vendredi 15 juin 2012

NASA Releases Workshop Data and Findings on Asteroid 2011 AG5











Asteroid and comet watch.

June 15, 2012

Researchers anticipate that asteroid 2011 AG5, discovered in January 2011, will fly safely past and not impact Earth in 2040.

Current findings and analysis data were reported at a May 29 workshop at NASA's Goddard Space Flight Center in Greenbelt, Md., attended by scientists and engineers from around the world. Discussions focused on observations of potentially hazardous asteroids (PHAs).

Observations to date indicate there is a slight chance that AG5 could impact Earth in 2040. Attendees expressed confidence that in the next four years, analysis of space and ground-based observations will show the likelihood of 2011 AG5 missing Earth to be greater than 99 percent.

Artist interpretation of the asteroid 2011 AG5 approaching the Earth

Measuring approximately 460 feet (140 meters) in size, the space rock was discovered by the NASA-supported Catalina Sky Survey operated by the University of Arizona in Tucson. Several observatories monitored 2011 AG5 for nine months before it moved too far away and grew too faint to see.

"While there is general consensus there is only a very small chance that we could be dealing with a real impact scenario for this object, we will still be watchful and ready to take further action if additional observations indicate it is warranted," said Lindley Johnson, program executive for the Near-Earth Object (NEO) Observation Program at NASA Headquarters in Washington.

Several years ago another asteroid, named Apophis, was thought to pose a similar impact threat in 2036. Additional observations taken from 2005 through 2008 enabled NASA scientists to refine their understanding of the asteroid's path, which showed a significantly reduced likelihood of a hazardous encounter.


Image above: Orbit and current location (6/15/2012) of asteroid 2011 AG5. Image credit: NASA/JPL-Caltech.

"Any time we're able to observe an asteroid and obtain new location data, we're able to refine our calculations of the asteroid's future path," said Don Yeomans, manager of NASA's NEO Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. "When few observations exist, our initial orbit calculation will include a wider swath to account for uncertainties. With more data points, the knowledge of the potential positions of the asteroid improves and the swath becomes smaller -- typically eliminating the risk of an impact."

Observations of 2011 AG5 have been limited to date because of its present location beyond the orbit of Mars and in the daytime sky on the other side of the sun. In fall 2013, conditions will improve to allow space- and ground-based telescopes to better track the asteroid's path. At that time, 2011 AG5 will be 91 million miles (147 million kilometers) from Earth but favorably located for observations in the late evening sky.

The level of hazard will gain even more clarity in 2023, when the asteroid is approximately 1.1 million miles (1.8 million kilometers) from Earth. If 2011 AG5 passes through a 227-mile-wide (365-kilometer) region in space called a keyhole in early February 2023, Earth's gravitational pull could influence the object's orbital path just enough to bring it back for an impact on February 5, 2040. If the asteroid misses the keyhole, an impact in 2040 will not occur.

"Given our current understanding of this asteroid's orbit, there is only a very remote chance of this keyhole passage even occurring," said Johnson.

Asteroid 2011 AG5

Although scientists widely expect it to be a safe flyby, they acknowledge the slight chance that computed odds could rise as a result of observations to be taken from 2013 to 2016. According to the experts at the workshop, even if the odds do increase, there is still ample time to plan and carry out at least one of several viable missions to change the asteroid's course.

PHAs are a subset of the larger group of near-Earth asteroids. They have the closest orbits to Earth's, coming within 5 million miles (about 8 million kilometers). They are large enough to enter Earth's atmosphere intact and cause damage on at least a local scale. Damage from an asteroid the size of 2011 AG5 could cover a region at least a hundred miles wide.

NASA established the NEO Program in 1998 to coordinate the agency's efforts to detect, track and characterize Earth-approaching NEOs and comets larger than 1 kilometer in size. The program now also searches for NEOs as small as object 2011 AG5. NASA supports NEO observation, tracking and analysis activities worldwide. Activities are coordinated through the NEO Program Office at JPL.

To read the workshop report and findings, visit: http://neo.jpl.nasa.gov/ .

For information about NASA asteroid missions and activities, visit: http://www.nasa.gov/asteroids .

EDITOR'S NOTE: Lindley Johnson and Don Yeomans are available for media interviews. To coordinate a time and date, email Dwayne Brown at dwayne.c.brown@nasa.gov

Images, Text, Credits: NASA / Dwayne Brown / JPL-Caltech / Orbiter.ch.

Best regards, Orbiter.ch

jeudi 14 juin 2012

Cassini Sees Tropical Lakes on Saturn Moon












NASA / ESA - Cassini Mission to Saturn patch.

June 14, 2012

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

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

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

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


Image above: Saturn's rings lie in the distance as the Cassini spacecraft looks toward Titan and its dark region called Shangri-La, east of the landing site of the Huygens Probe. Image credit: NASA/JPL-Caltech/Space Science Institute.

