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Sunday, January 20, 2013

NASA's Hubble Reveals Rogue Planetary Orbit For Fomalhaut B

This false-color composite image, taken with the Hubble Space Telescope, reveals the orbital motion of the planet Fomalhaut b. Based on these observations, astronomers calculated that the planet is in a 2,000-year-long, highly elliptical orbit. The planet will appear to cross a vast belt of debris around the star roughly 20 years from now. If the planet's orbit lies in the same plane with the belt, icy and rocky debris in the belt could crash into the planet's atmosphere and produce various phenomena. The black circle at the center of the image blocks out the light from the bright star, allowing reflected light from the belt and planet to be photographed. The Hubble images were taken with the Space Telescope Imaging Spectrograph in 2010 and 2012. Credit: NASA, ESA, and P. Kalas (University of California, Berkeley and SETI Institute)

Newly released NASA Hubble Space Telescope images of a vast debris disk encircling the nearby star Fomalhaut and a mysterious planet circling it may provide forensic evidence of a titanic planetary disruption in the system.

Astronomers are surprised to find the debris belt is wider than previously known, spanning a section of space from 14 to nearly 20 billion miles from the star. Even more surprisingly, the latest Hubble images have allowed a team of astronomers to calculate the planet follows an unusual elliptical orbit that carries it on a potentially destructive path through the vast dust ring.

The planet, called Fomalhaut b, swings as close to its star as 4.6 billion miles, and the outermost point of its orbit is 27 billion miles away from the star. The orbit was recalculated from the newest Hubble observation made last year.

"We are shocked. This is not what we expected," said Paul Kalas of the University of California at Berkeley and the SETI Institute in Mountain View, Calif.

The Fomalhaut team led by Kalas considers this circumstantial evidence there may be other planet-like bodies in the system that gravitationally disturbed Fomalhaut b to place it in such a highly eccentric orbit. The team presented its finding Tuesday at the 221st meeting of the American Astronomical Society in Long Beach, Calif.

Among several scenarios to explain Fomalhaut b's 2,000-year-long orbit is the hypothesis that an as yet undiscovered planet gravitationally ejected Fomalhaut b from a position closer to the star, and sent it flying in an orbit that extends beyond the dust belt.

"Hot Jupiters get tossed through scattering events, where one planet goes in and one gets thrown out," said co-investigator Mark Clampin of NASA's Goddard Space Flight Center in Greenbelt, Md. "This could be the planet that gets thrown out."

Hubble also found the dust and ice belt encircling the star Fomalhaut has an apparent gap slicing across the belt. This might have been carved by another undetected planet. Hubble's exquisite view of the dust belt shows irregularities that strongly motivate a search for other planets in the system.

If its orbit lies in the same plane with the dust belt, then Fomalhaut b will intersect the belt around 2032 on the outbound leg of its orbit. During the crossing, icy and rocky debris in the belt could crash into the planet's atmosphere and create the type of cosmic fireworks seen when Comet Shoemaker-Levy 9 crashed into Jupiter. Most of the fireworks from collisions will be seen in infrared light. However, if Fomalhaut b is not co-planar with the belt, the only thing to be seen will be a gradual dimming of Fomalhaut b as it travels farther from the star.

Kalas hypothesized that Fomalhaut b's extreme orbit is a major clue in explaining why the planet is unusually bright in visible light, but very dim in infrared light. It is possible the planet's optical brightness originates from a ring or shroud of dust around the planet, which reflects starlight. The dust would be rapidly produced by satellites orbiting the planet, which would suffer extreme erosion by impacts and gravitational stirring when Fomalhaut b enters into the planetary system after a millennium of deep freeze beyond the main belt. An analogy can be found by looking at Saturn, which has a tenuous, but very large dust ring produced when meteoroids hit the outer moon Phoebe.

The team has also considered a different scenario where a hypothetical second dwarf planet suffered a catastrophic collision with Fomalhaut b. The collision scenario would explain why the star Fomalhaut has a narrow outer belt linked to an extreme planet. But in this case the belt is young, less than 10,000 years old, and it is difficult to produce energetic collisions far from the star in such young systems.

