Saturn's Moon Enceladus Spreads Its Influence

Chalk up one more feat for Saturn’s intriguing moon Enceladus. The small, dynamic moon spews out dramatic plumes of water vapor and ice -- first seen by NASA’s Cassini spacecraft in 2005. It possesses simple organic particles and may house liquid water beneath its surface. Its geyser-like jets create a gigantic halo of ice, dust and gas around Enceladus that helps feed Saturn’s E ring. Now, thanks again to those icy jets, Enceladus is the only moon in our solar system known to influence substantially the chemical composition of its parent planet.

In June, the European Space Agency announced that its Herschel Space Observatory, which has important NASA contributions, had found a huge donut-shaped cloud, or torus, of water vapor created by Enceladus encircling Saturn. The torus is more than 373,000 miles (600,000 kilometers) across and about 37,000 miles (60,000 kilometers) thick. It appears to be the source of water in Saturn’s upper atmosphere.

Though it is enormous, the cloud had not been seen before because water vapor is transparent at most visible wavelengths of light. But Herschel could see the cloud with its infrared detectors. "Herschel is providing dramatic new information about everything from planets in our own solar system to galaxies billions of light-years away,” said Paul Goldsmith, the NASA Herschel project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

The discovery of the torus around Saturn did not come as a complete surprise. NASA’s Voyager and Hubble missions had given scientists hints of the existence of water-bearing clouds around Saturn. Then in 1997, the European Space Agency’s Infrared Space Observatory confirmed the presence of water in Saturn’s upper atmosphere. NASA’s Submillimeter Wave Astronomy Satellite also observed water emission from Saturn at far-infrared wavelengths in 1999.

While a small amount of gaseous water is locked in the warm, lower layers of Saturn’s atmosphere, it can’t rise to the colder, higher levels. To get to the upper atmosphere, water molecules must be entering Saturn’s atmosphere from somewhere in space. But from where and how? Those were mysteries until now.

Build the model and the data will come.

The answer came by combining Herschel’s observations of the giant cloud of water vapor created by Enceladus’ plumes with computer models that researchers had already been developing to describe the behavior of water molecules in clouds around Saturn.

One of these researchers is Tim Cassidy, a recent post-doctoral researcher at JPL who is now at the University of Colorado’s Laboratory for Atmospheric and Space Physics, Boulder. “What’s amazing is that the model,” said Cassidy, “which is one iteration in a long line of cloud models, was built without knowledge of the observation. Those of us in this small modeling community were using data from Cassini, Voyager and the Hubble telescope, along with established physics. We weren’t expecting such detailed ‘images’ of the torus, and the match between model and data was a wonderful surprise.”

The results show that, though most of the water in the torus is lost to space, some of the water molecules fall and freeze on Saturn’s rings, while a small amount -- about 3 to 5 percent -- gets through the rings to Saturn’s atmosphere. This is just enough to account for the water that has been observed there.

Source:

Cassini Presents Saturn Moon Quintet

With the artistry of a magazine cover shoot, NASA's Cassini spacecraft captured this portrait of five of Saturn's moons poised along the planet's rings.

From left to right are Janus, Pandora, Enceladus, Mimas and finally Rhea, bisected by the right side of the frame. The view was acquired at a distance of approximately 684,000 miles (1.1 million kilometers) from Rhea and 1.1 million miles (1.8 million kilometers) from Enceladus.

The image was taken in visible green light with the Cassini spacecraft narrow-angle camera on July 29, 2011. Image scale is about 4 miles (7 kilometers) per pixel on Rhea and 7 miles (11 kilometers) per pixel on Enceladus.

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.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Next Stop: Jupiter

We were reminded today, in dramatic fashion, that NASA is still open for business and leading the world in space exploration. At 12:25 p.m. EDT, we launched the Juno spacecraft from the Space Coast of Florida on its five-year journey to Jupiter, putting NASA on a mission to yet another new frontier. Our future in space exploration is bright and holds many such cutting-edge science missions that will help us better understand our solar system and an ever-increasing array of challenging destinations where humans might travel.

Juno will speed past our moon in less than a single day before it begins its trek of 1,740 million miles to reach the largest planet in our solar system. Those astounding distances and speeds are hard for us to fathom, but they are the kind of numbers our dedicated scientists and navigators work with every day to get the job done.