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

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

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

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

Artist view of the Cassini spacecraft. Credit: NASA/JPL-Caltech

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

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

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

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

Images (mentioned), Text, Credits: NASA / Dwayne Brown / JPL / Jia-Rui C. Cook.

Greetings, Orbiter.ch

A Trick of Perspective - Chance Alignment Mimics a Cosmic Collision












ESA - Hubble Space Telescope logo.

14 June 2012

 Hubble view of NGC 3314

The NASA/ESA Hubble Space Telescope has produced a highly detailed image of a pair of overlapping galaxies called NGC 3314. While the two galaxies look as if they are in the midst of a collision, this is in fact a trick of perspective: the two just happen to appear in the same direction from our vantage point.

NGC 3314A and B might look like they are in the midst of a galactic pile-up, but they are in fact separated by tens of millions of light years of void. Their apparent proximity is simply a trick of perspective.

How do we know this? The biggest hint as to whether galaxies are interacting is usually their shapes. The immense gravitational forces involved in galactic mergers are enough to pull a galaxy out of shape long before it actually collides. Deforming a galaxy like this does not just warp its structure, but it can trigger new episodes of star formation, usually visible as bright blue stars and glowing nebulae.

The area around NGC 3314 (ground-based view)

In the case of NGC 3314, we do indeed see deformation in the foreground galaxy (called NGC 3314A, NGC 3314B lies in the background), but this is almost certainly misleading. NGC 3314A’s deformed shape, particularly visible below and to the right of the core, where streams of hot blue-white stars extend out from the spiral arms, is not due to interaction with the galaxy in the background.

Studies of the motion of the two galaxies indicate that they are both relatively undisturbed, and that they are moving independently of each other. This indicates in turn that they are not, and indeed have never been, on any collision course. NGC 3314A’s warped shape is likely due instead to an encounter with another galaxy, perhaps nearby NGC 3312 (visible to the north in wide-field images) or another nearby galaxy.

The chance alignment of the two galaxies is more than just a curiosity, though. It greatly affects the way the two galaxies appear to us.

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Zoom into NGC 3314

NGC 3314B’s dust lanes, for example, appear far lighter than those of NGC 3314A. This is not because that galaxy lacks dust, but rather because they are lightened by the bright fog of stars in the foreground. NGC 3314A’s dust, in contrast, is backlit by the stars of NGC 3314B, silhouetting them against the bright background.

Such an alignment of galaxies is also helpful to astronomers studying gravitational microlensing, a phenomenon that occurs when stars in one galaxy cause small perturbations in the light coming from a more distant one. Indeed, the observations of NGC 3314 that led to this image were carried out in order to investigate this phenomenon.

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Pan across NGC 3314

This mosaic image covers a large field of view (several times the size of an individual exposure from Hubble’s Advanced Camera for Surveys). Thanks to a long exposure time of more than an hour in total exposure time for every frame, the image shows not only NGC 3314, but also many other more distant galaxies in the background.

The colour composite was produced from exposures taken in blue and red light.

Notes:

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

Data in this image of NGC 3314 were entered into the Hubble’s Hidden Treasures Image Processing Competition by contestants Andre vd Hoeven and nmoushon. Hidden Treasures is an initiative to invite astronomy enthusiasts to search the Hubble archive for stunning images that have never been seen by the general public. The competition is now closed and the winners will be announced soon.

Links:

    Images of Hubble: http://www.spacetelescope.org/images/archive/category/spacecraft/

Images, Text, Credit: NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and W. Keel (University of Alabama) / Videos: NASA, ESA, Digitized Sky Survey 2, N. Risinger (skysurvey.org). Music: Disasterpeace (disasterpeace.com).

Best regards, Orbiter.ch

mercredi 13 juin 2012

Small Planets Don't Need Stars with Heavy Metal Content to Form












NASA - Kepler Mission patch.

June 13, 2012

The formation of small worlds like Earth previously was thought to occur mostly around stars rich in heavy elements such as iron and silicon. However, new ground-based observations, combined with data collected by NASA's Kepler space telescope, shows small planets form around stars with a wide range of heavy element content and suggests they may be widespread in our galaxy.

A research team led by Lars A. Buchhave, an astrophysicist at the Niels Bohr Institute and the Centre for Star and Planet Formation at the University of Copenhagen, studied the elemental composition of more than 150 stars harboring 226 planet candidates smaller than Neptune.

"I wanted to investigate whether small planets needed a special environment in order to form, like the giant gas planets, which we know preferentially develop in environments with a high content of heavy elements," said Buchhave. "This study shows that small planets do not discriminate and form around stars with a wide range of heavy metal content, including stars with only 25 percent of the sun's metallicity."

