Xanadu on Titan

Saturn’s largest moon Titan. Image credit: NASA/JPL/SSI Click to enlarge
Titan’s equatorial latitudes are distinctly different in character from its south polar region, as this image shows.
The dark terrain, presumably lowland, seen here does not extend much farther south than about 30 degrees South. The successful Huygens probe landed in such a region. The Huygens probe is rotating into the light here, seeing the dawn of a new day.

The bright region toward the right side of Titan’s disk is Xanadu. This area is thought to consist of upland terrain that is relatively uncontaminated by the dark material that fills the lowland regions.

Near the moon’s south pole, and just eastward of the terminator, is the dark feature identified by imaging scientists as the best candidate (so far) for a past or present hydrocarbon lake on Titan (see Clouds in the Distance). Farther east of the lake-like feature, bright clouds arc around the pole. These clouds occupy a latitude range that is consistent with previously-seen convective cloud activity on Titan.

Titan is Saturn’s largest moon, at 5,150 kilometers (3,200 miles) across.

The image was taken with the Cassini spacecraft narrow angle camera on July 7, 2005, at a distance of approximately 1.3 million kilometers (800,000 miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 60 degrees. The image was obtained using a filter sensitive to wavelengths of infrared light centered at 938 nanometers. The image scale is 7 kilometers (5 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.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Original Source: NASA/JPL/SSI News Release

Mineral Mapper Traveling to Mars

CRISM. Image credit: NASA Click to enlarge
With today?s launch of NASA?s Mars Reconnaissance Orbiter spacecraft from Cape Canaveral Air Force Station, Fla., the Compact Reconnaissance Imaging Spectrometer for Mars ? or CRISM ? joins the set of high-tech detectives seeking traces of water on the red planet.

Built by the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., CRISM is the first visible-infrared spectrometer to fly on a NASA Mars mission. Its primary job: look for the residue of minerals that form in the presence of water, the ?fingerprints? left by evaporated hot springs, thermal vents, lakes or ponds on Mars when water could have existed on the surface.

With unprecedented clarity, CRISM will map areas on the martian surface down to house-sized scales ? as small as 60 feet (about 18 meters) across ? when the spacecraft is in its average orbit altitude of about 190 miles (more than 300 kilometers).

?CRISM plays a very important role in Mars exploration,? says APL?s Dr. Scott Murchie, the instrument?s principal investigator. ?Our data will identify sites most likely to have contained water, and which would make the best potential landing sites for future missions seeking fossils or even traces of life on Mars.?

Though certain landforms provide evidence that water may once have flowed on Mars, Murchie says scientists have little evidence of sites containing mineral deposits created by long-term interaction between water and rock. The NASA Rover Opportunity found evidence for liquid water in Meridian Planum ? a large plain near Mars? equator ? but that is only one of many hundreds of sites where future spacecraft could land.

Peering through a telescope with a 4-inch (10-centimeter) aperture, and with a greater capability to map spectral variations than any similar instrument sent to another planet, CRISM will read 544 ?colors? in reflected sunlight to detect minerals in the surface. Its highest resolution is about 20 times sharper than any previous look at Mars in infrared wavelengths.

?At infrared wavelengths, rocks that look absolutely the same to human eyes become very different,? Murchie says. ?CRISM has the capability to take images in which different rocks will ?light up? in different colors.?

CRISM is mounted on a gimbal, allowing it to follow targets on the surface as the orbiter passes overhead. CRISM will spend the first half of a two-year orbit mission mapping Mars at 650-foot (200-meter) scales, searching for potential study areas. Several thousand promising sites will then be measured in detail at CRISM?s highest spatial and spectral resolution. CRISM will also monitor seasonal variations in dust and ice particles in the atmosphere, supplementing data gathered by the orbiter?s other instruments and providing new clues about the Martian climate.

