NASA’s Marshall Space Flight Center-Analysis F-1 Engines

NASA has demolish a 239-foot-tall composition that engineers once used to check rocket engines that send astronauts to the moon, toppling it with explosive on Friday despite reservations from state record officials who wanted it conserved.

Contractors operational for the National Aeronautics and Space Management took down the remaining real towers of Test Stand 4696 at Red stone Arsenal, quarters of NASA’s Marshall Space Flight Center. The exceed was built in the early 1960s to analysis F-1 engines, which helped power Saturn V rockets to the moon. Documents illustrate the tower hadn’t be used for an F-1 test since February 1969, 5 months before astronauts first landed on the astral surface. NASA said it desirable to demolish the concrete-and-steel tower to keep on maintenance costs and compose way for a new organization for testing rocket engines.

The Huge Full Moon Of Earth's Shadow

 

In this week, lucky spectators will see the huge full moon darken as a penumbra l lunar cover graces the sky. But don't wait for much madness along with this astronomical occasion. Despite famous myths, there's not much proof to back up the idea that the moon has much of a result on human or animal activities.

During the Nov. 28 planetary eclipse the full moon will overtake into the hazy external edge (penumbra) of Earth's shadow. This subtle shadow crossways the moon's outside will be visible in East Asia, Australia, Hawaii and Alaska, with probable views at moon set and moonrise for the western United States and division of Europe and Africa.

NASA Developed Orion spaceship- Test Flight 2014

Orion space capsule life form developed to fly astronauts to asteroids, the moon and finally to Mars arrived at the Kennedy Space Center in Florida for a 2014 test air travel. The spacecraft, built by Lockheed-Martin, is embattled for launch aboard an unmanned Delta 4 Heavy rocket as of Cape Canaveral Air Force Station, contiguous to the NASA spaceport.

A second test air travel in 2017 using NASA's planned huge-lift Space Launch System rocket is planned to put an unmanned Orion capsule around the light moon. The third test air travel, targeted for 2021, is probable to include astronauts.

 By 2025, NASA intends to send astronauts to explore a near Earth asteroid and then top on to Mars in the 2030s.Humans have not fly beyond a few hundred miles over Earth since 1972 when the Apollo missions to the moon finished. With the departure of the space shuttle last summer, NASA is dependent on Russia to fly crews to the space station, a $100 billion project of 15 countries that orbits about 240 miles over the planet.

The Earth And The Moon Shaped Analyzed By NASA

 

The interior of the moon is covered into a hard, outer crust, a rigid outer mantle, a semi-rigid inner mantle, and a core. The interior of the moon is cooler than the center of the Earth. While the moon is so tiny it loses its heat rapidly into space. Since the Earth and the moon shaped, the moon has cooled down much extra than the Earth.

The moon's surface is so dry, dusty and rocky place. The rocky crust is about 37 miles (60 km) broad on the side of the moon that faces Earth and about 62 miles (100 km) thick on the reverse side of the Moon. Radioactive dating of moon rocks from NASA's Apollo task dates the construction of the moon from about 4.3 billion years ago (about 60 million years after the construction of the Earth). Moon rocks that have been analyzed by NASA are parallel to Earth rocks, but are richer in the basics aluminum and titanium.

NASA Selects Investigations For Future Key Planetary Mission

NASA has selected three science investigations from which it will pick one potential 2016 mission to look at Mars' interior for the first time; study an extraterrestrial sea on one of Saturn's moons; or study in unprecedented detail the surface of a comet's nucleus. Each investigation team will receive $3 million to conduct its mission's concept phase or preliminary design studies and analyses. After another detailed review in 2012 of the concept studies, NASA will select one to continue development efforts leading up to launch. The selected mission will be cost-capped at $425 million, not including launch vehicle funding.

NASA's Discovery Program requested proposals for spaceflight investigations in June 2010. A panel of NASA and other scientists and engineers reviewed 28 submissions. The selected investigations could reveal much about the formation of our solar system and its dynamic processes. Three technology developments for possible future planetary missions also were selected. "NASA continues to do extraordinary science that is re-writing textbooks," said NASA Administrator Charles Bolden. "Missions like these hold great promise to vastly increase our knowledge, extend our reach into the solar system and inspire future generations of explorers."

