Saturday, August 2, 2014

Cassini Spacecraft Reveals 101 Geysers and More on Icy Saturn Moon

Cassini Spacecraft Reveals 101 Geysers and More on Icy Saturn Moon:

Elevated View of Enceladus' South Pole
This view looks across the geyser basin of Saturn's moon Enceladus, along fractures spewing water vapor and ice particles into space. Cassini scientists have pinpointed the source locations of about 100 geysers and gained new insights into what powers them. Image credit: NASA/JPL-Caltech/SSI
› Full image and caption


July 28, 2014

Scientists using mission data from NASA's Cassini spacecraft have identified 101 distinct geysers erupting on Saturn's icy moon Enceladus. Their analysis suggests it is possible for liquid water to reach from the moon's underground sea all the way to its surface.

These findings, and clues to what powers the geyser eruptions, are presented in two articles published in the current online edition of the Astronomical Journal.

Over a period of almost seven years, Cassini's cameras surveyed the south polar terrain of the small moon, a unique geological basin renowned for its four prominent "tiger stripe" fractures and the geysers of tiny icy particles and water vapor first sighted there nearly 10 years ago. The result of the survey is a map of 101 geysers, each erupting from one of the tiger stripe fractures, and the discovery that individual geysers are coincident with small hot spots. These relationships pointed the way to the geysers' origin.

After the first sighting of the geysers in 2005, scientists suspected that repeated flexing of Enceladus by Saturn's tides as the moon orbits the planet had something to do with their behavior. One suggestion included the back-and-forth rubbing of opposing walls of the fractures generating frictional heat that turned ice into geyser-forming vapor and liquid.

Alternate views held that the opening and closing of the fractures allowed water vapor from below to reach the surface. Before this new study, it was not clear which process was the dominating influence. Nor was it certain whether excess heat emitted by Enceladus was everywhere correlated with geyser activity.

To determine the surface locations of the geysers, researchers employed the same process of triangulation used historically to survey geological features on Earth, such as mountains. When the researchers compared the geysers' locations with low-resolution maps of thermal emission, it became apparent the greatest geyser activity coincided with the greatest thermal radiation. Comparisons between the geysers and tidal stresses revealed similar connections. However, these correlations alone were insufficient to answer the question, "What produces what?"

The answer to this mystery came from comparison of the survey results with high-resolution data collected in 2010 by Cassini's heat-sensing instruments. Individual geysers were found to coincide with small-scale hot spots, only a few dozen feet (or tens of meters) across, which were too small to be produced by frictional heating, but the right size to be the result of condensation of vapor on the near-surface walls of the fractures. This immediately implicated the hot spots as the signature of the geysering process.

"Once we had these results in hand, we knew right away heat was not causing the geysers, but vice versa," said Carolyn Porco, leader of the Cassini imaging team from the Space Science Institute in Boulder, Colorado, and lead author of the first paper. "It also told us the geysers are not a near-surface phenomenon, but have much deeper roots."

Thanks to recent analysis of Cassini gravity data, the researchers concluded the only plausible source of the material forming the geysers is the sea now known to exist beneath the ice shell. They also found that narrow pathways through the ice shell can remain open from the sea all the way to the surface, if filled with liquid water.

In the companion paper, the authors report the brightness of the plume formed by all the geysers, as seen with Cassini's high-resolution cameras, changes periodically as Enceladus orbits Saturn. Armed with the conclusion that the opening and closing of the fractures modulates the venting, the authors compared the observations with the expected venting schedule due to tides.

They found the simplest model of tidal flexing provides a good match for the brightness variations Cassini observes, but it does not predict the time when the plume begins to brighten. Some other important effect is present and the authors considered several in the course of their work.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory (JPL) in Pasadena, California, manages the mission for NASA's Science Mission Directorate in Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team consists of scientists from the United States, England, France and Germany. The imaging team is based at the Space Science Institute.

Additional details, images and an animation are available at:

http://www.ciclops.org/view_event/202

More information about Cassini is available at:

http://www.nasa.gov/cassini

http://saturn.jpl.nasa.gov

Preston Dyches

Jet Propulsion Laboratory, Pasadena, Calif.

818-354-7013

preston.dyches@jpl.nasa.gov


Dwayne Brown

NASA Headquarters, Washington

202-358-1726

dwayne.c.brown@nasa.gov


Steve Mullins

Space Science Institute, Boulder, Colo.

720-974-5859

media@ciclops.org


2014-246
Posted by Nelio Inacio at 6:33 AM 0 comments

Printing the Metals of the Future

Printing the Metals of the Future:

Laser Printing of Gradient Metals
Scientists make a rocket nozzle using a new 3-D printing technique that allows for multiple metallic properties in the same object.
Credit: NASA-JPL/Caltech
› Full image and caption


July 28, 2014

3-D printers can create all kinds of things, from eyeglasses to implantable medical devices, straight from a computer model and without the need for molds. But for making spacecraft, engineers sometimes need custom parts that traditional manufacturing techniques and standard 3-D printers can't create, because they need to have the properties of multiple metals. Now, researchers at NASA's Jet Propulsion Laboratory in Pasadena, California, are implementing a printing process that transitions from one metal or alloy to another in a single object.

"You can have a continuous transition from alloy to alloy to alloy, and you can study a wide range of potential alloys," said R. Peter Dillon, a technologist at JPL. "We think it's going to change materials research in the future."

Although gradient alloys have been created in the past in research and development settings, this is the first time these composite materials have been used in making objects, such as a mount for a mirror, said John Paul Borgonia, a JPL mechanical engineer.

Why would you need to make a machine part like this? Say you want a metal object where you would like the ends to have different properties. One side could have a high melting temperature and the other a low density, or one side could be magnetic and the other not. Of course, you could separately make both halves of the object from their respective metals and then weld them together. But the weld itself may be brittle, so that your new object might fall apart under stress. That's not a good idea if you are constructing an interplanetary spacecraft, for example, which cannot be fixed once it is deployed.

JPL scientists have been developing a technique to address this problem since 2010. An effort to improve the methods of combining parts made of different materials in NASA's Mars Science Laboratory mission, which safely landed the Curiosity rover on the Red Planet in 2012, inspired a project to 3-D print components with multiple alloy compositions.

Researchers from JPL, the California Institute of Technology, Pasadena, and Pennsylvania State University, University Park, joined forces to tackle the issue. The result has implications for space travel and machinery on our own planet.

"We're taking a standard 3-D printing process and combining the ability to change the metal powder that the part is being built with on the fly," said Douglas Hofmann, a researcher in material science and metallurgy at JPL, and visiting associate at Caltech. "You can constantly be changing the composition of the material."

