Hubble Images of Asteroids Vesta and Ceres

These Hubble Space Telescope images of Vesta and Ceres show two of the most massive asteroids in the asteroid belt, a region between Mars and Jupiter. The images are helping astronomers plan for the Dawn spacecraft’s tour of these hefty asteroids.

On July 7, NASA is scheduled to launch the spacecraft on a four-year journey to the asteroid belt. Once there, Dawn will do some asteroid-hopping, going into orbit around Vesta in 2011 and Ceres in 2015. Dawn will be the first spacecraft to orbit two targets. At least 100,000 asteroids inhabit the asteroid belt, a reservoir of leftover material from the formation of our solar-system planets 4.6 billion years ago.

Dawn also will be the first satellite to tour a dwarf planet. The International Astronomical Union named Ceres one of three dwarf planets in 2006. Ceres is round like planets in our solar system, but it does not clear debris out of its orbit as our planets do.

To prepare for the Dawn spacecraft’s visit to Vesta, astronomers used Hubble’s Wide Field Planetary Camera 2 to snap new images of the asteroid. The image at right was taken on May 14 and 16, 2007. Using Hubble, astronomers mapped Vesta’s southern hemisphere, a region dominated by a giant impact crater formed by a collision billions of years ago. The crater is 285 miles (456 kilometers) across, which is nearly equal to Vesta's 330-mile (530-kilometer) diameter. If Earth had a crater of proportional size, it would fill the Pacific Ocean basin. The impact broke off chunks of rock, producing more than 50 smaller asteroids that astronomers have nicknamed “vestoids.” The collision also may have blasted through Vesta’s crust. Vesta is about the size of Arizona.

Hubble’s view reveals extensive global features stretching longitudinally from the northern hemisphere to the southern hemisphere. The image also shows widespread differences in brightness in the east and west, which probably reflect compositional changes. Both of these characteristics could reveal volcanic activity throughout Vesta. The size of these different regions varies. Some are hundreds of miles across.

The brightness differences could be similar to the effect seen on the Moon, where smooth, dark regions are more iron-rich than the brighter highlands that contain minerals richer in calcium and aluminum. When Vesta was forming 4.5 billion years ago, it was heated to the melting temperatures of rock. This heating allowed heavier material to sink to Vesta’s center and lighter minerals to rise to the surface.

Astronomers combined images of Vesta in two colors to study the variations in iron-bearing minerals. From these minerals, they hope to learn more about Vesta’s surface structure and composition. Astronomers expect that Dawn will provide rich details about the asteroid’s surface and interior structure.

The Hubble image of Ceres on the left reveals bright and dark regions on the asteroid’s surface that could be topographic features, such as craters and/or areas containing different surface material. Large impacts may have caused some of these features and potentially added new material to the landscape. The Texas-sized asteroid holds about 30 to 40 percent of the mass in the asteroid belt. Ceres’ round shape suggests that its interior is layered like those of terrestrial planets such as Earth. The asteroid may have a rocky inner core, an icy mantle and a thin, dusty outer crust. The asteroid may even have water locked beneath its surface. It is approximately 590 miles (950 kilometers) across and was the first asteroid discovered in 1801.

The observations were made in visible and ultraviolet light between December 2003 and January 2004 with the Advanced Camera for Surveys. The color variations in the image show either a difference in texture or composition on Ceres’ surface. Astronomers need the close-up views of the Dawn spacecraft to determine the characteristics of these regional differences.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. The Space Telescope Science Institute conducts Hubble science operations. The institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc., Washington.

Credits for Vesta: NASA; ESA; L. McFadden and J.Y. Li (University of Maryland, College Park); M. Mutchler and Z. Levay (Space Telescope Science Institute, Baltimore); P. Thomas (Cornell University); J. Parker and E.F. Young (Southwest Research Institute); and C.T. Russell and B. Schmidt (University of California, Los Angeles).

Credits for Ceres: NASA; ESA; J. Parker (Southwest Research Institute); P. Thomas (Cornell University); L. McFadden (University of Maryland, College Park); and M. Mutchler and Z. Levay (Space Telescope Science Institute).

Source: NASA

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Weather Without Water

Bright mid-latitude clouds near the bottom of this view hint at the ongoing cycling of methane on Titan. These cloud streaks are near the same latitude as similar clouds observed above different longitudes on Titan.

The view is centered on Titan's trailing hemisphere, over the 1,700 kilometer (1,050 mile) wide bright region known as Adiri. North on Titan (5,150 kilometers, or 3,200 miles across) is up and rotated 15 degrees to the right.

This view was created by combining multiple images taken using a combination of spectral filters sensitive to wavelengths of infrared light centered at 939 and 742 nanometers.

The images were taken with the Cassini spacecraft wide-angle camera on May 13, 2007 at a distance of approximately 104,000 kilometers (65,000 miles) from Titan. Image scale is 12 kilometers (8 miles) per pixel. Due to scattering of light by Titan's hazy atmosphere, the sizes of surface features that can be resolved are a few times larger than the actual pixel scale.

Credit: NASA/JPL/Space Science Institute

Source: JPL

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New Science on the Moon

NASA has selected proposals, including two from the Jet Propulsion Laboratory in Pasadena, Calif., for future lunar science activities. In addition, the agency has established two new programs that will enhance research made possible by the Vision for Space Exploration.