The planetary missions selected to pursue preliminary design studies are:

-- Geophysical Monitoring Station (GEMS) would study the structure and composition of the interior of Mars and advance understanding of the formation and evolution of terrestrial planets. Bruce Banerdt of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., is principal investigator. JPL would manage the project.

--Titan Mare Explorer (TiME) would provide the first direct exploration of an ocean environment beyond Earth by landing in, and floating on, a large methane-ethane sea on Saturn's moon Titan. Ellen Stofan of Proxemy Research Inc. in Gaithersburg, Md., is principal investigator. Johns Hopkins University's Applied Physics Laboratory in Laurel, Md., would manage the project.

Cassini Probe Sees Electric Link With Saturn And One Of Its Moons

NASA is releasing the first images and sounds of an electrical connection between Saturn and one of its moons. The data collected by the agency's Cassini spacecraft enable scientists to improve their understanding of the complex web of interaction between the planet and its numerous moons. The results of the data analysis are published in the journals Nature and Geophysical Research Letters. Scientists previously theorized an electrical circuit should exist at Saturn. After analyzing data that Cassini collected in 2008, scientists saw a glowing patch of ultraviolet light emissions near Saturn's north pole that marked the presence of a circuit, even though the moon is 150,000 miles (240,000 kilometers) away from the planet.

The patch occurs at the end of a magnetic field line connecting Saturn and its moon Enceladus. The area, known as an auroral footprint, is the spot where energetic electrons dive into the planet's atmosphere, following magnetic field lines that arc between the planet's north and south polar regions. "The footprint discovery at Saturn is one of the most important fields and particle revelations from Cassini and ultimately may help us understand Saturn's strange magnetic field," said Marcia Burton, a Cassini fields and particles scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "It gives us the first visual connection between Saturn and one of its moons."

The auroral footprint measures approximately 750 miles by less than 250 miles, covering an area comparable to California or Sweden. At its brightest, the footprint shone with an ultraviolet light intensity far less than Saturn's polar auroral rings, but comparable to the faintest aurora visible at Earth without a telescope in the visible light spectrum. Scientists have not found a matching footprint at the southern end of the magnetic field line. "Cassini fields and particles instruments found particle beams aligned with Saturn's magnetic field near Enceladus, and scientists started asking if we could see an expected ultraviolet spot at the end of the magnetic field line on Saturn," said Wayne Pryor, a lead author of the Nature study released today, and Cassini co-investigator at Central Arizona College in Coolidge, Ariz. "We were delighted to find the glow close to the 'bulls-eye' at the center of our target."

NASA Honors Pioneer Astronaut Alan Shepard With Moon Rock

NASA will posthumously honor Alan B. Shepard Jr., the first American astronaut in space who later walked on the moon, with an Ambassador of Exploration Award for his contributions to the U.S. space program. Shepard's family members will accept the award on his behalf during a ceremony at 5:30 p.m. EDT on Thursday, April 28, at the U.S. Naval Academy Museum, located at 74 Greenbury Point Road in Annapolis, Md. His family will present the award to the museum for permanent display. NASA's Chief Historian Bill Barry will represent the agency at the event, which will include a video message from NASA Administrator Charles Bolden.

Shepard, a 1945 graduate of the Naval Academy, was one of NASA's original seven Mercury astronauts selected in April 1959. On May 5, 1961, he was launched from Cape Canaveral, Fla., aboard the Freedom 7 spacecraft on a suborbital flight that carried him to an altitude of 116 miles. Shepard made his second spaceflight as the commander of Apollo 14 from Jan. 31 to Feb. 9, 1971. He was accompanied on the third lunar landing by astronauts Stuart Roosa and Edgar Mitchell. Maneuvering the lunar module "Antares" to a landing in the hilly upland Fra Mauro region of the moon, Shepard and Mitchell deployed and activated a number of scientific instruments and collected almost 100 pounds of lunar samples for return to Earth.

