Posted on by Fraser Cain

Large Rocky Planet Discovered

Artist illustration of the rocky planet around the M dwarf Gliese 876. Image credit: NSF. Click to enlarge.
Taking a major step forward in the search for Earth-like planets beyond our own solar system, a team of astronomers has announced the discovery of the smallest extrasolar planet yet detected. About seven-and-a-half times as massive as Earth, with about twice the radius, it may be the first rocky planet ever found orbiting a normal star not much different from our Sun.

All of the nearly 150 other extrasolar planets discovered to date around normal stars have been larger than Uranus, an ice-giant about 15 times the mass of the Earth.

“We keep pushing the limits of what we can detect, and we’re getting closer and closer to finding Earths,” said team member Steven Vogt, a professor of astronomy and astrophysics at the University of California, Santa Cruz.

?Today’s results are an important step toward answering one of the most profound questions that mankind can ask: Are we alone in the universe?? said Michael Turner, head of the Mathematical and Physical Sciences Directorate at the National Science Foundation, which provided partial funding for the research.

The newly-discovered ?super-Earth? orbits the star Gliese 876, located just 15 light years away in the direction of the constellation Aquarius. This star also possesses two larger, Jupiter-size planets. The new planet whips around the star in a mere two days, and is so close to the star’s surface that its temperature probably tops 400 to 750 degrees Fahrenheit (200 to 400 degrees Celsius)?oven-like temperatures far too hot for life as we know it.

Nevertheless, the ability to detect the tiny wobble that the planet induces in the star gives astronomers confidence that they will be able to detect even smaller rocky planets in orbits more hospitable to life.

“This is the smallest extrasolar planet yet detected and the first of a new class of rocky terrestrial planets,” said team member Paul Butler of the Carnegie Institution of Washington. “It’s like Earth’s bigger cousin.”

The team measures a minimum mass for the planet of 5.9 Earth masses, orbiting Gliese 876 with a period of 1.94 days at a distance of 0.021 astronomical units (AU), or 2 million miles.

Though the team has no direct proof that the planet is rocky, its low mass precludes it from retaining gas like Jupiter. Three other purported rocky planets have been reported, but they orbit a pulsar, the flashing corpse of an exploded star.

“This planet answers an ancient question,” said team leader Geoffrey Marcy, professor of astronomy at the University of California, Berkeley. “Over 2,000 years ago, the Greek philosophers Aristotle and Epicurus argued about whether there were other Earth-like planets. Now, for the first time, we have evidence for a rocky planet around a normal star.”

Marcy, Butler, theoretical astronomer Jack Lissauer of NASA/Ames Research Center, and post-doctoral researcher Eugenio J. Rivera of the University of California Observatories/Lick Observatory at UC Santa Cruz presented their findings today (Monday, June 13) during a press conference at NSF in Arlington, Va.

Their research, conducted at the Keck Observatory in Hawaii, was supported by NSF, the National Aeronautics and Space Administration, the University of California and the Carnegie Institution of Washington.

A paper detailing the results has been submitted to The Astrophysical Journal. Coauthors on the paper are Steven Vogt and Gregory Laughlin of the Lick Observatory at the University of California, Santa Cruz; Debra Fischer of San Francisco State University; and Timothy M. Brown of NSF?s National Center for Atmospheric Research in Boulder, Colorado.

Gliese 876 (or GJ 876) is a small, red star known as an M dwarf ? the most common type of star in the galaxy. It is located in the Aquarius constellation, and, at about one-third the mass of the sun, is the smallest star around which planets have been discovered. Butler and Marcy detected the first planet there in 1998; it proved to be a gas giant about twice the mass of Jupiter. Then, in 2001, they reported a second planet, another gas giant about half the mass of Jupiter. The two are in resonant orbits, the outer planet taking 60 days to orbit the star, twice the period of the inner giant planet.

Lissauer and Rivera have been analyzing Keck data on the Gliese 876 system in order to model the unusual motions of the two known planets, and three years ago got an inkling that there might be a smaller, third planet orbiting the star. In fact, if they hadn’t taken account of the resonant interaction between the two known planets, they never would have seen the third planet.

“We had a model for the two planets interacting with one another, but when we looked at the difference between the two-planet model and the actual data, we found a signature that could be interpreted as a third planet,” Lissauer said.

A three-planet model consistently gave a better fit to the data, added Rivera. “But because the signal from this third planet was not very strong, we were very cautious about announcing a new planet until we had more data,” he said.

Recent improvements to the Keck Telescope’s high-resolution spectrometer (HIRES) provided crucial new data. Vogt, who designed and built HIRES, worked with the technical staff in the UC Observatories/Lick Observatory Laboratories at UC Santa Cruz to upgrade the spectrometer’s CCD (charge coupled device) detectors last August.

“It is the higher precision data from the upgraded HIRES that gives us confidence in this result,” Butler said.

The team now has convincing data for the planet orbiting very close to the star, at a distance of about 10 stellar radii. That’s less than one-tenth the size of Mercury’s orbit in our solar system.