Juno will orbit Jupiter's poles 33 times. Its color camera will provide unprecedented close-up images of the planet, including the first detailed glimpse of the planet's poles. Juno's eight science instruments will peer through our mysterious neighbor's atmosphere and tell us more about what goes on in its atmosphere and magnetosphere. They'll also help us determine if there is a solid core to this gas giant.

Juno will power its systems using solar energy. This is the farthest out we've yet sent a spacecraft using this type of energy source. It's just one of many things we'll be looking at as we make the most of the spacecraft's journey to help refine technology for future exploration missions.

Source:

NASA Announces Design for New Deep Space Exploration System

NASA is ready to move forward with the development of the Space Launch System -- an advanced heavy-lift launch vehicle that will provide an entirely new national capability for human exploration beyond Earth's orbit. The Space Launch System will give the nation a safe, affordable and sustainable means of reaching beyond our current limits and opening up new discoveries from the unique vantage point of space.

The Space Launch System, or SLS, will be designed to carry the Orion Multi-Purpose Crew Vehicle, as well as important cargo, equipment and science experiments to Earth's orbit and destinations beyond. Additionally, the SLS will serve as a back up for commercial and international partner transportation services to the International Space Station.

"This launch system will create good-paying American jobs, ensure continued U.S. leadership in space, and inspire millions around the world," NASA Administrator Charles Bolden said. "President Obama challenged us to be bold and dream big, and that's exactly what we are doing at NASA. While I was proud to fly on the space shuttle, tomorrow's explorers will now dream of one day walking on Mars."

The SLS rocket will incorporate technological investments from the Space Shuttle Program and the Constellation Program in order to take advantage of proven hardware and cutting-edge tooling and manufacturing technology that will significantly reduce development and operations costs. It will use a liquid hydrogen and liquid oxygen propulsion system, which will include the RS-25D/E from the Space Shuttle Program for the core stage and the J-2X engine for the upper stage. SLS will also use solid rocket boosters for the initial development flights, while follow-on boosters will be competed based on performance requirements and affordability considerations. The SLS will have an initial lift capacity of 70 metric tons. That's more than 154,000 pounds, or 77 tons, roughly the weight of 40 sport utility vehicles. The lift capacity will be evolvable to 130 metric tons -- more than 286,000 pounds, or 143 tons -- enough to lift 75 SUVs. The first developmental flight, or mission, is targeted for the end of 2017.

This specific architecture was selected, largely because it utilizes an evolvable development approach, which allows NASA to address high-cost development activities early on in the program and take advantage of higher buying power before inflation erodes the available funding of a fixed budget. This architecture also enables NASA to leverage existing capabilities and lower development costs by using liquid hydrogen and liquid oxygen for both the core and upper stages. Additionally, this architecture provides a modular launch vehicle that can be configured for specific mission needs using a variation of common elements. NASA may not need to lift 130 metric tons for each mission and the flexibility of this modular architecture allows the agency to use different core stage, upper stage, and first-stage booster combinations to achieve the most efficient launch vehicle for the desired mission.

Source: Nasa

NASA's Dawn Collects a Bounty of Beauty from Vesta

A new video from NASA's Dawn spacecraft takes us on a flyover journey above the surface of the giant asteroid Vesta.

The data obtained by Dawn's framing camera, used to produce the visualizations, will help scientists determine the processes that formed Vesta's striking features. It will also help Dawn mission fans all over the world visualize this mysterious world, which is the second most massive object in the main asteroid belt.

The video, which shows Vesta as seen from Dawn's perspective, can be viewed at: http://www.jpl.nasa.gov/video/index.cfm?id=1020.

You'll notice in the video that Vesta is not entirely lit up. There is no light in the high northern latitudes because, like Earth, Vesta has seasons. Currently it is northern winter on Vesta, and the northern polar region is in perpetual darkness. When we view Vesta's rotation from above the south pole, half is in darkness simply because half of Vesta is in daylight and half is in the darkness of night .

Another distinct feature seen in the video is a massive circular structure in the south pole region. Scientists were particularly eager to see this area close-up, since NASA's Hubble Space Telescope first detected it years ago. The circular structure, or depression, is several hundreds of miles, or kilometers, wide, with cliffs that are also several miles high. One impressive mountain in the center of the depression rises approximately 9 miles (15 kilometers) above the base of this depression, making it one of the highest elevations on all known bodies with solid surfaces in the solar system.

