Thursday, October 28, 2010

NASA Spacecraft Preps for Comet Flyby

Epoxi team members in mission control
Navigators and mission controllers for NASA’s EPOXI mission communicated with the spacecraft for a trajectory correction maneuver on October 27, 2010. › Larger image
In one of its final mission trajectory correction maneuvers, the EPOXI mission spacecraft has refined its orbit, preparing it for the flyby of comet Hartley 2 on Nov. 4. The time of closest approach to the comet on that day is expected to be about 7:02 a.m. PDT (10:02 a.m. EDT).

Today's trajectory correction maneuver began at 11 a.m. PDT (2 p.m. EDT), when the spacecraft burned its engines for 60 seconds, changing its velocity by 1.59 meters per second (3.6 miles per hour).

On Nov. 4, the spacecraft will fly past Hartley 2 at a distance of about 700 kilometers (435 miles). It will be only the fifth time in history that a spacecraft has been close enough to image a comet's nucleus.

EPOXI is an extended mission that uses the already "in-flight" Deep Impact spacecraft to explore distinct celestial targets of opportunity. The name EPOXI itself is a combination of the names for the two extended mission components: the extrasolar planet observations, called Extrasolar Planet Observations and Characterization (EPOCh); and the flyby of comet Hartley 2, called the Deep Impact Extended Investigation (DIXI). The spacecraft will continue to be referred to as "Deep Impact."

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the EPOXI mission for NASA's Science Mission Directorate, Washington. The University of Maryland, College Park, is home to the mission's principal investigator, Michael A'Hearn. Drake Deming of NASA's Goddard Space Flight Center, Greenbelt, Md., is the science lead for the mission's extrasolar planet observations. The spacecraft was built for NASA by Ball Aerospace & Technologies Corp., Boulder, Colo.

For more information about EPOXI, visit: http://epoxi.umd.edu/ .

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Space Buckyballs Thrive, Finds NASA Spitzer Telescope

infrared photo of the Small Magellanic Cloud taken by Spitzer
An infrared photo of the Small Magellanic Cloud taken by Spitzer is shown here in this artist's illustration, with two callouts. The middle callout shows a magnified view of an example of a planetary nebula, and the right callout shows an even further magnified depiction of buckyballs, which consist of 60 carbon atoms arranged like soccer balls. › Full image and caption
Astronomers have discovered bucket loads of buckyballs in space. They used NASA's Spitzer Space Telescope to find the little carbon spheres throughout our Milky Way galaxy -- in the space between stars and around three dying stars. What's more, Spitzer detected buckyballs around a fourth dying star in a nearby galaxy in staggering quantities -- the equivalent in mass to about 15 of our moons.

Buckyballs, also known as fullerenes, are soccer-ball-shaped molecules consisting of 60 linked carbon atoms. They are named for their resemblance to the architect Buckminster Fuller's geodesic domes, an example of which is found at the entrance to Disney's Epcot theme park in Orlando, Fla. The miniature spheres were first discovered in a lab on Earth 25 years ago, but it wasn't until this past July that Spitzer was able to provide the first confirmed proof of their existence in space. At that time, scientists weren't sure if they had been lucky to find a rare supply, or if perhaps the cosmic balls were all around.

"It turns out that buckyballs are much more common and abundant in the universe than initially thought," said astronomer Letizia Stanghellini of the National Optical Astronomy Observatory in Tucson, Ariz. "Spitzer had recently found them in one specific location, but now we see them in other environments. This has implications for the chemistry of life. It's possible that buckyballs from outer space provided seeds for life on Earth."

Stanghellini is co-author of a new study appearing online Oct. 28 in the Astrophysical Journal Letters. Anibal García-Hernández of the Instituto de Astrofísica de Canarias, Spain, is the lead author of the paper. Another Spitzer study about the discovery of buckyballs in space was also recently published in the Astrophysical Journal Letters. It was led by Kris Sellgren of Ohio State University, Columbus.

The García-Hernández team found the buckyballs around three dying sun-like stars, called planetary nebulae, in our own Milky Way galaxy. These cloudy objects, made up of material shed from the dying stars, are similar to the one where Spitzer found the first evidence for their existence.

The new research shows that all the planetary nebulae in which buckyballs have been detected are rich in hydrogen. This goes against what researchers thought for decades -- they had assumed that, as is the case with making buckyballs in the lab, hydrogen could not be present. The hydrogen, they theorized, would contaminate the carbon, causing it to form chains and other structures rather than the spheres, which contain no hydrogen at all. "We now know that fullerenes and hydrogen coexist in planetary nebulae, which is really important for telling us how they form in space," said García-Hernández.

García-Hernández and his colleagues also located buckyballs in a planetary nebula within a nearby galaxy called the Small Magellanic Cloud. This was particularly exciting to the researchers, because, in contrast to the planetary nebulae in the Milky Way, the distance to this galaxy is known. Knowing the distance to the source of the buckyballs meant that the astronomers could calculate their quantity -- two percent of Earth's mass, or the mass of 15 of our moons.

The other new study, from Sellgren and her team, demonstrates that buckyballs are also present in the space between stars, but not too far away from young solar systems. The cosmic balls may have been formed in a planetary nebula, or perhaps between stars. A feature story about this research is online at http://www.spitzer.caltech.edu/news/1212-feature10-18 .

"It’s exciting to find buckyballs in between stars that are still forming their solar systems, just a comet’s throw away," Sellgren said. "This could be the link between fullerenes in space and fullerenes in meteorites."

The implications are far-reaching. Scientists have speculated in the past that buckyballs, which can act like cages for other molecules and atoms, might have carried substances to Earth that kick-started life. Evidence for this theory comes from the fact that buckyballs have been found in meteorites carrying extraterrestial gases.

"Buckyballs are sort of like diamonds with holes in the middle," said Stanghellini. "They are incredibly stable molecules that are hard to destroy, and they could carry other interesting molecules inside them. We hope to learn more about the important role they likely play in the death and birth of stars and planets, and maybe even life itself."

The little carbon balls are important in technology research too. They have potential applications in superconducting materials, optical devices, medicines, water purification, armor and more.

Other authors of the García-Hernández study are Arturo Manchado, the Instituto de Astrofísica de Canarias; Pedro García-Lario, European Space Agency Centre, Spain; Eva Villaver, Universidad Autónoma de Madrid, Spain; Richard Shaw, National Optical Astronomy Observatory; Ryszard Szczerba, Nicolaus Copernicus Astronomical Center, Poland; and José V. Perea-Calderon, European Space Astronomy Centre, Ingeniería y Servicios Aerospaciales, Spain.

Other authors of the Sellgren study are Michael Werner, Spitzer project scientist, NASA's Jet Propulsion Laboratory, Pasadena, Calif.; James Ingalls, NASA's Spitzer Science Center at the California Institute of Technology in Pasadena.; J.D.T. Smith, University of Toledo, Ohio; T.M. Carleton, University of Arizona, Tucson; and Christine Joblin, Université de Toulouse, France.

