Closest Northern Views of Saturn's Moon Enceladus

NASA's Cassini spacecraft has begun returning its best-ever views of the northern extremes of Saturn's icy, ocean-bearing moon Enceladus. The spacecraft obtained the images during its Oct. 14 flyby, passing 1,142 miles (1,839 kilometers) above the moon's surface. Mission controllers say the spacecraft will continue transmitting images and other data from the encounter for the next several days.

Scientists expected the north polar region of Enceladus to be heavily cratered, based on low-resolution images from the Voyager mission, but the new high-resolution Cassini images show a landscape of stark contrasts. "The northern regions are crisscrossed by a spidery network of gossamer-thin cracks that slice through the craters," said Paul Helfenstein, a member of the Cassini imaging team at Cornell University, Ithaca, New York. "These thin cracks are ubiquitous on Enceladus, and now we see that they extend across the northern terrains as well."

In addition to the processed images, unprocessed, or "raw," images are posted on the Cassini mission website at:

http://saturn.jpl.nasa.gov/mission/flybys/enceladus20151014

Cassini's next encounter with Enceladus is planned for Oct. 28, when the spacecraft will come within 30 miles (49 kilometers) of the moon's south polar region. During the encounter, Cassini will make its deepest-ever dive through the moon's plume of icy spray, sampling the chemistry of the extraterrestrial ocean beneath the ice. Mission scientists are hopeful data from that flyby will provide evidence of how much hydrothermal activity is occurring in the moon's ocean, along with more detailed insights about the ocean's chemistry -- both of which relate to the potential habitability of Enceladus.

Cassini's final close Enceladus flyby will take place on Dec. 19, when the spacecraft will measure the amount of heat coming from the moon's interior. The flyby will be at an altitude of 3,106 miles (4,999 kilometers).

Saturnian Snowman

NASA's Cassini spacecraft spied this tight trio of craters as it approached Saturn's icy moon Enceladus for a close flyby on Oct. 14, 2015.

Credits: NASA/JPL-Caltech/Space Science Institute

Full image and caption

An online toolkit for all three final Enceladus flybys is available at:

http://solarsystem.nasa.gov/finalflybys

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory in Pasadena, California, manages the mission for the agency's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena. The Cassini imaging operations center is based at the Space Science Institute in Boulder, Colorado.

For more information about Cassini, visit:

http://www.nasa.gov/cassini

http://saturn.jpl.nasa.gov

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Orbital Launch Rescheduled for Jan. 8 - Nasa Space news

The International Space Station Program and Orbital Sciences Corporation have decided to postpone the launch of the Antares rocket and its Cygnus cargo craft on the first Orbital commercial resupply mission to the space station to no earlier than Wednesday, Jan. 8 due to the forecast of cold temperatures for Tuesday, Jan. 7 at the launch site at NASA’s Wallops Flight Facility in Virginia.

The forecast for Wednesday also calls for cold temperatures, but the station program and Orbital plan to revisit the weather forecast at the beginning of the week. The main concern with the weather is the cold temperatures coupled with likely precipitation. Orbital says the Antares rocket has a lower limit temperature constraint of 20 degrees Fahrenheit.

Orbital still plans to roll out its Antares rocket to Launch Pad 0A at Wallops on Saturday night because the weather is forecast to be favorable at that time. The launch time for Wednesday, Jan. 8 is 1:32 p.m. Eastern time. NASA TV coverage of launch will begin at 1 p.m.

A launch on Wednesday will result in a grapple of Cygnus by the Expedition 38 crew aboard the station on Sunday, Jan. 12 at 6:02 a.m. NASA TV coverage will begin at 5 a.m. Coverage of the installation of Cygnus on the Earth-facing port of the Harmony module will begin at 7 a.m.