In their new technique, Hofmann and his colleagues deposit layers of metal on a rotating rod, thus transitioning metals from the inside out, rather than adding layers from bottom to top, as in the more traditional 3-D printing technique. A laser melts metal powder to create the layers.

Future space missions may incorporate parts made with this technique. The auto industry and the commercial aerospace industry may also find it useful, Hofmann said.

A report on this work was published in Scientific Reports on June 19. Coauthors include Douglas Hofmann; Scott Roberts, Joanna Kolodziejska and Andrew A. Shapiro from Caltech and JPL; R. Peter Dillon, Jong-ook Suh, and John-Paul Borgonia from JPL; and Richard Otis and Zi-Kui Liu from Pennsylvania State University. The work was funded by NASA. Caltech manages JPL for NASA.

Elizabeth Landau

818-354-6425

Jet Propulsion Laboratory, Pasadena, Calif.

elizabeth.landau@jpl.nasa.gov


Caltech science writer Cynthia Eller contributed to this release.


2014-247
Posted by Nelio Inacio at 6:32 AM 0 comments

New NASA Studies to Examine Climate/Vegetation Links

New NASA Studies to Examine Climate/Vegetation Links:

Two new spaceborne Earth-observing instruments will help scientists better understand how global forests
Two new spaceborne Earth-observing instruments will help scientists better understand how global forests and ecosystems are affected by changes in climate and land use change. This image of the Amazon rainforest is from a 2010 global map of the height of the world's forests based on multiple satellite datasets. Image credit: NASA Earth Observatory
› Larger image


July 30, 2014

NASA has selected proposals for two new instruments, including one from NASA's Jet Propulsion Laboratory, Pasadena, California, that will observe changes in global vegetation from the International Space Station. The sensors will give scientists new ways to see how forests and ecosystems are affected by changes in climate or in land use.

A high-resolution, multiple-wavelength imaging spectrometer from JPL will study the effectiveness of water use by vegetation. This instrument will be completed in 2018 and will not cost more than $30 million. A laser-based system from the University of Maryland, College Park, will observe the structure of forest canopy. This instrument will be completed in 2019 and will not cost more than $94 million.

"We are excited to expand the use of the International Space Station to make critical Earth observations that will help scientists understand the diversity of forests and vegetation and their response to a changing climate," said John Grunsfeld, associate administrator of NASA's Science Mission Directorate in Washington. "These innovative Earth Venture Instruments will join a growing suite of NASA Earth-observing sensors to be deployed to the station starting this year."

The instruments were competitively selected from 20 proposals submitted to NASA's Earth Venture Instrument program. Part of the Earth System Science Pathfinder program, Earth Venture investigations are small, targeted science investigations that complement NASA's larger research missions. The National Research Council recommended in 2007 that NASA undertake this type of regularly solicited, quick-turnaround project. The program's first selection was awarded in 2010.

Simon Hook of JPL is the principal investigator for the ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS). This project will use a high-resolution thermal infrared radiometer to measure plant evapotranspiration, the loss of water from growing leaves and evaporation from the soil. These data will reveal how ecosystems change with climate and provide a critical link between the water cycle and effectiveness of plant growth, both natural and agricultural.

The ECOSTRESS team has extensive experience in development and analysis of thermal infrared spectroscopic images of Earth's surface. Hook has served as project scientist for the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Earth Observing System Terra satellite and has been involved in numerous suborbital field campaigns. The team includes partnerships with the U.S. Department of Agriculture, Beltsville, Maryland, and Maricopa, Arizona; Princeton University, Princeton, New Jersey; and the University of Idaho, Moscow, Idaho.

Ralph Dubayah, of the University of Maryland, is the principal investigator for the Global Ecosystem Dynamics Investigation (GEDI) Lidar. This project will use a laser-based system to study a range of climates, including the observation of the forest canopy structure over the tropics, and the tundra in high northern latitudes. These data will help scientists better understand the changes in natural carbon storage within the carbon cycle from both human-influenced activities and natural climate variations.

The GEDI team has extensive experience in observing and modeling forest and vegetation dynamics. Dubayah has led numerous vegetation lidar observations from suborbital platforms throughout his career. The team includes partnerships with NASA's Goddard Space Flight Center, Greenbelt, Maryland; Woods Hole Research Center, Woods Hole, Massachusetts; the U.S. Forest Service, Ogden, Utah; and Brown University, Providence, Rhode Island.

The International Space Station provides several in-orbit capabilities useful to both instruments. The space station's orbit is inclined relative to the poles, providing more observation time of forests and vegetation over temperate land masses than possible from the polar orbits commonly used for other types of Earth observations. The GEDI laser requires significant power resources, which the space station can provide. Also, the relatively low altitude of the station's orbit, about 260 miles (418 kilometers) up, benefits GEDI by ensuring a higher return energy for laser pulses reflected from the ground.

In 2012, NASA selected the first Earth Venture Instrument investigation, the Tropospheric Emissions: Monitoring of Pollution (TEMPO) mission. TEMPO will be the first space-based sensor to monitor major air pollutants across North America hourly during daytime. It will share a ride on a commercial satellite as a hosted payload and orbit about 22,000 miles (35,400 kilometers) above the equator.

NASA's Langley Research Center in Hampton, Virginia, manages the Earth System Science Pathfinder program for NASA's Science Mission Directorate. The missions in this program provide an innovative approach to address Earth science research with periodic windows of opportunity to accommodate new scientific priorities. For more information, visit:

http://go.nasa.gov/MKvgJO

Alan Buis

Jet Propulsion Laboratory, Pasadena, California

818-354-0474

alan.buis@jpl.nasa.gov


Steve Cole

NASA Headquarters, Washington

202-358-0918

stephen.e.cole@nasa.gov


2014-249
Posted by Nelio Inacio at 6:32 AM 0 comments

Mars 2020 Rover's PIXL to Focus X-Rays on Tiny Targets

Mars 2020 Rover's PIXL to Focus X-Rays on Tiny Targets:

Artist's concept of the payload for NASA's Mars 2020 rover
This diagram shows components of the investigations payload for NASA's Mars 2020 rover mission. Image credit: NASA/JPL-Caltech

› Full image and caption


July 31, 2014

One of seven instruments selected for a Mars rover that NASA is developing for launch in 2020 would be able to identify chemical elements in target spots as small as a grain of table salt.

PIXL, for Planetary Instrument for X-Ray Lithochemistry, would be mounted at the end of the rover's robotic arm so that it can be placed next to a rock or soil target. It is designed to provide finer-scale identification of elemental composition than ever before possible on Mars.

The instrument's capabilities would help NASA's Mars 2020 rover mission accomplish its goals, which include seeking evidence for past life on Mars.