“In a two-day orbit , it’s about 200 degrees Celsius too hot for liquid water,” Butler said. “That tends to lead us to the conclusion that the most probable composition of this thing is like the inner planets of this solar system ? a nickel-iron rock, a rocky planet, a terrestrial planet.”

“The planet’s mass could easily hold onto an atmosphere,” noted Laughlin, an assistant professor of astronomy at UC Santa Cruz. “It would still be considered a rocky planet, probably with an iron core and a silicon mantle. It could even have a dense steamy water layer. I think what we are seeing here is something that’s intermediate between a true terrestrial planet like the Earth and a hot version of the ice giants Uranus and Neptune.”

Combined with improved computer software, the new CCD (charge coupled device) detectors designed by this team for Keck’s HIRES spectrometer can now measure the Doppler velocity of a star to within one meter per second ? human walking speed ? instead of the previous precision of three meters per second. This improved sensitivity will allow the planet-hunting team to detect the gravitational effect of an Earth-like planet within the habitable zone of M dwarf stars like Gliese 876.

“We are pushing a whole new regime at Keck to achieve one meter per second precision, triple our old precision, that should also allow us to see Earth-mass planets around sun-like stars within the next few years,” Butler said.

“Our UC Santa Cruz and Lick Observatory team has done an enormous amount of optical and technical and detector work to make the Keck telescope a rocky planet hunter, the best one in the world,” Marcy added.

Lissauer also is excited by another feat reported in the paper submitted to the journal. For the first time, he, Rivera and Laughlin have determined the line-of-sight inclination of the orbit of the stellar system solely from the observed Doppler wobble of the star. Using dynamical models of how the two Jupiter-size planets interact, they were able to calculate the masses of the two giant planets from the observed shapes and precession rates of their oval orbits. Precession is the slow turning of the long axis of a planet’s elliptical orbit.

They showed that the orbital plane is tilted 40 degrees to our line of sight. This allowed the team to estimate the most likely mass of the third planet as seven and a half Earth masses.

“There’s more dynamical modeling involved in this study than any previous study, much more,” Lissauer said.

The team plans to continue to observe the star Gliese 876, but is eager to find other terrestrial planets among the 150 or more M dwarf planets they observe regularly with Keck.

“So far we find almost no Jupiter-mass planets among the M dwarf stars we’ve been observing, which suggests that, instead, there is going to be a large population of smaller mass planets,” Butler noted.

Original Source: Carnegie Institute News Release

Posted on by Fraser Cain

What’s Up This Week – June 13 – June 19, 2005

Comet Tempel 1. Deep Impact Gallery. Click to enlarge.
Monday, June 13 – Today in 1983, Pioneer 10 made space history as it became the first manmade object to leave our solar system.

Have you been watching your equinox marker? Today marks an important date for the Sun’s journey across the sky. In ancient times, and even in our modern ones, sundials are used to measure time. The position of the Sun today will allow a well placed sundial will match a standard clock. Although a sundial is fairly accurate, we apply a correction known as the Equation of Time and only four times a year does it reach zero.

Comet 9/P Tempel 1 is sailing through Virgo and is now nearing magnitude 9 – putting it within reach of most telescopes. If you haven’t found the object of Deep Impact yet, you’ll be happy to know that Heaven’s Above is now offering highly accurate locator charts. In a smaller scope, it is dim, small, and has a slight concentration toward the core. For the very large scope, note the intense stellar nucleus and wide fan of the tail. I have been observing this comet now for weeks and it looks very much like the picture in a big scope. Now, go… Find it!

Tuesday, June 14 – For those located near 40 degrees north, today will be the earliest sunrise of the year. Tonight the Moon reaches first quarter and this would be a wonderful opportunity to look for the “Alpine Valley” in the lunar northern hemisphere. Valles Alpes will appear as a long, dark scar running through the foothills west of crater Aristotle.

If you would like more of a challenge, then know that Pluto is now at opposition and viewable in Serpens Caudia west of Xi Serpentis. At close to magnitude 14, the tiny planet will require at least a moderate-sized telescope to view, and a very accurate locator chart. In order to distinguish Pluto from background stars, I suggest sketching the field and observing over a number of nights to see which “star” moves.

Wednesday, June 15 – For most observers, Jupiter and the Moon will have wonderfully close encounter as they follow each other across the sky. Tonight on the lunar surface, look just south of central for the descending three rings of Ptolmaeus, Alphonsus and Arzachel. To the west of Arzachel near the terminator, you will see the smooth floor of Mare Nubium. Look for a very curious feature called the “Straight Wall”. It will appear like a very thin, black line that extends from crater Thebit.

While out, take the time to check out Alpha Herculis -Ras Algethi. You will find it not only to be an interesting variable, but a colorful double as well. The primary star is one of the largest known red giants and at about 430 light years away, it is also one of the coolest. Its 5.4 magnitude greenish companion star is easily separated in even small scopes – but even it is a binary! This entire star system is enclosed in an expanding gaseous shell that originates from the evolving red giant. Enjoy it tonight.