The Spitzer observations were made before it ran out of its liquid coolant in May 2009 and began its warm mission. JPL manages the Spitzer mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center. Caltech manages JPL for NASA. For more information about Spitzer, visit http://spitzer.caltech.edu/ and http://www.nasa.gov/spitzer .

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NASA Goddard Delivers Magnetometers for Juno Mission

Juno and Jupiter artist's depiction
NASA's Juno spacecraft passes in front of Jupiter in this artist's depiction. Juno, the second mission in NASA's New Frontiers program, will improve our understanding of the solar system by advancing studies of the origin and evolution of Jupiter. › Full image and caption
Magnetometers developed at NASA's Goddard Space Flight Center in Greenbelt, Md., for the Juno mission to Jupiter were delivered recently to Lockheed Martin in Denver. Designed and built by an in-house team of Goddard scientists, engineers and technicians, these instruments will map the planet's magnetic field with great accuracy and observe its variations over time. Each of the two vector magnetometers carries with it a pair of non-magnetic star cameras to determine its orientation in space with commensurate accuracy. These were designed and built by a team led by John Jorgensen at the Danish Technical University in Copenhagen, Denmark.

"Juno's magnetometers will measure Jupiter's magnetic field with extraordinary precision and give us a detailed picture of what the field looks like, both around the planet and deep within," says Goddard's Jack Connerney, the mission's deputy principal investigator and head of the magnetometer team. "This will be the first time we've mapped the magnetic field all around Jupiter-it will be the most complete map of its kind ever obtained about any planet with an active dynamo, except, of course, our Earth."

The Jet Propulsion Laboratory in Pasadena, Calif., manages the Juno mission for NASA. Scheduled for launch in 2011, Juno is the second mission in NASA's New Frontiers program. The mission will improve our understanding of the solar system by advancing studies of the origin and evolution of Jupiter. The spacecraft will carry nine instruments to investigate the existence of a solid planetary core, map Jupiter's intense magnetic field, measure the amount of water and ammonia in the deep atmosphere, and observe the planet's auroras.

"The magnetometers play a unique and important role in Juno's investigation of the formation and evolution of Jupiter," says Juno's principal investigator, Scott Bolton of Southwest Research Institute in San Antonio. "They provide one of the ways that Juno will see deep inside the giant planet, and this will help us understand how and where Jupiter's powerful magnetic field is generated."

The Juno magnetometers will study Jupiter's powerful magnetic field, which is nearly 20,000 times as strong as Earth's. The field is generated deep within the planet's atmosphere, where the intense pressure compresses hydrogen gas into an electrically conductive fluid. Fluid motion within the planet drives electric currents in this liquid hydrogen, and these currents generate the magnetic field. If a map were drawn of the magnetic field lines running between Jupiter's north and south poles, the region of space filled by the lines (called the magnetosphere) would be enormous. Jupiter's magnetosphere extends up to 3 million kilometers (nearly 2 million miles) toward the sun and as far as Saturn's orbit in the other direction.

"From a distance, Jupiter's magnetic field has two poles, north and south, like Earth's. But looking closer, below Jupiter's surface, the magnetic field is thought to be quite complex and tangled," says Connerney. "Juno will give us a detailed picture of the magnetic field extending down to the surface of the dynamo, or engine, that generates it."

Jupiter's powerful magnetic environment also creates the brightest auroras in the solar system, as charged particles get trapped by the field and rain down into the atmosphere. Juno will directly sample the charged particles and magnetic fields near Jupiter's poles for the first time, while simultaneously observing the auroras at ultraviolet wavelengths of light. These investigations will greatly improve the understanding of this remarkable phenomenon and of similar magnetic objects, such as young stars that have their own planetary systems.

"With Juno, we will learn much more about the structure and evolution of Jupiter, and this will help us understand our own solar system," says Connerney. "But astronomers have now found many other giant planets outside our solar system. What we learn about Jupiter also will help us understand the planets orbiting other stars."

Lockheed Martin Space Systems, Denver, Colo., is building the spacecraft. The Italian Space Agency in Rome is contributing an infrared spectrometer instrument and a portion of the radio science experiment.

For more information about Juno, visit: http://www.nasa.gov/juno .

For information about NASA and agency programs, visit: http://www.nasa.gov/home .

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Wednesday, October 27, 2010

NASA's Kepler Spacecraft Takes Pulse of Distant Stars

Artist's concept of Kepler
Artist's concept of Kepler in the distant solar system.
An international cadre of scientists using datafrom NASA's Kepler spacecraft has detected stellar oscillations, or "starquakes," that yield new insights about the size, age and evolution of stars.

The results were presented at a news conference at Aarhus University in Denmark by scientists representing the Kepler Asteroseismic Science Consortium. The team studied thousands of stars observed by Kepler, releasing what amounts to a roster of some of humanity's most well-characterized stars.

Analysis of stellar oscillations is similar to the way seismologists study earthquakes to probe the Earth's interior. This branch of science, called astroseismology, produces measurements of stars the Kepler science team is anxious to have.

"Using the unparalleled data provided by Kepler, Asteroseismic Science Consortium scientists are quite literally revolutionizing our understanding of stars and their structures," said Douglas Hudgins, Kepler Program Scientist at NASA Headquarters in Washington.

One oscillating star has taken center stage: KIC 11026764 has the most accurately known properties of any star in the Kepler field. In fact, few stars in the universe are known to similar accuracy. At an age of 5.94 billion years, it has grown to a little over twice the diameter of the sun and it will continue to grow as it transforms into a red giant. The oscillations reveal that this star is powered by hydrogen fusion in a thin shell around a helium-rich core.

Launched in March 2009, Kepler was designed to discover Earth-size planets orbiting other stars. The spacecraft uses a huge digital camera, known as a photometer, to continuously monitor the brightness of more than 150,000 stars in its field of view as it orbits around the sun. Kepler searches for distant worlds by looking for "transits," when a planet passes in front of a star, briefly causing it to dim. The amount of dimming reveals the size of the planet compared to the size of the star.

Ames is responsible for the ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed the Kepler mission development. Ball Aerospace and Technologies Corp. in Boulder, Colo., developed the Kepler flight system, and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. The Space Telescope Science Institute in Baltimore archives, hosts and distributes the Kepler science data.

Read full news release at: http://www.nasa.gov/centers/ames/news/releases/2010/M10-91.html .

More information about Kepler is online at: http://www.nasa.gov/kepler. and http://www.kepler.nasa.gov .

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Monday, October 25, 2010

Five Things About NASA's EPOXI Mission

Artist's concept of Deep Impact's encounter with comet Temple 1
This artist's concept shows us the first time Deep Impact encountered a comet - Tempel 1 in July 2005. Deep Impact, now in an extended mission called EPOXI, will fly by its next comet, Hartley 2, on Nov. 4, 2010. Full image and caption

Here are five quick facts about the EPOXI mission, scheduled to fly by comet Hartley 2 on Nov. 4, 2010.

1. High Fives - This is the fifth time humans will see a comet close-up, and the Deep Impact spacecraft flew by Earth for its fifth time on Sunday, June 27, 2010.