Reporters interested in covering the award ceremony must contact the Naval Academy's public affairs office at 410-293-2292 or mediarelations@usna.edu by noon, Wednesday, April 27, for access information. NASA is giving the Ambassador of Exploration Award to the first generation of explorers in the Mercury, Gemini and Apollo space programs for realizing America's goal of going to the moon. The award is a moon rock encased in Lucite, mounted for public display. The rock is part of the 842 pounds of lunar samples collected during six Apollo missions from 1969 to 1972. The astronauts or family members receiving the award present it to a museum of their choice, where the moon rock is placed on public display. 

Cassini Finds Enceladus is a Powerhouse

Heat output from the south polar region of Saturn's moon Enceladus is much greater than was previously thought possible, according to a new analysis of data collected by NASA's Cassini spacecraft. The study was published in the Journal of Geophysical Research on March 4. Data from Cassini's composite infrared spectrometer of Enceladus' south polar terrain, which is marked by linear fissures, indicate that the internal heat-generated power is about 15.8 gigawatts, approximately 2.6 times the power output of all the hot springs in the Yellowstone region, or comparable to 20 coal-fueled power stations. This is more than an order of magnitude higher than scientists had predicted, according to Carly Howett, the lead author of study, who is a postdoctoral researcher at Southwest Research Institute in Boulder, Colo., and a composite infrared spectrometer science team member.

"The mechanism capable of producing the much higher observed internal power remains a mystery and challenges the currently proposed models of long-term heat production," said Howett. It has been known since 2005 that Enceladus' south polar terrain is geologically active and the activity is centered on four roughly parallel linear trenches, 130 kilometers (80 miles) long and about 2 kilometers (1 mile) wide, informally known as the "tiger stripes." Cassini also found that these fissures eject great plumes of ice particles and water vapor continually into space. These trenches have elevated temperatures due to heat leaking out of Enceladus' interior.

A 2007 study predicted the internal heat of Enceladus, if principally generated by tidal forces arising from the orbital resonance between Enceladus and another moon, Dione, could be no greater than 1.1 gigawatts averaged over the long term. Heating from natural radioactivity inside Enceladus would add another 0.3 gigawatts. The latest analysis, which also involved the composite infrared spectrometer team members John Spencer at Southwest Research Institute, and John Pearl and Marcia Segura at NASA's Goddard Space Flight Center in Greenbelt, Md., uses observations taken in 2008, which cover the entire south polar terrain. They constrained Enceladus' surface temperatures to determine the region's surprisingly high output.

Cassini to Sample Magnetic Environment around Titan

NASA's Cassini spacecraft is set to skim close to Saturn's moon Titan on Friday, Feb. 18, to learn about the interaction between Titan and Saturn's magnetosphere, the magnetic bubble around the planet. The closest approach will take place at 8:04 a.m. PST (4:04 p.m. UTC) and bring Cassini within about 3,650 kilometers (2,270 miles) of Titan's surface. As Titan makes a complete 360-degree orbit around Saturn, the relative influence of the sun's illumination and the hot ionized gas trapped in the magnetic bubble changes. These factors are important for understanding the relationship between Titan and Saturn's magnetosphere. It is important to make measurements at a variety of locations in the Saturn magnetosphere, so this flyby will occur in a part of the magnetosphere that has been poorly sampled so far.

Previous flybys have shown the magnetic environment near Titan to be rather variable and unpredictable. For 12 hours before and after closest approach, the Cassini plasma spectrometer instrument will be pointing in a direction to capture ionized gas in the region. At the same time, Cassini's radio science subsystem will be gathering sensitive gravity data from Titan to improve understanding of the structure of the interior. Collecting data like these will eventually enable scientists to determine whether Titan has an ocean under its crust. Other instruments will also be collecting data, much of it pertaining to seasonal change.

Titan is currently in northern spring, approaching northern summer, and scientists want to know what has changed with the north polar winter vortex weather pattern. The composite infrared spectrometer, for instance, will be mapping temperatures in Titan's stratosphere. The imaging science subsystem will also be monitoring the lakes, clouds and transport of aerosols in the Titan atmosphere. This latest flyby is dubbed "T74," though planning changes early in the orbital tour have made this the 75th targeted flyby of Titan. 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 was designed, developed and assembled at JPL. 