Astronomers refer to all chemical elements heavier than hydrogen and helium as metals. They define metallicity as the metal content of heavier elements in a star. Stars with a higher fraction of heavy elements than the sun are considered metal-rich. Stars with a lower fraction of heavy elements are considered metal-poor.

Planets are created in disks of gas and dust around new stars. Planets like Earth are composed almost entirely of elements such as iron, oxygen, silicon and magnesium. The metallicity of a star mirrors the metal content of the planet-forming disk. Astronomers have hypothesized that large quantities of heavy elements in the disk would lead to more efficient planet formation. It has long been noted that giant planets with short orbital periods tend to be associated with metal-rich stars.

video

Video above: The artist conception shows a newly formed star surrounded by a swirling protoplanetary disk of dust and gas. Debris coalesces to create rocky 'planetesimals' that collide and grow to eventually form planets. The results of this study show that small planets form around stars with a wide range of heavy element content suggesting that their existence might be widespread in the galaxy. Credit: University of Copenhagen/Lars Buchhave.

Unlike gas giants, the occurrence of smaller planets is not strongly dependent on the heavy element content of their host stars. Planets up to four times the size of Earth can form around stars with a wide range of heavy element content, including stars with a lower metallicity than the sun. The findings are described in a new study published in the journal Nature.

"Kepler has identified thousands of planet candidates, making it possible to study big-picture questions like the one posed by Lars. Does nature require special environments to form Earth-size planets?" said Natalie Batalha, Kepler mission scientist at NASA's Ames Research Center at Moffett Field, Calif. "The data suggest that small planets may form around stars with a wide range of metallicities -- that nature is opportunistic and prolific, finding pathways we might otherwise have thought difficult."

The ground-based spectroscopic observations for this study were made at the Nordic Optical Telescope on La Palma in the Canary Islands; Fred Lawrence Whipple Observatory on Mt. Hopkins in Ariz.; McDonald Observatory at the University of Texas at Austin; and W.M. Keck Observatory atop Mauna Kea in Hawaii.

Kepler spacecraft. Credit: NASA

Launched in March 2009, Kepler searches for planets by continuously monitoring more than 150,000 stars, looking for telltale dips in their brightness caused by passing, or transiting, planets. At least three transits are required to verify a signal as a planet. Follow-up observations from ground-based telescopes are also needed to confirm a candidate as a planet.

Ames manages Kepler's ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed the Kepler mission development.

Ball Aerospace & 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 Kepler science data. Kepler is NASA's 10th Discovery Mission and is funded by NASA's Science Mission Directorate at the agency's headquarters in Washington.

For more information about the Kepler mission, visit: http://www.nasa.gov/kepler

Image, Video (mentioned), Text, Credits: NASA / Ames Research Center / Michele Johnson.

Cheers, Orbiter.ch

NASA's NuSTAR Mission Lifts Off








NASA - NuStar Mission patch.

06.13.12

NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) launched into the morning skies over the central Pacific Ocean at 9 a.m. PDT (noon EDT) Wednesday, beginning its mission to unveil secrets of buried black holes and other exotic objects.


This series of images show NASA's NuSTAR and its rocket dropping from the carrier "Stargazer" plane. Image credit: Orbital Sciences Corporation.

"We all eagerly await the launch of this novel X-ray observatory," said Paul Hertz, NASA's Astrophysics Division Director. "With its unprecedented spatial and spectral resolution to the previously poorly explored hard X-ray region of the electromagnetic spectrum, NuSTAR will open a new window on the universe and will provide complementary data to NASA's larger missions, including Fermi, Chandra, Hubble and Spitzer."

NuSTAR will use a unique set of eyes to see the highest energy X-ray light from the cosmos. The observatory can see through gas and dust to reveal black holes lurking in our Milky Way galaxy, as well as those hidden in the hearts of faraway galaxies.

Artist concept of the NuStar spacecraft. Credit: NASA

"NuSTAR will help us find the most elusive and most energetic black holes, to help us understand the structure of the universe," said Fiona Harrison, the mission's principal investigator at the California Institute of Technology in Pasadena.

The observatory began its journey aboard a L-1011 "Stargazer" aircraft, operated by Orbital Sciences Corporation, Dulles, Va. NuSTAR was perched atop Orbital's Pegasus XL rocket, both of which were strapped to the belly of the Stargazer plane. The plane left Kwajalein Atoll in the central Pacific Ocean one hour before launch. At 9:00:35 a.m. PDT (12:00:35 p.m. EDT), the rocket dropped, free-falling for five seconds before firing its first-stage motor.

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Launch of NuSTAR

About 13 minutes after the rocket dropped, NuSTAR separated from the rocket, reaching its final low Earth orbit. The first signal from the spacecraft was received at 9:14 a.m. PDT (12:14 p.m. EDT) via NASA's Tracking and Data Relay Satellite System.