Fomalhaut is a special system because it looks like scientists may have a snapshot of what our solar system was doing 4 billion years ago. The planetary architecture is being redrawn, the comet belts are evolving, and planets may be gaining and losing their moons. Astronomers will continue monitoring Fomalhaut b for decades to come because they may have a chance to observe a planet entering an icy debris belt that is like the Kuiper Belt at the fringe of our own solar system.


Saturday, January 19, 2013

NASA's Next Mars Rover on a Test Drive

Rover


In some sense, the Mars Science Laboratory rover's parts will be similar to what any living creature would need to keep it "alive" and able to explore.

The rover will have a:
  • body: a structure that protects the rovers´ "vital organs"
  • brains: computers to process information
  • temperature controls: internal heaters, a layer of insulation, and more
  • "neck and head": a mast for the cameras to give the rover a human-scale view
  • eyes and other "senses": cameras and instruments that give the rover information about its environment
  • arm and "hand": a way to extend its reach and collect rock samples for study
  • wheels and "legs": parts for mobility
  • energy: batteries and power
  • communications: antennas for "speaking" and "listening"
Fast Facts
Mission name: Mars Science Laboratory
Rover name: Curiosity rover
Size: About the size of a small SUV -- 10 feet long (not including the arm), 9 feet wide and 7 feet tall -- (about 3 meters long (not including the arm), 2.7 meters wide, and 2.2 meters tall), or about the height of a basketball player.
Arm Reach: About 7 feet (2.2 meters)
Weight: 900 kilograms (2,000 pounds)
Features: Geology lab, rocker-bogie suspension, rock-vaporizing laser and lots of cameras
Mission: To search areas of Mars for past or present conditions favorable for life, and conditions capable of preserving a record of life
Launched:
7:02 a.m. PST, Nov. 26, 2011
(10:02 a.m. EST)
Landed:
10:32 p.m. PDT, Aug. 5, 2012
(1:32 a.m. EDT, Aug. 6, 2012)
Length of mission on Mars: The prime mission will last one Mars year or about 23 Earth months.



Cassini Suggests Icing on a Lake



This artist's concept envisions what hydrocarbon ice forming on a liquid hydrocarbon sea of Saturn's moon Titan might look like. Image credit: NASA/JPL-Caltech/USGS  

It's not exactly icing on a cake, but it could be icing on a lake. A new paper by scientists on NASA's Cassini mission finds that blocks of hydrocarbon ice might decorate the surface of existing lakes and seas of liquid hydrocarbon on Saturn's moon Titan. The presence of ice floes might explain some of the mixed readings Cassini has seen in the reflectivity of the surfaces of lakes on Titan.
"One of the most intriguing questions about these lakes and seas is whether they might host an exotic form of life," said Jonathan Lunine, a paper co-author and Cassini interdisciplinary Titan scientist at Cornell University, Ithaca, N.Y. "And the formation of floating hydrocarbon ice will provide an opportunity for interesting chemistry along the boundary between liquid and solid, a boundary that may have been important in the origin of terrestrial life."
Titan is the only other body besides Earth in our solar system with stable bodies of liquid on its surface. But while our planet's cycle of precipitation and evaporation involves water, Titan's cycle involves hydrocarbons like ethane and methane. Ethane and methane are organic molecules, which scientists think can be building blocks for the more complex chemistry from which life arose. Cassini has seen a vast network of these hydrocarbon seas cover Titan's northern hemisphere, while a more sporadic set of lakes bejewels the southern hemisphere.
Up to this point, Cassini scientists assumed that Titan lakes would not have floating ice, because solid methane is denser than liquid methane and would sink. But the new model considers the interaction between the lakes and the atmosphere, resulting in different mixtures of compositions, pockets of nitrogen gas, and changes in temperature. The result, scientists found, is that winter ice will float in Titan's methane-and-ethane-rich lakes and seas if the temperature is below the freezing point of methane -- minus 297 degrees Fahrenheit (90.4 kelvins). The scientists realized all the varieties of ice they considered would float if they were composed of at least 5 percent "air," which is an average composition for young sea ice on Earth. ("Air" on Titan has significantly more nitrogen than Earth air and almost no oxygen.)
If the temperature drops by just a few degrees, the ice will sink because of the relative proportions of nitrogen gas in the liquid versus the solid. Temperatures close to the freezing point of methane could lead to both floating and sinking ice – that is, a hydrocarbon ice crust above the liquid and blocks of hydrocarbon ice on the bottom of the lake bed. Scientists haven't entirely figured out what color the ice would be, though they suspect it would be colorless, as it is on Earth, perhaps tinted reddish-brown from Titan's atmosphere.
"We now know it's possible to get methane-and-ethane-rich ice freezing over on Titan in thin blocks that congeal together as it gets colder -- similar to what we see with Arctic sea ice at the onset of winter," said Jason Hofgartner, first author on the paper and a Natural Sciences and Engineering Research Council of Canada scholar at Cornell. "We'll want to take these conditions into consideration if we ever decide to explore the Titan surface some day."
Cassini's radar instrument will be able to test this model by watching what happens to the reflectivity of the surface of these lakes and seas. A hydrocarbon lake warming in the early spring thaw, as the northern lakes of Titan have begun to do, may become more reflective as ice rises to the surface. This would provide a rougher surface quality that reflects more radio energy back to Cassini, making it look brighter. As the weather turns warmer and the ice melts, the lake surface will be pure liquid, and will appear to the Cassini radar to darken.
"Cassini's extended stay in the Saturn system gives us an unprecedented opportunity to watch the effects of seasonal change at Titan," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We'll have an opportunity to see if the theories are right."
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and ASI, 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, Washington.