"If you are looking for signs of ancient life, you want to look at a small scale and get detailed information about chemical elements present," said PIXL Principal Investigator Abigail Allwood of NASA's Jet Propulsion Laboratory, Pasadena, California.

PIXL will be fast. Its intended use is to spend a few seconds to 2 minutes with the instrument's X-ray focused on each spot to be analyzed, then move the beam to another spot, working in a linear or grid pattern to produce a detailed map of the elements in the rock or soil target. The mapped area would be up to about the size of a postage stamp.

The element-identification method is X-ray fluorescence. It reads the X-rays distinctively emitted by various types of atoms when they are excited by X-rays coming from the instrument.

PIXL's design also incorporates a high-resolution camera so that the map of elemental composition can be analyzed in conjunction with visible characteristics of the target area.

"We can correlate fine-scale textures and features with very detailed information about the chemistry," Allwood said. "Understanding these relationships is crucial for investigation goals such as searching for microbial biosignatures."

NASA announced selection of PIXL and six other investigations for the Mars 2020 rover's payload on July 31, 2014.

The Mars 2020 mission will be based on the design of the highly successful Mars Science Laboratory rover, Curiosity, which landed almost two years ago and currently is operating on Mars. The new rover will carry more sophisticated, upgraded hardware and new instruments to conduct geological assessments of the rover's landing site, determine the potential habitability of the environment, and directly search for signs of ancient Martian life.

Scientists will use the Mars 2020 rover to identify and select a collection of rock and soil samples that will be stored for potential return to Earth by a future mission. The Mars 2020 mission is responsive to the science objectives recommended by the National Research Council's 2011 Planetary Science Decadal Survey.

The Mars 2020 rover also will help advance our knowledge of how future human explorers could use natural resources available on the surface of the Red Planet. An ability to live off the Martian land would transform future exploration of the planet. Designers of future human expeditions can use this mission to understand the hazards posed by Martian dust and demonstrate technology to process carbon dioxide from the atmosphere to produce oxygen. These experiments will help engineers learn how to use Martian resources to produce oxygen for human respiration and potentially for use as an oxidizer for rocket fuel.

The California Institute of Technology, Pasadena, manages JPL for NASA.

Guy Webster

Jet Propulsion Laboratory, Pasadena, Calif.

818-354-6278

guy.webster@jpl.nasa.gov



2014-253
Posted by Nelio Inacio at 6:31 AM 0 comments

SHERLOC to Micro-Map Mars Minerals and Carbon Rings

SHERLOC to Micro-Map Mars Minerals and Carbon Rings:

Artist's concept of the payload for NASA's Mars 2020 rover
This diagram shows components of the investigations payload for NASA's Mars 2020 rover mission. Image credit: NASA/JPL-Caltech


› Full image and caption


July 31, 2014

An ultraviolet-light instrument on the robotic arm of NASA's Mars 2020 rover will use two types of ultraviolet-light spectroscopy, plus a versatile camera, to help meet the mission's ambitious goals, including a search for signs of past life on Mars and selection of rock samples for possible return to Earth.

It is called SHERLOC, for Scanning Habitable Environments with Raman & Luminescence for Organics and Chemicals.

"This instrument uses two distinct detection strategies," said its principal investigator, Luther Beegle of NASA's Jet Propulsion Laboratory in Pasadena, California. "It can detect an important class of carbon molecules with high sensitivity, and it also identifies minerals that provide information about ancient aqueous environments."

SHERLOC will shine a tiny dot of ultraviolet laser light at a target. This causes two different spectral phenomena to occur, which the instrument captures for analysis. The first is a distinctive fluorescence, or glow, from molecules that contain rings of carbon atoms. Such molecules may be clues to whether evidence of past life has been preserved. The second is an effect called Raman scattering, which can identify certain minerals, including ones formed from evaporation of salty water, and organic compounds. This dual use enables powerful analysis of many different compounds on the identical spot.

A moving mirror in the instrument will shift pointing of the ultraviolet laser beam in a scanning pattern to provide a map of the ingredients at a microscopic scale. The laser beam has a diameter of 50 microns -- about half the thickness of a piece of paper. It will provide information on that scale within a target area about half the breadth of a dime.

In addition, the instrument will include a contextual camera utilizing hardware originally developed by Malin Space Science Systems, San Diego, for the Mars Hand Lens Imager (MAHLI) camera on NASA's Curiosity Mars rover. This context imager will enable researchers to correlate the composition information with visible features in the target, resulting in more information than composition alone.

Beegle said, "We'll be able not just to detect these chemicals and minerals with high sensitivity, but we will produce powerful chemical maps. For example, we can see whether organics are clumped together or diffuse, and we can correlate minerals with visible veins or grains in the rock. This also allows us to integrate our results with the other instruments for even more informational content on the samples."

NASA announced selection of SHERLOC and six other investigations for the Mars 2020 rover's payload on July 31, 2014.

The Mars 2020 mission will be based on the design of the highly successful Mars Science Laboratory rover, Curiosity, which landed almost two years ago, and currently is operating on Mars. The new rover will carry more sophisticated, upgraded hardware and new instruments to conduct geological assessments of the rover's landing site, determine the potential habitability of the environment, and directly search for signs of ancient Martian life.

Scientists will use the Mars 2020 rover to identify and select a collection of rock and soil samples that will be stored for potential return to Earth by a future mission. The Mars 2020 mission is responsive to the science objectives recommended by the National Research Council's 2011 Planetary Science Decadal Survey.

The Mars 2020 rover also will help advance our knowledge of how future human explorers could use natural resources available on the surface of the Red Planet. An ability to live off the Martian land would transform future exploration of the planet. Designers of future human expeditions can use this mission to understand the hazards posed by Martian dust and demonstrate technology to process carbon dioxide from the atmosphere to produce oxygen. These experiments will help engineers learn how to use Martian resources to produce oxygen for human respiration and potentially for use as an oxidizer for rocket fuel.

The California Institute of Technology, Pasadena, manages JPL for NASA.

Guy Webster

Jet Propulsion Laboratory, Pasadena, Calif.

818-354-6278

guy.webster@jpl.nasa.gov



2014-254
Posted by Nelio Inacio at 6:31 AM 0 comments

Thursday, July 31, 2014

NASA Telescopes Help Solve Ancient Supernova Mystery

NASA Telescopes Help Solve Ancient Supernova Mystery:

All Eyes on Oldest Recorded Supernova
This image combines data from four different space telescopes to create a multi-wavelength view of all that remains of the oldest documented example of a supernova, called RCW 86.

› Full image and caption


October 24, 2011

PASADENA, Calif. -- A mystery that began nearly 2,000 years ago, when Chinese astronomers witnessed what would turn out to be an exploding star in the sky, has been solved. New infrared observations from NASA's Spitzer Space Telescope and Wide-field Infrared Survey Explorer, or WISE, reveal how the first supernova ever recorded occurred and how its shattered remains ultimately spread out to great distances.