?CRISM will improve significantly on the mapping technology currently orbiting Mars,? says CRISM Project Manager Peter Bedini, of APL. ?We?ll not only look for future landing sites, but we?ll be able to provide details on information the Mars Exploration Rovers are gathering now. There is a lot more to learn, and after CRISM and the Mars Reconnaissance Orbiter there will still be more to learn. But with this mission we?re taking a big step in exploring and understanding Mars.?

As the Mars Reconnaissance Orbiter cruises to its destination, the CRISM operations team continues to fine-tune the software and systems it will use to command the instrument and receive, read, process, and store a wealth of data from orbit ? more than 10 terabytes when processed back on Earth, enough to fill more than 15,000 compact discs. The spacecraft is set to reach Mars next March, use aerobraking to circularize its orbit, and settle into its science orbit by November 2006.

APL, which has built more than 150 spacecraft instruments over the past four decades, led the effort to develop, integrate and test CRISM. CRISM?s co-investigators are top planetary scientists from Brown University, the Jet Propulsion Laboratory, Northwestern University, Space Science Institute, Washington University in St. Louis, University of Paris, the Applied Coherent Technology Corporation, and NASA?s Goddard Space Flight Center, Ames Research Center and Johnson Space Center.

The Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, manages the Mars Reconnaissance Orbiter mission for NASA’s Science Mission Directorate.

For more information on CRISM and the Mars Reconnaissance Orbiter, including instrument images, visit: http://crism.jhuapl.edu

Original Source: APL News Release

What’s Up This Week – August 15 – August 21, 2005

Credit: Randy Brewer
Monday, August 15 – With the constellation of Cygnus now reaching the upper third of the eastern skyline, tonight would be the perfect opportunity for us to look at a summer favourite – Albireo. As the second brightest star in Cygnus, you can locate it easily by looking slightly more than a fist’s width below (east) Vega, and about a handspan roughly south of Deneb. Your best results for color will be at minimum power for telescopes and even a steady hand with binoculars can split this pair. Now let’s have a look at this beautiful double star!

With a wonderfully rich field as a setting, you will find the third magnitude primary star to be very golden in color – a true K3 spectrum type. The secondary is close to fifth magnitude and is definitely tinged blue as its B8 V class suggests. First logged by F.W.G. Struve in 1832, they are believed to be a true physical pair although no orbital motion has yet been detected. At around 410 light years away, the primary star shows a composite spectrum and is in itself a double star too close to be split telescopically. While you look at this pair, realize their true separation is about 4400 AU. We could place our solar system, end-for-end, 55 times in this amount of “space”!

Now let’s turn our attention towards the Moon.

If you are using binoculars, tonight’s study feature will be the easy C-shape of Sinus Iridium. Known as the “Bay of Rainbows”, this 160 mile wide circular plain may very well be the result of an impact on the edge of Mare Imbrium. For telescope users, continue south to the western shore of Mare Cognitum and look along the terminator for the Riphaeus Mountains. This is the largest remainder of mare’s wall.

Tuesday, August 16 – Tonight let’s start with lunar observations and features that can be seen with both binoculars and telescopes. Just slightly north of center along the terminator, look for the bright point of Kepler. Watch as this 20 mile wide feature develops a bright ray system in the coming days. To the north you will see equally bright Aristarchus. Only about 5 miles wider, Aristarchus is quite probably one of the youngest of the prominent features – around 50 million years old – and will also develop a ray system.

Now let’s head south to the sunny shores of Mare Humorum and have a look at a much older feature – the graceful Gassendi. Making its home on the northern edge of a mare that’s around the size of the state of Arkansas, this class V crater will appear as a bright ring to binoculars, but take on special beauty in the telescope. While most of its south wall has almost disappeared thanks to lava flows, the ancient Gassendi still holds an impressive central triple mountain peak and a wonderful collection of rilles and ridges along its floor.

Wednesday, August 17 – Tonight let’s start by observing our western planets as they begin drawing nearer to each other. For the northern hemisphere, you will find Venus very low just south of west at dusk and crossing the celestial equator. Keep an eye on it for the next six weeks as it sets farther south. Less than a handspan above it to the left is bright Jupiter. This pair will put on a wonderful show in the days ahead!