At Least One in Six Stars Has an Earth-sized Planet



The results of a new analysis of Kepler data show that one in six stars has an Earth-sized planet in a tight orbit. About a fourth of all stars in the Milky Way have a super-Earth, and the same fraction have a mini-Neptune. Only about 3 percent of stars have a large Neptune, and only 5 percent a gas giant at the orbital distances studied. Credit: F. Fressin (CfA)


This artist's illustration represents the variety of planets being detected by NASA's Kepler spacecraft. A new analysis has determined the frequencies of planets of all sizes, from Earths up to gas giants. Key findings include the fact that one in six stars hosts an Earth-sized planet in an orbit of 85 days or less, and that almost all sun-like stars have a planetary system of some sort. (Hat tip to Robert Hurt for inspiring this illustration.) Credit: C. Pulliam & D. Aguilar (CfA)


The quest to determine if planets like Earth are rare or common is taking another stride forward on the journey. Using NASA's Kepler spacecraft, managed by NASA Ames Research Center, astronomers are beginning to find Earth-sized planets orbiting distant stars. A new analysis of Kepler data shows that about 17 percent of stars have an Earth-sized planet in an orbit closer than Mercury. Since the Milky Way has about 100 billion stars, there are at least 17 billion Earth-sized worlds out there.

Francois Fressin, of the Harvard-Smithsonian Center for Astrophysics (CfA), presented the analysis today in a press conference at a meeting of the American Astronomical Society in Long Beach, Calif. A paper detailing the research has been accepted for publication in The Astrophysical Journal.

The research team found that 50 percent of all stars have a planet of Earth-size or larger in a close orbit. By adding larger planets detected in wider orbits up to the orbital distance of the Earth, this number increases to 70 percent.

Extrapolating from Kepler's currently ongoing observations and results from other detection techniques, scientists have determined that nearly all sun-like stars have planets.

Planets closer to their stars are easier to find because they transit more frequently. As more data are gathered, planets in larger orbits will be detected. In particular, Kepler's extended mission will enable the detection of Earth-sized planets at greater distances, including Earth-like orbits in the "habitable zone," the region in a planetary system where liquid water might exist on the surface of an orbiting planet.

Kepler is the first NASA mission capable of finding Earth-size planets orbiting in or near the habitable zone of the host star. NASA's Ames Research Center, Moffett Field, Calif., is the home organization of the science principal investigator, and is responsible for the ground system development, mission operations, and science data analysis.

NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed Kepler mission development. Ball Aerospace and Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with JPL at 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. Kepler is NASA's 10th Discovery Mission and is funded by NASA's Science Mission Directorate at the agency's headquarters. 