"NuSTAR spread its solar panels to charge the spacecraft battery and then reported back to Earth of its good health," said Yunjin Kim, the mission's project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We are checking out the spacecraft now and are excited to tune into the high-energy X-ray sky."

The mission's unique telescope design includes a 33-foot (10-meter) mast, which was folded up in a small canister during launch. In about seven days, engineers will command the mast to extend, enabling the telescope to focus properly. About 23 days later, science operations are scheduled to begin.


Image above: The Orbital Science Corporation's "Stargazer" plane is shown releasing its Pegasus rocket. (Credit: Orbital Sciences Corporation).

In addition to black holes and their powerful jets, NuSTAR will study a host of high-energy objects in our universe, including the remains of exploded stars; compact, dead stars; and clusters of galaxies. The mission's observations, in coordination with other telescopes such as NASA's Chandra X-ray Observatory, which detects lower-energy X-rays, will help solve fundamental cosmic mysteries. NuSTAR also will study our sun's fiery atmosphere, looking for clues as to how it is heated.

NuSTAR is a Small Explorer mission led by the Caltech and managed by JPL for NASA's Science Mission Directorate in Washington. The spacecraft was built by Orbital Sciences Corporation. Its instrument was built by a consortium including Caltech; JPL; the University of California, Berkeley; Columbia University, New York; NASA's Goddard Space Flight Center, Greenbelt, Md.; the Danish Technical University in Denmark; Lawrence Livermore National Laboratory, Livermore, Calif.; and ATK Aerospace Systems, Goleta, Calif. NuSTAR will be operated by UC Berkeley, with the Italian Space Agency providing its equatorial ground station located at Malindi, Kenya. The mission's outreach program is based at Sonoma State University, Rohnert Park, Calif. NASA's Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.

Launch management and government oversight for the mission are the responsibility of NASA's Launch Services Program at the Kennedy Space Center in Florida. NASA’s Space Network and Near Earth Network are providing space communication services for launch and early orbit and critical periods during the mission.

For more information about NuSTAR, visit: http://www.nasa.gov/nustar

Images, Video, Text, Credits: NASA / J.D. Harrington / NASA TV / JPL / Whitney Clavin.

Greetings, Orbiter.ch

mardi 12 juin 2012

NASA's Ocean Salinity Pathfinder Celebrates its First Year in Orbit












NASA - AQUARIUS Mission patch.

June 12. 2012

It's been a busy first year in space for Aquarius, NASA's pioneering instrument to measure ocean surface salinity from orbit.

Designed to advance our understanding of what changes in the saltiness of the ocean's top layer say about the water cycle and variations in climate, Aquarius took only two and a half months after its launch to start measuring global salinity patterns. Since then, it has also observed regional features such as the freshwater plume gushing from the Amazon River and localized changes in ocean saltiness following a tropical storm.


Image above: NASA's Aquarius instrument has been orbiting the Earth for a year, measuring changes in salinity, or salt concentration, in the surface of the oceans. The Aquarius team released last September this first global map of ocean saltiness, a composite of the first two and a half weeks of data since the instrument became operational on August 25. Credit: NASA/GSFC/JPL-Caltech.

"It was a very remarkable achievement, that within such a short period of time after turning the instrument on we were producing very good-looking data," said Aquarius Principal Investigator Gary Lagerloef, of Earth & Space Research in Seattle. "It was beyond our expectations."

Lagerloef said that objectives for Aquarius' second year in orbit include correcting a few remaining calibration errors and validating the Aquarius dataset with thousands of direct in-water measurements of salinity.

The Aquarius/Satélite de Aplicaciones Científicas (SAC)-D mission is an international collaboration of NASA and Argentina's space agency. The satellite also carries instruments from partner institutions in Canada, Italy and France.

A Delta II rocket carrying the international observatory launched from Vandenberg Air Force Base in California, on June 10, 2011. Less than an hour later, the satellite separated from the rocket, started its deployment and established communications with ground stations.


Image above: A Delta II rocket carrying the international Aquarius/SAC-D observatory launches from Vandenberg Air Force Base in California, on June 10, 2011. Credit: NASA/Bill Ingalls.

"The first time the thing chirped, we got the data and posted it on the Web. It was just basic telemetry at that point, but it showed that all the systems we had put in place to share the data worked," said Gene Feldman, Aquarius project manager at NASA Goddard Space Flight Center in Greenbelt, Md. "We didn't get to pop champagne – we didn't have the time!"

Aquarius is the first NASA instrument specifically designed to study superficial ocean salinity from space, and it does it at a rate of about 300,000 measurements per month. It uses three passive microwave sensors, called radiometers, to record the thermal signal from the oceans' top 0.4 inches (10.1 millimeters). This signal varies depending on the concentration of salt and the temperature of the waters.