Thursday, June 16 – North Australia and New Zealand are featured on this universal date as the Moon occults Jupiter. Be sure to check out this IOTA webpage for precise times in your area. You won’t want to miss it…

The June Lyrids meteor shower will also peak in the early morning hours and will be best after the the Moon has set. With the radiant near bright Vega. you may see up to 15 faint blue meteors per hour from this branch of the May Lyrid meteor stream.

Valentina Tereshkova became the first woman in space, 32 years ago today. She flew aboard the Russian spacecraft, Vostok 6, and her solo flight is still unique.

Although the Moon will fade the view, telescope users might be able to just make out Comet 2004 Q2 Machholz as it passes about a degree east of Alpha Canum. Although we have explored Cor Caroli before, take the time again to check out the soft orange and lavender colors of this splendid double star.

Friday, June 17 – Ah, to waltz around the “Bay of Rainbows” with you! Tonight the lunar surface will offer the telescopic opportunity to view one of perhaps the most romantic of areas – Sinus Iridium. Look to the lunar north where you will discover the smooth bay partially encircled by the Juras Mountains. Promentoriums Heraclides and LaPlace stand like distant lighthouses at either tip. If seeing conditions are good, you will note many graceful rilles, like frozen waves, crossing its floor.

If you don’t own a telescope, Sinus Iridium still shows quite well in binoculars. For unaided viewers? See if you can spot cool, blue Spica nearby.

Saturday, June 18 – Today in 1983, Sally Ride became the first American woman to go into orbit. Sally’s ride? The Space Shuttle!

But you won’t need the Space Shuttle to take you into orbit tonight as the lunar surface becomes a binocular hunter’s paradise. Starting in the lunar north, look for the blank, loveless eye of Plato and the dramatically brightening rays of Tycho to the south. Look for ancient Copernicus just slightly west of the mid-section and the brilliant points of light near the terminator that are Keplar to the north and Artistarchus to its south. Eroded crater Gassendi on the shore of Mare Humorum to the south will round out our lunar tour.

For North American observers, be sure to check out Saturn before it sets. Like a temporary “moon”, 7th magnitude star SAO79782 will be visible to its north.

Sunday, June 19 – If you are up just before dawn this morning, keep an eye on the sky as we pass through another portion of the Ophiuchid meteor stream. The radiant for this pass will be more near Sagittarius and the fall rate varies from 8 to 20, but can sometimes produce unexpectedly more.

No matter what time zone you live in, Jupiter will be a lively place tonight! For some viewers, you will see a very close pairing of Ganymede and Europa – and for others, Io and Europa. For viewers well positioned at 22:19 UT, the “Great Red Spot” will also transit.

If you haven’t been following the intricate dance of the evening planets, then go out just after sunset and look! Venus, Saturn, and Mercury are now within a fist width apart, sitting low in the west-northwest during. Mercury, the lowest of the three, sets about 1 1/2 hours after sunset, so don’t wait too late to observe. The planets will contine to move closer all next week, so mark your calendars for next weekend when they appear only 1.5 degrees apart. You won’t want to miss this!

Keep your eyes on the skies and may all your journeys be at Light Speed! …~Tammy Plotner

Posted on by Mark Mortimer

Book Review: Deep Space NASA Mission Reports

Deep Space – The NASA Mission Reports. Click to enlarge.
With the maturing of space flight in the 1960’s, NASA could set goals loftier than clambering around Earth’s nearest satellite for a few short hours. There existed the ability to travel anywhere in the solar system, take measurements and view the results. Grabbing this opportunity with both hands, NASA launched:

? the Pioneer 10 and 11 crafts on two missions to Jupiter,
? the Voyager 1 and 2 crafts on two missions to Jupiter, Saturn and beyond,
? the Galileo craft on a mission to Jupiter,
? the Cassini-Huygens craft on a mission to Saturn,
? the Deep Space 1 craft on a mission to comet 19P/Borrelly, and
? the Stardust craft on a mission to comet Wild-2.

Nominally each was to expand our knowledge of the solar system and to better understand our relative place within it.

NASA, as typical for all government bureaucracies, dutifully printed up extensive documentation for each mission. From these, the book provides reproductions of press kits, special reports, status reports and fact sheets. The press kits predominate. They describe the craft, the mission, current activities, any extenuating circumstances and expectations just prior to critical moments. Typically, one kit gives a pre-launch summary and others give a summary just before the first encounter of a target. The kits are quite detailed with break downs of the components and functions of each spacecraft. Descriptions of the purpose and equipment for each science experiments clarify the purpose. The trajectory, navigation and communication elements demonstrate some challenges to be overcome. Lists of project managers, principal investigators and contractors ensure posterity to many participants. Thin coverage of the results is an indicator that, though NASA ran the missions and wrote many transcripts, there were others that promulgated the results in their own distinct fashion.