A Race Against Time to Find Apollo 14's Lost Voyagers

In communities all across the U.S., travelers that went to the moon and back with the Apollo 14 mission are living out their quiet lives. The whereabouts of more than 50 are known. Many, now aging, reside in prime retirement locales: Florida, Arizona and California. A few are in the Washington, D.C., area. Hundreds more are out there or at least, they were. And Dave Williams of NASA's Goddard Space Flight Center in Greenbelt, Md., wants to find them before it's too late. The voyagers in question are not astronauts. They're "moon trees" redwood, loblolly pine, sycamore, Douglas fir, and sweetgum trees sprouted from seeds that astronaut Stuart Roosa took to the moon and back 40 years ago.

"Hundreds of moon trees were distributed as seedlings," says Williams, "but we don't have systematic records showing where they all went." And though some of the trees are long-lived species expected to live hundreds or thousands of years, others have started to succumb to the pressures of old age, severe weather and disease. At least a dozen have died, including the loblolly pine at the White House and a New Orleans pine that was damaged by Hurricane Katrina and later removed. To capture the vanishing historical record, Williams, a curator at the National Space Science Data Center, has been tracking down the trees, dead or alive.

His sleuthing started in 1996, prompted by an email from a third-grade teacher, Joan Goble, asking about a tree at the Camp Koch Girl Scout Camp in Cannelton, Ind. A simple sign nearby read "moon tree." "At the time, I had never heard of moon trees," Williams says. "The sign had a few clues, so I sent a message to the NASA history office and found more bits and pieces on the web. Then I got in touch with Stan Krugman and got more of the story." Krugman had been the U.S. Department of Agriculture Forest Service's staff director for forest genetics research in 1971. He had given the seeds to Roosa, who stowed them in his personal gear for the Apollo 14 mission. The seeds were symbolic for Roosa because he had fought wildfires as a smoke jumper before becoming an Air Force test pilot and then an astronaut. 

Proposed Mission to Jupiter System Achieves Milestone

With input from scientists around the world, American and European scientists working on the potential next new mission to the Jupiter system have articulated their joint vision for the Europa Jupiter System Mission. The mission is a proposed partnership between NASA and the European Space Agency. The scientists on the joint NASA-ESA definition team agreed that the overarching science theme for the Europa Jupiter System Mission will be "the emergence of habitable worlds around gas giants." The proposed Europa Jupiter System Mission would provide orbiters around two of Jupiter's moons: a NASA orbiter around Europa called the Jupiter Europa Orbiter, and an ESA orbiter around Ganymede called the Jupiter Ganymede Orbiter.

"We've reached hands across the Atlantic to define a mission to Jupiter's water worlds," said Bob Pappalardo, the pre-project scientist for the proposed Jupiter Europa Orbiter, who is based at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "The Europa Jupiter System Mission will create a leap in scientific knowledge about the moons of Jupiter and their potential to harbor life." The new reports integrate goals that were being separately developed by NASA and ESA working groups into one unified strategy. The ESA report is being presented to the European public and science community this week, and the NASA report was published online in December.

The proposed mission singles out the icy moons Europa and Ganymede as special worlds that can lead to a broader understanding of the Jovian system and of the possibility of life in our solar system and beyond. They are natural laboratories for analyzing the nature, evolution and potential habitability of icy worlds, because they are believed to present two different kinds of sub-surface oceans. The Jupiter Europa Orbiter would characterize the relatively thin ice shell above Europa's ocean, the extent of that ocean, the materials composing its internal layers, and the way surface features such as ridges and "freckles" formed. It will also identify candidate sites for potential future landers. 

