Salt-Seeking Spacecraft Arrives at Launch Site

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE 818-354-5011
http://www.jpl.nasa.gov

Alan Buis 818-354-0474
Jet Propulsion Laboratory, Pasadena, Calif.
Alan.buis@jpl.nasa.gov

Steve Cole 202-358-0918
NASA Headquarters, Washington
Stephen.e.cole@nasa.gov

News release: 2011-103 March 31, 2011

Salt-Seeking Spacecraft Arrives at Launch Site
NASA Instrument Will Measure Ocean Surface Salinity

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2011-103&cid=release_2011-103

PASADENA, Calif. – An international spacecraft that will take NASA's first space-based
measurements of ocean surface salinity has arrived at its launch site at Vandenberg Air Force Base in
California. The Aquarius/SAC-D mission will provide scientists with a key missing variable in satellite
observations of Earth that links ocean circulation, the global balance of freshwater and climate.

The Aquarius/SAC-D spacecraft left Sáo José dos Campos, Brazil, on March 29. Following final
tests, the spacecraft will be attached to a Delta II rocket for a June 9 launch.

The mission is a collaboration between NASA and Argentina's space agency, Comisión Nacional de
Actividades Espaciales (CONAE), with participation from Brazil, Canada, France and Italy.
Aquarius, the NASA-built primary instrument on CONAE's SAC-D spacecraft, will map global
changes in the concentration of dissolved salt at the ocean surface. Measuring salinity is important to
understanding how changes in rainfall, evaporation and the melting or freezing of ice influence ocean
circulation and are linked to climate changes. The three-year mission will provide new insights into
how variations in ocean surface salinity relate to these fundamental climate processes.

"Just as salt is essential to life as we know it, salinity is crucial to Earth's climate system," said
Aquarius Principal Investigator Gary Lagerloef of Earth and Space Research in Seattle. "Very small
changes in salinity can have large-scale effects on ocean circulation and the way the ocean moderates
our climate. These changes are linked to the movement of water between the ocean, atmosphere and
cryosphere."

Aquarius will greatly enhance the quantity of ocean salinity measurements that have been collected
from ships, buoys and floats.

"When combined with data from other sensors that measure sea level, ocean color, temperature,
winds, rainfall and evaporation, Aquarius' continuous, global salinity data will give scientists a much
clearer picture of how the ocean works, how it is linked to climate and how it may respond to climate
change," Lagerloef said.

Precise salinity measurements from Aquarius will reveal changes in patterns of global precipitation
and evaporation, and show how these affect ocean circulation. Studies from Aquarius eventually will
improve computer models used to forecast future climate conditions, including short-term climate
events such as El Niño and La Niña.

"The mission continues a long and successful partnership between NASA and CONAE, and it will
provide a new type of ocean observation for ocean and climate studies," said Amit Sen, Aquarius
project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

Aquarius will measure ocean surface salinity by sensing thermal microwave emissions from the water's
surface with a radiometer. When other environmental factors are equal, these emissions indicate how
salty the surface water is. Because salinity levels in the open ocean vary by only about five parts per
thousand, Aquarius employs new technologies to detect changes in salinity as small as about two
parts per 10,000, equivalent to about one-eighth of a teaspoon of salt in a gallon of water.

Flying in a 657-kilometer (408-mile) high, polar orbit, Aquarius/SAC-D will map the global ocean
once every seven days. Its measurements will be merged to yield monthly estimates of ocean surface
salinity with a spatial resolution of 150 kilometers (93 miles). The data will reveal how salinity
changes over time and from one part of the ocean to another.

Aquarius is a NASA Earth System Science Pathfinder Program mission. The Aquarius instrument was
jointly built by JPL and NASA's Goddard Space Flight Center in Greenbelt, Md. NASA's Launch
Services Program at the Kennedy Space Center in Florida is managing the launch. JPL will manage
Aquarius through the mission's commissioning phase and archive mission data. Goddard will manage
the mission's operations phase and process Aquarius science data.

CONAE is providing the SAC-D spacecraft, an optical camera, a thermal camera in collaboration
with Canada, a microwave radiometer, sensors developed by various Argentine institutions, and the
mission operations center in Argentina. France and Italy also are contributing instruments.

For more information on Aquarius, visit: http://aquarius.nasa.gov and
http://www.conae.gov.ar/eng/principal.html .

JPL is managed for NASA by the California Institute of Technology in Pasadena.

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Forensic Sleuthing Ties Ring Ripples to Impacts

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE 818-354-5011
http://www.jpl.nasa.gov

Jia-Rui Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.
jccook@jpl.nasa.gov

Michael Buckley 240-228-7536
Johns Hopkins University Applied Physics Laboratory, Laurel, Md.
michael.buckley@jhuapl.edu

News release: 2011-102 March 31, 2011

Forensic Sleuthing Ties Ring Ripples to Impacts

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2011-102&cid=release_2011-102

PASADENA, Calif. – Like forensic scientists examining fingerprints at a cosmic crime scene,
scientists working with data from NASA's Cassini, Galileo and New Horizons missions have traced
telltale ripples in the rings of Saturn and Jupiter back to collisions with cometary fragments dating
back more than 10 years ago.

The ripple-producing culprit, in the case of Jupiter, was comet Shoemaker-Levy 9, whose debris cloud
hurtled through the thin Jupiter ring system during a kamikaze course into the planet in July 1994.
Scientists attribute Saturn's ripples to a similar object – likely another cloud of comet debris --
plunging through the inner rings in the second half of 1983. The findings are detailed in a pair of
papers published online today in the journal Science.

"What's cool is we're finding evidence that a planet's rings can be affected by specific, traceable
events that happened in the last 30 years, rather than a hundred million years ago," said Matthew
Hedman, a Cassini imaging team associate, lead author of one of the papers, and a research associate
at Cornell University, Ithaca, N.Y. "The solar system is a much more dynamic place than we gave it
credit for."

From Galileo's visit to Jupiter, scientists have known since the late 1990s about patchy patterns in the
Jovian ring. But the Galileo images were a little fuzzy, and scientists didn't understand why such
patterns would occur. The trail was cold until Cassini entered orbit around Saturn in 2004 and started
sending back thousands of images. A 2007 paper by Hedman and colleagues first noted corrugations
in Saturn's innermost ring, dubbed the D ring.

A group including Hedman and Mark Showalter, a Cassini co-investigator based at the SETI Institute
in Mountain View, Calif., then realized that the grooves in the D ring appeared to wind together more
tightly over time. Playing the process backward, Hedman then demonstrated the pattern originated
when something tilted the D ring off its axis by about 100 meters (300 feet) in late 1983. The
scientists found the influence of Saturn's gravity on the tilted area warped the ring into a tightening
spiral.

Cassini imaging scientists got another clue when the sun shone directly along Saturn's equator and lit
the rings edge-on in August 2009. The unique lighting conditions highlighted ripples not previously
seen in another part of the ring system. Whatever happened in 1983 was not a small, localized event;
it was big. The collision had tilted a region more than 19,000 kilometers (12,000 miles) wide, covering
part of the D ring and the next outermost ring, called the C ring. Unfortunately spacecraft were not
visiting Saturn at that time, and the planet was on the far side of the sun, hidden from telescopes on
or orbiting Earth, so whatever happened in 1983 passed unnoticed by astronomers.

Hedman and Showalter, the lead author on the second paper, began to wonder whether the long-
forgotten pattern in Jupiter's ring system might illuminate the mystery. Using Galileo images from
1996 and 2000, Showalter confirmed a similar winding spiral pattern. They applied the same math
they had applied to Saturn – but now with Jupiter's gravitational influence factored in. Unwinding
the spiral pinpointed the date when Jupiter's ring was tilted off its axis: between June and September
1994. Shoemaker-Levy plunged into the Jovian atmosphere during late July 1994. The estimated size
of the nucleus was also consistent with the amount of material needed to disturb Jupiter's ring.

The Galileo images also revealed a second spiral, which was calculated to have originated in 1990.
Images taken by New Horizons in 2007, when the spacecraft flew by Jupiter on its way to Pluto,
showed two newer ripple patterns, in addition to the fading echo of the Shoemaker-Levy impact.

"We now know that collisions into the rings are very common – a few times per decade for Jupiter
and a few times per century for Saturn," Showalter said. "Now scientists know that the rings record
these impacts like grooves in a vinyl record, and we can play back their history later."