If you are looking for an early evening challenge, then why not try your hand at 8.6 magnitude asteroid Ceres? On this date, it will be just slightly (around 1 degree) northeast of visual double, Nu Librae. For very accurate locator charts on the 17th, visit Heavens Above.

Tonight let’s turn our binoculars or telescopes toward the southern lunar surface as we set out to view one of the most unusually formed craters – Schiller. Near the limb, it will appear as a strange looking gash bordered in white on the southwest and in black on the northeast. This oblong depression might be the fusion of two or three craters, yet shows no evidence of crater walls on its smooth floor. Although there is a slight ridge towards the northern edge, Schiller’s formation still remains a mystery.

Thursday, August 18 – Today in 1868, Norman Lockyer first sees helium in the Sun’s spectrum. Just before the sun rises in the northern hemisphere, look for Mars high in the southeast. While our own summer is ending, summer has just begun in Mar’s southern hemisphere. Let’s check it out in the telescope.

Right now. Mars’ south pole is tipped 15 degrees towards Earth. Its southern polar cap is shrinking and may be hard to spot. Although its north pole is away from us, that particular polar area is normally surrounded by a haze of carbon dioxide which extends well into the visible face of the Red Planet.

Don’t go back to bed yet! Look low to the east/northeast and you’ll see Saturn a little more than a fist’s width below Pollux in Gemini. Need more? Then grab your binoculars and look about half a handspan lower than Saturn for Mercury.

Tonight the great Grimaldi around central on the terminator is the best lunar bet for binoculars. If you would like to see how far you can push your telescopic skill, then let’s start there. About one Grimaldi length to the south, you’ll see a narrow black ellipse with a bright rim. This is Rocca. Go the same distance again (and a bit east) to spot a small, shallow crater with a dark floor. This is Cruger, and its lava filled interior is very similar to previous study – Billy. Now look between them. Can you see a couple of tiny dark markings? Believe it or not, this is called Mare Aestatis. It’s not even large enough to be considered a medium-sized crater, but yet it is considered a mare!

Friday, August 19 – Born today in 1646, let’s have a look at John Flamsteed. He was a self-educated English astronomer with a passion for what he did. Despite a rather difficult childhood and no education, he went on to become the First Observer at the Royal Observatory and his catalog of 3000 stars was perhaps the most accurate ever published. Flamsteed star numbers are still in use today. Also born on this day, but in 1891 was Milton Humason. He was a colleague of Edwin Hubble at Mt. Wilson and Palomar. He was instrumental in measuring the faint spectra of galaxies, which in turn provided evidence for the expansion of the universe.

Early this morning, at 06:00, the Moon reached perigee – the closest point of its orbit – and was 357,393 km (222,074 miles) from Earth. That makes tonight’s full Moon the second closest of the year, but it’s also special for another reason.. It’s a Blue Moon.

Most people believe that a Blue Moon means two full Moons within the same month, and they would be correct. But, the traditional definition belongs to the third Full Moon in a season which has four Full Moons. The actual phrase came from the Farmer’s Almanac, which used a blue symbol to denote its date. In astronomy, each season starts according to the position of the Sun against the fixed stars, but since our Earth’s orbit is elliptical, this would give seasons unequal length. The Almanac instead uses the right ascension of the mean Sun, which gives each season the same period of time.

Regardless of whether you call it the Blue Moon, the Fruit Moon, or the Barley Moon, enjoy it – and Moon Illusion – tonight as it rises. For those of you with children, it would be a good time to instill a love of the night sky by having them hold a coin against the sky as comparison. Although our “colorful” Moon might look larger than life as it rises – it always stays the same size.

Saturday, August 20 – After sunset tonight, have a look at the southwestern skyline as two of the brightest planets in the sky are rapidly approaching one another. Have you noticed how quickly they are closing the gap? If you hold out your fist at arm’s length, you see that separation is just a tiny bit more that your fist’s size. Monitor them each night as they will soon dance much closer!