Saturday, January 12, 2013

NASA's GALEX Reveals the Largest-Known Spiral Galaxy


This composite of the giant barred spiral galaxy NGC 6872 combines visible light images from the European Southern Observatory's Very Large Telescope with far-ultraviolet (1,528 angstroms) data from NASA's GALEX and 3.6-micron infrared data acquired by NASA's Spitzer Space Telescope. A previously unsuspected tidal dwarf galaxy candidate (circled) appears only in the ultraviolet, indicating the presence of many hot young stars. IC 4970, the small disk galaxy interacting with NGC 6872, is located above the spiral's central region. The spiral is 522,000 light-years across from the tip of one outstretched arm to the tip of the other, which makes it about 5 times the size of our home galaxy, the Milky Way. Images of lower resolution from the Digital Sky Survey were used to fill in marginal areas not covered by the other data. Credit: NASA's Goddard Space Flight Center/ESO/JPL-Caltech/DSS
The spectacular barred spiral galaxy NGC 6872 has ranked among the biggest stellar systems for decades. Now a team of astronomers from the United States, Chile and Brazil has crowned it the largest-known spiral, based on archival data from NASA's Galaxy Evolution Explorer (GALEX) mission, which has since been loaned to the California Institute of Technology, Pasadena, Calif. 

Measuring tip-to-tip across its two outsized spiral arms, NGC 6872 spans more than 522,000 light-years, making it more than five times the size of our Milky Way galaxy. 

"Without GALEX's ability to detect the ultraviolet light of the youngest, hottest stars, we would never have recognized the full extent of this intriguing system," said lead scientist Rafael Eufrasio, a research assistant at NASA's Goddard Space Flight Center in Greenbelt, Md., and a doctoral student at Catholic University of America in Washington. He presented the findings Thursday at the American Astronomical Society meeting in Long Beach, Calif.

The galaxy's unusual size and appearance stem from its interaction with a much smaller disk galaxy named IC 4970, which has only about one-fifth the mass of NGC 6872. The odd couple is located 212 million light-years from Earth in the southern constellation Pavo. 

Astronomers think large galaxies, including our own, grew through mergers and acquisitions -- assembling over billions of years by absorbing numerous smaller systems. 

Intriguingly, the gravitational interaction of NGC 6872 and IC 4970 may have done the opposite, spawning what may develop into a new small galaxy.

"The northeastern arm of NGC 6872 is the most disturbed and is rippling with star formation, but at its far end, visible only in the ultraviolet, is an object that appears to be a tidal dwarf galaxy similar to those seen in other interacting systems," said team member Duilia de Mello, a professor of astronomy at Catholic University.

Computer simulations of the collision between NGC 6872 and IC 4970 reproduce the basic features of the galaxies as we see them today. They indicate that IC 4970's closest encounter occurred 130 million years ago and that the smaller galaxy followed a path (dashed curve) close to the plane of the spiral's disk and in the same direction it rotates. Credit: NASA's Goddard Space Flight Center, after C. Horellou (Onsala Space Observatory) and B. Koribalski (ATNF)

The tidal dwarf candidate is brighter in the ultraviolet than other regions of the galaxy, a sign it bears a rich supply of hot young stars less than 200 million years old. 

The researchers studied the galaxy across the spectrum using archival data from the European Southern Observatory's Very Large Telescope, the Two Micron All Sky Survey, and NASA's Spitzer Space Telescope, as well as GALEX. 

By analyzing the distribution of energy by wavelength, the team uncovered a distinct pattern of stellar age along the galaxy's two prominent spiral arms. The youngest stars appear in the far end of the northwestern arm, within the tidal dwarf candidate, and stellar ages skew progressively older toward the galaxy's center. 

The southwestern arm displays the same pattern, which is likely connected to waves of star formation triggered by the galactic encounter.

A 2007 study by Cathy Horellou at Onsala Space Observatory in Sweden and Baerbel Koribalski of the Australia National Telescope Facility developed computer simulations of the collision that reproduced the overall appearance of the system as we see it today. According to the closest match, IC 4970 made its closest approach about 130 million years ago and followed a path that took it nearly along the plane of the spiral's disk in the same direction it rotates. The current study is consistent with this picture.