The proposals and programs are part of an effort by NASA to develop new opportunities to conduct important science investigations during the planned renewal of human exploration of the moon.

The seven selected proposals will result in advanced development for simple, autonomous instrument packages deployed on the lunar surface by astronauts. Such "suitcase science" packages could open up a wide variety of research applications regarding the moon and the lunar environment.

Some of the funded efforts will help scientists better understand the lunar dust that creates problems for astronauts on the moon. Other studies will provide a better understanding of the moon's interior, look for natural resources on the lunar surface and use lasers to provide precise information about the position of the moon and its features.

"The proposals we received show that the scientific community is excited about the opportunity to capitalize on the nation's planned lunar outpost. The moon has much to teach us about itself, the history of our solar system, and even the history of the sun. In the future, more and more scientists will be able to participate in lunar research as we focus attention on Earth's fascinating satellite," said Alan Stern, associate administrator for NASA's Science Mission Directorate.

The two selected proposals from JPL are:

"Autonomous Lunar Geophysical Experiment Package"--William Banerdt, principal investigator".

"Lunar Laser Transponder and Retroreflector Science"--Slava Turyshev, principal investigator".

The other selected proposals are:

Goddard Space Flight Center, Greenbelt, Md., "Volatile Analysis by Pyrolysis of Regolith on the Moon using Mass Spectrometry"-- Daniel Glavin, principal investigator.

Goddard Space Flight Center, "Seismology and Heat flow instrument package for Lunar Science and Hazards"-- Patrick Taylor, principal investigator.

Southwest Research Institute, Boulder, Colo., "Lunar Radiation Environment and Regolith Shielding Experiment"-- Donald Hassler, principal investigator.

U.S. Army Engineer Research and Development Center, Fort Wainwright, Alaska, "Lunar Suitcase Science: A Lunar Regolith Characterization Kit" --Jerome Johnson, principal investigator.

Ball Aerospace and Technologies Corp., Boulder, Colo., "Autonomous Lunar Dust Observer" -- Christian Grund, principal investigator.

Under the planned Lunar Advanced Science and Exploration Research program, proposals will be solicited for investigations to increase knowledge of the moon while also providing necessary information for humans to live and work there. Studies may include simulations and laboratory work to better understand the lunar environment and its hazards, such as dust and radiation. The program also will support analysis of existing lunar data, including the Apollo and robotic mission data archives, and work to understand the origin and evolution of the moon.

In the upcoming Lunar Reconnaissance Orbiter Participating Scientist Program, NASA will select researchers to perform detailed investigations using instruments aboard the spacecraft during its first years in lunar orbit. Proposals for both programs are due Sept. 7, 2007.

Lunar Reconnaissance Orbiter is NASA's next orbital mission to the moon. Launch is planned in late 2008. It will orbit the moon for at least one year, providing data to accelerate opportunities for future science missions and human exploration.

More information: http://www.nasa.gov/exploration

Image credit: USGS

Source: NASA

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Messenger Flies By Venus

The MESSENGER spacecraft snapped a series of images as it approached Venus on June 5. The planet is enshrouded by a global layer of clouds that obscures its surface to the MESSENGER Dual Imaging System (MDIS) cameras.

This single frame is part of a color sequence taken to help the MESSENGER team calibrate the camera in preparation for the spacecraft’s first flyby of Mercury on January 14, 2008. Over the next several months the camera team will pore over the 614 images taken during this Venus encounter to ascertain color sensitivity and other optical properties of the instrument. These tasks address two key goals for the camera at Mercury: understanding surface color variations and their relation to compositional variations in the crust, and ensuring accurate cartographic placement of features on Mercury’s surface.

Preliminary analysis of the Venus flyby images indicates that the cameras are healthy and will be ready for next January’s close encounter with Mercury.

After acquiring hundreds of high-resolution images during close approach to Venus, MESSENGER turned its wide-angle camera back to the planet and acquired a departure sequence. These images provide a spectacular good-bye to the cloud-shrouded planet while also providing valuable data to the camera calibration team.

The first image was taken June 6 at 12:58 UTC (8:58 p.m. EDT on June 5), and the final image on June 7 at 02:18 UTC (10:18 p.m. EDT on June 6). During this 25 hour, 20 minute period the spacecraft traveled 833,234 kilometers (517,748 miles—more than twice the distance from the Earth to the moon) with respect to Venus at an average speed of 9.13 kilometers per second (5.67 miles per second).

Credit: NASA

Source: NASA

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Crews to Fold Arrays, Prep for Spacewalk Repair Tasks

As Space Shuttle Atlantis and the International Space Station sail above Earth today, the STS-117 and Expedition 15 crews will continue retracting solar arrays and preparing for repair work during Friday’s spacewalk.

STS-117 Mission Specialists Jim Reilly and Danny Olivas will review procedures and practice techniques they will use during the spacewalk set to begin at 1:38 p.m. EDT Friday. The first task of the extravehicular activity is the repair of a thermal blanket that pulled away from the orbital maneuvering system pod on the rear of the shuttle.