The collection of images, obtained when Dawn was about 1,700 miles (2,700 kilometers) above Vesta's surface, was used to determine its rotational axis and a system of latitude and longitude coordinates. One of the first tasks tackled by the Dawn science team was to determine the precise orientation of Vesta's rotation axis relative to the celestial sphere.

The zero-longitude, or prime meridian, of Vesta was defined by the science team using a tiny crater about 1,640 feet (500 meters) in diameter, which they named "Claudia," after a Roman woman during the second century B.C. Dawn's craters will be named after the vestal virgins-the priestesses of the goddess Vesta, and famous Roman women, while other features will be named for festivals and towns of that era.

The Dawn mission to Vesta and Ceres is managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, for NASA's Science Mission Directorate, Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Ala. UCLA is responsible for overall Dawn mission science.

Other scientific partners include Planetary Science Institute, Tucson, Ariz.; Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany; DLR Institute for Planetary Research, Berlin, Germany; Italian National Institute for Astrophysics, Rome; and the Italian Space Agency, Rome. Orbital Sciences Corporation of Dulles, Va., designed and built the Dawn spacecraft.

NASA Mars Research Helps Find Buried Water on Earth

A NASA-led team has used radar sounding technology developed to explore the subsurface of Mars to create high-resolution maps of freshwater aquifers buried deep beneath an Earth desert, in the first use of airborne sounding radar for aquifer mapping.

The research may help scientists better locate and map Earth's desert aquifers, understand current and past hydrological conditions in Earth's deserts and assess how climate change is impacting them. Deserts cover roughly 20 percent of Earth's land surface, including highly populated regions in the Arabian Peninsula, North Africa, west and central Asia and the southwestern United States.

An international team led by research scientist Essam Heggy of NASA's Jet Propulsion Laboratory, Pasadena, Calif., recently traveled to northern Kuwait to map the depth and extent of aquifers in arid environments using an airborne sounding radar prototype. The 40-megahertz, low-frequency sounding radar was provided by the California Institute of Technology in Pasadena; and the Institut de Physique du Globe de Paris, France. Heggy's team was joined by personnel from the Kuwait Institute for Scientific Research (KISR), Kuwait City.

For two weeks, the team flew a helicopter equipped with the radar on 12 low-altitude passes (1,000 feet, or 305 meters) over two well-known freshwater aquifers, probing the desert subsurface down to the water table at depths ranging from 66 to 213 feet (20 to 65 meters). The researchers successfully demonstrated that the radar could locate subsurface aquifers, probe variations in the depth of the water table, and identify locations where water flowed into and out of the aquifers.

"This demonstration is a critical first step that will hopefully lead to large-scale mapping of aquifers, not only improving our ability to quantify groundwater processes, but also helping water managers drill more accurately," said Muhammad Al-Rashed, director of KISR's Division of Water Resources.

The radar is sensitive to changes in electrical characteristics of subsurface rock, sediments and water- saturated soils. Water-saturated zones are highly reflective and mirror the low-frequency radar signal. The returned radar echoes explored the thick mixture of gravel, sand and silt that covers most of Kuwait's northern desert and lies above its water table.

The team created high-resolution cross sections of the subsurface, showing variations in the fresh groundwater table in the two aquifers studied. The radar results were validated with ground measurements performed by KISR.

"This research will help scientists better understand Earth's fossil aquifer systems, the approximate number, occurrence and distribution of which remain largely unknown," said Heggy. "Much of the evidence for climate change in Earth's deserts lies beneath the surface and is reflected in its groundwater. By mapping desert aquifers with this technology, we can detect layers deposited by ancient geological processes and trace back paleoclimatic conditions that existed thousands of years ago, when many of today's deserts were wet."

Heggy said most recent observations, scientific interest and data analyses of global warming have concentrated on Earth's polar regions and forests, which provide direct measurable evidence of large-scale environmental changes. Arid and semi-arid environments, which represent a substantial portion of Earth's surface, have remained poorly studied. Yet water scarcity and salt content, changes in rainfall, flash floods, high rates of aquifer exploitation and growth of desert regions are all signs that suggest climate change and human activities are also affecting these arid and semi-arid zones.