2. Eco-friendly Spacecraft: Recycle, Reuse, Record - The EPOXI mission is recycling the Deep Impact spacecraft, whose probe intentionally collided with comet Tempel 1 on July 4, 2005, revealing, for the first time, the inner material of a comet. The spacecraft is now approaching a second comet rendezvous, a close encounter with Hartley 2 on Nov. 4. The spacecraft is reusing the same trio of instruments used during Deep Impact: two telescopes with digital imagers to record the encounter, and an infrared spectrometer.

3. Small, Mighty and Square-Dancing in Space - Although comet Hartley 2 is smaller than Tempel 1, the previous comet visited by Deep Impact, it is much more active. In fact, amateur skywatchers may be able to see Hartley 2 in a dark sky with binoculars or a small telescope. Engineers specifically designed the mighty Deep Impact spacecraft to point a camera at Tempel 1 while its antenna was directed at Earth. This flyby of comet Hartley 2 does not provide the same luxury. It cannot both photograph the comet and talk with mission controllers on Earth. Engineers have instead programmed Deep Impact to dance the do-si-do. The spacecraft will spend the week leading up to closest approach swinging back and forth between imaging the comet and beaming images back to Earth.

4. Storytelling Comets - Comets are an important aspect of studying how the solar system formed and Earth evolved. Comets are leftover building blocks of solar system formation, and are believed to have seeded an early Earth with water and organic compounds. The more we know about these celestial bodies, the more we can learn about Earth and the solar system.

5. What's in a Name? - EPOXI is a hybrid acronym binding two science investigations: the Extrasolar Planet Observation and Characterization (EPOCh) and Deep Impact eXtended Investigation (DIXI). The spacecraft keeps its original name of Deep Impact, while the mission is called EPOXI.

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Watch Construction of Nasa's New Mars Rover Live on the Web

The Curiosity Cam live video feed allows the public to watch technicians assemble and test NASA's next Mars rover in a clean room at the Jet Propulsion Laboratory, Pasadena, Calif.
The Curiosity Cam live video feed allows the public to watch technicians assemble and test NASA's next Mars rover in a clean room at the Jet Propulsion Laboratory, Pasadena, Calif.

A newly installed webcam is giving the public an opportunity to watch technicians assemble and test the next NASA Mars rover, one of the most technologically challenging interplanetary missions ever designed.

NASA's Mars Science Laboratory, also known as the Curiosity rover, is in a clean room at the agency's Jet Propulsion Laboratory in Pasadena, Calif. The webcam, affectionately called "Curiosity Cam," provides the video feed, without audio, from a viewing gallery above the clean room floor. The video will be supplemented periodically by live Web chats featuring Curiosity team members answering questions about the rover. Currently, work in the clean room begins at 8 a.m. PDT Monday through Friday.

Assembly engineers and technicians have been busy adding new avionics and instruments to the rover. Beginning Friday, viewers will see the assembly team carefully install the rover's suspension system and its six wheels. On Tuesday, the rover's 7-foot-long robotic arm will be carefully lifted and attached to the front of the rover.

Continuous live video of rover construction is available at: http://www.ustream.tv/channel/nasajpl . The feed is also available at http://www.nasa.gov/mission_pages/msl/building_curiosity.html and http://mars.jpl.nasa.gov/msl/mission/whereistherovernow/ . The camera shows a portion of the clean room that is typically active; but the rover, spacecraft components and technicians may move out of view as work shifts to other areas of the room. When activity takes place in other testing facilities around JPL, the clean room may be empty. The camera may also be turned off periodically for maintenance or technical issues.

Months of assembly and testing remain before the car-sized rover is ready for launch from Cape Canaveral, Fla. The rover and spacecraft components will ship to NASA's Kennedy Space Center in Florida in spring of 2011. The launch will occur between Nov. 25 and Dec. 18, 2011. Curiosity will arrive on Mars in August 2012.

Curiosity is engineered to drive longer distances over rougher terrain than previous rovers with a science payload 10 times the mass of instruments on NASA's Spirit and Opportunity. The new, large rover will investigate whether the landing region has had environments favorable for supporting microbial life and for preserving evidence about whether life existed on the Red Planet.

For information and news about Curiosity, visit: http://mars.jpl.nasa.gov/msl/ or http://www.nasa.gov/msl

Social media audiences can learn more about the mission on Twitter at http://www.twitter.com/MarsCuriosity and on Facebook at http://www.facebook.com/MarsCuriosity

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Friday, October 22, 2010

Lunar Impact May Impact Lunar Science For Years To Come

Surface temperature map of the moon
LRO Diviner Lunar Radiometer Experiment surface temperature map of the south polar region of the Moon. The data were acquired during September and October 2009, when south polar temperatures were close to their annual maximum values. The map shows the locations of several intensely cold impact craters that are potential cold traps for water ice as well as a range of other icy compounds commonly observed in comets. › Larger image
The lunar rocks brought back to Earth by the Apollo astronauts were found to have very little water, and were much drier than rocks on Earth. An explanation for this was that the moon formed billions of years ago in the solar system's turbulent youth, when a Mars-sized planet crashed into Earth. The impact stripped away our planet's outer layer, sending it into orbit. The pieces later coalesced under their own gravity to form our moon. Heat from all this mayhem vaporized most of the water in the lunar material, so the water was lost to space.

However, there was still a chance that water might be found in special places on the moon. Due to the moon's orientation to the sun, scientists theorized that deep craters at the lunar poles would be in permanent shadow and thus extremely cold and able to trap volatile material, like water as ice perhaps delivered there by comet impacts or chemical reactions with hydrogen carried by the solar wind.

In October 9, 2009, NASA's LCROSS (Lunar Crater Remote Observation and Sensing Satellite) was intentionally crashed into the Cabeus crater near the lunar south pole. The idea was to kick up debris from the bottom of the crater so its composition could be analyzed. LCROSS hit at over 9,000 kilometers (5,600 miles) per hour, sending up a plume of material over 19 kilometers (12 miles) high.

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

LCROSS was a companion mission to NASA's Lunar Reconnaissance Orbiter (LRO) mission. The two missions were designed to work together, and support from LRO was critical to the success of LCROSS. During impact, LRO, which is normally looking at the lunar surface, was tilted toward the horizon so it could observe the plume. Shortly after LCROSS hit the moon, LRO flew past debris and gas from the impact while its instruments collected data.

"LRO assisted LCROSS in two primary ways - selecting the impact site and confirming the LCROSS observations," said Gordon Chin of NASA's Goddard Space Flight Center, Greenbelt, Md., LRO associate project scientist.

"Since observatories on Earth were also planning to view the LCROSS impact, there were a lot of constraints on the location - the impact plume had to rise out of the crater and into sunlight, and it had to be visible from Earth," said Chin.