"An overarching question in climate research is to understand how changes in the Earth's water cycle – meaning rainfall and evaporation, river discharges and so forth – ocean circulation, and climate link together," Lagerloef said. Most global precipitation and evaporation events take place over the ocean and are very difficult to measure. But rainfall freshens the oceans' surface waters, and Aquarius can detect these changes in saltiness. "Salinity is the variable we can use to measure that coupling effect. It's a critical factor and it will eventually be used to improve climate forecast models."

Aquarius became operational on Aug. 25, 2011. The project's scientists soon created a map of global ocean saltiness using the first two and a half weeks of measurements, which had been compared against reference salinity data. The map showed variations in salinity patterns in much greater detail than Aquarius researchers had expected to see so early in the mission. Another welcome surprise was the observation of the effects on the ocean of Tropical Storm Lee (Sept. 2-3, 2011). Heavy rains produced a low-salinity feature that lasted more than a month in the Gulf of Mexico between the Mississippi River delta and the Florida panhandle.

video

"Aquarius has worked flawlessly over the first year of operations," said Amit Sen of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., who served as Aquarius project manager through the mission’s commissioning phase. "It is giving scientists new signatures and features of global ocean surface salinity that have not been studied before."

Lagerloef said that once the members of the Aquarius team obtain a whole year of Aquarius data, they will study the seasonal cycle of salinity variations, and how it relates to rainfall and ocean currents.

"Now that we have a lot of calibration issues resolved, the mantra for the second year is going to be to turn up the science, to better understand the salinity variations seen by Aquarius," Lagerloef said. Another, though more distant, goal will be to integrate Aquarius data with other measurements of salinity taken from ships, robotic floats, and the European Space Agency's Soil Moisture and Ocean Salinity satellite.

Aquarius was built by NASA's Jet Propulsion Laboratory and the Goddard Space Flight Center. NASA's Launch Services Program, at Kennedy Space Center in Florida, managed the launch. JPL managed Aquarius through its commissioning phase and is archiving mission data. Goddard now manages Aquarius mission operations and processes science data, beginning on Dec. 1, 2011. CONAE is providing the SAC-D spacecraft, optical camera, thermal camera with Canada, microwave radiometer, sensors from various Argentine institutions and the mission operations center. France and Italy also are contributing instruments.

For more information about Aquarius/SAC-D, (Spanish) visit: http://www.conae.gov.ar/eng/principal.html

Images (mentioned), Video, Text, Credits: NASA's Goddard Space Flight Center / Maria-Jose Vinas.

Greetings, Orbiter.ch

NASA Mars Rover Team Aims for Landing Closer to Prime Science Site










NASA - Mars Science Laboratory (MSL) patch.

June 12, 2012


This image shows changes in the target landing area for Curiosity, the rover of NASA's Mars Science Laboratory project. Image credit: NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS.

NASA has narrowed the target for its most advanced Mars rover, Curiosity, which will land on the Red Planet in August. The car-sized rover will arrive closer to its ultimate destination for science operations, but also closer to the foot of a mountain slope that poses a landing hazard.

"We're trimming the distance we'll have to drive after landing by almost half," said Pete Theisinger, Mars Science Laboratory project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "That could get us to the mountain months earlier."


Image above: A June 2012 revision of the landing target area for Curiosity, the big rover of NASA's Mars Science Laboratory mission, reduces the area's size. Image credit: NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS.

It was possible to adjust landing plans because of increased confidence in precision landing technology aboard the Mars Science Laboratory spacecraft, which is carrying the Curiosity rover. That spacecraft can aim closer without hitting Mount Sharp at the center of Gale crater. Rock layers located in the mountain are the prime location for research with the rover.

Mars Science Laboratory (MSL). Image Credit: NASA / JPL-Caltech

Curiosity is scheduled to land at approximately 10:31 p.m. PDT Aug. 5 (1:31 a.m. EDT, Aug. 6). Following checkout operations, Curiosity will begin a two-year study of whether the landing vicinity ever offered an environment favorable for microbial life.

Theisinger and other mission leaders described the target adjustment during an update to reporters on Monday, June 11, about preparations for landing and for operating Curiosity on Mars.


Image above: The ellipse is about 12 miles long and 4 miles wide (20 kilometers by 7 kilometers). Image credit: NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS.

The landing target ellipse had been approximately 12 miles wide and 16 miles long (20 kilometers by 25 kilometers). Continuing analysis of the new landing system's capabilities has allowed mission planners to shrink the area to approximately 4 miles wide and 12 miles long (7 kilometers by 20 kilometers), assuming winds and other atmospheric conditions are as predicted.

Even with the smaller ellipse, Curiosity will be able to touch down at a safe distance from steep slopes at the edge of Mount Sharp.

"We have been preparing for years for a successful landing by Curiosity, and all signs are good," said Dave Lavery, Mars Science Laboratory program executive at NASA. "However, landing on Mars always carries risks, so success is not guaranteed. Once on the ground we'll proceed carefully. We have plenty of time since Curiosity is not as life-limited as the approximate 90-day missions like NASA’s Mars Exploration Rovers and the Phoenix lander.”