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Atmosphere of Venus

The VeSpR (Venus Spectral Rocket) Experiment launched successfully from White Sand Missile Range.  VeSpR will study the present day escape of water from the atmosphere of Venus and relate it to the past abundance of water on Venus by measuring hydrogen (H) and the heavier, slower to escape, deuterated hydrogen (D) above 90 km on Venus. The use of a pre-dispersing prism to prevent long wavelengths from entering the spectrograph permits a long-aperture approach to echelle spectroscopy, and the chosen combination of imaging and dispersion scales provides high spectral resolution of emission line profiles with a several arc sec wide aperture for good sensitivity. For comparable spectral resolution the HST/STIS uses a 0.2 arc sec aperture, which provides 375 times less solid angle on the sky than a 3 x 5 arc sec region observed by the sounding rocket telescope.  Good data was obtained by both detectors with no obvious significant anomalies.  Preliminary reports indicate a successful mission.

The Mars Atmosphere and Volatile Evolution, or MAVEN, mission launched from Cape Canaveral Air Force Station in Florida on Nov. 18. Now, the Venus Spectral Rocket, VeSpR for short, is scheduled to lift off from White Sands, N.M., on Nov. 25.

"It is appropriate that these launch dates are close together, because both missions will study atmospheric loss," said Kelly Fast, the program scientist for MAVEN and the program officer for Planetary Astronomy at NASA Headquarters in Washington. "VeSpR will peek at Venus from above Earth's absorbing atmosphere, and MAVEN will journey to Mars to do a long-term study."

VeSpR is a two-stage system, combining a Terrier missile – originally built as a surface-to-air missile and later repurposed to support science missions – and a Black Brant model Mk1 sounding rocket with a telescope inside. Integration took place at NASA’s Wallops Flight Facility in Virginia.

The experiments will look at ultraviolet (UV) light that is being emitted from Venus' atmosphere, which can provide information about the history of the planet's water. Measurements like these cannot be done using Earth-based telescopes because our atmosphere absorbs most UV light before it reaches the ground.

For  more
http://www.nasa.gov/content/goddard/sounding-rocket-to-peek-at-atmosphere-of-venus/

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NASA Satellite Data Helps Pinpoint Glaciers'

A new study of glaciers worldwide using observations from two NASA satellites has helped resolve differences in estimates of how fast glaciers are disappearing and contributing to sea level rise.

The new research found glaciers outside of the Greenland and Antarctic ice sheets, repositories of 1 percent of all land ice, lost an average of 571 trillion pounds (259 trillion kilograms) of mass every year during the six-year study period, making the oceans rise 0.03 inches (0.7 mm) per year. This is equal to about 30 percent of the total observed global sea level rise during the same period and matches the combined contribution to sea level from the Greenland and Antarctica ice sheets.

The study compares traditional ground measurements to satellite data from NASA's Ice, Cloud, and Land Elevation Satellite (ICESat) and Gravity Recovery and Climate Experiment (GRACE) missions to estimate ice loss for glaciers in all regions of the planet. The study period spans 2003 to 2009, the years when the two missions overlapped.

"For the first time, we have been able to very precisely constrain how much these glaciers as a whole are contributing to sea level rise," said Alex Gardner, Earth scientist at Clark University in Worcester, Mass., and lead author of the study. "These smaller ice bodies are currently losing about as much mass as the ice sheets."

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NASA's Hubble Space Telescope Finds Dead Stars 'Polluted with Planet Debris

NASA's Hubble Space Telescope has found the building blocks for Earth-sized planets in an unlikely place-- the atmospheres of a pair of burned-out stars called white dwarfs.

These dead stars are located 150 light-years from Earth in a relatively young star cluster, Hyades, in the constellation Taurus. The star cluster is only 625 million years old. The white dwarfs are being polluted by asteroid-like debris falling onto them.

Hubble's Cosmic Origins Spectrograph observed silicon and only low levels of carbon in the white dwarfs' atmospheres. Silicon is a major ingredient of the rocky material that constitutes Earth and other solid planets in our solar system. Carbon, which helps determine properties and origin of planetary debris, generally is depleted or absent in rocky, Earth-like material.

"We have identified chemical evidence for the building blocks of rocky planets," said Jay Farihi of the University of Cambridge in England. He is lead author of a new study appearing in the Monthly Notices of the Royal Astronomical Society. "When these stars were born, they built planets, and there's a good chance they currently retain some of them. The material we are seeing is evidence of this. The debris is at least as rocky as the most primitive terrestrial bodies in our solar system."