"Originally, the LCROSS team was going with a site farther north than the Cabeus crater, because it was better for Earth visibility," said Chin. "However, LEND revealed that the area did not have a high hydrogen concentration, but Cabeus did. Also, Diviner showed that Cabeus was one of the coldest sites, and LOLA indicated it was in permanent shadow. So, we were able to influence the decision to aim for Cabeus farther south -- while it was a little less visible from Earth, Cabeus was ultimately better for what we were trying to find."

The Diviner instrument aboard the Lunar Reconnaissance Orbiter was built and is managed by NASA's Jet Propulsion Laboratory in Pasadena, Calif. Temperature maps from LRO's Diviner instrument were also crucial to identify where the coldest places were.

David Paige, principal investigator of the Diviner instrument from the University of California, Los Angeles, used temperature measurements of the lunar south pole obtained by Diviner to model the stability of water ice both at and near the surface.

"The temperatures inside these permanently shadowed craters are even colder than we had expected. Our model results indicate that in these extreme cold conditions, surface deposits of water ice would almost certainly be stable," said Paige, "but perhaps more significantly, these areas are surrounded by much larger permafrost regions where ice could be stable just beneath the surface."

"We conclude that large areas of the lunar south pole are cold enough to trap not only water ice, but other volatile compounds (substances with low boiling points) such as sulfur dioxide, carbon dioxide, formaldehyde, ammonia, methanol, mercury and sodium," Paige added.

A UCLA graduate student and Diviner team member, Paul Hayne, was monitoring the data in real-time as it was sent back from Diviner.

"During the flyby 90 seconds after impact, all seven of Diviner's infrared channels measured an enhanced thermal signal from the crater. The more sensitive of its two solar channels also measured the thermal signal, along with reflected sunlight from the impact plume. Two hours later, the three longest wavelength channels picked up the signal, and after four hours only one channel detected anything above the background temperature."

Scientists were able to learn two things from these measurements: first, they were able to constrain the mass of material that was ejected outwards into space from the impact crater; second, they were able to infer the initial temperature and make estimates about the effects of ice in the soil on the observed cooling behavior.

Another LRO instrument, the Lyman-Alpha Mapping Project (LAMP), used data on the gas cloud to confirm the presence of the gases molecular hydrogen, carbon monoxide and atomic mercury, along with smaller amounts of calcium and magnesium, also in gas form.

"We had hints from Apollo soils and models that the volatiles we see in the impact plume have been long collecting near the moon's polar regions," said Randy Gladstone, LAMP acting principal investigator, of Southwest Research Institute in San Antonio. "Now we have confirmation."

"The detection of mercury in the soil was the biggest surprise, especially that it's in about the same abundance as the water detected by LCROSS," said Kurt Retherford, LAMP team member, also of Southwest Research Institute.

"The observations by the suite of LRO and LCROSS instruments demonstrate the moon has a complex environment that experiences intriguing chemical processes," said Richard Vondrak, LRO project scientist at NASA Goddard. "This knowledge can open doors to new areas of research and exploration."

LCROSS launched with LRO aboard an Atlas V rocket from Cape Canaveral, Fla., on June 18, 2009.

The research was funded by NASA's Exploration Systems Missions Directorate at NASA Headquarters in Washington. LRO was built and is managed by NASA's Goddard Space Flight Center in Greenbelt, Md. LCROSS is managed by NASA's Ames Research Center, Moffett Field, Calif. LAMP was developed by the Southwest Research Institute in San Antonio, Texas; LOLA was built by NASA Goddard; LROC was provided by Arizona State University, Tempe; LEND was provided by Institute for Space Research, Moscow; The Diviner instrument was built and is managed by NASA's Jet Propulsion Laboratory in Pasadena, Calif. UCLA is the home institution of Diviner's principal investigator.

For more information on Diviner, visit: http://diviner.ucla.edu.

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Tuesday, October 19, 2010

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

These three views of Saturn's moon Rhea were made from data obtained by NASA's Cassini spacecraft.
These three views of Saturn's moon Rhea were made from data obtained by NASA's Cassini spacecraft. › Full image and caption
Taking a long-weekend road trip, NASA's Cassini spacecraft successfully glided near nine Saturnian moons, sending back a stream of raw images as mementos of its adrenaline-fueled expedition. The spacecraft sent back particularly intriguing images of the moons Dione and Rhea.

The Dione and Rhea pictures are the highest-resolution views yet of parts of their surfaces. The views of the southern part of Dione's leading hemisphere (the part of the moon that faces forward in its orbit around Saturn) and the equatorial region of Rhea's leading hemisphere are more detailed than the last time we saw these terrains with NASA's Voyager spacecraft in the early 1980s.

Of the five big icy moons of Saturn, Dione and Rhea are often considered a pair because they orbit close to each other, are darker than the others, and exhibit similar patterns of light reflecting off them. These new images, however, highlight the differences between these sister moons.

Both images show similar geographic regions on each satellite. However, scientists can identify differences in geological histories of the two bodies from differences in the numbers and sizes of visible craters on their surfaces. The number and size of craters on a body's surface help indicate the age of that surface – the more craters there are and the larger they are, the older the surface is.

Rhea, for example, shows ancient, intense bombardments throughout this region. However, the same region of Dione is divided into distinct areas that exhibit variations in the number and size of preserved craters. In particular, while parts of Dione are heavily cratered like Rhea, there are other areas covered by relatively smooth plains. Those areas have many small craters, but few large impact scars, which indicates that they are geologically younger than the heavily cratered areas. The smooth plains must have been resurfaced at some point in Dione's past -- an event that seems to be missing from Rhea's geological history on this side of the moon.

Images of the moon Mimas, captured just before it went into shadow behind Saturn, will be compared to thermal maps made earlier this year that showed an unexpected "Pac-Man" heat pattern. (See for more details.)

Cassini also caught a picture of the tiny, 4-kilometer-wide (3-mile-wide) moon Pallene, in front of the planet Saturn, which is more than 120,000 kilometers (75,000 miles) wide at its equator.

Cassini's elliptical orbital pattern around Saturn means it can target moons for flybys about once or twice a month. The flybys on this particular Cassini road trip were "non-targeted" flybys, meaning navigators did not refine Cassini's path to fly over particular points on each moon.

Cassini's long weekend started on Thursday, Oct. 14, at 5:07 p.m. UTC (9:07 a.m. PDT), when it passed by Saturn's largest moon Titan at an altitude of 172,368 kilometers (107,104 miles) above the surface. Then came a whirlwind 21 hours in which Cassini flew by Polydeuces at 116,526 kilometers (72,406 miles), Mimas at 69,950 kilometers (43,465 miles), Pallene at 36,118 kilometers (22,443 miles), Telesto at 48,455 kilometers (30,109 miles), Methone at 105,868 kilometers (65,783 miles), Aegaeon at 96,754 kilometers (60,120 miles) and Dione at 31,710 kilometers (19,704 miles). Cassini's last visit -- Rhea at 38,752 kilometers (24,079 miles) – took place at 6:47 a.m. UTC on Oct. 17 (10:47 p.m. PDT on Oct. 16).