As in all barred spirals, NGC 6872 contains a stellar bar component that transitions between the spiral arms and the galaxy's central regions. Measuring about 26,000 light-years in radius, or about twice the average length found in nearby barred spirals, it is a bar that befits a giant galaxy. 

The team found no sign of recent star formation along the bar, which indicates it formed at least a few billion years ago. Its aged stars provide a fossil record of the galaxy's stellar population before the encounter with IC 4970 stirred things up.

"Understanding the structure and dynamics of nearby interacting systems like this one brings us a step closer to placing these events into their proper cosmological context, paving the way to decoding what we find in younger, more distant systems," said team member and Goddard astrophysicist Eli Dwek.

The study also included Fernanda Urrutia-Viscarra and Claudia Mendes de Oliveira at the University of Sao Paulo in Brazil and Dimitri Gadotti at the European Southern Observatory in Santiago, Chile.

The GALEX mission is led by the California Institute of Technology in Pasadena, which is responsible for science operations and data analysis. NASA's Jet Propulsion Laboratory, also in Pasadena, manages the mission and built the science instrument. GALEX was developed under NASA's Explorers Program managed by NASA's Goddard Space Flight Center. In May 2012, NASA loaned GALEX to Caltech, which continues spacecraft operations and data management using private funds. 


Friday, January 11, 2013

NASA's Big Mars Rover Makes First Use of its Brush



This image from the Mars Hand Lens Imager (MAHLI) on NASA's Mars rover Curiosity shows the patch of rock cleaned by the first use of the rover's Dust Removal Tool (DRT). Image credit: NASA/JPL-Caltech/MSSS 
NASA's Mars rover Curiosity has completed first-time use of a brush it carries to sweep dust off rocks.
Nearing the end of a series of first-time uses of the rover's tools, the mission has cleared dust away from a targeted patch on a flat Martian rock using the Dust Removal Tool.
The tool is a motorized, wire-bristle brush designed to prepare selected rock surfaces for enhanced inspection by the rover's science instruments. It is built into the turret at the end of the rover's arm. In particular, the Alpha Particle X-ray Spectrometer and the Mars Hand Lens Imager, which share the turret with the brush and the rover's hammering drill, can gain information after dust removal that would not be accessible from a dust-blanketed rock.
Choosing an appropriate target was crucial for the first-time use of the Dust Removal Tool. The chosen target, called "Ekwir_1," is on a rock in the "Yellowknife Bay" area of Mars' Gale Crater. The rover team is also evaluating rocks in that area as potential targets for first use of the rover's hammering drill in coming weeks.
"We wanted to be sure we had an optimal target for the first use," said Diana Trujillo of NASA's Jet Propulsion Laboratory, Pasadena, Calif., the mission's activity lead for the Dust Removal Tool. "We need to place the instrument within less than half an inch of the target without putting the hardware at risk. We needed a flat target, one that wasn't rough, one that was covered with dust. The results certainly look good."
Honeybee Robotics, New York, N.Y., built the Dust Removal Tool for Curiosity, as well as tools for two previous Mars rovers, Spirit and Opportunity, which included wire brushes plus rock-grinding mechanisms.
NASA's Mars Science Laboratory project is using Curiosity to investigate whether the study area within Gale Crater has offered environmental conditions favorable for microbial life. JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Science Laboratory mission for the NASA Science Mission Directorate, Washington. 