On the lunar surface, let’s have a look at the ancient walled plain – Gauss. Located north of Mare Crisium, this oblong crater should have the terminator running through it for most viewers tonight. Its east wall will be quite bright and the west wall will by outlined by a black arc. It is a very old crater, and if you up the magnification, you will see its ruined, cracked floor contains numerous small craters.

Tonight is the peak of the Kappa Cygnid meteor shower. Although the Moon will greatly interfere, there’s no harm in keeping an eye on the radiant area near Deneb. The average fall rate is about 12 per hour with many fireballs. Be sure to watch in the future, because its duration is around 15 days.

Sunday, August 21 – Although the Moon won’t rise for a little over an hour after tonight’s sunset in the northern hemisphere, it’s going to be a race between skydark and moonrise. How about if we take a look at a bright star cluster that’s equally great in either binoculars or telescope? Its name is M39.

Located about a fist’s width northeast of Deneb, you will easily see a couple of dozen stars in a triangular pattern. The M39 is particularly beautiful because it will seem almost three dimensional against its backdrop of fainter stars. Younger than the Coma Berenices cluster, and older than the Plieades, this loose, bright galactic cluster is around 800 light years away. Its members are all main sequence stars and the brightest of them are beginning to evolve into giants. Enjoy it tonight!

Until next week and darker skies? May all your journeys be at light speed! …~Tammy Plotner

Filaments and Vortices

Faint filaments in Saturn’s atmosphere. Image credit: NASA/JPL/SSI Click to enlarge
Faint filaments in Saturn’s atmosphere spiral around two oval-shaped storms in a direction opposite to the winds which rotate around Southern Hemisphere hurricanes on Earth. One storm is seen near the lower right, and the other is near the lower left above a much darker storm.
Atmospheric scientists do not yet fully understand what these filaments are, but some possible explanations have been proposed. The filaments might represent material connecting the spots if the two have recently split from a single storm. The spirals could also represent wind flow in the atmosphere. Further investigation by Cassini imaging scientists is likely to clarify the precise nature of the filaments.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on July 6, 2005, at a distance of approximately 2.4 million kilometers (1.5 million miles) from Saturn using a filter sensitive to wavelengths of infrared light centered at 750 nanometers. The image scale is 14 kilometers (9 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.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Original Source: NASA/JPL/SSI News Release

Cosmonaut Will Break the Record for Spaceflight

ISS photographed by STS crewmember. Image credit: NASA Click to enlarge
After saying goodbye to the Space Shuttle Discovery’s crew on Saturday, International Space Station (ISS) Commander Sergei Krikalev and NASA Science Officer John Phillips spent much of the week preparing for a spacewalk scheduled for next week.

The six-hour spacewalk begins at 2:55 p.m. EDT, Thursday. Live coverage on NASA TV starts at 1:30 p.m. EDT.

On the spacewalk, the crew will change out a Russian biological experiment, retrieve some radiation sensors, remove a Japanese materials science experiment, photograph a Russian materials experiment, install a TV camera and relocate a grapple fixture.

At 1:44 a.m. EDT, Tuesday, Krikalev’s time spent in space will surpass any other human. Cosmonaut Sergei Avdeyev set the previous record with 748 days in orbit. Krikalev is a veteran of two long-duration flights to the Soviet Union’s Space Station Mir; two flights on the Shuttle; and two flights to the ISS. Krikalev was aboard Mir when the Soviet Union disintegrated; was the first Russian to fly on the Shuttle in 1994; was a member of the Shuttle crew that began assembly of the ISS in 1998; and a member of the first crew to live on board the Station in 2000.

Krikalev and Phillips had an off-duty day on Sunday. On Monday they unpacked and prepared spacewalk tools and the Pirs docking compartment. They will use the Pirs for the spacewalk. During the week, they checked the Russian Orlan spacesuits they will wear and talked with spacewalk experts in the Russian Mission Control Center and in Houston.