Scientists decided in advance which observations they wanted to make while the spacecraft was cruising past all the moons. They chose to obtain images of Titan, Mimas, Pallene, Dione and Rhea. They also obtained thermal scans of Mimas, Dione and Rhea.

For more raw images, visit: 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. The Jet Propulsion Laboratory manages the project for NASA's Science Mission Directorate in Washington. The Cassini orbiter was designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

More Cassini information is available, at t http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov.

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The Comet Cometh: Hartley 2 Visible in Night Sky

comet Hartley 2
This image of comet Hartley 2 was captured by amateur astronomer Byron Bergert on Oct. 6 in Gainesville, Florida using a 106 mm Takahashi astrograph. › Larger image
Backyard stargazers with a telescope or binoculars and a clear night's sky can now inspect the comet that in a little over two weeks will become only the fifth in history to be imaged close up. Comet Hartley 2 will come within 17.7 million kilometers (11 million miles) of Earth this Wed., Oct. 20 at noon PDT (3 p.m. EDT). NASA's EPOXI mission will come within 700 kilometers (435 miles) of Hartley 2 on Nov. 4.

"On October 20, the comet will be the closest it has ever been since it was discovered in 1986 by Australian astronomer Malcolm Hartley," said Don Yeomans, head of NASA's Near-Earth Object Office at the Jet Propulsion Laboratory in Pasadena, Calif. and a member of the EPOXI science team. "It's unusual for a comet to approach this close. It is nice of Mother Nature to give us a preview before we see Hartley 2 in all its cometary glory with some great close-up images less than two weeks later."

Comet Hartley 2, also known as 103P/Hartley 2, is a relatively small, but very active periodic comet that orbits the sun once every 6.5 years. From dark, pristine skies in the Northern Hemisphere, the comet should be visible with binoculars as a fuzzy object in the constellation Auriga, passing south of the bright star Capella. Viewing of Hartley 2 from high ambient light locations including urban areas may be more difficult.

In the early morning hours of Oct. 20, the optimal dark sky window for mid-latitude northern observers is under two hours in length. This dark interval will occur between the time when the nearly-full moon sets at about 4:50 a.m. (local time) and when the morning twilight begins at about 6:35 a.m.

By October 22, the comet will have passed through the constellation Auriga. It will continue its journey across the night sky in the direction of the constellation Gemini.

EPOXI is an extended mission that utilizes the already "in-flight" Deep Impact spacecraft to explore distinct celestial targets of opportunity. The name EPOXI itself is a combination of the names for the two extended mission components: the extrasolar planet observations, called Extrasolar Planet Observations and Characterization (EPOCh), and the flyby of comet Hartley 2, called the Deep Impact Extended Investigation (DIXI). The spacecraft will continue to be referred to as "Deep Impact."

JPL manages the EPOXI mission for NASA's Science Mission Directorate, Washington. The University of Maryland, College Park, is home to the mission's principal investigator, Michael A'Hearn. Drake Deming of NASA's Goddard Space Flight Center, Greenbelt, Md., is the science lead for the mission's extrasolar planet observations. The spacecraft was built for NASA by Ball Aerospace & Technologies Corp., Boulder, Colo.

Images and videos of comet Hartley 2 from both amateur observers and major observatories are online at: http://aop.astro.umd.edu/gallery/hartley.shtml .

For more information about EPOXI visit http://epoxi.umd.edu/ .

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Astronomers Find Weird, Warm Spot on an Exoplanet

NASA's Spitzer Space Telescope has found that the hottest part of a distant planet
NASA's Spitzer Space Telescope has found that the hottest part of a distant planet, named upsilon Andromedae b, is not under the glare of its host star as might be expected.
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Observations from NASA's Spitzer Space Telescope reveal a distant planet with a warm spot in the wrong place.

The gas-giant planet, named upsilon Andromedae b, orbits tightly around its star, with one face perpetually boiling under the star's heat. It belongs to a class of planets termed hot Jupiters, so called for their scorching temperatures and large, gaseous constitutions.

One might think the hottest part of these planets would be directly under the sun-facing side, but previous observations have shown that their hot spots may be shifted slightly away from this point. Astronomers thought that fierce winds might be pushing hot, gaseous material around.

But the new finding may throw this theory into question. Using Spitzer, an infrared observatory, astronomers found that upsilon Andromedae b's hot spot is offset by a whopping 80 degrees. Basically, the hot spot is over to the side of the planet instead of directly under the glare of the sun.

"We really didn't expect to find a hot spot with such a large offset," said Ian Crossfield, lead author of a new paper about the discovery appearing in an upcoming issue of Astrophysical Journal. "It's clear that we understand even less about the atmospheric energetics of hot Jupiters than we thought we did."

The results are part of a growing field of exoplanet atmospheric science, pioneered by Spitzer in 2005, when it became the first telescope to directly detect photons from an exoplanet, or a planet orbiting a star other than our sun. Since then, Spitzer, along with NASA's Hubble Space Telescope, has studied the atmospheres of several hot Jupiters, finding water, methane, carbon dioxide and carbon monoxide.

In the new study, astronomers report observations of upsilon Andromedae b taken across five days in February of 2009. This planet whips around its star every 4.6 days, as measured using the "wobble," or radial velocity technique, with telescopes on the ground. It does not transit, or cross in front of, its star as many other hot Jupiters studied by Spitzer do.

Spitzer measured the total combined light from the star and planet, as the planet orbited around. The telescope can't see the planet directly, but it can detect variations in the total infrared light from the system that arise as the hot side of the planet comes into Earth's field of view. The hottest part of the planet will give off the most infrared light.

One might think the system would appear brightest when the planet was directly behind the star, thus showing its full sun-facing side. Likewise, one might think the system would appear darkest when the planet swings around toward Earth, showing its backside. But the system was the brightest when the planet was to the side of the star, with its side facing Earth. This means that the hottest part of the planet is not under its star. It's sort of like going to the beach at sunset to feel the most heat. The researchers aren't sure how this could be.

They've guessed at some possibilities, including supersonic winds triggering shock waves that heat material up, and star-planet magnetic interactions. But these are just speculation. As more hot Jupiters are examined, astronomers will test new theories.

"This is a very unexpected result," said Michael Werner, the Spitzer project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif., who was not a part of the study. "Spitzer is showing us that we are a long way from understanding these alien worlds."

The Spitzer observations were made before it ran out of its liquid coolant in May 2009, officially beginning its warm mission.

Other authors of the study are Brad Hansen of UCLA; Joseph Harrington at the University of Central Florida, Orlando; James Y-K. Cho of Queen Mary, University of London, United Kingdom; Drake Deming of NASA's Goddard Space Flight Center, Greenbelt, Md.; Kristen Menou of Columbia University, New York, N.Y.; and Sara Seager of the Massachusetts Institute of Technology, Boston.

JPL 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, also in Pasadena. Caltech manages JPL for NASA. For more information about Spitzer, visit http://spitzer.caltech.edu/ and http://www.nasa.gov/spitzer .