The findings show that the stellar explosion took place in a hollowed-out cavity, allowing material expelled by the star to travel much faster and farther than it would have otherwise.


"This supernova remnant got really big, really fast," said Brian J. Williams, an astronomer at North Carolina State University in Raleigh. Williams is lead author of a new study detailing the findings online in the Astrophysical Journal. "It's two to three times bigger than we would expect for a supernova that was witnessed exploding nearly 2,000 years ago. Now, we've been able to finally pinpoint the cause."


A new image of the supernova, known as RCW 86, is online at http://go.nasa.gov/pnv6Oy .


In 185 A.D., Chinese astronomers noted a "guest star" that mysteriously appeared in the sky and stayed for about 8 months. By the 1960s, scientists had determined that the mysterious object was the first documented supernova. Later, they pinpointed RCW 86 as a supernova remnant located about 8,000 light-years away. But a puzzle persisted. The star's spherical remains are larger than expected. If they could be seen in the sky today in infrared light, they'd take up more space than our full moon.


The solution arrived through new infrared observations made with Spitzer and WISE, and previous data from NASA's Chandra X-ray Observatory and the European Space Agency's XMM-Newton Observatory.


The findings reveal that the event is a "Type Ia" supernova, created by the relatively peaceful death of a star like our sun, which then shrank into a dense star called a white dwarf. The white dwarf is thought to have later blown up in a supernova after siphoning matter, or fuel, from a nearby star.


"A white dwarf is like a smoking cinder from a burnt-out fire," Williams said. "If you pour gasoline on it, it will explode."


The observations also show for the first time that a white dwarf can create a cavity around it before blowing up in a Type Ia event. A cavity would explain why the remains of RCW 86 are so big. When the explosion occurred, the ejected material would have traveled unimpeded by gas and dust and spread out quickly.


Spitzer and WISE allowed the team to measure the temperature of the dust making up the RCW 86 remnant at about minus 325 degrees Fahrenheit, or minus 200 degrees Celsius. They then calculated how much gas must be present within the remnant to heat the dust to those temperatures. The results point to a low-density environment for much of the life of the remnant, essentially a cavity.


Scientists initially suspected that RCW 86 was the result of a core-collapse supernova, the most powerful type of stellar blast. They had seen hints of a cavity around the remnant, and, at that time, such cavities were only associated with core-collapse supernovae. In those events, massive stars blow material away from them before they blow up, carving out holes around them.


But other evidence argued against a core-collapse supernova. X-ray data from Chandra and XMM-Newton indicated that the object consisted of high amounts of iron, a telltale sign of a Type Ia blast. Together with the infrared observations, a picture of a Type Ia explosion into a cavity emerged.


"Modern astronomers unveiled one secret of a two-millennia-old cosmic mystery only to reveal another," said Bill Danchi, Spitzer and WISE program scientist at NASA Headquarters in Washington. "Now, with multiple observatories extending our senses in space, we can fully appreciate the remarkable physics behind this star's death throes, yet still be as in awe of the cosmos as the ancient astronomers."


NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA. For more information about Spitzer, visit http://spitzer.caltech.edu/ and http://www.nasa.gov/spitzer .


JPL manages, and operated, WISE for NASA's Science Mission Directorate. The spacecraft was put into hibernation mode after it scanned the entire sky twice, completing its main objectives. Edward Wright is the principal investigator and is at UCLA. The mission was selected competitively under NASA's Explorers Program managed by the agency's Goddard Space Flight Center in Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory in Logan. The spacecraft was built by Ball Aerospace & Technologies Corp. in Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA. More information is online at http://www.nasa.gov/wise and http://wise.astro.ucla.edu and http://www.jpl.nasa.gov/wise .

Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov


Trent J. Perrotto 202-358-0321

NASA Headquarters, Washington                                                                

trent.j.perrotto@nasa.gov


2011-329
Posted by Nelio Inacio at 1:05 PM 0 comments

NASA's Cassini Makes a New Pass at Enceladus

NASA's Cassini Makes a New Pass at Enceladus:

Enceladus 'E-16' Flyby: Radar Looks at Enceladus
The primary goal of this flyby is to obtain the first detailed radar observation of Enceladus. This will be the first close radar pass of an icy moon besides Titan; the results will enable a comparison of the radar properties of a moon with a known composition (Enceladus) with that of Titan.
› Larger image


November 03, 2011

NASA's Cassini spacecraft will acquire the first detailed radar images of Saturn's moon Enceladus during a flyby on Sunday, Nov. 6. These will be the first high-resolution radar observations made of an icy moon other than Titan. The results will provide new information about the surface of Enceladus and enable researchers to compare its geological features as seen by radar with those of Titan.


The spacecraft will fly past Enceladus at a distance of about 300 miles (500 kilometers) at its closest point. During the encounter, Cassini's synthetic aperture radar will sweep across a long, narrow swath of the surface just north of the moon's south pole. Cassini will use other radar techniques to map much more of the surface of Enceladus at lower resolutions and determine some of the surface's physical properties as the spacecraft approaches and then speeds away from the icy body. 


During this flyby, the mission's visible-light cameras will take images of Enceladus and its famous jets, and the composite infrared spectrometer will make new measurements of hot spots from which the jets emerge. Cassini's ultraviolet imaging spectrograph will also make distant observations of Saturn's moon Dione and its environment.


The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate in Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL.


For more information about the Cassini-Huygens mission visit: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov/ .

Rosemary Sullivant 818-354-0850

Jet Propulsion Laboratory, Pasadena, Calif.

rosemary.sullivant@jpl.nasa.gov

2011-340
Posted by Nelio Inacio at 1:05 PM 0 comments

Voyager 2 to Switch to Backup Thruster Set

Voyager 2 to Switch to Backup Thruster Set:

This artist's concept shows NASA's two Voyager spacecraft exploring a turbulent region of space known as the heliosheath
This artist's concept shows NASA's two Voyager spacecraft exploring a turbulent region of space known as the heliosheath, the outer shell of the bubble of charged particles around our sun. Image credit: NASA/JPL-Caltech
› Full image and caption







November 05, 2011

Voyager Mission Status Report

NASA's Deep Space Network personnel sent commands to the Voyager 2 spacecraft Nov. 4 to switch to the backup set of thrusters that controls the roll of the spacecraft. Confirmation was received today that the spacecraft accepted the commands. The change will allow the 34-year-old spacecraft to reduce the amount of power it requires to operate and use previously unused thrusters as it continues its journey toward interstellar space, beyond our solar system.