On Thursday, the Russian Vozdukh carbon dioxide removal system shut down. The system is one of multiple systems used to scrub the Station cabin air. Flight controllers in Houston activated a U.S. Carbon Dioxide Removal Assembly to perform that function while the Vozdukh is not operating. Russian specialists are analyzing the problem.

Information about crew activities on board the Station, future launch dates, previous status reports and sighting ISS opportunities is available on the Web at: http://www.nasa.gov/station

For information about NASA and other agency programs on the Web, visit: http://www.nasa.gov/home/index.html

Original Source: NASA News Release

Sun Was Shining Early On

Artist’s concept of protosun at the center of the solar nebula. Image credit: NASA Click to enlarge
From chemical fingerprints preserved in primitive meteorites, scientists at UCSD have determined that the collapsing gas cloud that eventually became our sun was glowing brightly during the formation of the first material in the solar system more than 4.5 billion years ago.

Their discovery, detailed in a paper that appears in the August 12 issue of Science, provides the first conclusive evidence that this ?protosun? played a major role in chemically shaping the solar system by emitting enough ultraviolet energy to catalyze the formation of organic compounds, water and other compounds necessary for the evolution of life on Earth.

Scientists have long argued whether the chemical compounds created in the early solar system were produced with the help of the energy of the early sun or were formed by other means.

?The basic question was, Was the sun on or was it off?? says Mark H. Thiemens, Dean of UCSD?s Division of Physical Sciences and chemistry professor who headed the research team that conducted the study. ?There is nothing in the geological record before 4.55 billion years ago that could answer this.?

Vinai Rai, a postdoctoral fellow working in Thiemens? lab, came up with a solution, developing an extremely sensitive measurement that could answer the question. He searched for chemical fingerprints of the high-energy wind that emanated from the protosun and became trapped in the isotopes, or forms, of sulfide found in four primitive groups of meteorites, the oldest remnants of the early solar system. Astronomers believe this wind blew matter from the core of the rotating solar nebula into its pancake-like accretion disk, the region in which meteorites, asteroids and planets later formed.

Applying a technique Thiemens developed five years ago to reveal details about the Earth?s early atmosphere from variations in the oxygen and sulfur isotopes embedded in ancient rocks, the UCSD chemists were able to infer from sulfides in the meteorites the intensity of the solar wind and, hence, the intensity of the protosun. They conclude in their paper that the slight excess of one isotope of sulfur, ??S, in the meteorites indicated the presence of ?photochemical reactions in the early solar nebula,? meaning that the protosun was shining strongly enough to drive chemical reactions.

?This measurement tells us for the first time that the sun was on, that there was enough ultraviolet light to do photochemistry,? says Thiemens. ?Knowing that this was the case is a huge help in understanding the processes that formed compounds in the early solar system.?

Astronomers believe the solar nebula began to form about 5 billion years ago when a cloud of interstellar gas and dust was disturbed, possibly by the shock wave of a large exploding star, and collapsed under its own gravity. As the nebula?s spinning pancake-like disk grew thinner and thinner, whirlpools of clumps began to form and grow larger, eventually forming the planets, moons and asteroids. The protosun, meanwhile, continued to contract under its own gravity and grew hotter, developing into a young star. That star, our sun, emanated a hot wind of electrically charged atoms that blew most of the gas and dust that remained from the nebula out of the solar system.

Planets, moons and many asteroids have been heated and had their material reprocessed since the formation of the solar nebula. As a result, they have had little to offer scientists seeking clues about the development of the solar nebula into the solar system. However, some primitive meteorites contain material that has remained unchanged since the protosun spewed this material from the center of the solar nebula more than 4.5 billion years ago.

Thiemens says the technique his team used to determine that the protosun was glowing brightly also can be applied to estimate when and where various compounds originated in the hot wind spewed out by the protosun.

?That will be the next goal,? he says. ?We can look mineral by mineral and perhaps say here?s what happened step by step.?