Since the spacecraft was launched in November 2011, engineers have continued testing and improving its landing software. Mars Science Laboratory will use an upgraded version of flight software installed on its computers during the past two weeks. Additional upgrades for Mars surface operations will be sent to the rover about a week after landing.

Mars Science Laboratory (MSL) Mission description. Image Credit: NewScientist

Other preparations include upgrades to the rover's software and understanding effects of debris coming from the drill the rover will use to collect samples from rocks on Mars. Experiments at JPL indicate that Teflon from the drill could mix with the powdered samples. Testing will continue past landing with copies of the drill. The rover will deliver the samples to onboard instruments that can identify mineral and chemical ingredients.

"The material from the drill could complicate, but will not prevent analysis of carbon content in rocks by one of the rover's 10 instruments. There are workarounds,” said John Grotzinger, the mission’s project scientist at the California Institute of Technology in Pasadena. "Organic carbon compounds in an environment are one prerequisite for life. We know meteorites deliver non-biological organic carbon to Mars, but not whether it persists near the surface. We will be checking for that and for other chemical and mineral clues about habitability."

Curiosity will be in good company as it nears landing. Two NASA Mars orbiters, along with a European Space Agency orbiter, will be in position to listen to radio transmissions as Mars Science Laboratory descends through Mars' atmosphere.

The mission is managed by JPL for NASA's Science Mission Directorate in Washington. Curiosity was designed, developed and assembled at JPL. Caltech manages JPL for NASA.

Follow the mission on Facebook and Twitter at:
http://www.facebook.com/marscuriosity
http://www.twitter.com/marscuriosity

For more information on the Mars Science Laboratory/Curiosity mission, visit: http://www.nasa.gov/msl

Images (mentioned), Text, Credits: NASA / JPL / Guy Webster.

Best regards, Orbiter.ch

Black Hole Growth Found to Be Out of Sync












NASA - Chandra X-ray Observatory logo.

June 12, 2012

New evidence from NASA's Chandra X-ray Observatory challenges prevailing ideas about how black holes grow in the centers of galaxies. Astronomers long have thought that a supermassive black hole and the bulge of stars at the center of its host galaxy grow at the same rate -- the bigger the bulge, the bigger the black hole. However, a new study of Chandra data has revealed two nearby galaxies with supermassive black holes that are growing faster than the galaxies themselves.

The mass of a giant black hole at the center of a galaxy typically is a tiny fraction -- about 0.2 percent -- of the mass contained in the bulge, or region of densely packed stars, surrounding it. The targets of the latest Chandra study, galaxies NGC 4342 and NGC 4291, have black holes 10 times to 35 times more massive than they should be compared to their bulges. The new observations with Chandra show the halos, or massive envelopes of dark matter in which these galaxies reside, also are overweight.

This study suggests the two supermassive black holes and their evolution are tied to their dark matter halos and did not grow in tandem with the galactic bulges. In this view, the black holes and dark matter halos are not overweight, but the total mass in the galaxies is too low.


Image above: Galaxies NGC 4342 and NGC 4291. (X-ray: NASA/CXC/SAO/A.Bogdan et al; Infrared: 2MASS/UMass/IPAC-Caltech/ NASA/NSF).

"This gives us more evidence of a link between two of the most mysterious and darkest phenomena in astrophysics -- black holes and dark matter -- in these galaxies," said Akos Bogdan of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., who led the new study.

NGC 4342 and NGC 4291 are close to Earth in cosmic terms, at distances of 75 million and 85 million light years. Astronomers had known from previous observations that these galaxies host black holes with relatively large masses, but are not certain what is responsible for the disparity. Based on the new Chandra observations, however, they are able to rule out a phenomenon known as tidal stripping.

Tidal stripping occurs when some of a galaxy's stars are stripped away by gravity during a close encounter with another galaxy. If such tidal stripping had taken place, the halos mostly would have been missing. Because dark matter extends farther away from the galaxies, it is more loosely tied to them than the stars and more likely to be pulled away.

To rule out tidal stripping, astronomers used Chandra to look for evidence of hot, X-ray-emitting gas around the two galaxies. Because the pressure of hot gas -- estimated from X-ray images -- balances the gravitational pull of all the matter in the galaxy, the new Chandra data can provide information about the dark matter halos. The hot gas was found to be distributed widely around NGC 4342 and NGC 4291, implying that each galaxy has an unusually massive dark matter halo and that tidal stripping is unlikely.

"This is the clearest evidence we have, in the nearby universe, for black holes growing faster than their host galaxy," said co-author Bill Forman, also of CfA. "It's not that the galaxies have been compromised by close encounters, but instead they had some sort of arrested development."