Launched in 1977, Voyager 1 and Voyager 2 are each equipped with six sets, or pairs, of thrusters to control their movement. These include three pairs of primary thrusters and three backup, or redundant, pairs. Voyager 2 is currently using the two pairs of backup thrusters that control the pitch and yaw motion of the spacecraft. Switching to the backup thruster pair that controls roll motion will allow engineers to turn off the heater that keeps the fuel line to the primary thruster warm. This will save about 12 watts of power. The spacecraft's power supply now provides about 270 watts of electricity. By reducing its power usage, the spacecraft can continue to operate for another decade even as its available power continues to decline.


The thrusters involved in this switch have fired more than 318,000 times. The backup pair has not been used in flight. Voyager 1 changed to the backup for this same component after 353,000 pulses in 2004 and is now using all three sets of its backup thrusters.


Voyager 2 will relay the results of the switch back to Earth on Nov. 13. The signal will arrive on Earth on Nov. 14. Voyager 2 is currently located about 9 billion miles (14 billion kilometers) from Earth in the "heliosheath" -- the outermost layer of the heliosphere where the solar wind, which streams out from the sun, is slowed by the pressure of interstellar gas.




The Voyagers were built by NASA's Jet Propulsion Laboratory in Pasadena, Calif., which continues to operate both spacecraft. JPL is a division of the California Institute of Technology in Pasadena. The Voyager missions are a part of the NASA Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate. For more information about the Voyager spacecraft, visit: http://www.nasa.gov/voyager .




Rosemary Sullivant 818-354-0880

Jet Propulsion Laboratory, Pasadena, Calif.

Rosemary.sullivant@jpl.nasa.gov


2011-341
Posted by Nelio Inacio at 1:05 PM 0 comments

NASA's Voyager Hits New Region at Solar System Edge

NASA's Voyager Hits New Region at Solar System Edge:

Artist concept of Voyager 1 encountering a stagnation region
Artist concept of Voyager 1 encountering a stagnation region. Image credit: NASA/JPL-Caltech
› Full image and caption







December 05, 2011

PASADENA, Calif. -- NASA's Voyager 1 spacecraft has entered a new region between our solar system and interstellar space. Data obtained from Voyager over the last year reveal this new region to be a kind of cosmic purgatory. In it, the wind of charged particles streaming out from our sun has calmed, our solar system's magnetic field is piled up, and higher-energy particles from inside our solar system appear to be leaking out into interstellar space.

"Voyager tells us now that we're in a stagnation region in the outermost layer of the bubble around our solar system," said Ed Stone, Voyager project scientist at the California Institute of Technology in Pasadena. "Voyager is showing that what is outside is pushing back. We shouldn't have long to wait to find out what the space between stars is really like."

Although Voyager 1 is about 11 billion miles (18 billion kilometers) from the sun, it is not yet in interstellar space. In the latest data, the direction of the magnetic field lines has not changed, indicating Voyager is still within the heliosphere, the bubble of charged particles the sun blows around itself. The data do not reveal exactly when Voyager 1 will make it past the edge of the solar atmosphere into interstellar space, but suggest it will be in a few months to a few years.

The latest findings, described today at the American Geophysical Union's fall meeting in San Francisco, come from Voyager's Low Energy Charged Particle instrument, Cosmic Ray Subsystem and Magnetometer.

Scientists previously reported the outward speed of the solar wind had diminished to zero in April 2010, marking the start of the new region. Mission managers rolled the spacecraft several times this spring and summer to help scientists discern whether the solar wind was blowing strongly in another direction. It was not. Voyager 1 is plying the celestial seas in a region similar to Earth's doldrums, where there is very little wind.

During this past year, Voyager's magnetometer also detected a doubling in the intensity of the magnetic field in the stagnation region. Like cars piling up at a clogged freeway off-ramp, the increased intensity of the magnetic field shows that inward pressure from interstellar space is compacting it.

Voyager has been measuring energetic particles that originate from inside and outside our solar system. Until mid-2010, the intensity of particles originating from inside our solar system had been holding steady. But during the past year, the intensity of these energetic particles has been declining, as though they are leaking out into interstellar space. The particles are now half as abundant as they were during the previous five years.

At the same time, Voyager has detected a 100-fold increase in the intensity of high-energy electrons from elsewhere in the galaxy diffusing into our solar system from outside, which is another indication of the approaching boundary.

"We've been using the flow of energetic charged particles at Voyager 1 as a kind of wind sock to estimate the solar wind velocity," said Rob Decker, a Voyager Low-Energy Charged Particle Instrument co-investigator at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "We've found that the wind speeds are low in this region and gust erratically. For the first time, the wind even blows back at us. We are evidently traveling in completely new territory. Scientists had suggested previously that there might be a stagnation layer, but we weren't sure it existed until now."

Launched in 1977, Voyager 1 and 2 are in good health. Voyager 2 is 9 billion miles (15 billion kilometers) away from the sun.

The Voyager spacecraft were built by NASA's Jet Propulsion Laboratory in Pasadena, Calif., which continues to operate both. JPL is a division of the California Institute of Technology. The Voyager missions are a part of the NASA Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate in Washington. For more information about the Voyager spacecraft, visit: http://www.nasa.gov/voyager .

For more information about NASA media events at the American Geophysical Union meeting, visit: http://www.nasa.gov/agu .

Jia-Rui C. Cook/Alan Buis 818-354-0850/818-653-8339

Jet Propulsion Laboratory, Pasadena, Calif.

jccook@jpl.nasa.gov/alan.d.buis@jpl.nasa.gov

Steve Cole 202-358-0918

NASA Headquarters, Washington                                                             

stephen.e.cole@nasa.gov

2011-372
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Portraits of Moons Captured by Cassini

Portraits of Moons Captured by Cassini:

NASA's Cassini spacecraft obtained this unprocessed image on Dec. 12, 2011
NASA's Cassini spacecraft obtained this unprocessed image on Dec. 12, 2011. The camera was pointing toward Saturn's moon Dione from approximately 69,989 miles (112,636 kilometers) away. Image credit: NASA/JPL-Caltech/SSI

› Full image and caption







December 12, 2011

NASA's Cassini spacecraft successfully completed its closest-ever pass over Saturn's moon Dione on Monday, Dec. 12, slaloming its way through the Saturn system on its way to tomorrow's close flyby of Titan. Cassini is expected to glide about 2,200 miles (3,600 kilometers) over the Titan surface on Dec. 13.


In the selection of the raw images obtained during the Cassini Dione flyby, Dione is sometimes joined by other moons. Mimas appears just beyond the dark side of Dione in one view. In another view, Epimetheus and Pandora appear together, along with Saturn's rings.