The enclosed DVD shows how NASA has leapt into the new media of video. Audio/video footage from NASA TV and other NASA sources show boosters lofting payloads up and away. During final countdown, often a lengthy time of apparent inactivity, images of trucks and transport aeroplanes delivering components liven up the proceedings. Clean room activities, such as checking solar arrays and mating components, give some insight into preflight activities. Video results of encounters particularly reward viewers. A wonderful segment shows a complete 360 degree coverage of the tumbling asteroid Eros from a very close perspective. Voyager’s visual imagery of the swirling storms on Jupiter transfix the eye and certainly credit the usage of video as a strong communication media.

With the inclusion of all these deep space missions, the editors Godwin and Whitfield provide a marvellous resource for reviewing any deep space mission. Further, by proceeding in a chronological order, the reader can easily grasp how results of an earlier mission influenced the investigations of the following one. From the Pioneer mission, where transit of the asteroid belt came with much misgivings, to Cassini-Huygens dropping a capable probe onto a moon of Saturn, the press kits look the same but the contents just keep getting better.

One thing about having dual missions like Pioneer 10 and 11 or Voyager 1 and 2 is that a lot of similarity exists. The same must be said for their press kits. Though the editors appear to have tried to remove some repetitive verbiage, there are still many tracts, drawings and lists that appear time and again in the book. This is true whether the kits are for different moments of the same mission or of related missions. Also, in keeping with government-eze, just about all the dissertation blandly recites facts and figures. Qualitative descriptors are few and far between. Regarding the DVD, the short 8 page PDF file for Galileo seems an injustice especially considering the 100’s of pages and videos for both Pioneer and Voyager.

One truly rewarding decisions created NASA as a non-military organization. In consequence, they hide little in the quest to learn more about the universe in which we live. The book Deep Space – The NASA Mission Reports as edited by Robert Godwin and Steve Whitfield compiles the very detailed official announcements from NASA for their missions that travelled beyond Mars. In it, facts, figures, data and images corroborate our new awareness and appreciation of our planetary neighbourhood.

Order a copy online from Countdown Creations or Amazon.com.

Review by Mark Mortimer

Posted on by Fraser Cain

Mmmm, Food From Mars

Spirulina Gnocchis, a recipe that could be cooked up from food grown in space. Image credit: ESA. Click to enlarge.
‘Martian bread and green tomato jam’, ‘Spirulina gnocchis’ and ‘Potato and tomato mille-feuilles’ are three delicious recipes that two French companies have created for ESA and future space explorers to Mars and other planets.

The challenge for the chefs was to offer astronauts well-flavoured food, made with only a few ingredients that could be grown on Mars. The result was 11 tasty recipes that could be used on future ESA long-duration space missions. ADF ? Alain Ducasse Formation and GEM are the two French companies that produced the recipes, and their mutual experience in creating new products and ?haute cuisine? have led to excellent results.

The menus were all based on nine main ingredients that ESA envisions could be grown in greenhouses of future colonies on Mars or other planets. The nine must comprise at least 40% of the final diet, while the remaining (up to) 60% could be additional vegetables, herbs, oil, butter, salt, pepper, sugar and other seasoning brought from Earth.

“We are aiming initially at producing 40% locally for astronauts’ food on future long-duration space missions, for example to Mars,” says Christophe Lasseur, ESA’s biological life-support coordinator responsible for recycling and production of air, water and food for long-term space missions.

“Why 40%? By growing enough plants to cover around 40% of what we eat, we also get ‘for free’ the oxygen and water needed to live”, explains Lasseur.

The nine basic ingredients that Lasseur plans to grow on other planets are: rice, onions, tomatoes, soya, potatoes, lettuce, spinach, wheat and spirulina ? all common ingredients except the last. Spirulina is a blue-green algae, a very rich source of nutrition with lots of protein (65% by weight), calcium, carbohydrates, lipids and various vitamins that cover essential nutritional needs for energy in extreme environments.

Today all the food for astronauts in space is brought from Earth, but this will not be possible for longer missions. Although still on the drawing board, ESA has already started research to see what could be grown on other planets – and what a self-supporting eco-system might look like on Mars.

“In addition to being healthy and sufficiently nutritious for survival, good food could potentially provide psychological support for the crew, away from Earth for years,” emphasises Lasseur.

ADF chef Armand Arnal, adds: “The main challenge was to create a wide panel of recipes, distinct and full-flavoured, with only nine basic products.”

“Moreover, we had absolute restrictions on using salt, but were allowed to add a bit of sugar and fat, ingredients normally essential to the elaboration of a dish and to highlight its flavours.”

Original Source: ESA News Release

Posted on by Fraser Cain

Pluto Mission Arrives at NASA for Testing

Artist illustration of New Horizons with Pluto and Charon. Image credit: JHUAPL/SwRI. Click to enlarge.
The first spacecraft designed to study Pluto, the last planet in our solar system, arrived at NASA?s Goddard Space Flight Center (GSFC) in Greenbelt, Md., today for a series of pre-launch checkouts.