This afternoon, the STS-117 crew will resume retraction of the starboard P6 solar array. Almost half of the 31½ array bays were retracted Wednesday. If the arrays are not fully retracted today, efforts will resume Friday with the assistance of the spacewalkers.

About an hour and 20 minutes before this morning’s scheduled wakeup call, the crews were awakened by a false alarm on the station. The alarm was triggered by the restart of Russian navigation computers that provide backup attitude control and orbital altitude adjustments. For now, the station’s control moment gyroscopes are handling attitude control, with the shuttle’s propulsion system providing backup.

Credit: NASA

Source: NASA

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ESA takes steps toward quantum communications

A team of European scientists has proved within an ESA study that the weird quantum effect called 'entanglement' remains intact over a distance of 144 kilometres. The experiment allows ESA to take a step closer to exploiting entanglement as a way of communicating with satellites with total security.

Quantum entanglement is one of the many non-intuitive features of quantum mechanics. If two photons of light are allowed to properly interact with one another, they can become entangled. One can even directly create pairs of entangled photons using a non-linear process called Spontaneous Parametric Down Conversion (SPDC).

Those two entangled photons can then be separated but as soon as one of them interacts with a third particle, the other photon of the pair will change its quantum state instantaneously. This happens according to the random outcome of the interaction, even though this photon never did interact with a third particle.

Such behaviour has the potential to allow messages to be swapped with complete confidence. This is because, if an eavesdropper listens into the message, the act of detecting the photons will change the entangled partner. These changes would be obvious to the legitimate receiving station and the presence of the eavesdropper would be instantly detected.

A quantum communications system would be a valuable way to transmit banking information, or military communications, or even to distribute feature films without the fear of piracy.

Even though entanglement has been known about for decades, no one has known whether the entanglement decays over long distance. For example, would a beam of entangled photons remain entangled if it passed through the atmosphere of the Earth? On their journey, the photons could interact with atoms and molecules in the air. Would this destroy the entanglement?

If so, entanglement would be useless as a means of communicating with satellites in orbit, because all signals would have to pass through the Earth's atmosphere. Now, an Austrian-German led team have proved conclusively that photons remain entangled over a distance of 144 kilometres through the atmosphere. That means that entangled signal will survive the journey from the surface of the Earth into space, and vice versa.

In September 2005, the European team aimed ESA's one-metre telescope on the Canary Island of Tenerife toward the Roque de los Muchachos Observatory on the neighbouring island of La Palma, 144 kilometres away. On La Palma, a specially built quantum optical terminal generated entangled photon pairs, using the SPDC process, and then sent one photon towards Tenerife, whilst keeping the other for comparison.

Upon comparing the results from Tenerife with those from La Palma, it was obvious that the photons had remained entangled. "We were sending the single-photon beam on a 144 kilometres path through the atmosphere, so this horizontal quantum link can be considered a 'worst case scenario' for a space to ground link," says Josep Perdigues, ESA's Study Manager.

Additional tests with a quantum communication source that generated faint laser pulses instead of entangled photon pairs were performed in 2006. Faint laser pulse sources emulate single photon sources by attenuating the optical power of a standard laser down to single photon regime. Attenuated lasers are technologically much simpler than entangled photon sources or 'true' single photon sources.

The price you have to pay is the unwanted opportunity for information leakage, due to the non-zero probability of having more than one photon per pulse. In practice, this limits the maximum link distance for exchanging securely a key. By implementing a decoy-state protocol in the experiments using a faint laser pulse source, the maximum link distance (yet secure against an eavesdropper’s action) was extended to values representative of a space to ground experiment.

The team are now studying ways to take the experiment into space. "Being in space will mean that we can test entanglement over lines of sight longer than 1 000 kilometres, unfeasible on Earth, thereby extending the validity of Quantum Physics theory to macroscopic scales," says Perdigues. One option is to use the external pallet on the Columbus module of the International Space Station. Another would be to put the quantum optical terminal on a dedicated satellite of its own. The quantum optical terminal is about 100 kg in mass and fits into a one-cubic-metre box.

Credits: ESA

Source: ESA

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Enceladus

Peeking over the crescent of Enceladus, the Cassini spacecraft views the towering plume of ice particles erupting from the moon's south polar region.

Multiple components of the overall plume are visible in this view of Enceladus (505 kilometers, or 314 miles across).

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on April 24, 2007 at a distance of approximately 188,000 kilometers (117,000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 153 degrees. Image scale is 1 kilometer (0.6 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, 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 imaging operations center is based at the Space Science Institute in Boulder, Colo.

Credit: NASA/JPL/Space Science Institute

Source: NASA

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Boring Star May Mean Livelier Planet

“Boring” light from red dwarf star Gliese 581 means better odds for extraterrestrial life in that planetary system, according to University of British Columbia astronomer Jaymie Matthews. Approximately 20.5 light years from the Earth, Gliese 581 made the headlines in April 2007 when European scientists discovered a planet, named Gliese 581c. Dubbed “superEarth,” the planet orbits Gliese 581 and could have water -- and thus able to support life.