How can the mass of a black hole grow faster than the stellar mass of its host galaxy? The study's authors suggest a large concentration of gas spinning slowly in the galactic center is what the black hole consumes very early in its history. It grows quickly, and as it grows, the amount of gas it can accrete, or swallow, increases along with the energy output from the accretion. After the black hole reaches a critical mass, outbursts powered by the continued consumption of gas prevent cooling and limit the production of new stars.

"It's possible that the supermassive black hole reached a hefty size before there were many stars at all in the galaxy," said Bogdan. "That is a significant change in our way of thinking about how galaxies and black holes evolve together."

The results were presented June 11 at the 220th meeting of the American Astronomical Society in Anchorage, Alaska. The study also has been accepted for publication in The Astrophysical Journal.

Chandra X-ray Observatory description. Credit: NASA.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for the agency's NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Mass., controls Chandra's science and flight operations.

For an additional interactive image, podcast and video on the new finding, visit: http://chandra.si.edu

For Chandra images, multimedia and related materials, visit: http://www.nasa.gov/chandra

Images (mentioned), Text, Credits: NASA / J.D. Harrington / Marshall Space Flight Center / Janet Anderson / Chandra X-ray Center / Megan Watzke.

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lundi 11 juin 2012

NASA's Fermi Detects the Highest-Energy Light From a Solar Flare











NASA - Fermi Gamma-ray Space Telescope logo.

06.11.12

During a powerful solar blast on March 7, NASA's Fermi Gamma-ray Space Telescope detected the highest-energy light ever associated with an eruption on the sun. The discovery heralds Fermi's new role as a solar observatory, a powerful new tool for understanding solar outbursts during the sun's maximum period of activity.

video

Video above: NASA's Solar Dynamics Observatory (SDO) captured dramatic views of the March 7 X5.4 solar flare in extreme ultraviolet light. The gold images show the sun at a wavelength of 171 Angstroms, which corresponds to a temperature of 1 million degrees F (600,000 C). Teal images (131 Angstroms) show features 18 times hotter. The blast triggers waves that traverse the sun at 1 million mph. (Credit: NASA/SDO; NASA's Goddard Space Flight Center).

A solar flare is an explosive blast of light and charged particles. The powerful March 7 flare, which earned a classification of X5.4 based on the peak intensity of its X-rays, is the strongest eruption so far observed by Fermi's Large Area Telescope (LAT). The flare produced such an outpouring of gamma rays -- a form of light with even greater energy than X-rays -- that the sun briefly became the brightest object in the gamma-ray sky.

"For most of Fermi's four years in orbit, its LAT saw the sun as a faint, steady gamma-ray source thanks to the impacts of high-speed particles called cosmic rays," said Nicola Omodei, an astrophysicist at Stanford University in California. "Now we're beginning to see what the sun itself can do."

Omodei described Fermi's solar studies to journalists today at the 220th meeting of the American Astronomical Society in Anchorage, Alaska.

At the flare's peak, the LAT detected gamma rays with two billion times the energy of visible light, or about four billion electron volts (GeV), easily setting a record for the highest-energy light ever detected during or immediately after a solar flare. The flux of high-energy gamma rays, defined as those with energies beyond 100 million electron volts (MeV), was 1,000 times greater than the sun's steady output.

The March flare also is notable for the persistence of its gamma-ray emission. Fermi's LAT detected high-energy gamma rays for about 20 hours, two and a half times longer than any event on record.

Additionally, the event marks the first time a greater-than-100-MeV gamma-ray source has been localized to the sun's disk, thanks to the LAT's keen angular resolution.


This image from Fermi's Large Area Telescope (LAT) shows how the entire sky looked on March 7 in the light of gamma rays with energies beyond 100 MeV. Although the Vela pulsar is the brightest continuous LAT source, it was outmatched this day by the X5.4 solar flare, which brightened the gamma-ray sun by 1,000 times. (Credit: NASA/DOE/Fermi LAT Collaboration).

Flares and other eruptive solar events produce gamma rays by accelerating charged particles, which then collide with matter in the sun's atmosphere and visible surface. For instance, interactions among protons result in short-lived subatomic particles called pions, which produce high-energy gamma rays when they decay. Nuclei excited by collisions with lower-energy ions give off characteristic gamma rays as they settle down. Accelerated electrons emit gamma rays as they collide with protons and atomic nuclei.

video

Video above: Solar flares produce gamma rays by several processes, one of which is illustrated here. The energy released in a solar flare rapidly accelerates charged particles. When a high-energy proton strikes matter in the sun's atmosphere and visible surface, the result may be a short-lived particle -- a pion -- that emits gamma rays when it decays. (Credit: NASA's Goddard Space Flight Center).

Fermi's LAT scans the entire sky every 3 hours, looking for gamma rays with energies ranging from 20 MeV to more than 300 GeV. Its high sensitivity and wide field of view make the LAT an excellent tool for solar monitoring.