“We are extremely proud to have the NASA’s New Horizons mission make Goddard the first stop in its journey to the last planet,” said Dr. Ed Weiler, GSFC Center Director. “The New Horizons mission to Pluto is an historic journey of exploration to unlock secrets from a mysterious planet so distant that the Sun is just a bright star in the sky.”

The spacecraft will be at Goddard for the next three months where team members will check New Horizons? balance and alignment in a series of spin tests; put it before wall-sized speakers that simulate the noisy vibrations of launch; and seal it for several weeks in a four-story thermal-vacuum chamber that duplicates the extreme cold and airless conditions of space. After departing Goddard in the Fall, the spacecraft will make its way to the Kennedy Space Center, Fla. for final launch preparations.

New Horizons is the first mission to Pluto and its moon, Charon. As part of an extended mission, the spacecraft would head deeper into the Kuiper Belt to study one or more of the icy mini worlds in that vast region. New Horizons is scheduled for launch in January 2006 from Cape Canaveral Air Force Station, Fla., aboard a Lockheed Martin Atlas V. New Horizons should begin its five-month-long flyby reconnaissance of Pluto-Charon in summer 2015.

New Horizons is carrying an extensive complement of science instruments. Goddard has a major role in the Southwest Research Institute?s Ralph instrument. Ralph’s main objectives are to obtain high resolution color and surface composition maps of the surfaces of Pluto and Charon. The instrument has two separate channels: the Multispectral Visible Imaging Camera (MVIC) and the Linear Etalon Imaging Spectral Array (LEISA). A single telescope with a 3-inch (6-centimeter) aperture collects and focuses the light used in both channels. MVIC, provided by Ball Aerospace in from Boulder Colo., operates at the visible wavelength to produce color maps. LEISA operates at infrared wavelengths. LEISA, provided by Goddard, will be used to map the distribution of frosts of methane, molecular nitrogen, carbon monoxide, and water over the surface of Pluto and the water frost distribution over the surface of Charon.

New Horizons is the first mission in NASA?s New Frontiers program of medium-class, high-priority solar system exploration projects. The spacecraft is managed by the John Hopkins University Applied Physics Laboratory in Laurel, Md. The Principal Investigator Dr. Alan Stern, is from the Southwest Research Institute, San Antonio, TX. The mission team includes Goddard Space Flight Center, APL, Ball Aerospace Corporation, the Boeing Company, the Jet Propulsion Laboratory, Pasadena, Calif. Stanford University, Calif. KinetX, Inc., Tempe, AZ, Lockheed Martin Corporation, University of Colorado at Boulder, the U.S. Department of Energy and a number of other firms, NASA centers and university partners.

For more information on the mission, visit: http://pluto.jhuapl.edu.

Original Source: NASA News Release

Update: Pluto is not a planet

Posted on by Fraser Cain

Spitzer View of a Dead Star

Supernova remnant Cassiopeia A. Image credit: NASA/JPL. Click to enlarge.
An enormous light echo etched in the sky by a fitful dead star was spotted by the infrared eyes of NASA’s Spitzer Space Telescope.

The surprising finding indicates Cassiopeia A, the remnant of a star that died in a supernova explosion 325 years ago, is not resting peacefully. Instead, this dead star likely shot out at least one burst of energy as recently as 50 years ago.

“We had thought the stellar remains inside Cassiopeia A were just fading away,” said Dr. Oliver Krause, University of Arizona, Tucson. “Spitzer came along and showed us this exploded star, one of the most intensively studied objects in the sky, is still undergoing death throes before heading to its final grave.”

Infrared echoes trace the dusty journeys of light waves blasted away from supernova or erupting stars. As the light waves move outward, they heat up clumps of surrounding dust, causing them to glow in infrared light. The echo from Cassiopeia A is the first witnessed around a long-dead star and the largest ever seen. It was discovered by accident during a Spitzer instrument test.

“We had no idea that Spitzer would ever see light echoes,” said Dr. George Rieke of the University of Arizona. “Sometimes you just trip over the biggest discoveries.”

To view the echoes dancing through clouds of dust surrounding Cassiopeia A, visit:
http://www.spitzer.caltech.edu/Media/releases/ssc2005-14/visuals.shtml.

A supernova remnant like Cassiopeia A typically consists of an outer, shimmering shell of expelled material and a core skeleton of a once-massive star, called a neutron star. Neutron stars come in several varieties, ranging from intensely active to silent. Typically, a star that has recently died will continue to act up. Consequently, astronomers were puzzled that the star responsible for Cassiopeia A appeared to be silent so soon after its death.

The new infrared echo indicates the Cassiopeia A neutron star is active and may even be an exotic, spastic type of object called a magnetar. Magnetars are like screaming dead stars, with eruptive surfaces that rupture and quake, pouring out tremendous amounts of high-energy gamma rays. Spitzer may have captured the “shriek” of such a star in the form of light zipping away through space and heating up its surroundings.