The Gliese 581 system is the first to be found -- beyond our own Earth -- that might have a liveable planet,” said Matthews. Using Canada Space Agency’s suitcase-sized space telescope, the Microvariability and Oscillations of STars (MOST), Matthews put Gliese 581 on a six-week scientific stakeout following the April discovery. He will present his findings today at the Canadian Astronomical Society’s annual meeting in Kingston, Ontario.

Matthews and his team searched for the subtle dips in the light from the star when the planet’s orbit carried it directly between the star and the Earth, resulting in a “mini-eclipse” every 13 days. The depth of the dips would help researchers determine the size of the planet Gliese 581c, while the behaviour of the starlight at other times would help astronomers gauge the suitability of Gliese 581 as a “home star,” a star able to sustain life on planets around it.

“Gliese 581 seems remarkably stable over the six weeks it was monitored by MOST,” said Matthews. “The brightness of the star changed by only a few tenths of a percent over that time. This level of stability means that it provides a stable source of light -- hence heat -- to the surface of planet Gliese 581c.

“The climate there should not be a wild rollercoaster ride that would make it difficult for life to get a foothold,” said Matthews. “It also suggests the star is quite old, and settled in its ways, and that the planets around it have probably been around for billions of years.”

It took approximately 3.5 billion years for life on Earth to reach the level of complexity that we call human, said Matthews. “So if Gliese 581 has been around for at least that long, it’s more encouraging for the prospects of complex life on any planet around it.”

With space missions like MOST, the French satellite COROT, which joined MOST in orbit late last December, and the American Kepler mission due for launch in November 2008, Matthews predicts that other ‘Earthy’ worlds will come to light in the coming months and years.

“Some of them will have orbits that produce planetary alignments,” said Matthews. “Not the kind that excites somebody reading a horoscope but the kind that’s exciting for astronomers because they will allow us to test our models of alien worlds -- worlds that might be homes to neighbours in our Galactic city, the Milky Way.”

Credit: European Southern Observatory

Source: University of British Columbia

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STS-117 Crew Inspected Shuttle Heat Shield

The STS-117 crew members completed the day's scheduled inspections of Space Shuttle Atlantis’ heat shield. They used Atlantis’ robotic arm and an attached boom extension to check the spacecraft’s underside, nose cap and leading edges of the wings as well as hard to reach shuttle surfaces.

The inspections are performed to check if any damage occurred to the heat shield during the climb to orbit that began when Atlantis lifted off Friday from Kennedy Space Center, Fla. Over the next few days, engineers and flight controllers will analyze the data collected by the STS-117 crew.

Last night during the robot arm checkout, the robotic arm cameras were used to take a closer look at an area of insulation blanket on the port orbital maneuvering system pod that pulled away from adjacent thermal tiles. Engineers are analyzing the imagery

Throughout the day, the crew has been preparing for Sunday’s arrival at the International Space Station. The day's activities include the extension of the shuttle’s docking ring and the check out of tools they will use to rendezvous and link up with the station. Docking is set for 3:38 p.m. Sunday.

Earlier today, the STS-117 crew checked out spacesuits to be used during the mission’s three scheduled spacewalks at the space station. The major objective of the spacewalks is to install and activate the station’s newest component, the Starboard 3 and 4 (S3/S4) truss segments, and to assist in the retraction of the starboard array on the Port 6 truss.

STS-117 is also delivering a new crew member to the station.

Credit: NASA TV

Source: NASA

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Mars photos by HiRISE

The first image shows gullies in a crater in Terra Sirenum in the southern hemisphere of Mars. This image was acquired during the winter, which explains the abundant frost (the bright material) seen throughout the image. The frost is likely water frost, as opposed to carbon dioxide, because temperatures at this latitude probably do not get cold enough for carbon dioxide to condense.

The formation mechanism of gullies is much debated. Several theories support erosion by liquid water, while others favor dry debris flows or carbon dioxide. A major unknown is, if the gullies are formed by liquid water, does the water originate from the surface or subsurface? Dendritic structures, such as those seen in the alcove displayed in the subimage (approximately 1.3 km across; 2560 x 3000, 7MB), form from surface runoff on Earth. Water originating in the subsurface would not produce a structure like this. This alcove is evidence for a surface source for the water possibly required to form gullies.

Also interesting about this scene is the fact that the gullies occur at multiple elevations along the same crater wall. This is uncommon on Mars. Gullies, whether or not they are found in conjunction with an obvious horizontal layer, usually form at the same elevation on a given slope. It is unknown what caused these gullies to form at multiple elevations. Their locations are suggestive of a distributed water source, which also favors a surface, rather than a confined subsurface origin of water, such as an aquifer.

The second image shows the formation of the approximately 150 km diameter Holden Crater interrupted the northward flowing Uzboi Vallis channel system. Relief associated with the rim of Holden effectively blocked the channel.

HiRISE image PSP_003710_1530 covers the portion of Holden Crater's rim where it was overtopped by water that had backed up in Uzboi Vallis to the south. Water flowing over the rim in multiple locations eventually focused on a single channel that then cut deeply into the rim. After the impounded water drained into the crater, the steep wall on the east side of the main channel collapsed in a landslide that remains visible along the floor. Several outcroppings of variably bright material are visible in the scar produced by the slide.