The ripples also give scientists clues to the size of the clouds of cometary debris that hit the rings. In
each of these cases, the nuclei of the comets – before they likely broke apart – were a few kilometers
wide.

"Finding these fingerprints still in the rings is amazing and helps us better understand impact
processes in our solar system," said Linda Spilker, Cassini project scientist, based at NASA's Jet
Propulsion Laboratory, Pasadena, Calif. "Cassini's long sojourn around Saturn has helped us tease out
subtle clues that tell us about the history of our origins."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the
Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages
the Cassini-Huygens 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
team is based at the Space Science Institute in Boulder, Colo. JPL managed the Galileo mission for
NASA, and designed and built the Galileo orbiter. The New Horizons mission is led by Principal
Investigator Alan Stern of Southwest Research Institute, Boulder, Colo., and managed by the Johns
Hopkins Applied Physics Laboratory, Laurel, Md., for NASA's Science Mission Directorate.

More information about Cassini can be found at http://www.nasa.gov/cassini .

Additional contacts: Blaine Friedlander, Cornell University, Ithaca, N.Y., 607-254-6235,
bpf2@cornell.edu; Karen Randall, SETI Institute, Mountain View, Calif., 650-960-4537,
krandall@seti.org; and Joe Mason, Space Science Institute, Boulder, Colo., 720-974-5859,
jmason@ciclops.org.

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When is an Asteroid Not an Asteroid?

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
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Jia-Rui C. Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.
jccook@jpl.nasa.gov

News release: 2011-100 March 29, 2011

When is an Asteroid Not an Asteroid?

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2011-100&cid=release_2011-100

On March 29, 1807, German astronomer Heinrich Wilhelm Olbers spotted Vesta as
a pinprick of light in the sky. Two hundred and four years later, as NASA's Dawn
spacecraft prepares to begin orbiting this intriguing world, scientists now know
how special this world is, even if there has been some debate on how to classify it.

Vesta is most commonly called an asteroid because it lies in the orbiting rubble
patch known as the main asteroid belt between Mars and Jupiter. But the vast
majority of objects in the main belt are lightweights, 100-kilometers-wide (about
60-miles wide) or smaller, compared with Vesta, which is about 530 kilometers
(330 miles) across on average. In fact, numerous bits of Vesta ejected by collisions
with other objects have been identified in the main belt.

"I don't think Vesta should be called an asteroid," said Tom McCord, a Dawn co-
investigator based at the Bear Fight Institute, Winthrop, Wash. "Not only is Vesta so
much larger, but it's an evolved object, unlike most things we call asteroids."

The layered structure of Vesta (core, mantle and crust) is the key trait that makes
Vesta more like planets such as Earth, Venus and Mars than the other asteroids,
McCord said. Like the planets, Vesta had sufficient radioactive material inside when
it coalesced, releasing heat that melted rock and enabled lighter layers to float to
the outside. Scientists call this process differentiation.

McCord and colleagues were the first to discover that Vesta was likely
differentiated when special detectors on their telescopes in 1972 picked up the
signature of basalt. That meant that the body had to have melted at one time.

Officially, Vesta is a "minor planet" -- a body that orbits the sun but is not a proper
planet or comet. But there are more than 540,000 minor planets in our solar
system, so the label doesn't give Vesta much distinction. Dwarf planets – which
include Dawn's second destination, Ceres -- are another category, but Vesta doesn't
qualify as one of those. For one thing, Vesta isn't quite large enough.

Dawn scientists prefer to think of Vesta as a protoplanet because it is a dense,
layered body that orbits the sun and began in the same fashion as Mercury, Venus,
Earth and Mars, but somehow never fully developed. In the swinging early history
of the solar system, objects became planets by merging with other Vesta-sized
objects. But Vesta never found a partner during the big dance, and the critical time
passed. It may have had to do with the nearby presence of Jupiter, the
neighborhood's gravitational superpower, disturbing the orbits of objects and
hogging the dance partners.

Other space rocks have collided with Vesta and knocked off bits of it. Those
became debris in the asteroid belt known as Vestoids, and even hundreds of
meteorites that have ended up on Earth. But Vesta never collided with something
of sufficient size to disrupt it, and it remained intact. As a result, Vesta is a time
capsule from that earlier era.

"This gritty little protoplanet has survived bombardment in the asteroid belt for
over 4.5 billion years, making its surface possibly the oldest planetary surface in
the solar system," said Christopher Russell, Dawn's principal investigator, based at
UCLA. "Studying Vesta will enable us to write a much better history of the solar
system's turbulent youth."

Dawn's scientists and engineers have designed a master plan to investigate these
special features of Vesta. When Dawn arrives at Vesta in July, the south pole will be
in full sunlight, giving scientists a clear view of a huge crater at the south pole. That
crater may reveal the layer cake of materials inside Vesta that will tell us how the
body evolved after formation. The orbit design allows Dawn to map new terrain as
the seasons progress over its 12-month visit. The spacecraft will make many
measurements, including high-resolution data on surface composition, topography
and texture. The spacecraft will also measure the tug of Vesta's gravity to learn
more about its internal structure.

"Dawn's ion thrusters are gently carrying us toward Vesta, and the spacecraft is
getting ready for its big year of exploration," said Marc Rayman, Dawn's chief
engineer at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We have designed
our mission to get the most out of this opportunity to reveal the exciting secrets of
this uncharted, exotic world."

The Dawn mission to Vesta and Ceres is managed by the Jet Propulsion
Laboratory, a division of the California Institute of Technology in Pasadena, for
NASA's Science Mission Directorate, Washington. The Dawn mission is part of the
Discovery Program managed by NASA's Marshall Space Flight Center in Huntsville,
Ala. UCLA is responsible for overall Dawn mission science. Orbital Sciences
Corporation of Dulles, Va., designed and built the Dawn spacecraft. The German
Aerospace Center, the Max Planck Society, the Italian Space Agency and the Italian
National Astrophysical Institute are part of the mission team.

For more information about Dawn, visit http://www.nasa.gov/dawn and
http://dawn.jpl.nasa.gov .

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NASA Announces 2011 Carl Sagan Fellows

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
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Priscilla Vega (818) 354-1357
Jet Propulsion Laboratory, Pasadena, Calif.
Priscilla.r.vega@jpl.nasa.gov


News release: 2011-099 March 29, 2011

NASA Announces 2011 Carl Sagan Fellows

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2011-099&cid=release_2011-099

NASA has selected five potential discoverers as the recipients of the 2011 Carl Sagan
Postdoctoral Fellowships, named after the late astronomer. The Carl Sagan Fellowship
takes a theme-based approach, in which fellows will focus on compelling scientific
questions, such as "Are there Earth-like planets orbiting other stars?"

Sagan once said, "Somewhere, something incredible is waiting to be known," which is in
line with the Sagan Fellowship's primary goal: to discover and characterize planetary
systems and Earth-like planets around other stars. Planets outside of our solar system are
called exoplanets. The fellowship also aims to support outstanding recent postdoctoral
scientists in conducting independent research broadly related to the science goals of
NASA's Exoplanet Exploration Program.

Previous Sagan Fellows have contributed significant discoveries in exoplanet exploration.
including: the first characterizations of a super-Earth's atmosphere using a ground-based
telescope; and the discovery of a massive disk of dust and gas encircling a giant young
star, which could potentially answer the long-standing question of how massive stars are
born.

"The Sagan Fellowship program seeks to identify the most highly qualified young
researchers in the field of exoplanets. Nowhere is the dynamism of this young branch of
astronomy demonstrated more dramatically than by the intellectual quality and
enthusiasm of these five new Sagan Fellows," said Charles Beichman, executive director
of the NASA Exoplanet Science Institute at the California Institute of Technology in
Pasadena. "These scientists are certain to be leaders of this exciting and rapidly growing
field for many years to come."

The program, created in 2008, awards selected postdoctoral scientists with annual
stipends of approximately $64,500 for up to three years, plus an annual research budget
of up to $16,000. Topics range from techniques for detecting the glow of a dim planet in
the blinding glare of its host star, to searching for the crucial ingredients of life in other
planetary systems.

The 2011 Sagan Fellows are:

-- David Kipping, who will work at the Harvard-Smithsonian Center for Astrophysics,
Cambridge, to combine theory and observation to conduct a search for the moons of
exoplanets.