“Magnetars are very rare and hard to study, especially if they are no longer associated with their place of origin. If we have indeed uncovered one, then it will be just about the only one for which we know what kind of star it came from and when,” Rieke said.

Astronomers first saw hints of the infrared echo in strange, tangled dust features that showed up in the Spitzer test image. When they looked at the same dust features again a few months later using ground-based telescopes, the dust appeared to be moving outward at the speed of light. Follow-up Spitzer observations taken one year later revealed the dust was not moving, but was being lit up by passing light.

A close inspection of the Spitzer pictures revealed a blend of at least two light echoes around Cassiopeia A, one from its supernova explosion, and one from the hiccup of activity that occurred around 1953. Additional Spitzer observations of these light echoes may help pin down their enigmatic source.

Krause was lead author with Rieke of a study about the discovery appearing this week in the journal Science.

JPL manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate. Science operations are conducted at the Spitzer Science Center, California Institute of Technology, Pasadena, Calif. JPL is a division of Caltech. Spitzer’s multiband imaging photometer, which made the new observations, was built by Ball Aerospace Corporation, Boulder, Colo.; the University of Arizona; and Boeing North America, Canoga Park, Calif. Its development was led by Rieke.

For additional images and information about Spitzer on the Web, visit: http://www.spitzer.caltech.edu/Media. For information about NASA and agency programs on the Web, visit: http://www.nasa.gov/home/index.html.

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

Coprates Chasma on Mars

Perspective view of Coprates Chasma and Catena. Image credit: ESA. Click to enlarge.
This image, taken by the High Resolution Stereo Camera (HRSC) on board ESA?s Mars Express spacecraft, shows Coprates Chasma, a major trough in the Valles Marineris canyon system.

The HRSC obtained this image during orbit 449 with a ground resolution of approximately 48 metres per pixel.

The scene shows the region containing the sections of Coprates Chasma and Coprates Catena, over an area centred at about 13.5? South and 300? East, roughly in the centre of the Valles Marineris canyon system.

The trough of Coprates Chasma appears in the north, and ranges from approximately 60 km to 100 km wide and extends 8-9 km below the surrounding plains.

Coprates Catena lies parallel to Coprates Chasma and can be seen in the south as three troughs, ranging from a few kilometres to 22 km wide and up to 5 km deep. These troughs have been modified by erosion, as indicated by the linear features extending from the upper edge of the trough walls.

In contrast to the relatively sharp appearance of the upper regions of the trough walls, the lower slopes and the floors of the troughs have a softer appearance, which is probably the result of atmospheric dust.

Linear features, prevalent throughout the image and running generally parallel to the major troughs, may be faults.

Scientists are unsure of the mechanism responsible for the creation of the Valles Marineris canyon system. Some suggest that the formation of the Tharsis uplift, located west of the canyon system, caused tension and fracturing of the Martian crust.

Other researchers believe that water may have removed rock material from the subsurface, which caused the surface to collapse. A related theory suggests that large quantities of subsurface ice melted, causing surface collapse. Possibly all of these processes together were active in forming the structure.

Valles Marineris provides scientists with a window into the depths of Mars and enables them to study the complex geological and climatic history of the Red Planet.

By supplying new data for Valles Marineris, including colour and stereo images, the Mars Express HRSC camera aids scientists in this endeavour, ultimately improving our understanding of this fascinating planet.

Original Source: ESA News Release

Posted on by Fraser Cain

Capturing the Fastest Events in the Universe

ULTRACAM instrument mounted on the Very Large Telescope. Image credit: ESO. Click to enlarge.
British scientists have opened a new window on the Universe with the recent commissioning of the Visitor Instrument ULTRACAM on the European Southern Observatory’s (ESO) Very Large Telescope (VLT) in Chile.

ULTRACAM is an ultra fast camera capable of capturing some of the most rapid astronomical events. It can take up to 500 pictures a second in three different colours simultaneously. It has been designed and built by scientists from the Universities of Sheffield and Warwick (United Kingdom), in collaboration with the UK Astronomy Technology Centre in Edinburgh.

ULTRACAM employs the latest in charged coupled device (CCD) detector technology in order to take, store and analyse data at the required sensitivities and speeds. CCD detectors can be found in digital cameras and camcorders, but the devices used in ULTRACAM are special because they are larger, faster and most importantly, much more sensitive to light than the detectors used in today’s consumer electronics products.

In May 2002, the instrument saw “first light” on the 4.2-m William Herschel Telescope (WHT) on La Palma. Since then the instrument has been awarded a total of 75 nights of time on the WHT to study any object in the Universe which eclipses, transits, occults, flickers, flares, pulsates, oscillates, outbursts or explodes.

These observations have produced a bonanza of new and exciting results, leading to already 11 scientific publications published or in press.

To study the very faintest stars at the very highest speeds, however, it is necessary to use the largest telescopes. Thus, work began 2 years ago preparing ULTRACAM for use on the VLT.