Credit: NASA/JPL/University of Arizona

Source: HiRISE

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New View of Titan III

This image of Titan's surface, obtained by Huygens' DISR imager, shows patterns of tectonic and fluid-flow activity. The tectonic patterns are indicated by blue lines; the drainage divide is indicated by the red line; flow directions are indicated by the green arrows. The Huygens landing site is marked by a white cross.

Credits: ESA/NASA/JPL/University of Arizona

Source: NASA

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New View of Titan II

This composite of Huygens DISR images shows patterns of drainage, flow and erosion in the Huygens landing site region.

The top panel shows two types of drainage networks in the bright region about 5-10 kilometres north of the landing site. The lower-left panel is a high-resolution view of the erosional channels around the landing site. The lower right panel is a medium-resolution view of bright ridges standing above the dark plains carved by surface flows.

Credits: ESA/NASA/JPL/University of Arizona

Source: NASA

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Titan

Despite centuries of speculation and decades of research, scientists are still seeking fundamental clues to the question of how life began on Earth. Titan [TIE-tun] is the frozen vault that may contain these secrets for the Cassini-Huygens mission to discover.

Titan is the largest of Saturn's moons, bigger than the planets Mercury and Pluto. The study of Titan is one of the major goals of the Cassini-Huygens mission because it may preserve, in deep-freeze, many of the chemical compounds that preceded life on Earth.

Long hidden behind a thick veil of haze, Titan is the only moon in the solar system that possesses a dense atmosphere (10 times denser than Earth's). The fact that this atmosphere is rich in organic material and that living organisms as we know them are composed of organic material is particularly intriguing. "Organic" means only that the material is carbon-based, and does not necessarily imply any connection to living organisms.

The story of Titan is gradually unfolding. Titan is a dynamic place with complex geologic processes. The lack of many craters indicates that Titan's surface may be relatively young, because Earth-like processes of tectonics, erosion, winds, and perhaps volcanism, shape its surface. Though hazy, Titan's atmosphere is relatively cloud-free.

Cassini will execute 45 flybys of Titan, some of them only several hundred kilometers from its surface. The European Space Agency's Huygens probe, which pierced Titan's thick-dense haze, was dedicated to the study of Titan's atmosphere. The probe actually survived for several hours on the surface and returned stunning images.

Credit: NASA/JPL/Space Science Institute

Source: NASA

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NASA Updates Shuttle Target Launch Date for Hubble Mission

NASA managers officially are targeting Sept. 10, 2008, for the launch of the fifth and final space shuttle servicing mission to the Hubble Space Telescope. During the 11-day flight, Atlantis' seven astronauts will repair and improve the observatory's capabilities through 2013.

Mission planners have been working since last fall, when the flight was announced, to determine the best time in the shuttle manifest to support the needs of Hubble while minimizing the impact to International Space Station assembly. NASA also will support a "launch on need" flight during the Hubble mission. In the unlikely event a rescue flight becomes necessary, shuttle Endeavour currently is planned to lift off from Launch Pad 39-B at NASA's Kennedy Space Center, Fla. However, managers constantly are evaluating the manifest to determine the best mission options.

Shuttle missions beyond the Hubble flight still are being assessed. Shuttle and station program officials will continue to consider options for the remainder of the shuttle flights to complete construction of the space station by 2010, when the fleet will be retired. Those target launch dates are subject to change.

The Hubble Space Telescope is an international cooperative project between NASA and the European Space Agency. For more information about Hubble, visit: Hubble

Source: NASA

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STS 117 Mission

At today's Launch Readiness News Conference, the Mission Management Team announced that they were in agreement that Space Shuttle Atlantis is ready to fly on Friday.

"The team is ready to go and we're just really excited to be at this point after a very long and arduous spring and a lot of really hard work by the entire team," said LeRoy Cain, launch integration manager for the Space Shuttle Program. "I'm very proud of the team."

NASA Launch Director Mike Leinbach reported that the countdown is going fine and there no significant issues to report.

The forecast for launch day, according to U.S. Air Force Lt. Col. Pat Barrett, weather officer from the 45th squadron, remains at a 30-percent chance of violating launch constraints. A high-pressure ridge is expected to move to the north which could help clear out any thunderstorm activity over Kennedy Space Center.

At 10:30 p.m. EDT Thursday, the protective rotating service structure will be rolled away from the space shuttle. External tank fuel loading is scheduled to begin at around 9:30 a.m. EDT Friday.

The launch countdown for Atlantis officially began at 9 p.m. EDT Tuesday, at T-43 hours. Included in the countdown is nearly 28 hours of built-in hold time prior to a targeted 7:38 p.m. EDT launch on Friday.

credit: NASA/Troy Cryder

Source: NASA

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MESSENGER spacecraft approaches the brightly illuminated Venus on June 5

In the coming evenings, sky watchers can acquaint themselves with the MESSENGER spacecraft mission to Mercury. Late afternoon on Tuesday, June 5, 2007, MESSENGER will fly within about 210 miles (340 kilometers) of the surface of the planet Venus, and get a gravity kick toward its ultimate destination, the sun-baked planet Mercury.

Both Venus and Mercury will be well-placed for viewing during dusk the week before MESSENGER's encounter with Venus. Go to a location away from bright lights with a good view of the western and northwestern horizon. Venus is the brilliant "evening star" fairly high above the western horizon. Forty-five minutes after sunset (or between 8:45 p.m. and 9:45 p.m. Daylight Time, depending on your location within your time zone), you should start to see other bright stars and planets as the sky darkens.