-- Bryce Croll, who will work at the Massachusetts Institute of Technology, Cambridge,
Mass., to characterize the atmospheres of both large and small exoplanets using a variety
of telescopes.

-- Wladimir Lyra, who will work at NASA's Jet Propulsion Laboratory, Pasadena, Calif.,
to study planet-forming disks and exoplanet formation.

-- Katie Morzinski, who will work at the University of Arizona, Tucson, to commission
and employ high-contrast adaptive optics systems that will directly image Jupiter-like
exoplanets.

-- Sloane Wiktorowicz, who will work at the University of California, Santa Cruz to use a
technique called optical polarimetry to directly detect exoplanets.

NASA has two other astrophysics theme-based fellowship programs: the Einstein
Fellowship Program, which supports research into the physics of the cosmos, and the
Hubble Fellowship Program, which supports research into cosmic origins. The Sagan
Fellowship Program is administered by the NASA Exoplanet Science Institute as part of
NASA's Exoplanet Exploration Program at JPL in Pasadena, Calif. The California
Institute of Technology manages JPL for NASA.

A full description of the 2011 fellows and their projects, and other information about
these programs is available at:
http://nexsci.caltech.edu/sagan/2011postdocRecipients.shtml .

More information about NASA's Astrophysics Division is at:
http://nasascience.nasa.gov/astrophysics .

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NASA Stardust Spacecraft Officially Ends Operations

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
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DC Agle 818-393-9011
Jet Propulsion Laboratory, Pasadena, Calif.
agle@jpl.nasa.gov

Dwayne Brown 202-358-1726
NASA Headquarters, Washington
Dwayne.c.brown@nasa.gov

News release: 2011-096 March 25, 2011

NASA Stardust Spacecraft Officially Ends Operations

PASADENA, Calif. -- NASA's Stardust spacecraft sent its last transmission to Earth at 4:33 .m.
PDT (7:33 p.m. EDT) Thursday, March 24, shortly after depleting fuel and ceasing operations.
During a 12-year period, the venerable spacecraft collected and returned comet material to Earth and
was reused after the end of its prime mission in 2006 to observe and study another comet during
February 2011.

The Stardust team performed the burn to depletion because the comet hunter was literally running on
fumes. The depletion maneuver command was sent from the Stardust-NExT mission control area at
Lockheed Martin Space Systems in Denver. The operation was designed to fire Stardust's rockets
until no fuel remained in the tank or fuel lines. The spacecraft sent acknowledgment of its last
command from approximately 312 million kilometers (194 million miles) away in space.

"This is the end of the spacecraft's operations, but really just the beginnings of what this spacecraft's
accomplishments will give to planetary science," said Lindley Johnson, Stardust-NExT and
Discovery program executive at NASA Headquarters in Washington. "The treasure-trove of science
data and engineering information collected and returned by Stardust is invaluable for planning future
deep space planetary missions."

After completion of the burn, mission personnel began comparing the computed amount of fuel
consumed during the engine firing with the anticipated amount based on consumption models. The
models are required to track fuel levels, because there are no fully reliable fuel gauges for spacecraft
in the weightless environment of space. Mission planners use approximate fuel usage by reviewing
the history of the vehicle's flight, how many times and how long its rocket motors fired.

"Stardust's motors burned for 146 seconds," said Allan Cheuvront, Lockheed Martin Space Systems
Company program manager for Stardust-NExT in Denver. "We'll crunch the numbers and see how
close the reality matches up with our projections. That will be a great data set to have in our back
pocket when we plan for future missions."

Launched Feb. 7, 1999, Stardust flew past the asteroid named Annefrank and traveled halfway to
Jupiter to collect the particle samples from the comet Wild 2. The spacecraft returned to Earth's
vicinity to drop off a sample return capsule eagerly awaited by comet scientists.

NASA re-tasked the spacecraft as Stardust-NExT to perform a bonus mission and fly past comet
Tempel 1, which was struck by the Deep Impact mission in 2005. The mission collected images and
other scientific data to compare with images of that comet collected by the Deep Impact mission in
2005. Stardust traveled approximately 21 million kilometers (13 million miles) around the sun in the
weeks after the successful Tempel 1 flyby. The Stardust-NExT mission met all mission goals, and
the spacecraft was extremely successful during both missions. From launch until final rocket engine
burn, Stardust travelled approximately 5.69 billion kilometers (3.54 billion miles).

After the mileage logged in space, the Stardust team knew the end was near for the spacecraft. With
its fuel tank empty and final radio transmission concluded, history's most traveled comet hunter will
move from NASA's active mission roster to retired.

"This kind of feels like the end of one of those old western movies where you watch the hero ride his
horse towards the distant setting sun -- and then the credits begin to roll," said Stardust-NExT
project manager Tim Larson from NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Only
there's no setting sun in space."

Stardust and Stardust-NExT missions were managed by JPL for NASA's Science Mission
Directorate in Washington. The missions were part of the Discovery Program managed at NASA's
Marshall Space Flight Center in Huntsville, Ala. Joe Veverka of Cornell University was the
Stardust-NExT principal investigator. Don Brownlee of the University of Washington in Seattle was
the Stardust principal investigator. Lockheed Martin Space Systems built the spacecraft and
managed day-to-day mission operations.

For more information about Stardust and Stardust-NExT, visit: http://stardustnext.jpl.nasa.gov

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Cassini Finds Saturn Sends Mixed Signals

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Jia-Rui Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.
jccook@jpl.nasa.gov

Feature: 2011-091 March 22, 2011

Cassini Finds Saturn Sends Mixed Signals

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2011-091&cid=release_2011-091

Like a petulant adolescent, Saturn is sending out mixed signals.

Recent data from NASA's Cassini spacecraft show that the variation in radio waves
controlled by the planet's rotation is different in the northern and southern hemispheres.
Moreover, the northern and southern rotational variations also appear to change with the
Saturnian seasons, and the hemispheres have actually swapped rates. These two radio
waves, converted to the human audio range, can be heard in a new video available online
at: http://www.nasa.gov/multimedia/videogallery/index.html?media_id=74390781

"These data just go to show how weird Saturn is," said Don Gurnett, Cassini's radio and
plasma wave science instrument team lead and professor of physics at the University of
Iowa, Iowa City. "We thought we understood these radio wave patterns at gas giants,
since Jupiter was so straightforward. Without Cassini's long stay, scientists wouldn't have
understood that the radio emissions from Saturn are so different."

Saturn emits radio waves known as Saturn Kilometric Radiation, or SKR for short. To
Cassini, they sound a bit like bursts of a spinning air raid siren, since the radio waves vary
with each rotation of the planet. This kind of radio wave pattern had been previously
used at Jupiter to measure the planet's rotation rate, but at Saturn, as is the case with
teenagers, the situation turned out to be much more complicated.

When NASA's Voyager spacecraft visited Saturn in the early 1980s, the radiation
emissions indicated the length of Saturn's day was about 10.66 hours. But as its clocking
continued by a flyby of the joint ESA-NASA Ulysses spacecraft and Cassini, the radio
burst varied by seconds to minutes. A paper in Geophysical Research Letters in 2009
analyzing Cassini data showed that the Saturn Kilometric Radiation was not even a solo,
but a duet, with two singers out of sync. Radio waves emanating from near the north pole
had a period of around 10.6 hours; radio waves near the south pole had a period of
around 10.8 hours.

A new paper led by Gurnett that was published in Geophysical Research Letters in
December 2010 shows that, in recent Cassini data, the southern and northern SKR
periods crossed over around March 2010, about seven months after equinox, when the
sun shines directly over a planet's equator. The southern SKR period decreased from
about 10.8 hours on Jan. 1, 2008 and crossed with the northern SKR period around
March 1, 2010, at around 10.67 hours. The northern period increased from about 10.58
hours to that convergence point.

Seeing this kind of crossover led the Cassini scientists to go back into data from previous
Saturnian visits. With a new eye, they saw that NASA's Voyager data taken in 1980,
about a year after Saturn's 1979 equinox, showed different warbles from Saturn's
northern and southern poles. They also saw a similar kind of effect in the Ulysses radio
data between 1993 and 2000. The northern and southern periods detected by Ulysses
converged and crossed over around August 1996, about nine months after the previous
Saturnian equinox.