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NASA and Gowalla Launch Partnership With Search for Moon Rocks

NASA and Gowalla are bringing people one small step closer to the universe. Anyone who uses Gowalla, a mobile and web service, now has the opportunity to find and collect four NASA-related virtual items -- a moon rock, a NASA patch, a spacesuit and a space shuttle.

Gowalla's mission is to inspire discovery by connecting people with the places around them. When Gowalla users virtually "check-in" at NASA-related venues via their iPhone, Blackberry, Android, Palm or iPad, they now have a chance to find one of the four items.

Virtual moon rocks can be found when Gowalla users check in to any location where a real one is on display. The United States successfully brought lunar samples back to Earth during the Apollo 11, 12, 14, 15, 16, and 17 missions. NASA provides a number of these moon rocks for display and public viewing at museums, planetariums and scientific expositions around the world.

To help people find the lunar samples, Gowalla and JESS3, a creative agency that specializes in data visualization, created a special edition NASA+Gowalla Map: Search for the Moon Rocks.

Gowalla users can find the virtual NASA patch, spacesuit and space shuttles by checking in to NASA visitor centers, agency-related locations, or one of the more than 400 museums, science centers, planetariums, observatories, parks, nature centers, zoos and aquariums that are part of NASA's Museum Alliance.

The partnership also enables a NASA account on Gowalla and an account for astronaut Mike Massimino, both linked to their respective Twitter accounts, @NASA, and @Astro_Mike. NASA and Massimino also will drop virtual items for users to find and collect throughout the nation.

Anyone with a Gowalla account who collects three of the four items will receive a special pin in their Gowalla Passport. In addition, the first 100 people to collect three items will receive a poster of the map in the mail.

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Monday, October 18, 2010

Long-Lived Mars Odyssey Gets New Project Manager

Mars Odyssey Project Manager Gaylon McSmith, of NASA's Jet Propulsion Laboratory
Mars Odyssey Project Manager Gaylon McSmith, of NASA's Jet Propulsion Laboratory
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The new project manager for the longest-working spacecraft currently active at Mars, NASA's Mars Odyssey, has a long track record himself.

He is Gaylon McSmith, a former pilot of U.S. Air Force fighter jets and Continental Airlines airliners. At NASA's Jet Propulsion Laboratory, Pasadena, Calif., he has been a leader on the Odyssey team since two months after the spacecraft began orbiting Mars in October 2001.

On Dec. 15 of this year, Odyssey will break the record for the longest-working spacecraft ever at Mars, surpassing the mark set by NASA's Mars Global Surveyor, which operated in orbit from 1997 to 2006. Odyssey completed its prime mission in 2004 and has operated on an extended-mission basis since then.

"The spacecraft continues to be a very reliable platform that conducts its own science investigations, plus important support for other Mars missions," McSmith said. "It's a great honor for me to work with the Odyssey team."

Odyssey's science instruments have discovered vast supplies of frozen water just beneath the surface; run a radiation-safety check for future astronauts; and mapped surface textures, minerals and elements all over Mars. Its camera has provided the highest-resolution map of the entire planet.

Observations by Odyssey have contributed to selection and analysis of landing sites for four Mars surface missions. Thousands of students have participated in a groundbreaking educational program enabling them to select Odyssey imaging targets on Mars and conduct real scientific investigations.

In addition to its own science, Odyssey has relayed to Earth nearly all of the data provided by NASA's Mars rovers Spirit and Opportunity. It provided relay service for the Phoenix Mars Lander and will be in position to do so for the Mars Science Laboratory mission during and after the 2012 landing of the mission's rover, Curiosity.

Odyssey's Thermal Emission Imaging System, Neutron Spectrometer and High Energy Neutron Detector continue examining Mars.

McSmith joined the Odyssey team as manager of the mission's science office in 2001. He served as mission manager from 2008 until this month, when he succeeded Phil Varghese as project manager. Varghese had become project manager for NASA's Mars Reconnaissance Orbiter.

McSmith, who now has a home in Pasadena, grew up in the Eagle Rock district of Los Angeles, a few miles from JPL. He graduated from California State University, Fresno, in 1970, with a degree in computer sciences. After service with the U.S. Air Force and eight years as an airline pilot, he came to work at JPL on an aviation weather project supported by the Federal Aviation Administration. Subsequently he worked on the Deep Space 1 mission to comet Borrelly and the Galileo mission to Jupiter.

Mars Odyssey, launched in 2001, is managed by JPL, a division of the California Institute of Technology in Pasadena, for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project. Investigators at Arizona State University, Tempe, operate the Thermal Emission Imaging System. Investigators at the University of Arizona, Tucson, head operation of the Gamma Ray Spectrometer suite of instruments. Additional science partners are located at the Russian Aviation and Space Agency, which provided the high-energy neutron detector, and at Los Alamos National Laboratories, New Mexico, which provided the neutron spectrometer.

For more about the Mars Odyssey mission, visit: http://mars.jpl.nasa.gov/odyssey .

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Friday, October 15, 2010

NASA Study of Haiti Quake Yields Surprising Results

Radar interferogram showing ground deformation from Haiti quake
Radar interferogram image from the Japan Aerospace Exploration Agency's Advanced Land Observing Satellite Phased Array type L-band Synthetic Aperture Radar (ALOS PALSAR), showing ground deformation from the Haiti earthquake in the city of Léogâne, west of Port-au-Prince. › Full image and caption
The magnitude 7.0 earthquake that caused more than 200,000 casualties and devastated Haiti's economy in January resulted not from the Enriquillo fault, as previously believed, but from slip on multiple faults -- primarily a previously unknown, subsurface fault -- according to a study published online this week in Nature Geoscience.

In addition, because the earthquake did not involve slip near Earth's surface, the study suggests that it did not release all of the strain that has built up on faults in the area over the past two centuries, meaning that future surface-rupturing earthquakes in this region are likely.

Geophysicist Eric Fielding of NASA's Jet Propulsion Laboratory, Pasadena, Calif., along with lead author Gavin Hayes of the U.S. Geological Survey and other colleagues from USGS, the California Institute of Technology in Pasadena, the University of Texas at Austin, and Nagoya University, Japan, used a combination of seismological observations, geologic field data and satellite geodetic measurements to analyze the earthquake source. Initially the Haiti earthquake was thought to be the consequence of movement along a single fault -- the Enriquillo -- that accommodates the motion between the Caribbean and North American tectonic plates. But scientists in the field found no evidence of surface rupture on that fault.

The researchers found the pattern of surface deformation was dominated by movement on a previously unknown, subsurface thrust fault, named the Léogâne fault, which did not rupture the surface.

Fielding, who processed synthetic aperture radar interferometry data from a Japan Aerospace Exploration Agency (JAXA) satellite used in the study, said, "I was surprised when I saw the satellite data showed the Haiti earthquake must have ruptured a different fault than the major Enriquillo fault, which everybody expected was the source. Without the radar images, we might still be wondering what happened."

Fielding said NASA images acquired after the earthquake over the major fault zones of Hispaniola by the JPL-built Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) airborne instrument will give scientists much more detailed information should another large earthquake occur in the region in the future.