“Astronomers using the VLT now have an instrument specifically designed for the study of high-speed phenomena”, said Vik Dhillon, from the University of Sheffield (UK) and the ULTRACAM project scientist. “Using ULTRACAM in conjunction with the current generation of large telescopes makes it now possible to study high-speed celestial phenomena such as eclipses, oscillations and occultations in stars which are millions of times too faint to see with the unaided eye.”

Observing Black Holes
The instrument saw first light on the VLT on May 4, 2005, and was then used for 17 consecutive nights on the telescope to study extrasolar planets, black-hole binary systems, pulsars, white dwarfs, asteroseismology, cataclysmic variables, brown dwarfs, gamma-ray bursts, active-galactic nuclei and Kuiper-belt objects.

One of the faint objects studied with ULTRACAM on the VLT is GU Muscae. This object consists of a black hole in a 10-hour orbit with a normal, solar-like star. The black hole is surrounded by a disc of material transferred from the normal star. As this material falls onto the black hole, energy is released, producing large-amplitude flares visible in the light curve. This object has magnitude 21.4, that is, it is one million times fainter than what can be seen with the unaided eye. Yet, to study it in detail and detect the shortest possible pulses, it is necessary to use exposure times as short as 5 seconds. This is possible with the large aperture and great efficiency of the VLT.

These unique observations have revealed a series of sharp spikes, separated by approximately 7 minutes. Such a stable signal must be tied to a relatively stable structure in the disc of matter surrounding the black hole. The astronomers are now in the process of analysing these results in great details in order to understand the origin of this structure.

Another series of observations were dedicated to the study of extrasolar planets, more particularly those that transit in front of their host star. ULTRACAM observations have allowed the astronomers to obtain simultaneous light curves, in several colour-bands, of four known transiting exoplanets discovered by the OGLE survey, and this with a precision of a tenth of a percent and with a 4 second time resolution. This is a factor ten better than previous measurements and will provide very accurate masses and radii for these so-called “hot-Jupiters”. Because ULTRACAM makes observations in three different wavebands, such observations will also allow astronomers to establish whether the radius of the exoplanet is different at different wavelengths. This could provide crucial information on the possible exoplanets’ atmosphere.

The camera is the first instrument to make use of the Visitor Focus on Melipal (UT3), and the first UK-built instrument to be mounted at the VLT. The Visitor Focus allows innovative technologies and instrumentation to be added to the telescope for short periods of time, permitting studies to take place that are not available with the current suite of instruments.

“These few nights with ULTRACAM on the VLT have demonstrated the unique discoveries that can be made by combining an innovative technology with one of the best astronomical facilities in the world,” said Tom Marsh of the University of Warwick and member of the team. “We hope that ULTRACAM will now become a regular visitor at the VLT, giving European astronomers access to a unique new tool with which to study the Universe.”

More information
The ULTRACAM team is composed of Vik Dhillon, Stuart Littlefair, and Paul Kerry (Sheffield, UK), Tom Marsh (Warwick, UK), Andy Vick and Dave Atkinson (UKATC, Edinburgh, UK). For the installation on the VLT, they received support from Kieran O’Brien and Pascal Robert (ESO, Chile). The ULTRACAM project page can be found at http://www.shef.ac.uk/~phys/people/vdhillon/ultracam.

Original Source: ESO News Release

Posted on by Fraser Cain

First Aurora Seen on Mars

Terra Cimmeria region of Mars where the aurora was detected. Image credit: ESA. Click to enlarge.
ESA?s Mars Express spacecraft has for the first time ever detected an aurora on Mars. This aurora is of a type never previously observed in the Solar System.

Observations by the SPICAM instrument (SPectroscopy for the Investigations and the Characteristics of the Atmosphere on Mars) taken on 11 August 2004, revealed light emissions now interpreted as an aurora.

Aurorae are spectacular displays often seen at the highest latitudes on Earth. On our planet, as well as on the giant planets Jupiter, Saturn, Uranus and Neptune, they lie at the foot of the planetary magnetic field lines near the Poles, and are produced by charged particles ? electrons, protons or ions ? precipitating along these lines.

Aurorae have also been observed on the night side of Venus, a planet with no intrinsic (planetary) magnetic field. Unlike Earth and the giant planets, venusian aurorae appear as bright and diffuse patches of varying shape and intensity, sometimes distributed across the full planetary disc. Venusian aurorae are produced by the impact of electrons originating from the solar wind and precipitating in the night-side atmosphere.

Like Venus, Mars is a planet with no intrinsic magnetic field. A few years ago it was suggested that auroral phenomena could exist on Mars too. This hypothesis was reinforced by the recent Mars Global Surveyor discovery of crustal magnetic anomalies, most likely the remnants of an old planetary magnetic field.

SPICAM detected light emissions in the Southern hemisphere on Mars, during night time observations. The total size of the emission region is about 30 kilometres across, possibly about 8 kilometres high. Whilst the detected emission is typical for day-time, it must indicate the excitation of the upper atmosphere by fluxes of charged particles ? probably electrons ? if observed during night-time.