Cassini scientists don't think the differences in the radio wave periods had to do with
hemispheres actually rotating at different rates, but more likely came from variations in
high-altitude winds in the northern and southern hemispheres. Two other papers involving
Cassini investigators were published in December, with results complementary to the
radio and plasma wave science instrument -- one by Jon Nichols, University of Leicester,
U.K., in the same issue of Geophysical Research Letters, and the other led by David
Andrews, also of University of Leicester, in the Journal of Geophysical Research.

In the Nichols paper, data from the NASA/ESA Hubble Space Telescope showed the
northern and southern auroras on Saturn wobbled back and forth in latitude in a pattern
matching the radio wave variations, from January to March 2009, just before equinox.
The radio signal and aurora data are complementary because they are both related to the
behavior of the magnetic bubble around Saturn, known as the magnetosphere. The paper
by Andrews, a Cassini magnetometer team associate, showed that from mid-2004 to mid-
2009, Saturn's magnetic field over the two poles wobbled at the same separate periods as
the radio waves and the aurora.

"The rain of electrons into the atmosphere that produces the auroras also produces the
radio emissions and affects the magnetic field, so scientists think that all these variations
we see are related to the sun's changing influence on the planet," said Stanley Cowley, a
co-author on both papers, co-investigator on Cassini's magnetometer instrument, and
professor at the University of Leicester.

As the sun continues to climb towards the north pole of Saturn, Gurnett's group has
continued to see the crossover trend in radio signals through Jan. 1, 2011. The period of
the southern radio signals continued to decrease to about 10.54 hours, while the period of
the northern radio signals increased to 10.71 hours.

"These papers are important in helping to explain the complicated dance between the sun
and Saturn's magnetic bubble, something normally invisible to the human eye and
imperceptible to the human ear," said Marcia Burton, a Cassini fields and particles
scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif., who was not involved in
the work. "Cassini will continue to keep an eye on these changes."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space
Agency and the Italian Space Agency. JPL, 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 radio and plasma wave science team is based at the
University of Iowa, Iowa City, where the instrument was built. The magnetometer team is
based at Imperial College, London, U.K.

The Hubble Space Telescope is a project of international cooperation between NASA and
the European Space Agency. NASA's Goddard Space Flight Center manages the
telescope. The Space Telescope Science Institute conducts Hubble science operations.
STScI is operated for NASA by the Association of Universities for Research in
Astronomy, Inc., in Washington, D.C.

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Wanted: Student Questions for Voyager, Humanity's Farthest Journey

Wanted: Student Questions for Voyager, Humanity's Farthest Journey
This is a feature from the NASA/JPL Education Office.

03.21.11 -- NASA's Voyager spacecraft are hurtling towards the edge of our solar system, more
than 10 billion miles away from our sun. Interstellar space - the medium between stars - is a region
no human-made craft has ever been. On Apr. 28, 2011, a live NASA TV program will feature mission
scientists discussing the distant areas Voyager 1 and 2 are exploring, 10 billion miles away from our sun.

NASA is inviting classrooms to submit their single best question about the Voyager mission and
interstellar space to the science panel. We are also inviting students to submit their best idea about what
they would put on a new Golden Record, if one were ever created.

How to Submit a Question:

Teachers interested in submitting a classroom question should email jplspaceeducation@gmail.com as soon
as possible to hold a spot in our random drawing. Please put "Voyager Question" in the subject line. Due to
resources, only the first 20 educators who express interest will have their class' question and answer posted
on the Voyager website (http://voyager.jpl.nasa.gov and www.nasa.gov/voyager). Approximately 5 of these 20
questions will be randomly selected and submitted to our Voyager science panel during the live NASA TV program.
(Please note, teachers do not need to send the question immediately; they need only send an email stating their
interest in submitting a question.) The first 20 respondents will be given a deadline for question submission.

How to Submit an Idea for the Golden Record:

Teachers should send their students' best idea for the Golden Record by Apr. 21, 2011, to jplspaceeducation@gmail.com.
Please put Golden Record in the subject line. Ideas will be posted in a timely manner on the Voyager website.
Please include school name, city and state along with the Golden Record idea. Please state if you would like teacher
name and grade level included when we post the idea.

Resources:

There are many websites to help gather information for questions and Golden Record ideas. Here are a few to check:

http://voyager.jpl.nasa.gov

Space Weather Media Viewer http://sunearthday.nasa.gov/spaceweather/ (go to Videos on the left and use the
drop-down menu for videos to select heliosphere)

Space Place: Voyager: http://spaceplace.nasa.gov/en/kids/voyager/index.shtml

JPL Virtual Field Trip (visit the "Sun Zone" once you go inside) http://virtualfieldtrip.jpl.nasa.gov/smmk/top/gates

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E-card: Stars Gather in 'Downtown' Milky Way

Stars Gather in 'Downtown' Milky Way

A view from the bustling center of our galactic metropolis. Spitzer Space Telescope offers us a fresh, infrared view of the frenzied scene at the center of our Milky Way, revealing what lies behind the dust. View the image at http://www.jpl.nasa.gov/news/news.cfm?release=2011-088.

A wallpaper of this image is available at http://www.jpl.nasa.gov/wallpaper/index.cfm?cid=spitzerecard

+ JPL Homepage: http://www.jpl.nasa.gov/

+ Spitzer Homepage: http://www.spitzer.caltech.edu/

Media Contact:

Whitney Clavin (818) 354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@jpl.nasa.gov

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Cassini Sees Seasonal Rains Transform Titan's Surface

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE 818-354-5011
http://www.jpl.nasa.gov

Jia-Rui C. Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.
jccook@jpl.nasa.gov

Joe Mason 720-974-5859
Space Science Institute, Boulder, Colo.
jmason@ciclops.org

Michael Buckley 240-228-7536
Johns Hopkins University Applied Physics Laboratory, Laurel, Md.
michael.buckley@jhuapl.edu

News Release: 2011-084 March 17, 2011

Cassini Sees Seasonal Rains Transform Titan's Surface

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2011-084&cid=release_2011-084

PASADENA, Calif. -- As spring continues to unfold at Saturn, April showers on the planet's
largest moon, Titan, have brought methane rain to its equatorial deserts, as revealed in images
captured by NASA's Cassini spacecraft. This is the first time scientists have obtained current
evidence of rain soaking Titan's surface at low latitudes.

Extensive rain from large cloud systems, spotted by Cassini's cameras in late 2010, has
apparently darkened the surface of the moon. The best explanation is these areas remained wet
after methane rainstorms. The observations released today in the journal Science, combined with
earlier results in Geophysical Research Letters last month, show the weather systems of Titan's
thick atmosphere and the changes wrought on its surface are affected by the changing seasons.

"It's amazing to be watching such familiar activity as rainstorms and seasonal changes in weather
patterns on a distant, icy satellite," said Elizabeth Turtle, a Cassini imaging team associate at the
Johns Hopkins University Applied Physics Lab in Laurel, Md., and lead author of today's
publication. "These observations are helping us to understand how Titan works as a system, as
well as similar processes on our own planet."

The Saturn system experienced equinox, when the sun lies directly over a planet's equator and
seasons change, in August 2009. (A full Saturn "year" is almost 30 Earth years.) Years of Cassini
observations suggest Titan's global atmospheric circulation pattern responds to the changes in
solar illumination, influenced by the atmosphere and the surface, as detailed in the Geophysical
Research Letters paper. Cassini found the surface temperature responds more rapidly to sunlight
changes than does the thick atmosphere. The changing circulation pattern produced clouds in
Titan's equatorial region.

Clouds on Titan are formed of methane as part of an Earth-like cycle that uses methane instead
of water. On Titan, methane fills lakes on the surface, saturates clouds in the atmosphere, and
falls as rain. Though there is evidence that liquids have flowed on the surface at Titan's equator in
the past, liquid hydrocarbons, such as methane and ethane, had only been observed on the
surface in lakes at polar latitudes. The vast expanses of dunes that dominate Titan's equatorial
regions require a predominantly arid climate. Scientists suspected that clouds might appear at
Titan's equatorial latitudes as spring in the northern hemisphere progressed. But they were not
sure if dry channels previously observed were cut by seasonal rains or remained from an earlier,
wetter climate.