Thursday, January 10, 2013

NASA's NuSTAR Catches Black Holes in Galaxy Web



This new view of spiral galaxy IC 342, also known as Caldwell 5, includes data from NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR. Image credit: NASA/JPL-Caltech/DSS  
This new view of the historical supernova remnant Cassiopeia A, located 11,000 light-years away, was taken by NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR. Image credit: NASA/JPL-Caltech/DSS 
NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, set its X-ray eyes on a spiral galaxy and caught the brilliant glow of two black holes lurking inside.
The new image is being released Monday along with NuSTAR's view of the supernova remnant Cassiopeia A, at the American Astronomical Society meeting in Long Beach, Calif.
"These new images showcase why NuSTAR is giving us an unprecedented look at the cosmos," said Lou Kaluzienski, NuSTAR program scientist at NASA headquarters in Washington. "With NuSTAR's greater sensitivity and imaging capability, we're getting a wealth of new information on a wide array of cosmic phenomena in the high-energy X-ray portion of the electromagnetic spectrum."
Launched last June, NuSTAR is the first orbiting telescope with the ability to focus high-energy X-ray light. It can view objects in considerably greater detail than previous missions operating at similar wavelengths. Since launch, the NuSTAR team has been fine-tuning the telescope, which includes a mast the length of a school bus connecting the mirrors and detectors.
The mission has looked at a range of extreme, high-energy objects already, including black holes near and far, and the incredibly dense cores of dead stars. In addition, NuSTAR has begun black hole searches in the inner region of the Milky Way galaxy and in distant galaxies in the universe.
Among the telescope's targets is the spiral galaxy IC342, also known as Caldwell 5, featured in one of the two new images. This galaxy lies 7 million light-years away in the constellation Camelopardalis (the Giraffe). Previous X-ray observations of the galaxy from NASA's Chandra X-ray Observatory revealed the presence of two blinding black holes, called ultraluminous X-ray sources (ULXs).
How ULXs can shine so brilliantly is an ongoing mystery in astronomy. While these black holes are not as powerful as the supermassive black hole at the hearts of galaxies, they are more than 10 times brighter than the stellar-mass black holes peppered among the stars in our own galaxy. Astronomers think ULXs could be less common intermediate-mass black holes, with a few thousand times the mass of our sun, or smaller stellar-mass black holes in an unusually bright state. A third possibility is that these black holes don't fit neatly into either category.
"High-energy X-rays hold a key to unlocking the mystery surrounding these objects," said Fiona Harrison, NuSTAR principal investigator at the California Institute of Technology in Pasadena. "Whether they are massive black holes, or there is new physics in how they feed, the answer is going to be fascinating."
In the image, the two bright spots that appear entangled in the arms of the IC342 galaxy are the black holes. High-energy X-ray light has been translated into the color magenta, while the galaxy itself is shown in visible light.
"Before NuSTAR, high-energy X-ray pictures of this galaxy and the two black holes would be so fuzzy that everything would appear as one pixel," said Harrison.
The second image features the well-known, historical supernova remnant Cassiopeia A, located 11,000 light-years away in the constellation Cassiopeia. The color blue indicates the highest-energy X-ray light seen by NuSTAR, while red and green signify the lower end of NuSTAR's energy range. The blue region is where the shock wave from the supernova blast is slamming into material surrounding it, accelerating particles to nearly the speed of light. As the particles speed up, they give off a type of light known as synchrotron radiation. NuSTAR will be able to determine for the first time how energetic the particles are, and address the mystery of what causes them to reach such great speeds.
"Cas A is the poster child for studying how massive stars explode and also provides us a clue to the origin of the high-energy particles, or cosmic rays, that we see here on Earth," said Brian Grefenstette of Caltech, a lead researcher on the observations. "With NuSTAR, we can study where, as well as how, particles are accelerated to such ultra-relativistic energies in the remnant left behind by the supernova explosion."
NuSTAR is a Small Explorer mission led by Caltech and managed by NASA's Jet Propulsion Laboratory in Pasadena for NASA's Science Mission Directorate in Washington. Orbital Sciences Corporation of Dulles, Va., built the spacecraft. Its instrument was built by a consortium including Caltech; JPL; the University of California (UC) Berkeley; Columbia University; NASA's Goddard Space Flight Center in Greenbelt, Md.; the Danish Technical University in Denmark; Lawrence Livermore National Laboratory in Livermore, Calif.; and ATK Aerospace Systems of Goleta, Calif.
NuSTAR's mission operations center is at UC Berkeley, with the Italian Space Agency providing an equatorial ground station located at Malindi, Kenya. The mission's outreach program is based at Sonoma State University in Rohnert Park, Calif. Goddard manages NASA's Explorer Program. Caltech manages JPL for NASA.