By analysing the map of crustal magnetic anomalies compiled with Mars Global Surveyor?s data, scientists observed that the region of the emissions corresponds to the area where the strongest magnetic field is localised. This correlation indicates that the origin of the light emission actually is a flux of electrons moving along the crust magnetic lines and exciting the upper atmosphere of Mars.

SPICAM observations provide for the first time a key insight into the role of the martian crustal magnetic field in producing original cusp-like magnetic structures. Such structures concentrate fluxes of electrons into small regions of the martian atmosphere. Eventually, they induce the formation of highly concentrated aurorae whose formation mechanism ? a localised emission controlled by anomalies in the crust?s magnetic field ? is unique in the Solar System.

Original Source: ESA News Release

Posted on by Fraser Cain

Possible Methane Volcano Discovered on Titan

Infrared image of Titan taken by Cassini during its Oct. 26, 2004 flyby. Image credit: NASA/JPL/SSI. Click to enlarge.
A recent flyby of Saturn’s hazy moon Titan by the Cassini spacecraft has revealed evidence of a possible volcano, which could be a source of methane in Titan’s atmosphere.

Images taken in infrared light show a circular feature roughly 30 kilometers (19 miles) in diameter that does not resemble any features seen on Saturn’s other icy moons. Scientists interpret the feature as an “ice volcano,” a dome formed by upwelling icy plumes that release methane into Titan’s atmosphere. The findings appear in the June 9 issue of Nature.

“Before Cassini-Huygens, the most widely accepted explanation for the presence of methane in Titan’s atmosphere was the presence of a methane-rich hydrocarbon ocean,” said Dr. Christophe Sotin, distinguished visiting scientist at NASA’s Jet Propulsion Laboratory, Pasadena, Calif.

“The suite of instruments onboard Cassini and the observations at the Huygens landing site reveal that a global ocean is not present,” said Sotin, a team member of the Cassini visual and infrared mapping spectrometer instrument and professor at the Universit? de Nantes, France.

“Interpreting this feature as a cryovolcano provides an alternative explanation for the presence of methane in Titan’s atmosphere. Such an interpretation is supported by models of Titan’s evolution,” Sotin said.

Titan, Saturn’s largest moon, is the only known moon to have a significant atmosphere, composed primarily of nitrogen, with 2 to 3 percent methane. One goal of the Cassini mission is to find an explanation for what is replenishing and maintaining this atmosphere. This dense atmosphere makes the surface very difficult to study with visible-light cameras, but infrared instruments like the visual and infrared mapping spectrometer can peer through the haze. Infrared images provide information about both the composition and the shape of the area studied.

The highest resolution image obtained by the visual and infrared mapping spectrometer instrument covers an area 150 kilometers square (90 miles) that includes a bright circular feature about 30 kilometers (19 miles) in diameter, with two elongated wings extending westward. This structure resembles volcanoes on Earth and Venus, with overlapping layers of material from a series of flows. “We all thought volcanoes had to exist on Titan, and now we’ve found the most convincing evidence to date. This is exactly what we’ve been looking for,” said Dr. Bonnie Buratti, team member of the Cassini visual and infrared mapping spectrometer at JPL.

In the center of the area, scientists clearly see a dark feature that resembles a caldera, a bowl-shaped structure formed above chambers of molten material. The material erupting from the volcano might be a methane-water ice mixture combined with other ices and hydrocarbons. Energy from an internal heat source may cause these materials to upwell and vaporize as they reach the surface. Future Titan flybys will help determine whether tidal forces can generate enough heat to drive the volcano, or whether some other energy source must be present. Black channels seen by the European Space Agency’s Huygens probe, which piggybacked on Cassini and landed on Titan’s surface in January 2005, could have been formed by erosion from liquid methane rains following the eruptions.

Scientists have considered other explanations. They say the feature cannot be a cloud because it does not appear to move and it is the wrong composition. Another alternative is that an accumulation of solid particles was transported by gas or liquid, similar to sand dunes on Earth. But the shape and wind patterns don’t match those normally seen in sand dunes.

The data for these findings are from Cassini’s first targeted flyby of Titan on Oct. 26, 2004, at a distance of 1,200 kilometers (750 miles) from the moon’s surface.

The visual and infrared mapping spectrometer instrument can detect 352 wavelengths of light from 0.35 to 5.1 micrometers. It measures the intensities of individual wavelengths and uses the data to infer the composition and other properties of the object that emitted the light; each chemical has a unique spectral signature that can be identified.

Forty-five flybys of Titan are planned during Cassini’s four-year prime mission. The next one is Aug. 22, 2005. Radar data of the same sites observed by the visual and infrared mapping spectrometer may provide additional information.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini . The visual and infrared mapping spectrometer page is at http://wwwvims.lpl.arizona.edu .

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 was designed, developed and assembled at JPL. The visual and infrared mapping spectrometer team is based at the University of Arizona.

Original Source: NASA/JPL/SSI News Release