Credit: NASA/JHUAPL

Source: NASA

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Pillars of Creation

This image composite highlights the pillars of the Eagle nebula, as seen in infrared light by NASA's Spitzer Space Telescope (bottom) and visible light by NASA's Hubble Space Telescope (top insets).

The top right inset focuses on the three famous pillars, dubbed the "Pillars of Creation," which were photographed by Hubble in 1995. Hubble's optical view shows the dusty towers in exquisite detail, while Spitzer's infrared eyes penetrate through the thick dust, revealing ghostly transparent structures. The same effect can be seen for the pillar outlined in the top left box.

In both cases, Spitzer's view exposes newborn stars that were hidden inside the cocoon-like pillars, invisible to Hubble. These stars were first uncovered by the European Space Agency's Infrared Satellite Observatory. In the Spitzer image, two embedded stars are visible at the tip and the base of the left pillar, while one star can be seen at the tip of the tallest pillar on the right.

Image Credit: NASA/JPL-Caltech/STScI/ Institut d'Astrophysique Spatiale

Source: NASA

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Pleiades Cluster

The Seven Sisters, also known as the Pleiades star cluster, seem to float on a bed of feathers in a new infrared image from NASA's Spitzer Space Telescope. Clouds of dust sweep around the stars, swaddling them in a cushiony veil.

The Pleiades, located more than 400 light-years away in the Taurus constellation, are the subject of many legends and writings. Greek mythology holds that the flock of stars was transformed into celestial doves by Zeus to save them from a pursuant Orion. The 19th-century poet Alfred Lord Tennyson described them as "glittering like a swarm of fireflies tangled in a silver braid."

The star cluster was born when dinosaurs still roamed the Earth, about 100 million years ago. It is significantly younger than our 5-billion-year-old sun. The brightest members of the cluster, also the highest-mass stars, are known in Greek mythology as two parents, Atlas and Pleione, and their seven daughters, Alcyone, Electra, Maia, Merope, Taygeta, Celaeno and Asterope. There are thousands of additional lower-mass members, including many stars like our sun. Some scientists believe that our sun grew up in a crowded region like the Pleiades, before migrating to its present, more isolated home.

The new infrared image from Spitzer highlights the "tangled silver braid" mentioned in the poem by Tennyson. This spider-web-like network of filaments, colored yellow, green and red in this view, is made up of dust associated with the cloud through which the cluster is traveling. The densest portion of the cloud appears in yellow and red, and the more diffuse outskirts are shown in green hues. One of the parent stars, Atlas, can be seen at the bottom, while six of the sisters are visible at top. Additional stars in the cluster are sprinkled throughout the picture in blue.

The Spitzer data also reveal never-before-seen brown dwarfs, or "failed stars," and disks of planetary debris (not pictured). John Stauffer of NASA's Spitzer Space Telescope mission says Spitzer's infrared vision allows astronomers to better study the cooler, lower-mass stars in the region, which are much fainter when viewed in optical light. Stauffer, who admits to being biased because the Pleiades is his favorite astronomical object, says the cluster is the perfect laboratory for understanding the evolution of stars.

This image is made up of data taken by Spitzer's multiband imaging photometer and its infrared array camera. Light with a wavelength of 4.5 microns is blue; light of 8 microns is green; and light of 24 microns is red.

Image Credit: NASA/JPL-Caltech

Source: NASA

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Rosset nebula

This infrared image from NASA's Spitzer Space Telescope shows the Rosette nebula, a pretty star-forming region more than 5,000 light-years away in the constellation Monoceros. In optical light, the nebula looks like a rosebud, or the "rosette" adornments that date back to antiquity.

But lurking inside this delicate cosmic rosebud are so-called planetary "danger zones" (see spheres illustrations in figure 1). These zones surround super hot stars, called O-stars (blue stars inside spheres), which give off intense winds and radiation. Young, cooler stars that just happen to reside within one of these zones are in danger of having their dusty planet-forming materials stripped away.

While O-star danger zones were known about before, their parameters were not. Astronomers used Spitzer's infrared vision to survey the extent of the five danger zones shown here. The results showed that young stars lying beyond 1.6 light-years, or 10 trillion miles, of any O-stars are safe, while young stars within this zone are likely to have their potential planets blasted into space.

Radiation and winds from the super hot stars have collectively blown layers of dust (green) and gas away, revealing the cavity of cooler dust (red). The largest two blue stars in this picture are in the foreground, and not in the nebula itself.

This image shows infrared light captured by Spitzer's infrared array camera. Light with wavelengths of 24 microns is red; light of 8 microns is green; and light of 4.5 microns is blue.

Image Credit: NASA/JPL-Caltech/Univ. of Ariz

Source: NASA

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Wind Streaks Landscape and Boosts Rover Power Levels

Opportunity recently completed work on soil exposures north of the rim of Victoria Crater where winds channeled by alcoves have produced alternating light and dark streaks. The rover finished in-situ analyses with measurements at a target known as "Alicante," where there appears to be a concentration of dark sand on the downwind side of a rock, on sol 1149 (April 18, 2007). Analysis continues of data collected from this and other sites.