Monday, January 7, 2013

Curiosity Rover Explores 'Yellowknife Bay'

The NASA Mars rover Curiosity used its left Navigation Camera to record this view of the step down into a shallow depression called "Yellowknife Bay." Image credit: NASA/JPL-Caltech 

This map traces where NASA's Mars rover Curiosity drove between landing at a site subsequently named "Bradbury Landing," and the position reached during the mission's 130th Martian day, or sol, (Dec. 17, 2012). Image credit: NASA/JPL-Caltech/Univ. of Arizona 




Mission status report
The NASA Mars rover Curiosity this week is driving within a shallow depression called "Yellowknife Bay," providing information to help researchers choose a rock to drill.
Using Curiosity's percussive drill to collect a sample from the interior of a rock, a feat never before attempted on Mars, is the mission's priority for early 2013. After the powdered-rock sample is sieved and portioned by a sample-processing mechanism on the rover's arm, it will be analyzed by instruments inside Curiosity.
Yellowknife Bay is within a different type of terrain from what the rover has traversed since landing inside Mars' Gale Crater on Aug. 5, PDT (Aug. 6, UTC). The terrain Curiosity has entered is one of three types that intersect at a location dubbed "Glenelg," chosen as an interim destination about two weeks after the landing.

Curiosity reached the lip of a 2-foot (half-meter) descent into Yellowknife Bay with a 46-foot (14-meter) drive on Dec. 11. The next day, a drive of about 86 feet (26.1 meters) brought the rover well inside the basin. The team has been employing the Mast Camera (Mastcam) and the laser-wielding Chemistry and Camera (ChemCam) for remote-sensing studies of rocks along the way.
On Dec. 14, Curiosity drove about 108 feet (32.8 meters) to reach rock targets of interest called "Costello" and "Flaherty." Researchers used the Alpha Particle X-Ray Spectrometer (APXS) and Mars Hand Lens Imager (MAHLI) at the end of the rover's arm to examine the targets. After finishing those studies, the rover drove again on Dec. 17, traveling about 18 feet (5.6 meters) farther into Yellowknife Bay. That brings the mission's total driving distance to 0.42 mile (677 meters) since Curiosity's landing.
One additional drive is planned this week before the rover team gets a holiday break. Curiosity will continue studying the Martian environment from its holiday location at the end point of that drive within Yellowknife Bay. The mission's plans for most of 2013 center on driving toward the primary science destination, a 3-mile-high (5-kilometer) layered mound called Mount Sharp.
NASA's Mars Science Laboratory Project is using Curiosity during a two-year prime mission to assess whether areas inside Gale Crater ever offered a habitable environment for microbes. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the project for NASA's Science Mission Directorate in Washington.

Saturday, December 29, 2012

Mars Rover Self-Portrait Shoot Uses Arm Choreography



On the 84th and 85th Martian days of the NASA Mars rover Curiosity's mission on Mars (Oct. 31 and Nov. 1, 2012), NASA's Curiosity rover used the Mars Hand Lens Imager (MAHLI) to capture dozens of high-resolution images to be combined into self-portrait images of the rover. Image credit: NASA/JPL-Caltech/MSSS  
The robotic arm on NASA's Mars rover Curiosity held the rover's Mars Hand Lens Imager (MAHLI) camera in more than 50 positions in one day to generate a single scene combining all the images, creating a high-resolution, full-color portrait of the rover itself.

A larger version of the previously released self-portrait is now available online, along with an animation video showing how it was taken, and a practice self-portrait taken earlier by Curiosity's test-rover double on Earth.
The animation video at:http://www.nasa.gov/multimedia/videogallery/index.html?media_id=156880341depicts how the rover moved its robotic arm on Oct. 31 to record the component images that would be combined into the self-portrait. The same software that rover planners use when designing the rover's moves was used to generate the animation.
The arm movements were practiced on Earth first, using the closest double that exists for Curiosity, the Vehicle System Test Bed rover at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The rover team typically uses that rover to test maneuvers before they are tried by Curiosity. The Vehicle System Test Bed's self-portrait, from the engineering model of MAHLI on that rover, is at:http://photojournal.jpl.nasa.gov/catalog/PIA16458 .
MAHLI is mounted on a turret at the end of Curiosity's robotic arm. The arm is not visible in the portrait because the arm was positioned out of the shot in the images or portions of images used in the mosaic. Some images taken during the day show portions of the arm. However, the Martian ground that the arm hides from view in those images is visible in alternative images chosen for the mosaic, taking the arm out of the scene.
During a two-year prime mission, researchers are using Curiosity's 10 science instruments to assess whether the study area in Gale Crater ever has offered environmental conditions favorable for microbial life.
Malin Space Science Systems, San Diego, developed, built and operates MAHLI. JPL, a division of the California Institute of Technology, Pasadena, manages the Mars Science Laboratory Project for NASA's Science Mission Directorate, Washington. JPL designed and built the project's Curiosity rover.