This Dione encounter was intended primarily for Cassini's composite infrared spectrometer and radio science subsystem. However, the imaging team did capture views of the distinctive, wispy fractures on the side of Dione that always trails in its orbit around Saturn. It also obtained images of a ridge called Janiculum Dorsa on the hemisphere of Dione that always leads in its orbit around Saturn. While other flybys produced more detailed views of the surface, the best resolved images from this flyby have scales ranging from about 1,100 feet (350 meters) to about 1,600 feet (500 meters) per pixel. Janiculum Dorsa will be imaged by Cassini at higher resolution in May 2012.


All of Cassini's raw images can be seen at http://saturn.jpl.nasa.gov/photos/raw/ .


The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory in Pasadena manages the mission for the agency's Science Mission Directorate in Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations team is based at the Space Science Institute in Boulder, Colo. JPL is a division of Caltech.


For more information about the Cassini-Huygens mission, visit http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini .

Jia-Rui Cook 818-354-0850

Jet Propulsion Laboratory, Pasadena, Calif.

jccook@jpl.nasa.gov


2011-385
NASA's Cassini spacecraft obtained this unprocessed image on Dec. 12, 2011

NASA's Cassini spacecraft obtained this unprocessed image on Dec. 12, 2011. The camera was pointing toward Saturn's moon Dione from approximately 48,236 miles (77,682 kilometers) away. Image credit: NASA/JPL-Caltech/SSI

› Full image and caption


enlarge image

NASA's Cassini spacecraft obtained this unprocessed image on Dec. 12, 2011

NASA's Cassini spacecraft obtained this unprocessed image on Dec. 12, 2011. The camera was pointing toward Saturn's moon Dione from approximately 76,344 miles (122,864 kilometers) away. Image credit: NASA/JPL-Caltech/SSI

› Full image and caption


enlarge image




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Black Hole Caught Red-Handed in a Stellar Homicide

Black Hole Caught Red-Handed in a Stellar Homicide:

Computer-simulated image shows gas from a tidally shredded star
This computer-simulated image shows gas from a tidally shredded star
falling into a black hole. Image credit: NASA/JPL-Caltech/JHU/UCSC

› Full image and caption May 02, 2012

PASADENA, Calif. - Astronomers have gathered the most direct evidence yet of a supermassive black hole shredding a star that wandered too close. NASA's Galaxy Evolution Explorer, a space-based observatory, and the Pan-STARRS1 telescope on the summit of Haleakala in Hawaii were among the first to help identify the stellar remains.


Supermassive black holes, weighing millions to billions times more than the sun, lurk in the centers of most galaxies. These hefty monsters lie quietly until an unsuspecting victim, such as a star, wanders close enough to get ripped apart by their powerful gravitational clutches.


Astronomers had spotted these stellar homicides before, but this is the first time they have identified the victim. Using several ground- and space-based telescopes, a team of astronomers led by Suvi Gezari of the Johns Hopkins University, Baltimore, Md., identified the victim as a star rich in helium gas. The star resides in a galaxy 2.7 billion light-years away. The team's results appear in today's online edition of the journal Nature.


"When the star is ripped apart by the gravitational forces of the black hole, some part of the star's remains falls into the black hole, while the rest is ejected at high speeds," Gezari said. "We are seeing the glow from the stellar gas falling into the black hole over time. We're also witnessing the spectral signature of the ejected gas, which we find to be mostly helium. It is like we are gathering evidence from a crime scene. Because there is very little hydrogen and mostly helium in the gas, we detect from the carnage that the slaughtered star had to have been the helium-rich core of a stripped star."


This observation yields insights about the harsh environment around black holes and the types of stars swirling around them. It is not the first time the unlucky star had a brush with the behemoth black hole.


The team believes the star's hydrogen-filled envelope surrounding the core was lifted off a long time ago by the same black hole. The star may have been near the end of its life. After consuming most of its hydrogen fuel, it had probably ballooned in size, becoming a red giant. Astronomers think the bloated star was looping around the black hole in a highly elliptical orbit, similar to a comet's elongated orbit around the sun. On one of its close approaches, the star was stripped of its puffed-up atmosphere by the black hole's powerful gravity. The stellar remains continued its journey around the center, until it ventured even closer to the black hole to face its ultimate demise.


Astronomers predict stripped stars circle the central black hole of our Milky Way galaxy. These close encounters are rare, occurring roughly every 100,000 years. To find this event, Gezari's team monitored hundreds of thousands of galaxies in ultraviolet light with the Galaxy Evolution Explorer, and in visible light with Pan-STARRS1. Pan-STARRS, short for Panoramic Survey Telescope and Rapid Response System, scans the entire night sky for all kinds of transient phenomena, including supernovae.


The team was looking for a bright flare in ultraviolet light from the nucleus of a galaxy with a previously dormant black hole. Both telescopes spotted one in June 2010. Astronomers continued to monitor the flare as it reached peak brightness a month later and slowly faded during the next 12 months. The brightening event was similar to the explosive energy unleashed by a supernova, but the rise to the peak was much slower, taking nearly one-and-a-half months.


"The longer the event lasted, the more excited we got, because we realized this is either a very unusual supernova or an entirely different type of event, such as a star being ripped apart by a black hole," said team member Armin Rest of the Space Telescope Science Institute in Baltimore.


By measuring the increase in brightness, the astronomers calculated the black hole's mass to be several million suns, which is comparable to the size of our Milky Way's black hole.


Spectroscopic observations with the Multiple Meter Telescope Observatory on Mount Hopkins in Arizona showed the black hole was swallowing lots of helium. Spectroscopy divides light into its rainbow colors, which yields an object's characteristics, such as its temperature and gaseous makeup.


To completely rule out the possibility of an active nucleus flaring up in the galaxy, the team used NASA's Chandra X-ray Observatory to study the hot gas. Chandra showed that the characteristics of the gas didn't match those from an active galactic nucleus.


For images, video and more information about this study, visit: http://hubblesite.org/news/2012/18 .


For graphics and information about the Galaxy Evolution Explorer, visit: http://www.nasa.gov/galex and http://www.galex.caltech.edu .



Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

Whitney.clavin@jpl.nasa.gov

J.D. Harrington 202-358-0321

Headquarters, Washington

j.d.harrington@nasa.gov

2012-122
Posted by Nelio Inacio at 1:03 PM 0 comments

NASA's Spitzer Sees the Light of Alien 'Super Earth'

NASA's Spitzer Sees the Light of Alien 'Super Earth':

How to See a Super Earth
NASA's Spitzer Space Telescope was able to detect a super Earth's direct light for the first time using its sensitive heat-seeking infrared vision. Super Earth's are more massive than Earth but lighter than gas giants like Neptune. As this artist's concept shows, in visible light, a planet is lost in the glare of its star (top view). When viewed in infrared, the planet becomes brighter relative to its star. This is largely due to the fact that the planet's scorching heat blazes with infrared light. Even on our own bodies emanate more infrared light than visible due to our heat. Image credit: NASA/JPL-Caltech
› Full image and caption





May 08, 2012

PASADENA, Calif. - NASA's Spitzer Space Telescope has detected light emanating from a "super-Earth" planet beyond our solar system for the first time. While the planet is not habitable, the detection is a historic step toward the eventual search for signs of life on other planets.