In addition, strong winds perhaps associated with channeling caused by the crater's jagged rim may have contributed to deck-cleaning events for Opportunity. On two separate occasions, sols 1153 (April 22, 2007) and 1158 (April 27, 2007), the solar array power increased significantly. In fact, the power level of 848 watt-hours, reached on sol 1160 (April 29, 2007), was the highest measured since about sol 300 (Nov. 26, 2004), early in the mission. (A watt-hour is the amount of power needed to light a 100-watt bulb for one hour.)

This orbital view was acquired by the High-Resolution Imaging Science Experiment camera on the Mars Reconnaissance Orbiter.

Image credit: NASA/JPL-Caltech/UofA/USGS

Source: NASA

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M81 Galaxy is Pretty in Pink

The perfectly picturesque spiral galaxy known as Messier 81, or M81, looks sharp in this new composite from NASA's Spitzer and Hubble space telescopes and NASA's Galaxy Evolution Explorer. M81 is a "grand design" spiral galaxy, which means its elegant arms curl all the way down into its center. It is located about 12 million light-years away in the Ursa Major constellation and is one of the brightest galaxies that can be seen from Earth through telescopes.

The colors in this picture represent a trio of light wavelengths: blue is ultraviolet light captured by the Galaxy Evolution Explorer; yellowish white is visible light seen by Hubble; and red is infrared light detected by Spitzer. The blue areas show the hottest, youngest stars, while the reddish-pink denotes lanes of dust that line the spiral arms. The orange center is made up of older stars.

Image Credit: NASA/JPL-Caltech/ESA/Harvard-Smithsonian CfA

Source: Planetary Photojournal

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New view of Titan

Today, two and a half years after the historic landing of ESA’s Huygens probe on Titan, a new set of results on Saturn’s largest moon is ready to be presented. Titan, as seen through the eyes of Huygens still holds exciting surprises, scientists say.

On 14 January 2005, after a seven-year voyage on board the NASA/ESA/ASI Cassini spacecraft, ESA’s Huygens probe spent 2 hours and 28 minutes descending by parachute to land on Titan. It then sent transmissions from the surface for another seventy minutes before Cassini moved out of range.

On 8 December that year, a combined force of scientists published their preliminary findings in Nature. Now, after another year and a half of patient work, they are ready to add fresh details to their picture of Titan. This time, the papers are published in a special issue of the Planetary and Space Science magazine.

“The added value comes from computer modelling,” says Jonathan Lunine, Huygens Interdisciplinary Scientist from the Lunar and Planetary Laboratory, University of Arizona.

By driving their computer models of Titan to match the data returned from the probe, planetary scientists can now visualise Titan as a working world. “Even though we have only four hours of data, it is so rich that after two years of work we have yet to retrieve all the information it contains,” says François Raulin, Huygens Interdisciplinary Scientist, at the Laboratoire de Physique et Chimie de l'Environnement, Paris.

The new details add greatly to the picture of Saturn’s largest moon. “Titan is a world very similar to the Earth in many respects,” says Jean-Pierre Lebreton, ESA Huygens Project Scientist.Huygens found that the atmosphere was hazier than expected because of the presence of dust particles – called ‘aerosols’. Now, scientists are learning how to interpret their analysis of these aerosols, thanks to a special chamber that simulates Titan’s atmosphere.

When the probe dropped below 40 kilometres in altitude, the haze cleared and the cameras were able to take their first distinct images of the surface. They revealed an extraordinary landscape showing strong evidence that a liquid, possibly methane, has flowed on the surface, causing erosion. Now, images from Cassini are being coupled with the ‘ground truth’ from Huygens to investigate how conditions on Titan carved out this landscape.

Credits: ESA/NASA/JPL/University of Arizona

Source: ESA

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Enceladus

Peeking over the crescent of Enceladus, the Cassini spacecraft views the towering plume of ice particles erupting from the moon's south polar region.

Multiple components of the overall plume are visible in this view of Enceladus (505 kilometers, or 314 miles across).

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on April 24, 2007 at a distance of approximately 188,000 kilometers (117,000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 153 degrees. Image scale is 1 kilometer (0.6 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, 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 imaging operations center is based at the Space Science Institute in Boulder, Colo.

Credit: NASA/JPL/Space Science Institute

Source: NASA

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Neon Saturn

Flying over the unlit side of Saturn's rings, the Cassini spacecraft captures Saturn's glow, represented in brilliant shades of electric blue, sapphire and mint green, while the planet's shadow casts a wide net on the rings.

This striking false-color mosaic was created from 25 images taken by Cassini's visual and infrared mapping spectrometer over a period of 13 hours, and captures Saturn in nighttime and daytime conditions. The visual and infrared mapping spectrometer acquires data simultaneously at 352 different wavelengths, or spectral channels. Data at wavelengths of 2.3, 3.0 and 5.1 microns were combined in the blue, green and red channels of a standard color image, respectively, to make this false-color mosaic.