The UCSD team?s study was financed by a grant from the National Aeronautics and Space Administration.

Original Source: UCSD News Release

Mars Reconnaissance Orbiter Launched

NASA’s Mars Reconnaissance Orbiter (MRO) launch. Image credit: NASA/KSC Click to enlarge
A seven-month flight to Mars began this morning for NASA’s Mars Reconnaissance Orbiter (MRO). It will inspect the red planet in fine detail and assist future landers.

An Atlas V launch vehicle, 19 stories tall with the two-ton spacecraft on top, roared away from Launch Complex 41 at Cape Canaveral Air Force Station at 7:43 a.m. EDT. Its powerful first stage consumed about 200 tons of fuel and oxygen in just over four minutes, then dropped away to let the upper stage finish the job of putting the spacecraft on a path toward Mars. This was the first launch of an interplanetary mission on an Atlas V.

“We have a healthy spacecraft on its way to Mars and a lot of happy people who made this possible,” said James Graf, project manager for MRO at NASA’s Jet Propulsion Laboratory (JPL), Pasadena, Calif.

MRO established radio contact with controllers 61 minutes after launch and within four minutes of separation from the upper stage. Initial contact came through an antenna at the Japan Aerospace Exploration Agency’s Uchinoura Space Center in southern Japan.

Health and status information about the orbiter’s subsystems were received through Uchinoura and the Goldstone, Calif., antenna station of NASA’s Deep Space Network. By 14 minutes after separation, the craft’s solar panels finished unfolding, enabling the MRO to start recharging batteries and operate as a fully functional spacecraft.

The orbiter carries six scientific instruments for examining the surface, atmosphere and subsurface of Mars in unprecedented detail from low orbit. For example, its high-resolution camera will reveal features as small as a dishwasher. NASA expects to get several times more data about Mars from MRO than from all previous Martian missions combined.

Researchers will use the instruments to learn more about the history and distribution of Mars’ water. That information will improve understanding of planetary climate change and will help guide the quest to answer whether Mars ever supported life. The orbiter will also evaluate potential landing sites for future missions. MRO will use its high-data-rate communications system to relay information between Mars surface missions and Earth.

Mars is 72 million miles from Earth today, but the spacecraft will travel more than four times that distance on its outbound-arc trajectory to intercept the red planet on March 10, 2006. The cruise period will be busy with checkups, calibrations and trajectory adjustments.

On arrival day, the spacecraft will fire its engines and slow itself enough for Martian gravity to capture it into a very elongated orbit. The spacecraft will spend half a year gradually shrinking and shaping its orbit by “aerobraking,” a technique using the friction of carefully calculated dips into the upper atmosphere to slow the vehicle. The mission’s main science phase is scheduled to begin in November 2006.

The launch was originally scheduled for August 10, but was delayed first due to a gyroscope issue on a different Atlas V, and the next day because of a software glitch.

The mission is managed by JPL, a division of the California Institute of Technology, Pasadena, for the NASA Science Mission Directorate. Lockheed Martin Space Systems, Denver, prime contractor for the project, built both the spacecraft and the launch vehicle.

NASA’s Launch Services Program at the Kennedy Space Center is responsible for government engineering oversight of the Atlas V, spacecraft/launch vehicle integration and launch day countdown management.

For more information about MRO on the Web, visit:
http://www.nasa.gov/mro

Original Source: NASA News Release

Impressions from Cassini

Saturn’s turbulent atmosphere. Image credit: NASA/JPL/SSI Click to enlarge
Saturn’s turbulent atmosphere is reminiscent of a Van Gogh painting in this view from Cassini. However, unlike the famous impressionist painter, Cassini records the world precisely as it appears to the spacecraft’s cameras.
The feathery band that cuts across from the upper left corner to the right side of this scene has a chevron, or arrow, shape near the right. The center of the chevron is located at the latitude (about 28 degrees South) of an eastward-flowing zonal jet in the atmosphere. Counter-flowing eastward and westward jets are the dominant dynamic features seen in the giant planet atmospheres. A chevron-shaped feature with the tip pointed east means that this is a local maximum in the eastward wind and a region of horizontal wind shear, where clouds to the north and south of the jet are being swept back by the slower currents on the sides of the jet.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on July 6, 2005, at a distance of approximately 2.5 million kilometers (1.5 million miles) from Saturn using a filter sensitive to wavelengths of infrared light centered at 727 nanometers. The image scale is 14 kilometers (9 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.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Original Source: NASA/JPL/SSI News Release