For more information, read the USGS news release: http://www.usgs.gov/newsroom/article.asp?ID=2612 .
To read the full study, visit: http://dx.doi.org/10.1038/ngeo977 .

For more on UAVSAR, see: http://uavsar.jpl.nasa.gov/mission_flights.html .

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Thursday, October 14, 2010

Camera That Saved Hubble Leaves Nest for Good

The historic Wide Field and Planetary Camera 2, developed and built by the Jet Propulsion Laboratory for NASA's Hubble Space Telescope, left JPL Wednesday morning, Oct. 13, for points east. Known informally as "The Camera That Saved Hubble," the baby-grand-piano-sized camera was on temporary loan from the Smithsonian Air and Space Museum in Washington.

During its stay at JPL, the historic camera was a popular attraction for groups of school children and other visitors, including thousands of people who attended JPL's annual Open House in May.

Next stop for the camera: It will be on display for a short time at the Denver Museum of Nature and Science in Colorado, and then it will return to the Smithsonian Air and Space Museum in Washington, where it will go on permanent display. The Wide Field and Planetary Camera 2 was the workhorse camera on Hubble after being added to the observatory in December 1993 to correct an imaging problem created by the telescope's faulty primary mirror. During its tenure aboard Hubble, the camera produced many of the mission's most stunning deep space images. Its high-image resolution and quality are some of the reasons the camera became the space telescope's most requested instrument during its operational lifetime. Logging 15 years aboard the observatory, the Wide Field and Planetary Camera 2 was Hubble's longest-serving instrument. Space-walking astronauts retrieved the camera during the final Hubble servicing mission in May 2009. More information about the Wide Field and Planetary Camera 2 is at http://www.jpl.nasa.gov/wfpc2 . An image gallery contains some of the camera's historic photos.

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Wednesday, October 13, 2010

Giant Star Goes Supernova, Smothered by its Own Dust

While searching the skies for black holes using NASA's Spitzer Space Telescope, astronomers discovered a giant supernova that was smothered in its own dust.
While searching the skies for black holes using NASA's Spitzer Space Telescope, astronomers discovered a giant supernova that was smothered in its own dust. › Full image and caption
Astronomers using NASA's Spitzer Space Telescope have discovered that a giant star in a remote galaxy ended its life with a dust-shrouded whimper instead of the more typical bang.

Researchers suspect that this odd event -- the first one of its kind ever viewed by astronomers – was more common early in the universe.

It also hints at what we would see if the brightest star system in our Milky Way galaxy exploded, or went supernova.

The discovery is reported in a paper published online in the Astrophysical Journal. The lead author is Christopher Kochanek, a professor of astronomy at Ohio State University, Columbus.

Read more at http://researchnews.osu.edu/archive/dustynova.htm .

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Tuesday, October 12, 2010

Small Asteroid to Pass Within Earth-Moon System Tuesday

A newly-discovered car-sized asteroid will fly past Earth early Tuesday.
A newly discovered car-sized asteroid will fly past Earth early Tuesday. The asteroid, 2010 TD54, will make its closest approach to Earth at 6:51 EDT a.m. (3:51 a.m. PDT).
› Larger image › Wider view
A small asteroid will fly past Earth early Tuesday within the Earth-moon system. The asteroid, 2010 TD54, will have its closest approach to Earth's surface at an altitude of about 45,000 kilometers (27,960 miles) at 6:50 EDT a.m. (3:50 a.m. PDT). At that time, the asteroid will be over southeastern Asia in the vicinity of Singapore. During its flyby, Asteroid 2010 TD54 has zero probability of impacting Earth. A telescope of the NASA-sponsored Catalina Sky Survey north of Tucson, Arizona discovered 2010 TD54 on Oct. 9 at (12:55 a.m. PDT) during routine monitoring of the skies.

2010 TD54 is estimated to be about 5 to 10 meters (16 to 33 feet) wide. Due to its small size, the asteroid would require a telescope of moderate size to be viewed. A five-meter-sized near-Earth asteroid from the undiscovered population of about 30 million would be expected to pass daily within a lunar distance, and one might strike Earth's atmosphere about every 2 years on average. If an asteroid of the size of 2010 TD54 were to enter Earth's atmosphere, it would be expected to burn up high in the atmosphere and cause no damage to Earth's surface.

The distance used on the Near Earth Object page is always the calculated distance from the center of Earth. The distance stated for 2010 TD54 is 52,000 kilometers (32,000 miles). To get the distance it will pass from Earth's surface you need to subtract the distance from the center to the surface (which varies over the planet), or about one Earth radii. That puts the pass distance at about 45,500 kilometers (28,000 miles) above the planet. NASA detects, tracks and characterizes asteroids and comets passing close to Earth using both ground-and space-based telescopes. The Near-Earth Object Observations Program, commonly called "Spaceguard," discovers these objects, characterizes a subset of them, and plots their orbits to determine if any could be potentially hazardous to our planet.

JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena.

More information about asteroids is available at http://www.jpl.nasa.gov/asteroidwatch/ . You can also follow the latest news about asteroids on Twitter at @asteroidwatch .

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Monday, October 11, 2010

NASA Mission to Asteroid Gets Help from Hubble

Hubble Space Telescope snapped these images of the asteroid Vesta in preparation for the Dawn spacecraft's visit in 2011.
NASA's Hubble Space Telescope snapped these images of the asteroid Vesta in preparation for the Dawn spacecraft's visit in 2011. › Full image and caption
NASA's Hubble Space Telescope has captured images of the large asteroid Vesta that will help refine plans for the Dawn spacecraft's rendezvous with Vesta in July 2011.

Scientists have constructed a video from the images that will help improve pointing instructions for Dawn as it is placed in a polar orbit around Vesta. Analyses of Hubble images revealed a pole orientation, or tilt, of approximately four degrees more to the asteroid's east than scientists previously thought.

This means the change of seasons between the southern and northern hemispheres of Vesta may take place about a month later than previously expected while Dawn is orbiting the asteroid. The result is a change in the pattern of sunlight expected to illuminate the asteroid. Dawn needs solar illumination for imaging and some mapping activities.

"While Vesta is the brightest asteroid in the sky, its small size makes it difficult to image from Earth," said Jian-Yang Li, a scientist participating in the Dawn mission from the University of Maryland in College Park. "The new Hubble images give Dawn scientists a better sense of how Vesta is spinning, because our new views are 90 degrees different from our previous images. It's like having a street-level view and adding a view from an airplane overhead."

The recent images were obtained by Hubble's Wide Field Camera 3 in February. The images complemented previous ones of Vesta taken from ground-based telescopes and Hubble's Wide Field and Planetary Camera 2 between 1983 and 2007. Li and his colleagues looked at 216 new images -- and a total of 446 Hubble images overall -- to clarify how Vesta was spinning. The journal Icarus recently published the report online.