"Spitzer has amazed us yet again," said Bill Danchi, Spitzer program scientist at NASA Headquarters in Washington. "The spacecraft is pioneering the study of atmospheres of distant planets and paving the way for NASA's upcoming James Webb Space Telescope to apply a similar technique on potentially habitable planets."

The planet, called 55 Cancri e, falls into a class of planets termed super Earths, which are more massive than our home world but lighter than giant planets like Neptune. The planet is about twice as big and eight times as massive as Earth. It orbits a bright star, called 55 Cancri, in a mere 18 hours.

Previously, Spitzer and other telescopes were able to study the planet by analyzing how the light from 55 Cancri changed as the planet passed in front of the star. In the new study, Spitzer measured how much infrared light comes from the planet itself. The results reveal the planet is likely dark, and its sun-facing side is more than 2,000 Kelvin (3,140 degrees Fahrenheit), hot enough to melt metal.

The new information is consistent with a prior theory that 55 Cancri e is a water world: a rocky core surrounded by a layer of water in a "supercritical" state where it is both liquid and gas, and topped by a blanket of steam.

"It could be very similar to Neptune, if you pulled Neptune in toward our sun and watched its atmosphere boil away," said Michaël Gillon of Université de Liège in Belgium, principal investigator of the research, which appears in the Astrophysical Journal. The lead author is Brice-Olivier Demory of the Massachusetts Institute of Technology in Cambridge.

The 55 Cancri system is relatively close to Earth, at 41 light-years away. It has five planets, with 55 Cancri e the closest to the star and tidally locked, so one side always faces the star. Spitzer discovered the sun-facing side is extremely hot, indicating the planet probably does not have a substantial atmosphere to carry the sun's heat to the unlit side.

NASA's James Webb Space Telescope, scheduled to launch in 2018, likely will be able to learn even more about the planet's composition. The telescope might be able to use a similar infrared method to Spitzer to search other potentially habitable planets for signs of molecules possibly related to life.

"When we conceived of Spitzer more than 40 years ago, exoplanets hadn't even been discovered," said Michael Werner, Spitzer project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Because Spitzer was built very well, it's been able to adapt to this new field and make historic advances such as this."

In 2005, Spitzer became the first telescope to detect light from a planet beyond our solar system. To the surprise of many, the observatory saw the infrared light of a "hot Jupiter," a gaseous planet much larger than the solid 55 Cancri e. Since then, other telescopes, including NASA's Hubble and Kepler space telescopes, have performed similar feats with gas giants using the same method.

In this method, a telescope gazes at a star as a planet circles behind it. When the planet disappears from view, the light from the star system dips ever so slightly, but enough that astronomers can determine how much light came from the planet itself. This information reveals the temperature of a planet, and, in some cases, its atmospheric components. Most other current planet-hunting methods obtain indirect measurements of a planet by observing its effects on the star.

During Spitzer's ongoing extended mission, steps were taken to enhance its unique ability to see exoplanets, including 55 Cancri e. Those steps, which included changing the cycling of a heater and using an instrument in a new way, led to improvements in how precisely the telescope points at targets.

JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate in Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology (Caltech) in Pasadena. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA.

For more information about Spitzer, visit: http://www.nasa.gov/spitzer and http://spitzer.caltech.edu .

Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

Whitney.clavin@jpl.nasa.gov

J. D. Harrington 202-358-5241

NASA Headquarters, Washington

j.d.harrington@nasa.gov

2012-127
Posted by Nelio Inacio at 1:02 PM 0 comments

Cassini Sees Tropical Lakes on Saturn Moon

Cassini Sees Tropical Lakes on Saturn Moon:

Saturn's rings lie in the distance as the Cassini spacecraft looks toward Titan
Saturn's rings lie in the distance as the Cassini spacecraft looks toward Titan and its dark region called Shangri-La, east of the landing site of the Huygens Probe. Image Credit:
NASA/JPL-Caltech/Space Science Institute
› Full image and caption June 13, 2012

PASADENA, Calif. - NASA's Cassini spacecraft has spied long-standing methane lakes, or puddles, in the "tropics" of Saturn's moon Titan. One of the tropical lakes appears to be about half the size of Utah's Great Salt Lake, with a depth of at least 3 feet (1 meter).

The result, which is a new analysis of Cassini data, is unexpected because models had assumed the long-standing bodies of liquid would only exist at the poles. The findings appear in this week's issue of the journal Nature.

Where could the liquid for these lakes come from?  "A likely supplier is an underground aquifer," said Caitlin Griffith, the paper's lead author and a Cassini team associate at the University of Arizona, Tucson. "In essence, Titan may have oases."

Understanding how lakes or wetlands form on Titan helps scientists learn about the moon's weather. Like Earth's hydrological cycle, Titan has a "methane" cycle, with methane rather than water circulating. In Titan's atmosphere, ultraviolet light breaks apart methane, initiating a chain of complicated organic chemical reactions. But existing models haven't been able to account for the abundant supply of methane.

"An aquifer could explain one of the puzzling questions about the existence of methane, which is continually depleted," Griffith said. "Methane is a progenitor of Titan's organic chemistry, which likely produces interesting molecules like amino acids, the building blocks of life."

Global circulation models of Titan have theorized that liquid methane in the moon's equatorial region evaporates and is carried by wind to the north and south poles, where cooler temperatures cause methane to condense. When it falls to the surface, it forms the polar lakes. On Earth, water is similarly transported by the circulation, yet the oceans also transport water, thereby countering the atmospheric effects.

The latest results come from Cassini's visual and infrared mapping spectrometer, which detected the dark areas in the tropical region known as Shangri-La, near the spot where the European Space Agency's Huygens probe landed in 2005. When Huygens landed, the heat of the probe's lamp vaporized some methane from the ground, indicating it had landed in a damp area.

Areas appear dark to the visual and infrared mapping spectrometer when liquid ethane or methane are present. Some regions could be shallow, ankle-deep puddles. Cassini's radar mapper has seen lakes in the polar region, but hasn't detected any lakes at low latitudes.

The tropical lakes detected by the visual and infrared mapping spectrometer have remained since 2004. Only once has rain been detected falling and evaporating in the equatorial regions, and only during the recent expected rainy season. Scientists therefore deduce the lakes could not be substantively replenished by rain.