Micro Vortices Seen in the Earth’s Magnetosphere

Artist’s impression of micro turbulence seen by Cluster. Image credit: ESA Click to enlarge
Thanks to measurements by ESA?s Cluster mission, a team of European scientists have identified ?micro?-vortices in Earth?s magnetosphere.

Such small-scale vortex turbulence, whose existence was predicted through mathematical models, has not been observed before in space. The results are not only relevant for space physics, but also for other applications like research on nuclear fusion.

On 9 March 2002, the four Cluster satellites, flying in tetrahedral formation at 100 kilometres distance from each other, were crossing the northern ?magnetic cusp? when they made their discovery. Magnetic cusps are the regions over the magnetic poles where the magnetic field lines surrounding Earth form a magnetic funnel.

The magnetic cusps are the two important regions in Earth?s magnetosphere where the ?solar wind? – a constant flow of charged particles generated by the Sun that crosses the whole Solar System – can directly access the upper layer of Earth?s atmosphere (the ionosphere).

Large amounts of plasma (a gas of charged particles) and energy are transported through these and other ?accessible? regions, to penetrate the magnetosphere – Earth?s natural protective shield. Only less than one percent of all the energy carried by the solar wind and hitting the Earth?s magnetosphere actually manages to sneak through, but it still can have a significant impact on earthly systems, like telecommunication networks and power lines.

The solar material sneaking in generates turbulence in the plasma surrounding Earth, similar to that in fluids but with more complex forces involved. Such turbulence is generated for instance in the areas of transition between layers of plasma of different density and temperature, but its formation mechanisms are not completely clear yet.

The turbulence exists at different scales, from few thousand to few kilometres across. With in situ ?multi-point? measurements, the four Cluster satellites reported in the year 2004 the existence of large scale turbulence – vortices up to 40 000 kilometres wide, at the flank of the ?magnetopause? (a boundary layer separating the magnetosphere from free space). The new discovery of ?micro? turbulence, with vortices of only 100 kilometres across, is a first in the study of the plasma surrounding Earth.

Cluster: an unprecedented diagnostic tool

Such a discovery is very relevant. For example, it allows scientists to start linking small and large-scale turbulence, and start questioning how it is actually formed and what are the connections. For instance, what are the basic mechanisms driving and shaping the turbulence? How much do vortices contribute to the transport of mass and energy through boundary layers? Are small vortices needed to generate large ones? Or, on the other hand, do large vortices dissipate their energy and create a cascade of smaller ones?

In trying to answer these questions, Cluster is an unprecedented diagnostic tool for the first three-dimensional map of the near-Earth environment, its exceptionality being given by its multi-spacecraft simultaneous observations. Cluster is revolutionising our understanding of the ways and the mechanisms by which solar activity affects Earth.

Besides, Cluster?s study of the turbulence in Earth?s plasma, with the dynamics and the energies involved, is contributing to the advancement of fundamental theories on plasma. This is not only important in astrophysics, but also as far as the understanding and the handling of plasma in laboratories is concerned, given the high energies involved. This is particularly relevant for research on nuclear fusion.

For example, Cluster?s data are complementing research on plasma physics in the international ITER project, an experimental step involving several research institutes around the world for tomorrow?s electricity-producing power plants. In this respect, by probing into the magnetosphere, Cluster has free access to the only open ?natural laboratory? for the study of plasma physics.

Original Source: ESA Portal