbles slightly as it rotates.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency, and the Italian Space Agency. NASA’s Jet Propulsion Laboratory, Pasadena, Calif., a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The composite infrared spectrometer team is based at NASA Goddard, where the instrument was built.

More…