An arrow-shaped storm appeared in the equatorial regions on Sept. 27, 2010 -- the equivalent of
early April in Titan's "year" -- and a broad band of clouds appeared the next month. As described
in the Science paper, over the next few months, Cassini's imaging science subsystem captured
short-lived surface changes visible in images of Titan's surface. A 193,000-square-mile (500,000-
square-kilometer) region along the southern boundary of Titan's Belet dune field, as well as
smaller areas nearby, had become darker. Scientists compared the imaging data to data obtained
by other instruments and ruled out other possible causes for surface changes. They concluded this
change in brightness is most likely the result of surface wetting by methane rain.

These observations suggest that recent weather on Titan is similar to that over Earth's tropics. In
tropical regions, Earth receives its most direct sunlight, creating a band of rising motion and rain
clouds that encircle the planet.

"These outbreaks may be the Titan equivalent of what creates Earth's tropical rainforest climates,
even though the delayed reaction to the change of seasons and the apparently sudden shift is
more reminiscent of Earth's behavior over the tropical oceans than over tropical land areas," said
Tony Del Genio of NASA's Goddard Institute for Space Studies, New York, a co-author and a
member of the Cassini imaging team.

On Earth, the tropical bands of rain clouds shift slightly with the seasons but are present within
the tropics year-round. On Titan, such extensive bands of clouds may only be prevalent in the
tropics near the equinoxes and move to much higher latitudes as the planet approaches the
solstices. The imaging team intends to watch whether Titan evolves in this fashion as the seasons
progress from spring toward northern summer.

"It is patently clear that there is so much more to learn from Cassini about seasonal forcing of a
complex surface-atmosphere system like Titan's and, in turn, how it is similar to, or differs from,
the Earth's," said Carolyn Porco, Cassini imaging team lead at the Space Science Institute,
Boulder, Colo. "We are eager to see what the rest of Cassini's Solstice Mission will bring."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and
the Italian Space Agency. The Jet Propulsion Laboratory (JPL), a division of the California
Institute of Technology in Pasadena, manages the Cassini-Huygens 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 team is based at the Space Science
Institute in Boulder, Colo. For more information about the Cassini-Huygens mission, visit
http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov.

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New Web Page to Watch Mar. 15 Robotics Competition

New Web Page to Watch Mar. 15 Robotics Competition
This is a feature from the NASA/JPL Education Office.

03.15.11 -- We have two new web pages to visit to watch today's live student robotics competition.
Please go to http://www.ustream.tv/channel/nasa-hd-tv or http://www.nasa.gov/multimedia/nasatv/index.html .

More details about the competition: Student teams from nine local elementary, middle and high schools
will put their software-enabled, battery-powered LEGO robots against the clock in the 5th Annual Southern
California Robotics Competition at NASA's Jet Propulsion Laboratory, in Pasadena, Calif., on Tues., March 15.

The competition will also be broadcast live on the Web from 12:15 to 3:15 p.m. (Pacific). Please see a detailed schedule below.

In a challenge that simulates planetary exploration, the tabletop-size robots must perform different tasks within
two minutes. They include placing sensors in volcanoes, deploying habitats, and rescuing a stranded "moon buggy,"
or small robot. This robotic competition aims to engage students in math, science, technology and engineering.

Each team has four students. The contest will be divided into two sections: one for elementary-school teams,
and the other for middle- and high-school teams.

Detailed program schedule (All times listed in Pacific):

12:15 to 2 p.m. - Competition rounds
2 p.m. - 15-minute break
2:15 p.m. - NASA/JPL robotics engineer Paulo Younse addresses students and discusses careers in robotics, engineering, science
2:45 p.m. - Awards ceremony
3:15 p.m. - End of program

The 17 teams from nine schools that will participate are:

Charles T. Kranz Intermediate School, El Monte
Lake View Elementary School, Huntington Beach
Johnson STEM Magnet School, San Diego
Mesa Union School, Somis
North Ridge Magnet School, Moreno Valley
Roosevelt Middle School, Glendale
Sycamore Hills Elementary School, Fontana
Village Academy High School, Pomona
Vintage Math Science Technology Magnet School, North Hills



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Does Your Class Have Questions About Earthquakes? Send Them Now

Does Your Class Have Questions About Earthquakes? Send Them Now
This is a feature from the NASA/JPL Education Office.

03.15.11 -- With Japan's devastating earthquake and tsunami uppermost in peoples' minds, the
Education Office at NASA's Jet Propulsion Laboratory in Pasadena, Calif., is hosting a live video
chat about earthquakes. We are seeking questions from students, preferably in grades 4 - 6, about
earthquakes and how scientists study them. Please limit your questions to the topic of earthquakes.

Questions should be sent to jplspaceeducation@gmail.com. They must be received by Wed., Mar. 16, at
3 p.m. Pacific. Educators will be contacted if their student's question is selected for the program. Please note,
we will make our best effort to answer all selected questions but due to time, there is no guarantee that all
selected questions will be answered. Please include a class name or student first name with each question.

The 30-minute program will air on Friday, Mar. 18 at 10 a.m. Pacific. Classrooms and the general public can
watch the program at http://www.ustream.tv/nasajpl2 . The program will also be archived on the same web page.

Our expert will be Greg Lyzenga, a JPL geophysicist and a Professor of Physics at Harvey Mudd College in
Claremont, Calif. Greg studies earthquakes and how computer models may help understand how Earth responds
to shifts in tectonic plates.

Our chats are fairly fast-paced to allow as many questions as possible. Please see an archive of a recent chat
to see if this will work for your class: http://www.ustream.tv/recorded/12283600 .

To see a collection of space-based images that show the aftermath of the Mar. 11 earthquake and tsunami, go
to http://www.nasa.gov/topics/earth/features/japanquake/index.html .

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NASA Study Goes to Earth's Core for Climate Insights

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE 818-354-5011
http://www.jpl.nasa.gov

Alan Buis 818-354-0474
Jet Propulsion Laboratory, Pasadena, Calif.
Alan.buis@jpl.nasa.gov

Feature: 2011-074 March 9, 2011

NASA Study Goes to Earth's Core for Climate Insights

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2011-074&cid=release_2011-074

The latest evidence of the dominant role humans play in changing Earth's climate comes
not from observations of Earth's ocean, atmosphere or land surface, but from deep within
its molten core.

Scientists have long known that the length of an Earth day — the time it takes for Earth to
make one full rotation — fluctuates around a 24-hour average. Over the course of a year,
the length of a day varies by about 1 millisecond, getting longer in the winter and shorter in
the summer. These seasonal changes in Earth's length of day are driven by exchanges of
energy between the solid Earth and fluid motions of Earth's atmosphere (blowing winds
and changes in atmospheric pressure) and its ocean. Scientists can measure these small
changes in Earth's rotation using astronomical observations and very precise geodetic
techniques.

But the length of an Earth day also fluctuates over much longer timescales, such as
interannual (two to 10 years), decadal (approximately 10 years), or those lasting multiple
decades or even longer. A dominant longer timescale mode that ranges from 65 to 80
years was observed to change the length of day by approximately 4 milliseconds at the
beginning of the 20th century.

These longer fluctuations are too large to be explained by the motions of Earth's
atmosphere and ocean. Instead, they're due to the flow of liquid iron within Earth's outer
core, where Earth's magnetic field originates. This fluid interacts with Earth's mantle to
affect Earth's rotation. While scientists cannot observe these flows directly, they can
deduce their movements by observing Earth's magnetic field at the surface. Previous
studies have shown that this flow of liquid iron in Earth's outer core oscillates, in waves of
motion that last for decades with timescales that correspond closely to long-duration
variations in Earth's length of day.

Still other studies have observed a link between the long-duration variations in Earth's
length of day and fluctuations of up to 0.2 degrees Celsius (0.4 degree Fahrenheit) in
Earth's long-term global average surface air temperature.

So how might all three of these variables — Earth's rotation, movements in Earth's core
(formally known as the core angular momentum) and global surface air temperature — be
related? That's what researchers Jean Dickey and Steven Marcus of NASA's Jet
Propulsion Laboratory, Pasadena, Calif., and colleague Olivier de Viron of the Universite
Paris Diderot and Institut de Physique du Globe de Paris in France, set out to discover in a
first-of-its-kind study.