Another Fermi instrument, the Gamma-ray Burst Monitor (GBM), observes the entire sky not blocked by the Earth at any given moment. Designed to detect light at energies from 8,000 eV to 40 MeV, the GBM's complementary capabilities give scientists access to a lower, but overlapping energy range where solar phenomena produce interesting features.

Both instruments observed a strong, but less powerful solar flare on June 12, 2010.

"Seeing the rise and fall of this brief flare in both instruments allowed us to determine that some of these particles were accelerated to two-thirds of the speed of light in as little as 3 seconds," said Michael Briggs, a member of GBM team at the University of Alabama in Huntsville.

Solar eruptions are on the rise as the sun progresses toward the peak of its roughly 11-year-long activity cycle, now expected in mid-2013.

"Merged with available theoretical models, Fermi observations will give us the ability to reconstruct the energies and types of particles that interact with the sun during flares, an understanding that will open up whole new avenues in solar research," said Gerald Share, an astrophysicist at the University of Maryland in College Park.

NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership. Fermi is managed by NASA's Goddard Space Flight Center, Greenbelt, Md. It was developed in collaboration with the U.S. Department of Energy, with contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.

Related Links:

NASA's SDO website: http://www.nasa.gov/sdo

SDO project website: http://sdo.gsfc.nasa.gov/

Guide to Solar Flare Classification (video): http://www.nasa.gov/multimedia/videogallery/index.html?media_id=102328541

Scientists Answer Space Weather Questions (video): http://www.nasa.gov/multimedia/videogallery/index.html?media_id=141114891

Image (mentioned), Video (mentioned), Text, Credit: NASA / Francis Reddy.

Cheers, Orbiter.ch

Bion: to stay alive












ROSCOSMOS logo.

06/11/2012

This year will go into Earth orbit spacecraft Bion-M № 1. The crew of the new biosatellites formed at the Institute of Biomedical Problems. After a month of living organisms of the expedition returned to Earth in the descent capsule. The main objective of "Bion" - to confirm or refute the theory of "panspermia" that is placed on the life of our planet from outer space.

Meteorite or comet seeding life on Earth

The experiment, called "meteorite" that is conducted by scientists from the Institute of Biomedical Problems, probably will be one more proof that life originated beyond Earth.

Inside the small holes are different kinds of bacteria and fungi. Scientists zaplombiruyut hole, then attach to the outer skin of the spacecraft "Bion-M." And in space, for a month. The task - to see whether the microbes survive space travel. And most importantly - the most powerful overheating, which they are subjected to on the way home.

"The carrier passes through the atmosphere, where a significant overheating, which is so strong that it has a bactericidal action," - said Vyacheslav Ilyin, head of the Laboratory of Biomedical Problems.

Simulate the fall of the meteorite with microbes have tried before. A similar experiment was performed and the European microbiologists. However, when running the bacteria did not survive high temperatures. Russian scientists did not stop, chose the most heat resistant.

"We can say that 80 per cent once we approximate our understanding as to what brought life in our universe" - continues to Vyacheslav Ilyin.

Supporters of the hypothesis of "panspermia", that is the life of the entry space, more and more. One of the main arguments - found in some samples, meteorites, fossils of these microbes.

"If you can find the remains of an elephant or a dinosaur, you say that this is life. In the meteorites are remnants, of course, primitive bacteria. Meteorites are older, as a rule, our Earth, that is, life originated elsewhere and was brought in, "- says Alexei Rozanov, director of the Paleontological Museum. Yu.A.Yurlova.

Panspermia is the idea that life could travel between stars seeding

Hydrogen, carbon and oxygen - one of the most common chemical elements in the universe. Therefore, such an unusual surprising findings in meteorites, there is nothing, say scientists. Our carbon life is not such a unique thing.

"Water for life of the carbon is the most abundant compound in the Universe" - says Valery Galchenko, director of the Institute of Microbiology. SN Winogradsky.

However, what or who brought the microbes on Earth - the issue is still controversial. Someone says that life is not brought meteorites and comets, which is composed of water. Perhaps this controversy will allow the launch vehicle "Bion-M," which is scheduled for this year.

Bion-M:

Bion-M 1

Bion-M is the next generation of russian biological research satellites. While retaining the Vostok/Zenit-derived reentry module of the earlier Bion, the propulsion module has been replace by a Yantar type module, which provides maneuvering capabilities and longer mission support. The mission duration has been increased to up to 6 months by using solar cells for energy generation. The weight of scientific equipment has been increased by 100 kilograms.

Original text in Russian: http://www.federalspace.ru/main.php?id=2&nid=19190

Images, Text, Credits: TV Studio Space Agency / Roscosmos PAO / Translation: Orbiter.ch.

Greetings, Orbiter.ch