This discovery suggests rocky planet assembly is common around stars, and it offers insight into what will happen in our own solar system when our sun burns out 5 billion years from now.

Farihi's research suggests asteroids less than 100 miles (160 kilometers) wide probably were torn apart by the white dwarfs' strong gravitational forces. Asteroids are thought to consist of the same materials that form terrestrial planets, and seeing evidence of asteroids points to the possibility of Earth-sized planets in the same system.

The pulverized material may have been pulled into a ring around the stars and eventually funneled onto the dead stars. The silicon may have come from asteroids that were shredded by the white dwarfs' gravity when they veered too close to the dead stars.

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IBEX: Glimpses of the Interstellar Material Beyond our Solar System

A great magnetic bubble surrounds the solar system as it cruises through the galaxy. The sun pumps the inside of the bubble full of solar particles that stream out to the edge until they collide with the material that fills the rest of the galaxy, at a complex boundary called the heliosheath. On the other side of the boundary, electrically charged particles from the galactic wind blow by, but rebound off the heliosheath, never to enter the solar system. Neutral particles, on the other hand, are a different story. They saunter across the boundary as if it weren't there, continuing on another 7.5 billion miles for 30 years until they get caught by the sun's gravity, and sling shot around the star.



There, NASA's Interstellar Boundary Explorer lies in wait for them. Known as IBEX for short, this spacecraft methodically measures these samples of the mysterious neighborhood beyond our home. IBEX scans the entire sky once a year, and every February, its instruments point in the correct direction to intercept incoming neutral atoms. IBEX counted those atoms in 2009 and 2010 and has now captured the best and most complete glimpse of the material that lies so far outside our own system.

The results? It's an alien environment out there: the material in that galactic wind doesn't look like the same stuff our solar system is made of.
"We've directly measured four separate types of atoms from interstellar space and the composition just doesn't match up with what we see in the solar system," says Eric Christian, mission scientist for IBEX at NASA's Goddard Space Flight Center in Greenbelt, Md. "IBEX's observations shed a whole new light on the mysterious zone where the solar system ends and interstellar space begins."

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Heliophysics

We live in the extended atmosphere of an active star. While sunlight enables and sustains life, the Sun's variability produces streams of high energy particles and radiation that can harm life or alter its evolution. Under the protective shield of a magnetic field and atmosphere, the Earth is an island in the Universe where life has developed and flourished. The origins and fate of life on Earth are intimately connected to the way the Earth responds to the Sun's variations.

Understanding the Sun, Heliosphere, and Planetary Environments as a single connected system is the goal of the Science Mission Directorate's Heliophysics Research Program. In addition to solar processes, our domain of study includes the interaction of solar plasma and radiation with Earth, the other planets, and the Galaxy. By analyzing the connections between the Sun, solar wind, planetary space environments, and our place in the Galaxy, we are uncovering the fundamental physical processes that occur throughout the Universe. Understanding the connections between the Sun and its planets will allow us to predict the impacts of solar variability on humans, technological systems, and even the presence of life itself.

We have already discovered ways to peer into the internal workings of the Sun and understand how the Earth's magnetosphere responds to solar activity. Our challenge now is to explore the full system of complex interactions that characterize the relationship of the Sun with the solar system. Understanding these connections is especially critical as we contemplate our destiny in the third millennium. Heliophysics is needed to facilitate the accelerated expansion of human experience beyond the confines of our Earthly home. Recent advances in technology allow us, for the first time, to realistically contemplate voyages beyond the solar system.

There are three primary objectives that define the multi-decadal studies needed:

To understand the changing flow of energy and matter throughout the Sun, Heliosphere, and Planetary Environments.
To explore the fundamental physical processes of space plasma systems.
To define the origins and societal impacts of variability in the Earth-Sun System.

A combination of interrelated elements is used to achieve these objectives. They include complementary missions of various sizes; timely development of enabling and enhancing technologies; and acquisition of knowledge through research, analysis, theory, and modeling.

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