Contract Marks New Generation for Deep Space Network

NASA has taken the next step toward a new generation of Deep Space Network antennas. A $40.7 million contract with General Dynamics SATCOM Technologies, San Jose, Calif., covers implementation of two additional 34-meter (112-foot) antennas at Canberra, Australia. This is part of Phase I of a plan to eventually retire the network's aging 70-meter-wide antennas. The Deep Space Network (DSN) consists of three communications complexes: in Goldstone, Calif.; Madrid, Spain; and Canberra, Australia. The 70-meter antennas are more than 40 years old and are showing signs of surface deterioration from constant use. Additional 34-meter antennas are being installed in Canberra in the first phase; subsequent phases will install additional 34-meter antennas in Goldstone and Madrid.

The 34-meter beam waveguide antennas are essential to keep communications flowing smoothly as NASA's fleet of spacecraft continues to expand. In addition, the waveguide design of the antennas provides easier access for maintenance and future upgrades, because sensitive electronics are housed in a below-the-ground pedestal equipment room, instead of in the center of the dish. "As a result of several studies, it was determined that arrays of 34-meter beam waveguide antennas were the best solution to long-term continuation of DSN 70-meter capabilities," said Miguel Marina, who manages the 70-meter replacement task force at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "The new antennas are critical communication resources for all current and future NASA missions."

NASA expects to complete the building of the first two 34-meter antennas in Canberra by 2016. They will be named Deep Space Stations 35 and 36. Deep Space Station 35 is due to be online in 2014, and Deep Space Station 36 is expected to follow in 2016. In 1958, NASA established the Deep Space Network as a separately managed and operated communications facility to accommodate all deep space missions. This avoided the need for each flight project to acquire its own specialized space communications network. During the Apollo period (1967-1972), these stations supported America's missions to the moon, including the historic first manned landing. The Goldstone antenna, in particular, captured Neil Armstrong's words and sent them on to American television sets while the images came through another antenna. 

Cassini Spots Potential Ice Volcano On Saturn Moon

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. Topography and surface composition data have enabled scientists to make the best case yet in the outer solar system for an Earth-like volcano landform that erupts in ice. The results were presented today at the American Geophysical Union meeting in San Francisco. "When we look at our new 3-D map of Sotra Facula on Titan, we are struck by its resemblance to volcanoes like Mt. Etna in Italy, Laki in Iceland and even some small volcanic cones and flows near my hometown of Flagstaff," said Randolph Kirk, who led the 3-D mapping work, and is a Cassini radar team member and geophysicist at the U.S. Geological Survey (USGS) Astrogeology Science Center in Flagstaff, Ariz.

Scientists have been debating for years whether ice volcanoes, also called cryovolcanoes, exist on ice-rich moons, and if they do, what their characteristics are. The working definition assumes some kind of subterranean geological activity warms the cold environment enough to melt part of the satellite's interior and sends slushy ice or other materials through an opening in the surface. Volcanoes on Jupiter's moon Io and Earth spew silicate lava. Some cryovolcanoes bear little resemblance to terrestrial volcanoes, such as the tiger stripes at Saturn's moon Enceladus, where long fissures spray jets of water and icy particles that leave little trace on the surface.

At other sites, eruption of denser materials might build up volcanic peaks or finger-like flows. But when such flows were spotted on Titan in the past, theories explained them as non-volcanic processes, such as rivers depositing sediment. At Sotra, however, cryovolcanism is the best explanation for two peaks more than 3000 feet high with deep volcanic craters and finger-like flows. "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."

NASA Scientists Theorize Final Growth Spurt For Planets

A team of NASA-funded researchers has unveiled a new theory that contends planets gained the final portions of their mass from a limited number of large comet or asteroid impacts more than 4.5 billion years ago. These impacts added less than one percent of the planets' mass. Scientists hope the research not only will provide a better historical picture of the birth and evolution of Earth, the moon and Mars, but also allow researchers to better explore what happened in our solar system's beginning and middle stages of planet formation. “No one has a model of precisely what happened at the end of planet formation we’ve had a broad idea but variables such as impactor size, the approximate timing of the impacts, and how they affect the evolution of the planets are unknown,” said William Bottke, principal investigator from the Southwest Research Institute (SWRI) in Boulder, Colo.