The scientists mapped existing data from a model of fluid movements within Earth's core
and data on yearly averaged length-of-day observations against two time series of
observed annual global average surface temperature: one from NASA's Goddard Institute
of Space Studies in New York that extends back to 1880, and another from the United
Kingdom's Met Office that extends back to 1860. Since total air temperature is composed of
two components — temperature changes that occur naturally and those caused by human
activities — the researchers used results from computer climate models of Earth's
atmosphere and ocean to account for temperature changes due to human activities. These
human-produced temperature changes were then subtracted from the total observed
temperature records to generate corrected temperature records.

The researchers found that the uncorrected temperature data correlated strongly with data
on movements of Earth's core and Earth's length of day until about 1930. They then began
to diverge substantially: that is, global surface air temperatures continued to increase, but
without corresponding changes in Earth's length of day or movements of Earth's core. This
divergence corresponds with a well-documented, robust global warming trend that has
been widely attributed to increased levels of human-produced greenhouse gases.

But an examination of the corrected temperature record yielded a different result: the
corrected temperature record remained strongly correlated with both Earth's length of day
and movements of Earth's core throughout the entire temperature data series. The
researchers performed robust tests to confirm the statistical significance of their results.

"Our research demonstrates that, for the past 160 years, decadal and longer-period
changes in atmospheric temperature correspond to changes in Earth's length of day if we
remove the very significant effect of atmospheric warming attributed to the buildup of
greenhouse gases due to mankind's enterprise," said Dickey. "Our study implies that
human influences on climate during the past 80 years mask the natural balance that exists
among Earth's rotation, the core angular momentum and the temperature at Earth's
surface."

So what mechanism is driving these correlations? Dickey said scientists aren't sure yet,
but she offered some hypotheses.

Since scientists know air temperature can't affect movements of Earth's core or Earth's
length of day to the extent observed, one possibility is the movements of Earth's core might
disturb Earth's magnetic shielding of charged-particle (i.e., cosmic ray) fluxes that have
been hypothesized to affect the formation of clouds. This could affect how much of the
sun's energy is reflected back to space and how much is absorbed by our planet. Other
possibilities are that some other core process could be having a more indirect effect on
climate, or that an external (e.g. solar) process affects the core and climate simultaneously.

Regardless of the eventual connections to be established between the solid Earth and
climate, Dickey said the solid Earth's impacts on climate are still dwarfed by the much
larger effects of human-produced greenhouse gases. "The solid Earth plays a role, but the
ultimate solution to addressing climate change remains in our hands," she concluded.

Study results were published recently in the Journal of Climate.

For more information, see: http://www.jpl.nasa.gov/news/features.cfm?feature=2420 and
http://www.jpl.nasa.gov/news/features.cfm?feature=15 .

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Dawn Gets Vesta Target Practice

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE 818-354-5011
http://www.jpl.nasa.gov

Jia-Rui C. Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.
jccook@jpl.nasa.gov

Feature: 2011-075 March 10, 2011

Dawn Gets Vesta Target Practice

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2011-075&cid=release_2011-075

There is an old chestnut about a pedestrian who once asked a virtuoso violinist
near Carnegie Hall how to get to the famed concert venue. The virtuoso's answer:
practice!

The same applies to NASA's Dawn mission to the giant asteroid Vesta. In the lead-
up to orbiting the second most massive body in the asteroid belt this coming July,
Dawn mission planners and scientists have been practicing mapping Vesta's
surface, producing still images and a rotating animation that includes the scientists'
best guess to date of what the surface might look like.

The animation and images incorporate the best data on the dimples and bulges of
Vesta from ground-based telescopes and NASA's Hubble Space Telescope. The The
topography is color-coded by altitude. The cratering and small-scale surface
variations are computer-generated, based on the patterns seen on Earth's moon,
an inner solar system object with a surface appearance that may be similar to
Vesta.

"We won't know what Vesta really looks like until Dawn gets there," said Carol
Raymond, Dawn's deputy principal investigator, based at NASA's Jet Propulsion
Laboratory, Pasadena, Calif., who helped orchestrate the activity. "But we needed a
way to make sure our imaging plans would give us the best results possible. The
products have proven that Dawn's mapping techniques will reveal a detailed view
of this world that we've never seen up close before."

Vesta is one of the brightest asteroids in the night sky. Under the right conditions,
Vesta can be seen with binoculars. But the best images so far from ground-based
telescopes and Hubble still show Vesta as a bright, mottled orb. Once in orbit
around Vesta, Dawn will pass about 650 kilometers (400 miles) above the
asteroid's surface, snapping multi-angle images that will allow scientists to produce
topographic maps. Later, Dawn will orbit at a lower altitude of about 200
kilometers (120 miles), getting closer shots of parts of the surface.

The Dawn mission will have the capability to map 80 percent of the asteroid's
surface in the year the spacecraft is in orbit around Vesta. (The north pole will be
dark when Dawn arrives in July 2011 and is expected to be only dimly lit when
Dawn leaves in July 2012.) The mission will map Vesta at a spatial resolution on the
order of the best global topography maps of Earth made by NASA's Shuttle Radar
Topography mission.

Vesta formed very early in the history of the solar system and has one of the oldest
surfaces in the system. Scientists are eager to get their first close-up look so they
can better understand this early chapter.

Starting in August 2009, Dawn's optical navigation lead, Nick Mastrodemos, based
at JPL, developed a computer simulation of the orbits and images to be taken by
the spacecraft. He adapted software developed by Bob Gaskell of the Planetary
Science Institute, Tuscon, Ariz. Mastrodemos created a model using scientists' best
knowledge of Vesta and simulated the pictures that Dawn would take from the
exact distances and geometries in the Dawn science plan.

He sent those images to two teams that use different techniques to derive
topographical heights from imaging. One, led by Thomas Roatsch, was based at the
Institute of Planetary Research of the German Aerospace Center (DLR) in Berlin.
The other, led by Gaskell, was based at the Planetary Science Institute in Tuscon.
(Like the Roatsch team, the Gaskell team did not have prior knowledge of the
model from which the simulated data were created.) The groups sent their digital
terrain models back to JPL, including the video produced by Frank Preusker from
DLR that is based on his full stereo processing.

Mastrodemos compared their products to the original model he made. Both
techniques reproduced the known data set well with only minor differences in
spatial resolution and height accuracy. "Working through this exercise, the mission
planners and the scientists learned that we could improve the overall accuracy of
the topographic reconstruction, using a somewhat different observation
geometry," Mastrodemos said. "Since then, Dawn science planners have worked to
tweak the plans to implement the lessons of the exercise."

The exercise helped both teams get an early start on updating their software and
planning the necessary computer resources. "In order to plan for proper stereo
coverage of an unknown body like Vesta, practice is essential," said Roatsch, who is
responsible for the framing camera team's stereo observation planning.

For now, the Virtual Vesta exercise gives the Dawn science team a fleshed-out
model to consider. But to see whether their educated guesses were right, the team
will have to wait until Dawn arrives at its target in four months.

The Dawn mission to Vesta and Ceres is managed for NASA's Science Mission
Directorate in Washington by JPL, a division of the California Institute of
Technology in Pasadena, and is a project of the Discovery Program managed at
NASA's Marshall Space Flight Center, Huntsville, Ala. UCLA is home of the
mission's principal investigator, Christopher Russell, and is responsible for overall
Dawn mission science. The Dawn framing cameras have been developed and built
under the leadership of the Max Planck Institute for Solar System Research,
Katlenburg-Lindau, Germany, with significant contributions by the German
Aerospace Center (DLR) Institute of Planetary Research, Berlin, and in
coordination with the Institute of Computer and Communication Network
Engineering, Braunschweig. The framing camera project is funded by the Max
Planck Society, DLR and NASA.

To learn more about Dawn and its mission to the asteroid belt, and to see the new
visuals, visit: http://www.nasa.gov/dawn or http://dawn.jpl.nasa.gov .

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Prolific NASA Orbiter Reaches Five-Year Mark

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109 PHONE 818-354-5011
http://www.jpl.nasa.gov

Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
guy.webster@jpl.nasa.gov

Dwayne Brown 202-358-1726
NASA Headquarters, Washington
dwayne.c.brown@nasa.gov

News release: 2011-073 March 9, 2011

Prolific NASA Orbiter Reaches Five-Year Mark

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2011-073&cid=release_2011-073

PASADENA, Calif. -- NASA's versatile Mars Reconnaissance Orbiter, which began orbiting
Mars five years ago tomorrow, March 10, has radically expanded our knowledge of the Red
Planet and is now working overtime.