This image was acquired on Feb. 24, 2007, while the spacecraft was 1.58 million kilometres (1 million miles) from the planet and 34.6 degrees above the ring plane. The solar phase angle was 69.5 degrees. In this view, Cassini was looking down on the northern, unlit side of the rings, which are rendered visible by sunlight filtering through from the sunlit, southern face.

On the night side (right side of image), with no sunlight, Saturn's own thermal radiation lights things up. This light at 5.1 microns wavelength (some seven times the longest wavelength visible to the human eye) is generated deep within Saturn, and works its way upward, eventually escaping into space. Thick clouds deep in the atmosphere block that light. An amazing array of dark streaks, spots, and globe-encircling bands is visible instead. Saturn's strong thermal glow at 5.1 microns even allows these deep clouds to be seen on portions of the dayside (left side), especially where overlying hazes are thin and the glint of the sun off of them is minimal. These deep clouds are likely made of ammonium hydrosulphide and cannot be seen in reflected light on the dayside, since the glint of the sun on overlying hazes and ammonia clouds blocks the view of this level.

A pronounced difference in the brightness between the northern and southern hemispheres is apparent. The northern hemisphere is about twice as bright as the southern hemisphere. This is because high-level, fine particles are about half as prevalent in the northern hemisphere as in the south. These particles block Saturn's glow more strongly, making Saturn look brighter in the north.

At 2.3 microns (shown in blue), the icy ring particles are highly reflecting, while methane gas in Saturn's atmosphere strongly absorbs sunlight and renders the planet very dark. At 3.0 microns (shown in green), the situation is reversed: water ice in the rings is strongly absorbing, while the planet's sunlit hemisphere is bright. Thus the rings appear blue in this representation, while the sunlit side of Saturn is greenish-yellow in color. Within the rings, the most opaque parts appear dark, while the more translucent regions are brighter. In particular, the opaque, normally-bright B ring appears here as a broad, dark band separating the brighter A (outer) and C (inner) rings

At 5.1 microns (shown in red), reflected sunlight is weak and thus light from the planet is dominated by thermal (i.e., heat) radiation that wells up from the planet's deep atmosphere. This thermal emission dominates Saturn's dark side as well as the north polar region (where the hexagon is again visible) and the shadow cast by the A and B rings. Variable amounts of clouds in the planet's upper atmosphere block the thermal radiation, leading to a speckled and banded appearance, which is ever-shifting due to the planet's strong winds.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini obiter was designed, developed and assembled at JPL. The Visual and Infrared Mapping Spectrometer team is based at the University of Arizona, where this image was produced.

Credit: NASA/JPL/University of Arizona

Source: NASA

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Spitzer Nets Thousands of Galaxies in a Giant Cluster

In just a short amount of time, NASA’s Spitzer Space Telescope has bagged more than a thousand previously unknown dwarf galaxies in a giant cluster of galaxies.

Despite their diminutive sizes, dwarf galaxies play a crucial role in cosmic evolution. Astronomers think they were the first galaxies to form, and they provided the building blocks for larger galaxies. They are by far the most numerous galaxies in our Universe, and are an important tracer of the large-scale structure of the cosmos. Computer simulations of cosmic evolution suggest that high-density regions of the Universe, such as giant clusters, should contain significantly more dwarf galaxies than astronomers have observed to date.

A team led by Leigh Jenkins and Ann Hornschemeier, both at NASA Goddard Space Flight Center in Greenbelt, Md., used Spitzer to study the Coma Berenices cluster, an enormous congregation of galaxies 320 million light-years away in the constellation Coma. The cluster contains hundreds of previously known galaxies that span a volume 20 million light-years across.

Jenkins, Hornschemeier, and their collaborators used data from Spitzer’s Infrared Array Camera (IRAC) to study galaxies at the cluster’s center. They also targeted an outlying region with the goal of comparing the galaxy populations in the different locations to see how environmental variations influence the evolution of galaxies. They stitched together 288 individual Spitzer exposures, each lasting 70 to 90 seconds, into a large mosaic covering 1.3 square degrees of sky.

The team found almost 30,000 objects, whose catalog will be made available to the astronomical
community. Some of these are galaxies in the Coma cluster, but the team realized that a large fraction had to be background galaxies. Using data taken with the 4-meter (13 foot) William Herschel Telescope on the Canary island of La Palma, team member Bahram Mobasher of the Space Telescope Science Institute, in Baltimore, Md., measured distances to hundreds of galaxies in these fields to estimate what fraction are cluster members.

Credit: NASA/JPL-Caltech/GSFC/SDSS

Source: NASA

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Research Finds That Earth's Climate is Approaching Dangerous Point

NASA and Columbia University Earth Institute research finds that human-made greenhouse gases have brought the Earth’s climate close to critical tipping points, with potentially dangerous consequences for the planet.

Image above: Antarctica lost much more ice to the sea than it gained from snowfall according to a NASA survey done between 1992 and 2002. It also had a corresponding rise in sea level. The survey documented for the first time extensive thinning of the West Antarctic ice shelves.

From a combination of climate models, satellite data, and paleoclimate records the scientists conclude that the West Antarctic ice sheet, Arctic ice cover, and regions providing fresh water sources and species habitat are under threat from continued global warming. The research appears in the current issue of Atmospheric Chemistry and Physics.

Credit: NASA/SVS

Source: NASA

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