The radar sounding prototype shares similar characteristics with two instruments flying on Mars-orbiting spacecraft: Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS), on the European Space Agency's Mars Express, and Shallow Radar (SHARAD), on NASA's Mars Reconnaissance Orbiter. MARSIS, jointly developed by JPL and the Italian Space Agency, probes the Martian subsurface sediments and polar ice caps to a maximum depth of about 1.9 miles (3 kilometers). SHARAD, also built by the Italian Space Agency, looks for liquid or frozen water in the first few hundred feet of Mars' crust and probes Mars' polar caps. Both instruments have found evidence of ice in the Martian subsurface, but have not yet detected liquid water. The Kuwait results may lead to revised interpretations of data from these two instruments.

The research follows earlier work by JPL scientists to probe the subsurface of the Sahara desert using higher-frequency Synthetic Aperture Radar instruments flown onboard three space shuttle missions in 1981, 1984 and 1994. That work located shallow drainage networks and large dry basins, suggesting the Sahara has had extensive surface water activity in its recent geological past.
Kuwait's well-mapped shallow aquifers and flat surface provided the team with an ideal test location. Extreme dryness, such as that present in this region of Kuwait, is necessary to allow the radar's waves to penetrate deep into the surface and reflect on water-saturated layers beneath. Kuwait's flat topography and low radio noise also reduced clutter and improved the radar signal's return.

"Results of this study pave the way for potential airborne mapping of aquifers in hyper-arid regions such as the Sahara and Arabian Peninsula, and can be applied to design concepts for a possible future satellite mission to map Earth's desert aquifers," said Craig Dobson, program officer for Geodetic Imaging and Airborne Instrument Technology Transition programs at NASA Headquarters, Washington. The work is a pathfinder for the Orbiting Arid Subsurface and Ice Sheet Sounder (OASIS), a NASA spacecraft mission concept designed to map shallow aquifers in Earth's most arid desert regions and measure ice sheet volume, thickness, basal topography and discharge rates.

The study was co-funded by the California Institute of Technology's Keck Institute for Space Studies and KISR. The Kuwaiti Police Air Force provided technical support for the flight tests.

NASA Gives Public New Internet Tool to Explore the Solar System

NASA is giving the public the power to journey through the solar system using a new interactive Web-based tool.

The "Eyes on the Solar System" interface combines video game technology and NASA data to create an environment for users to ride along with agency spacecraft and explore the cosmos. Screen graphics and information such as planet locations and spacecraft maneuvers use actual space mission data.

"This is the first time the public has been able to see the entire solar system and our missions moving together in real time," said Jim Green, director of NASA's Planetary Science Division at the agency's Headquarters in Washington. "It demonstrates NASA's continued commitment to share our science with everyone."

The virtual environment uses the Unity game engine to display models of planets, moons, asteroids, comets and spacecraft as they move through our solar system. With keyboard and mouse controls, users cruise through space to explore anything that catches their interest. A free browser plug-in, available at the site, is required to run the Web application.

"You are now free to move about the solar system," said Blaine Baggett, executive manager in the Office of Communication and Education at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. "See what NASA's spacecraft see -- and where they are right now -- all without leaving your computer."

Users may experience missions in real time, and "Eyes on the Solar System" also allows them to travel through time. The tool is populated with NASA data dating back to 1950 and projected to 2050.
The playback rate can be sped up or slowed down. When NASA's Juno spacecraft launched on Aug. 5, 2011, users could look ahead to see the mission's five-year journey to Jupiter in a matter of seconds.

Point of view can be switched from faraway to close-up to right "on board" spacecraft. Location, motion and appearance are based on predicted and reconstructed mission data. Dozens of controls on a series of pop-up menus allow users to fully customize what they see, and video and audio tutorials explain how to use the tool's many options. Users may choose from 2-D or 3-D modes, with the latter simply requiring a pair of red-cyan glasses to see.

"By basing our visualization primarily on mission data, this tool will help both NASA and the public better understand complex space science missions," said Kevin Hussey, manager of Visualization Technology Applications and Development at JPL, whose team developed "Eyes on the Solar System."

"Eyes on the Solar System" is in beta release. It has been demonstrated at science conferences, in classrooms and at the 2011 South by Southwest Interactive Conference in Austin, Texas.

Designers are updating "Eyes on the Solar System" to include NASA science missions launching during the coming months, including GRAIL to the moon and the Mars Science Laboratory Curiosity rover.

"Eyes on the Solar System" and an introduction video are available at http://solarsystem.nasa.gov/eyes .

Updates on new features are available through the tool's Twitter account: http://twitter.com/NASA_Eyes .

JPL is a division of the California Institute of Technology in Pasadena.