The mission has provided copious information about ancient environments, ice-age-scale climate
cycles and present-day changes on Mars.

The orbiter observes Mars' surface, subsurface and atmosphere in unprecedented detail. The
spacecraft's large solar panels and dish antenna have enabled it to transmit more data to Earth --
131 terabits and counting, including more than 70,000 images -- than all other interplanetary
missions combined. Yet many things had to go well for the mission to achieve these milestones.

After a seven-month journey from Earth, the spacecraft fired its six main engines for nearly 27
minutes as it approached Mars on March 10, 2006. Mars could not capture it into orbit without
this critically timed maneuver to slow the spacecraft. The orbiter's intended path took it behind
Mars, out of communication, during most of the engine burn.

"That was tense, waiting until the spacecraft came back out from behind Mars and we had
contact," recalled Dan Johnston, now the mission's deputy project manager at NASA's Jet
Propulsion Laboratory, Pasadena, Calif.

The Mars Reconnaissance Orbiter mission met all its science goals in a two-year primary science
phase. Two extensions, the latest beginning in 2010, have added to the bounty of science returns.

The mission has illuminated three very different periods of Mars history. Its observations of the
heavily cratered terrains of Mars, the oldest on the planet, show that different types of ancient
watery environments formed water-related minerals. Some of these would have been more
favorable for life than others.

In more recent times, water appears to have cycled as a gas between polar ice deposits and lower-
latitude deposits of ice and snow. Extensive layering in ice or rock probably took hundreds of
thousands to millions of years to form and, like ice ages on Earth, is linked to cyclic changes in
the tilt of the planet's rotation axis and the changing intensity of sunlight near the poles.

The present climate is also dynamic, with volatile carbon dioxide and, just possibly, summertime
liquid water modifying gullies and forming new streaks. With observations of new craters,
avalanches and dust storms, the orbiter has shown a partially frozen world, but not frozen in
time, as change continues today.

In addition to its science observations, the mission provides support for other spacecraft as they
land and operate on the surface. The orbiter's cameras captured the Phoenix Mars Lander as it
parachuted to the surface in 2008 and monitored the atmosphere for dust storms that would
affect Phoenix and the Mars Exploration Rovers Spirit and Opportunity. The Mars
Reconnaissance Orbiter augmented NASA's Mars Odyssey in performing relay functions for
these missions.

JPL's Phil Varghese, project manager for the Mars Reconnaissance Orbiter, said, "The spacecraft
is still in excellent health. After five years at Mars, it continues with dual capabilities for
conducting science observations, monitoring the Mars environment and serving as a relay."

The orbiter has examined potential landing sites for NASA's Mars Science Laboratory mission,
which will land a rover named Curiosity at one of those sites in August 2012. "We are preparing
to support the arrival of the Mars Science Laboratory and the rover's surface operations,"
Varghese said. "In the meantime, we will extend the science observations into a third Martian
year." One Mars year lasts nearly two Earth years.

The orbiter's Mars Color Imager has produced more than four Earth years of daily global weather
maps. More than 18,500 images from the High Resolution Imaging Science Experiment camera
have resolved features as small as a desk in target areas scattered around the planet that,
combined, cover about as much ground as Alaska. More than 36,900 images from the Context
Camera cover nearly two-thirds of the surface of Mars at a resolution that allows detection of
features the size of large buildings.

The Compact Reconnaissance Spectrometer for Mars has mapped minerals on more than three-
fourths of the planet's surface. The Mars Climate Sounder has monitored atmospheric
temperature and aerosols with more than 59 million soundings. The Shallow Radar has checked
for underground layers in more than 8,600 swaths of ground-penetrating observations.

"Each Mars year is unique, and additional coverage gives us a better chance to understand the
nature of changes in the atmosphere and on the surface," said JPL's Rich Zurek, project scientist
for the Mars Reconnaissance Orbiter. "We have already learned that Mars is a more dynamic and
diverse planet than what we knew five years ago. We continue to see new things."

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars
Reconnaissance Orbiter for NASA's Science Mission Directorate in Washington. Lockheed
Martin Space Systems, Denver, built the orbiter and partners with JPL in spacecraft operations.
For more about the Mars Reconnaissance Orbiter, visit http://www.nasa.gov/mro .

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Color View from Orbit Shows Mars Rover Beside Crater

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE 818-354-5011
http://www.jpl.nasa.gov

Guy Webster 818-354-0474
Jet Propulsion Laboratory, Pasadena, Calif.
guy.webster@jpl.nasa.gov

Feature: 2011-072 March 9, 2011

Color View from Orbit Shows Mars Rover Beside Crater

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2011-072&cid=release_2011-072

NASA's Mars Exploration Rover Opportunity has nearly completed its three-month examination
of a crater informally named "Santa Maria," but before the rover resumes its overland trek, an
orbiting camera has provided a color image of Opportunity beside Santa Maria.

The High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars
Reconnaissance Orbiter acquired the image on March 1, while Opportunity was extending its
robotic arm to take close-up photos of a rock called "Ruiz Garcia." From orbit, the tracks
Opportunity made as it approached the crater from the west are clearly visible. Santa Maria
crater is about 90 meters (295 feet) in diameter.

The HiRISE image is at http://photojournal.jpl.nasa.gov/catalog/PIA13803 . March 1
corresponded to the 2,524th Martian day, or sol, of Opportunity's work on Mars. A raw image
from Opportunity's front hazard-avoidance camera from the same day, showing the arm
extended to Ruiz Garcia, is at
http://marsrovers.jpl.nasa.gov/gallery/all/1/f/2524/1F352255948EFFB1F5P1110L0M1.HTML .
To complete the scale of imaging, a raw image taken by Opportunity's microscopic imager that
day, showing textural detail of the rock, is at
http://marsrovers.jpl.nasa.gov/gallery/all/1/m/2524/1M352254519EFFB1F5P2935M2M1.HTML .

Opportunity completed its three-month prime mission on Mars in April 2004 and has been
working in bonus extended missions since then. The Mars Reconnaissance Orbiter, which
arrived at Mars on March 10, 2006, has also completed its prime mission and is operating in an
extended mission.

The High Resolution Imaging Science Experiment is operated by the University of Arizona,
Tucson. The instrument was built by Ball Aerospace & Technologies Corp., Boulder, Colo.
NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in
Pasadena, manages the Mars Reconnaissance Orbiter and the Mars Exploration Rover projects
for NASA's Science Mission Directorate, Washington, and built Opportunity and its twin rover,
Spirit. Lockheed Martin Space Systems, Denver, is NASA's industry partner for the Mars
Reconnaissance Orbiter project and built that spacecraft.

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Some of Mars' Missing Carbon Dioxide May be Buried

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109. TELEPHONE 818-354-5011
http://www.jpl.nasa.gov

Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
guy.webster@jpl.nasa.gov

Lauren Gold 607-255-9736
Cornell University, Ithaca, N.Y.
lg34@cornell.edu

Geoffrey Brown 240-228-5618
Johns Hopkins University Applied Physics Laboratory, Laurel, Md.
Geoffrey.Brown@jhuapl.edu

News release: 2011-071 March 8, 2011

Some of Mars' Missing Carbon Dioxide May be Buried

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2011-071&cid=release_2011-071

HOUSTON -- Rocks on Mars dug from far underground by crater-blasting impacts are providing
glimpses of one possible way Mars' atmosphere has become much less dense than it used to be.

At several places where cratering has exposed material from depths of about 5 kilometers (3
miles) or more beneath the surface, observations by a mineral-mapping instrument on NASA's
Mars Reconnaissance Orbiter indicate carbonate minerals.

These are not the first detections of carbonates on Mars. However, compared to earlier findings,
they bear closer resemblance to what some scientists have theorized for decades about the
whereabouts of Mars' "missing" carbon. If deeply buried carbonate layers are found to be
widespread, they would help answer questions about the disappearance of most of ancient Mars'
atmosphere, which is deduced to have been thick and mostly carbon dioxide. The carbon that
goes into formation of carbonate minerals can come from atmospheric carbon dioxide.

"We're looking at a pretty lucky location in terms of exposing something that was deep beneath
the surface," said planetary scientist James Wray of Cornell University, Ithaca, N.Y., who
reported the latest carbonate findings today at the Lunar and Planetary Science Conference near
Houston. Huygens crater, a basin 467 kilometers (290 miles) in diameter in the southern
highlands of Mars, had already hoisted material from far underground, and then the rim of
Huygens, containing the lifted material, was drilled into by a smaller, unnamed cratering event.