"We had thought that Titan simply had extensive dunes at the equator and lakes at the poles, but now we know that Titan is more complex than we previously thought," said Linda Spilker, the Cassini project scientist based at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Cassini still has multiple opportunities to fly by this moon going forward, so we can't wait to see how the details of this story fill out."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory manages the mission for NASA's Science Mission Directorate, Washington. The visual and infrared mapping spectrometer team is based at the University of Arizona, Tucson.

For more information, visit http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov .

Jia-Rui C. Cook 818-354-0850

Jet Propulsion Laboratory, Pasadena, Calif.

jccook@jpl.nasa.gov

Dwayne Brown 202-358-1726

NASA Headquarters

dwayne.c.brown@nasa.gov
Posted by Nelio Inacio at 1:01 PM 0 comments

Dawn has Departed the Giant Asteroid Vesta

Dawn has Departed the Giant Asteroid Vesta:

A Last Look Back at Vesta
This image is from the last sequence of images NASA's Dawn spacecraft
obtained of the giant asteroid Vesta, looking down at Vesta's north pole as it was departing. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

› Full image and caption


September 05, 2012

Dawn Mission Status Report



PASADENA, Calif. -- Mission controllers received confirmation today that NASA's Dawn spacecraft has escaped from the gentle gravitational grip of the giant asteroid Vesta. Dawn is now officially on its way to its second destination, the dwarf planet Ceres.

Dawn departed from Vesta at about 11:26 p.m. PDT on Sept. 4 (2:26 a.m. EDT on Sept. 5). Communications from the spacecraft via NASA's Deep Space Network confirmed the departure and that the spacecraft is now traveling toward Ceres.

"As we respectfully say goodbye to Vesta and reflect on the amazing discoveries over the past year, we eagerly look forward to the next phase of our adventure at Ceres, where even more exciting discoveries await," said Robert Mase, Dawn project manager, based at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

Launched on Sept. 27, 2007, Dawn slipped into orbit around Vesta on July 15, 2011 PDT (July 16 EDT). Over the past year, Dawn has comprehensively mapped this previously uncharted world, revealing an exotic and diverse planetary building block. The findings are helping scientists unlock some of the secrets of how the solar system, including our own Earth, was formed.


A web video celebrating Dawn's "greatest hits" at Vesta is available at http://www.nasa.gov/multimedia/videogallery/index.html?media_id=151669301 . Two of Dawn's last looks at Vesta are also now available, revealing the creeping dawn over the north pole.


Dawn spiraled away from Vesta as gently as it arrived. It is expected to pull into its next port of call, Ceres, in early 2015.


Dawn's mission is managed by JPL for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Ala. UCLA is responsible for overall Dawn mission science. Orbital Sciences Corp. in Dulles, Va., designed and built the spacecraft. The German Aerospace Center, the Max Planck Institute for Solar System Research, the Italian Space Agency and the Italian National Astrophysical Institute are international partners on the mission team. The California Institute of Technology in Pasadena manages JPL for NASA.



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

Jia-Rui C. Cook 818-354-0850

Jet Propulsion Laboratory, Pasadena, Calif.

Jia-Rui.C.Cook@jpl.nasa.gov


2012-277
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First Planets Found Around Sun-Like Stars in a Cluster

First Planets Found Around Sun-Like Stars in a Cluster:

Starry Starry Skies (Artist's Concept)
Astronomers have discovered two gas giant planets orbiting stars in the Beehive cluster, a collection of about 1,000 tightly packed stars. Image credit: NASA/JPL-Caltech
› Full image and caption


September 14, 2012

PASADENA, Calif. -- NASA-funded astronomers have, for the first time, spotted planets orbiting sun-like stars in a crowded cluster of stars. The findings offer the best evidence yet that planets can sprout up in dense stellar environments. Although the newfound planets are not habitable, their skies would be starrier than what we see from Earth.

The starry-skied planets are two so-called hot Jupiters, which are massive, gaseous orbs that are boiling hot because they orbit tightly around their parent stars. Each hot Jupiter circles a different sun-like star in the Beehive Cluster, also called the Praesepe, a collection of roughly 1,000 stars that appear to be swarming around a common center.

The Beehive is an open cluster, or a grouping of stars born at about the same time and out of the same giant cloud of material. The stars therefore share a similar chemical composition. Unlike the majority of stars, which spread out shortly after birth, these young stars remain loosely bound together by mutual gravitational attraction.

"We are detecting more and more planets that can thrive in diverse and extreme environments like these nearby clusters," said Mario R. Perez, the NASA astrophysics program scientist in the Origins of Solar Systems Program. "Our galaxy contains more than 1,000 of these open clusters, which potentially can present the physical conditions for harboring many more of these giant planets."


The two new Beehive planets are called Pr0201b and Pr0211b. The star's name followed by a "b" is the standard naming convention for planets.


"These are the first 'b's' in the Beehive," said Sam Quinn, a graduate student in astronomy at Georgia State University in Atlanta and the lead author of the paper describing the results, which was published in the Astrophysical Journal Letters.


Quinn and his team, in collaboration with David Latham at the Harvard-Smithsonian Center for Astrophysics, discovered the planets by using the 1.5-meter Tillinghast telescope at the Smithsonian Astrophysical Observatory's Fred Lawrence Whipple Observatory near Amado, Arizona to measure the slight gravitational wobble the orbiting planets induce upon their host stars. Previous searches of clusters had turned up two planets around massive stars but none had been found around stars like our sun until now.


"This has been a big puzzle for planet hunters," Quinn said. "We know that most stars form in clustered environments like the Orion nebula, so unless this dense environment inhibits planet formation, at least some sun-like stars in open clusters should have planets. Now, we finally know they are indeed there."


The results also are of interest to theorists who are trying to understand how hot Jupiters wind up so close to their stars. Most theories contend these blistering worlds start out much cooler and farther from their stars before migrating inward.


"The relatively young age of the Beehive cluster makes these planets among the youngest known," said Russel White, the principal investigator on the NASA Origins of Solar Systems grant that funded this study. "And that's important because it sets a constraint on how quickly giant planets migrate inward -- and knowing how quickly they migrate is the first step to figuring out how they migrate."


The research team suspects planets were turned up in the Beehive cluster because it is rich in metals. Stars in the Beehive have more heavy elements such as iron than the sun has.


According to White, "Searches for planets around nearby stars suggest that these metals act like a 'planet fertilizer,' leading to an abundant crop of gas giant planets. Our results suggest this may be true in clusters as well."


NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages NASA's Exoplanet Exploration Program office. More information about exoplanets and NASA's planet-finding program is available at: http://planetquest.jpl.nasa.gov .

Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov


J.D. Harrington 202-358-5241

Headquarters, Washington

j.d.harrington@nasa.gov


2012-289
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