“This research hopefully provides better insights into the early stages of planet formation.” The team used numerical models, lunar samples returned by Apollo astronauts and meteorites believed to be from Mars to develop its findings. The scientists examined the abundances of elements such as gold and platinum in the mantles, or layers beneath the crust, of Earth, the moon and Mars. Consistent with previous studies, they concluded the elements were added by a process called late accretion during a planet's final growth spurt. "These impactors probably represent the largest objects to hit Earth since the giant impact that formed our moon," Bottke said. “They also may be responsible for the accessible abundance of gold, platinum, palladium, and other important metals used by our society today in items ranging from jewelry to our cars’ catalytic convertors.”

The results indicate the largest Earth impactor was between 1,500 - 2,000 miles in diameter, roughly the size of Pluto. Because it is smaller than Earth, the moon avoided such enormous projectiles and was only hit by impactors 150 - 200 miles wide. These impacts may have played important roles in the evolution of both worlds. For example, the projectiles that struck Earth may have modified the orientation of its spin axis by 10 degrees, while those that hit the moon may have delivered water to its mantle. "Keep in mind that while the idea the Earth-moon system owes its existence to a single, random event was initially viewed as radical, it is now believed that large impacts were commonplace during the final stages of planet formation,’ Bottke said. “Our new results provide additional evidence that the effects of large impacts did not end with the moon-forming event."

Cassini Back to Normal, Ready for Enceladus

NASA's Cassini spacecraft resumed normal operations today, Nov. 24. All science instruments have been turned back on, the spacecraft is properly configured and Cassini is in good health. Mission managers expect to get a full stream of data during next week's flyby of the Saturnian moon Enceladus. Cassini went into safe mode on Nov. 2, when one bit flipped in the onboard command and data subsystem computer. The bit flip prevented the computer from registering an important instruction, and the spacecraft, as programmed, went into the standby mode.

Engineers have traced the steps taken by the computer during that time and have determined that all spacecraft responses were proper, but still do not know why the bit flipped. The flyby on Nov. 30 will bring Cassini to within about 48 kilometers (30 miles) of the surface of Enceladus. At 61 degrees north latitude, this encounter and its twin three weeks later at the same altitude and latitude, are the closest Cassini will come to the northern hemisphere surface of Enceladus during the extended Solstice mission. During the closest part of the Nov. 30 flyby, Cassini's radio science subsystem will make gravity measurements.

The results will be compared with those from an earlier flyby of the Enceladus south pole to understand the moon's interior structure better. Cassini's fields and particles instruments will sample the charged particle environment around Enceladus. Other instruments will capture images in visible light and other parts of the light spectrum after Cassini makes its closest approach. 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, D.C. 

LRO Supports Historic Lunar Impact Mission

The lunar rocks brought back to the Earth by the Apollo astronauts were found to have very little water, and to be much drier than rocks on Earth. An explanation for this was that the Moon formed billions of years ago in the solar system's turbulent youth, when a Mars-sized planet crashed into Earth. The impact stripped away our planet's outer layer, sending it into orbit. The pieces later coalesced under their own gravity to form our Moon. Heat from all this mayhem vaporized most of the water in the lunar material, so the water was lost to space.

However, there was still a chance that water might be found in special places on the Moon. 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 perhaps delivered there by comet impacts or chemical reactions with hydrogen carried by the solar wind. Last year on October 9, NASA's LCROSS intentionally crashed its companion Centaur upper stage into the Cabeus crater near the lunar south pole. The idea was to kick up debris from the bottom of the crater so its composition could be analyzed. The Centaur hit at over 5,600 miles per hour, sending up a plume of material over 12 miles high.

"Seeing mostly pure water ice grains in the plume means water ice was somehow delivered or chemical processes are causing ice to accumulate in large quantities," said Anthony Colaprete, LCROSS project scientist and principal investigator at NASA's Ames Research Center, Moffett Field, Calif. "Furthermore, the diversity and abundance of certain materials called volatiles in the plume, suggest a variety of sources, like comets and asteroids, and an active water cycle within the lunar shadows." LCROSS was a companion mission to NASA's Lunar Reconnaissance Orbiter (LRO) mission.

The (Long) Weekend Warrior: Nine Moons, 62 Hours

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 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.