Observations in the high-resolution mode of the Compact Reconnaissance Imaging Spectrometer
for Mars (CRISM) instrument on the Mars Reconnaissance Orbiter show spectral characteristics
of calcium or iron carbonate at this site. Detections of clay minerals in lower-resolution mapping
mode by CRISM had prompted closer examination with the spectrometer, and the carbonates are
found near the clay minerals. Both types of minerals typically form in wet environments.

The occurrence of this type of carbonate in association with the largest impact features suggests
that it was buried by a few kilometers (or miles) of younger rocks, possibly including volcanic
flows and fragmented material ejected from other, nearby impacts.

These findings reinforce a report by other researchers five months ago identifying the same types
of carbonate and clay minerals from CRISM observation of a site about 1,000 kilometers (600
miles) away. At that site, a meteor impact has exposed rocks from deep underground, inside
Leighton crater. In their report of that discovery, Joseph Michalski of the Planetary Science
Institute, Tucson, Ariz., and Paul Niles of NASA Johnson Space Center, Houston, proposed that
the carbonates at Leighton "might be only a small part of a much more extensive ancient
sedimentary record that has been buried by volcanic resurfacing and impact ejecta."

Carbonates found in rocks elsewhere on Mars, from orbit and by NASA's Spirit rover, are rich in
magnesium. Those could form from reaction of volcanic deposits with moisture, Wray said. "The
broader compositional range we're seeing that includes iron-rich and calcium-rich carbonates
couldn't form as easily from just a little bit of water reacting with igneous rocks. Calcium
carbonate is what you typically find on Earth's ocean and lake floors."

He said the carbonates at Huygens and Leighton "fit what would be expected from atmospheric
carbon dioxide interacting with ancient bodies of water on Mars." Key additional evidence
would be to find similar deposits in other regions of Mars. A hunting guide for that search is the
CRISM low-resolution mapping, which has covered about three-fourths of the planet and
revealed clay-mineral deposits at thousands of locations.

"A dramatic change in atmospheric density remains one of the most intriguing possibilities about
early Mars," said Mars Reconnaissance Orbiter Project Scientist Richard Zurek, of NASA's Jet
Propulsion Laboratory, Pasadena, Calif. "Increasing evidence for liquid water on the surface of
ancient Mars for extended periods continues to suggest that the atmosphere used to be much
thicker."

Carbon dioxide makes up nearly all of today's Martian air and likely was most of a thicker early
atmosphere, too. In today's thin, cold atmosphere, liquid water quickly freezes or boils away.

What became of that carbon dioxide? NASA will launch the Mars Atmosphere and Volatile
Evolution Mission (MAVEN) in 2013 to investigate processes that could have stripped the gas
from the top of the atmosphere into interplanetary space. Meanwhile, CRISM and other
instruments now in orbit continue to look for evidence that some of the carbon dioxide in that
ancient atmosphere was removed, in the presence of liquid water, by formation of carbonate
minerals now buried far beneath the present surface.

The Johns Hopkins University Applied Physics Laboratory, Laurel, Md., provided and operates
CRISM, one of six instruments on the Mars Reconnaissance Orbiter. JPL, a division of the
California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter
project and the Mars Exploration Program for the NASA Science Mission Directorate,
Washington. For more about CRISM, see http://crism.jhuapl.edu . For more about the Mars
Reconnaissance Orbiter, visit http://www.nasa.gov/mro .

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NASA Finds Polar Ice Adding More to Rising Seas

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE 818-354-5011
http://www.jpl.nasa.gov

Alan Buis 818-354-0474
Jet Propulsion Laboratory, Pasadena, Calif.
Alan.buis@jpl.nasa.gov

Janet Wilson 949-824-3969
University of California, Irvine
janethw@uci.edu

News release: 2011-070 March 8, 2011

NASA Finds Polar Ice Adding More to Rising Seas

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2011-070&cid=release_2011-070

PASADENA, Calif. -- The Greenland and Antarctic ice sheets are losing mass at an accelerating
pace, according to a new NASA-funded satellite study. The findings of the study -- the longest to
date of changes in polar ice sheet mass -- suggest these ice sheets are overtaking ice loss from Earth's
mountain glaciers and ice caps to become the dominant contributor to global sea level rise, much
sooner than model forecasts have predicted.

The nearly 20-year study reveals that in 2006, a year in which comparable results for mass loss in
mountain glaciers and ice caps are available from a separate study conducted using other methods, the
Greenland and Antarctic ice sheets lost a combined mass of 475 gigatonnes a year on average. That's
enough to raise global sea level by an average of 1.3 millimeters (.05 inches) a year. (A gigatonne is
one billion metric tons, or more than 2.2 trillion pounds.)

The pace at which the polar ice sheets are losing mass was found to be accelerating rapidly. Each year
over the course of the study, the two ice sheets lost a combined average of 36.3 gigatonnes more than
they did the year before. In comparison, the 2006 study of mountain glaciers and ice caps estimated
their loss at 402 gigatonnes a year on average, with a year-over-year acceleration rate three times
smaller than that of the ice sheets.

"That ice sheets will dominate future sea level rise is not surprising -- they hold a lot more ice mass
than mountain glaciers," said lead author Eric Rignot, jointly of NASA's Jet Propulsion Laboratory,
Pasadena, Calif., and the University of California, Irvine. "What is surprising is this increased
contribution by the ice sheets is already happening. If present trends continue, sea level is likely to be
significantly higher than levels projected by the United Nations Intergovernmental Panel on Climate
Change in 2007. Our study helps reduce uncertainties in near-term projections of sea level rise."

Rignot's team combined nearly two decades (1992-2009) of monthly satellite measurements with
advanced regional atmospheric climate model data to examine changes in ice sheet mass and trends in
acceleration of ice loss.

The study compared two independent measurement techniques. The first characterized the difference
between two sets of data: interferometric synthetic aperture radar data from European, Canadian and
Japanese satellites and radio echo soundings, which were used to measure ice exiting the ice sheets;
and regional atmospheric climate model data from Utrecht University, The Netherlands, used to
quantify ice being added to the ice sheets. The other technique used eight years of data from the
NASA/German Aerospace Center's Gravity Recovery and Climate Experiment (Grace) satellites,
which track minute changes in Earth's gravity field due to changes in Earth's mass distribution,
including ice movement.

The team reconciled the differences between techniques and found them to be in agreement, both for
total amount and rate of mass loss, over their data sets' eight-year overlapping period. This validated
the data sets, establishing a consistent record of ice mass changes since 1992.

The team found that for each year over the 18-year study, the Greenland ice sheet lost mass faster
than it did the year before, by an average of 21.9 gigatonnes a year. In Antarctica, the year-over-year
speedup in ice mass lost averaged 14.5 gigatonnes.

"These are two totally independent techniques, so it is a major achievement that the results agree so
well," said co-author Isabella Velicogna, also jointly with JPL and UC Irvine. "It demonstrates the
tremendous progress that's being made in estimating how much ice the ice sheets are gaining and
losing, and in analyzing Grace's time-variable gravity data."

The authors conclude that, if current ice sheet melting rates continue for the next four decades, their
cumulative loss could raise sea level by 15 centimeters (5.9 inches) by 2050. When this is added to the
predicted sea level contribution of 8 centimeters (3.1 inches) from glacial ice caps and 9 centimeters
(3.5 inches) from ocean thermal expansion, total sea level rise could reach 32 centimeters (12.6
inches). While this provides one indication of the potential contribution ice sheets could make to sea
level in the coming century, the authors caution that considerable uncertainties remain in estimating
future ice loss acceleration.

Study results are published this month in Geophysical Research Letters. Other participating
institutions include the Institute for Marine and Atmospheric Research, Utrecht University, The
Netherlands; and the National Center for Atmospheric Research, Boulder, Colo.

JPL developed Grace and manages the mission for NASA. The University of Texas Center for Space
Research in Austin has overall mission responsibility. GeoForschungsZentrum Potsdam (GFZ),
Potsdam, Germany, is responsible for German mission elements.

More on Grace is online at http://www.csr.utexas.edu/grace/ and http://grace.jpl.nasa.gov/ .

JPL is managed for NASA by the California Institute of Technology in Pasadena.

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