Thursday, December 27, 2012

NASA'S Hubble Provides First Census of Galaxies Near Cosmic Dawn



This new image of the Hubble Ultra Deep Field (HUDF) 2012 campaign reveals a previously unseen population of seven faraway galaxies, which are observed as they appeared in a period 350 million to 600 million years after the big bang. Credit: NASA, ESA, R. Ellis (Caltech), and the UDF 2012 Team
 Using NASA's Hubble Space Telescope, astronomers have uncovered a previously unseen population of seven primitive galaxies that formed more than 13 billion years ago, when the universe was less than 4 percent of its present age. The deepest images to date from Hubble yield the first statistically robust sample of galaxies that tells how abundant they were close to the era when galaxies first formed.


The results are from an ambitious Hubble survey of an intensively studied patch of sky known as the Ultra Deep Field (UDF). In the 2012 campaign, called UDF12, a team of astronomers led by Richard Ellis of the California Institute of Technology in Pasadena used Hubble's Wide Field Camera 3 (WFC 3) to peer deeper into space in near-infrared light than any previous Hubble observation.

The observations were made during six weeks in August and September, and the first scientific results now are appearing in a series of scientific papers. The UDF12 team is releasing these unique data to the public after preparing them for other research groups to use.

The results show a smooth decline in the number of galaxies looking back in time to about 450 million years after the big bang. The observations support the idea galaxies assembled continuously over time and also may have provided enough radiation to reheat, or re-ionize, the universe a few hundred million years after the theorized big bang.

Looking deeper into the universe also means peering further back in time. The universe is estimated to be 13.7 billion years old. The newly discovered galaxies are seen as they looked 350 to 600 million years after the big bang. Their light is just arriving at Earth now.

Astronomers study the distant universe in near-infrared light because the expansion of space stretches ultraviolet and visible light from galaxies into infrared wavelengths, a phenomenon called "redshift." The more distant a galaxy, the higher its redshift.

The greater depth of the new Hubble images, together with a carefully designed survey strategy, allows this work to go further than previous studies, thereby providing what researchers say is the first reliable census of this epoch. Notably, one of the galaxies may be a distance record breaker, observed 380 million years after the birth of our universe in the big bang, corresponding to a redshift of 11.9.

A major goal of the new program was to determine how rapidly the number of galaxies increases over time in the early universe. This measure is the key evidence for how quickly galaxies build up their constituent stars.

"Our study has taken the subject forward in two ways," Ellis explained. "First, we have used Hubble to make longer exposures. The added depth is essential to reliably probe the early period of cosmic history. Second, we have used Hubble's available color filters very effectively to more precisely measure galaxy distances."

The team estimated the galaxy distances by studying their colors through a carefully chosen set of four filters at specific near-infrared wavelengths. "We added one filter, and undertook much deeper exposures in some filters than in earlier work, in order to convincingly reject the possibility that some of our galaxies might be foreground objects," said team member James Dunlop of the Institute for Astronomy at the University of Edinburgh in Scotland.

Astronomers have long debated whether hot stars in such early galaxies could have provided enough radiation to warm the cold hydrogen that formed soon after the big bang. This process, called "re-ionization," is thought to have occurred 200 million to 1 billion years after the birth of the universe. This process made the universe transparent to light, allowing astronomers to look far back into time. The galaxies in the new study are seen in this early epoch.

"Our data confirm re-ionization was a gradual process, occurring over several hundred million years, with galaxies slowly building up their stars and chemical elements," said Brant Robertson of the University of Arizona in Tucson. "There wasn’t a single dramatic moment when galaxies formed. It was a gradual process."