"The new results give us food for thought as we make our way toward Vesta," said
Christopher Russell, Dawn's principal investigator at the University of California, Los Angeles. "Because our goal is to take pictures of the entire surface and measure the elevation of features over most of the surface to an accuracy of about 33 feet, or the height of a three-story building, we need to pay close attention to the solar illumination. It looks as if Vesta is going to have a late northern spring next year, or at least later than we planned."

Launched in September 2007, Dawn will leave Vesta to encounter the dwarf planet Ceres in 2015. Vesta and Ceres are the most massive objects in the main asteroid belt between Mars and Jupiter. Scientists study these celestial bodies as examples of the building blocks of terrestrial planets like Earth. Dawn is approximately 216 million kilometers (134 million miles) away from Vesta. Next summer, the spacecraft will make its own measurements of Vesta's rotating surface and allow mission managers to pin down its axis of spin.

"Vesta was discovered just over 200 years ago, and we are excited now to be on the threshold of exploring it from orbit," said Bob Mase, Dawn's project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We planned this mission to accommodate our imprecise knowledge of Vesta. Ours is a journey of discovery and, with our ability to adapt, we are looking forward to collecting excellent science data at our target."

The Dawn mission is managed by JPL, a division of the California Institute of Technology in Pasadena, for NASA's Science Mission Directorate at the agency's headquarters in Washington. Orbital Sciences Corporation of Dulles, Va., designed and built the spacecraft. Several international space organizations are part of the mission team.

To see the Vesta images and video, visit: http://www.nasa.gov/mission_pages/dawn/multimedia/vestavid20101008.html .

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

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Thursday, October 7, 2010

Enceladus May Keep its Oceans Liquid by Wobbling

Enceladus May Keep its Oceans Liquid by Wobbling
At least four distinct plumes of water ice spew out from the south polar region of Saturn's moon Enceladus in this dramatically illuminated image. › Full image and caption
NASA's Cassini spacecraft discovered a giant plume of water gushing from cracks in the surface near the south pole of Saturn’s moon Enceladus in 2005, indicating that there was a reservoir of water beneath the ice. Cassini data also suggest that the south polar has been continuously releasing about 13 billion watts of energy. But how does Enceladus stay warm enough to maintain liquid water underground?

In smaller moons like Enceladus, the cache of radioactive elements usually is not massive enough to produce significant heat for long. So, scientists have considered the role of tidal heating – the gravitational pull from Saturn as Enceladus orbits the planet – as a way to keep Enceladus warm enough for liquid water to remain under its surface.

Scientists with the Cassini team have compared a map of the gravitational tidal stress on the icy crust of Enceladus to a map of the warm zones created using Cassini's composite infrared spectrometer instrument. Areas with the most stress should overlap the warmest zones on the CIRS map, but they don’t exactly match.

Terry Hurford, of NASA's Goddard Space Flight Center, Greenbelt, Md., and his team believe the discrepancy can be resolved if Enceladus’ rotation rate is not uniform – if it wobbles slightly as it rotates.

To read the full story, go to: http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20100708-b.html

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency, and the Italian Space Agency. NASA's Jet Propulsion Laboratory, Pasadena, Calif., a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The composite infrared spectrometer team is based at NASA Goddard, where the instrument was built.

More Cassini information is available, at http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov .

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Wednesday, October 6, 2010

WISE Captures Key Images of Comet Mission's Destination

WISE snapped this photo of comet Hartley 2
This visitor from deep space, seen here by NASA's Wide-field Infrared Survey Explorer, or WISE, is comet Hartley 2 -- the destination for NASA's EPOXI mission. › Full image and caption
NASA's Wide-field Infrared Survey Explorer, or WISE, caught a glimpse of the comet that the agency's EPOXI mission will visit in November. The WISE observation will help the EPOXI team put together a large-scale picture of the comet, known as Hartley 2.

"WISE's infrared vision provides data that complement what EPOXI will see with its visible-light and near-infrared instruments," said James Bauer, of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "It's as if WISE can see an entire country, and EPOXI will visit its capital."

WISE's infrared vision will allow the telescope to get a new estimate of the size of the comet's nucleus, or core, as well as a more thorough look at the sizes of dust particles that surround it. This information, when combined with what EPOXI finds as it gets closer to Hartley 2, will reveal how the comet has changed over time.

The WISE image is available at: http://photojournal.jpl.nasa.gov/catalog/PIA13438.

On Nov. 4, the EPOXI mission, which uses the already "in flight" Deep Impact flyby spacecraft, will reach its closet approach to Hartley 2. The spacecraft will examine the dusty, icy body in detail as it flies by, providing the best, extended view of a comet in history. WISE and several other ground- and space-based telescopes are participating in the viewing, working together to tackle mysteries about our solar system's origins that are frozen inside comets.

For stargazers, opportunities to view the comet are possible throughout October. On Wednesday, Oct. 20, Hartley 2 will reach its closest approach to Earth since it was discovered in 1986. The comet will be approximately 17.7 million kilometers away (11 million miles) and should be visible with the naked eye near the constellation Perseus if viewed in dark skies. Observers will need binoculars or telescopes from urban areas in the Northern Hemisphere. Southern Hemisphere stargazers will be able to see the comet later in the month.

WISE captured its view of the comet during an ongoing scan of the sky in infrared light. The mission has been busy cataloging hundreds of millions of objects, from comets to distant, powerful galaxies. In late September, it used up its frozen cryogen coolant as expected and began a new phase of its survey. Called the NEOWISE Post-Cryogenic Mission, it primarily focuses on finding additional asteroids and comets. To date, the WISE mission has observed more than 150,000 asteroids and 110 comets, including Hartley 2.

"Astronomers can reference our catalogue to get detailed infrared data about their favorite asteroid or comet," said Amy Mainzer, the principal investigator of NEOWISE at JPL. "Space missions can also use our observations for more information on their targets, as EPOXI is doing."

WISE's view of Hartley 2 was taken on May 10, 2010. It gives astronomers a unique look at the comet, complementing what other telescopes can see. Because WISE scanned the whole sky, it captured the most extensive view of Hartley 2's trail, the dusty path left by the comet on its repeated journey around the sun.

Bauer said, "We want to know how the comet behaves as it comes toward the sun and out of deep freeze. The WISE image is one critical puzzle piece of many that will give a comprehensive view of the behavior of the comet through the time of the encounter."

The comet started to show signs of activity in the spring, spitting out gas and dust. By July, there were clear jets of gas. "Comparing the dust early on to what we see later with EPOXI helps us understand how the activity started on Hartley 2," said Michael A'Hearn, the principal investigator of EPOXI at the University of Maryland in College Park.

The term EPOXI is a combination of the names for the two extended mission components: the Extrasolar Planet Observations and Characterization (EPOCh), and the Hartley 2 flyby, called the Deep Impact eXtended Investigation (DIXI). The name NEOWISE comes from combining WISE and the acronym for near-Earth object, NEO.

More information about EPOXI is at: http://www.nasa.gov/epoxi and http://epoxi.umd.edu/.

More information about WISE is at: http://www.nasa.gov/wise and http://wise.astro.ucla.edu/ .

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