Posted on by Fraser Cain

Fractured Crater on Mars

This perspective image of a fractured crater near Valles Marineris on Mars was obtained by the High Resolution Stereo Camera (HRSC) on board the ESA Mars Express spacecraft.

The image was taken during orbit 61 in January 2004 with a resolution of 12. 5 metres per pixel. It shows part of a cratered landscape to the north of the Valles Marineris, at 0.6? S latitude and 309? E longitude, with this crater having a fractured base.

This crater has a rim diameter of 27.5 kilometres and is about 800 metres deep. It is not known yet how these fractures are generated. On Earth, polygonal fractures may occur in contracting material, which breaks at weak zones. For example, we may see this appearing in cooled lava, dried clay or frozen ground.

Original Source: ESA News Release

Posted on by Fraser Cain

Closer to Titan

About a day after entering orbit around Saturn, Cassini sped silently past Titan, passing some 339,000 kilometers (210,600 miles) above the moon?s south polar region. This natural color image represents Cassini?s view only about two hours after closest approach to the moon.

The superimposed coordinate system grid in the accompanying image at right illustrates the geographical regions of the moon that are illuminated and visible, as well as the orientation of Titan ? lines of longitude converge on the South Pole above center in the image. The yellow curve marks the position of the boundary between day and night on Titan.

Images taken through blue, green and red filters were combined to create this natural color view. The images were obtained using the wide angle camera on July 2, 2004, from a distance of about 347,000 kilometers (216,000 miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 62 degrees. This view is an improvement in resolution of nearly a factor of four over the previously released natural color view of Titan (PIA 06081). The image scale is 21 kilometers (13 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 Cassini-Huygens mission for NASA’s Office of Space Science, Washington, D.C. The imaging team is based at the Space Science Institute, Boulder, Colorado.

For more information about the Cassini-Huygens mission, visit http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org.

Original Source: CICLOPS News Release

Posted on by Fraser Cain

SMART-1’s View of the Middle East

Now more than 100 000 kilometres away from Earth, ESA’s Moon-bound spacecraft SMART-1 looked back at Earth and returned this planetary perspective of the Middle East and Mediterranean Sea.

‘Smart’ usage of the solar-electric propulsion system (the ion engine) has saved a lot of fuel and the spacecraft will get to the Moon earlier than expected.

Almost 20 kilograms of the xenon fuel could be saved out of the original 84 kilograms, which could then be used to get closer to the Moon than planned, to within distances of between 300 and 3000 kilometres. This will give a coverage of the lunar surface at higher resolution and sensitivity.

Original Source: ESA News Release

Posted on by Fraser Cain

Get Ready for the Perseids

Image credit: ESA
The annual Perseid meteor shower is coming, and astronomers say it could be unusually good this year.

The shower begins gently in mid-July when Earth enters the edge of a cloud of debris from Comet Swift-Tuttle.

Dust-sized particles will hit our atmosphere and appear to streak across the night sky. At first there will be just a few meteors each night, but then the rate will build. The Perseids are visible between 23 July and 22 August but, by 12 August, at the peak of the shower, skywatchers can expect to see possibly 80-100 meteors per hour if skies are clear.

This is a good year for Perseids for two reasons. First, the Moon is new in mid-August, so moonlight will not spoil the show as much as it would have done last year, had the sky been clear! Second, in addition to the usual shower on 12 August, there might be an extra show of meteors late in the evening of 11 August caused by a ?filament? of dust drifting across Earth’s orbit for the first time.

This filament, like all the dust in the Perseid cloud, again comes from Comet Swift-Tuttle. The difference is, the filament is relatively young. It ?boiled? off the comet in 1862. Other dust in the cloud is older (perhaps thousands of years old), more dispersed, and responsible for the month-long shower that peaks on 12 August. The filament will eventually disperse, too, but for now it retains some of its original ribbon shape.

According to current predictions, Earth will move through the filament on Wednesday, 11 August at 23:00 CEST. This will produce a surge of mostly faint meteors over Europe and Asia. Because of the way Comet Swift-Tuttle?s orbit is tilted, its dust falls on Earth’s northern hemisphere. Meteors appear to stream out of the constellation Perseus, which is barely visible south of the equator.

Later that night and into the early morning hours of Thursday, 12 August, observers will see the ?traditional? Perseid peak caused by the older dust from Swift-Tuttle. The best time to look for these traditional Perseids is during the hours before dawn on Thursday.

How to observe the Perseids
The best way to observe them is to look towards the northeast after dark. They appear to originate from the constellation of Perseus which at midnight lies just below the easily recognisable ‘W’ of Cassiopeia.

Try looking around 22:00-23:00 CEST on Wednesday, when Perseus is hanging low in the eastern sky. You won’t see many meteors then, but the ones you do see could be memorable. On Thursday morning, the highest frequency of meteors is likely just before dawn.

Original Source: ESA News Release

Posted on by Fraser Cain

China Launches Second Double Star

Yesterday, 25 July at 09:05 CEST (15:05 local time) the Chinese National Space Administration successfully launched Tan Ce 2, the second of the Double Star science satellites. This marks the latest important milestone in the scientific collaboration between China and the European Space Agency.

Tan Ce (“Explorer”) 2 was launched from the Taiyuan spaceport west of Beijing (Zhangye province) using a Long March 2C rocket. The launch, initially scheduled for today 26 July, took place one day earlier in order to avoid adverse weather conditions expected in the days to come. The spacecraft will join Tan Ce 1, which was launched on 29 December 2003, to complete the Double Star configuration.

About 8 hours after launch the two solid booms holding the magnetometers were successfully deployed. In the next few weeks, all spacecraft sub-systems will be checked out and the commissioning of the on-board scientific instrument will follow.

Double Star will operate alongside ESA?s quartet of Cluster satellites to closely study the interaction between the solar wind and the Earth?s magnetic field. Together, these missions will provide the most detailed view to date. TC-1 is already returning a wealth of scientific data. Back in January, both missions tracked a coronal mass ejection from the Sun and gathered valuable data about the Earth’s bow shock.

Tan Ce 2 reached its nominal orbit, with perigee at 682 km, apogee at 38279 km and inclination of 90.1 deg. The positions and orbit of the Double Star satellites have been carefully defined to enable exploration of the magnetosphere on a larger scale than is possible with Cluster alone. One example of this coordinated activity is the study of the substorms that produce aurorae.

The exact region where these emissions of brightness form is still unclear, but the simultaneous high-resolution measurements combined under these two missions are expected to provide an answer.

ESA is contributing eight scientific instruments to the mission, seven of which are Cluster-derived units.

These are the first ever European experiments to fly on a Chinese satellite. ESA will also be providing ground segment support, four hours each day, via its Villafranca satellite tracking station in Spain.

Scientific cooperation between China and ESA goes back quite a long way. A first Agreement signed back in 1980 facilitated the exchange of scientific information. Thirteen years later, the collaboration focused on a specific mission, Cluster, to study the Earth’s magnetosphere.

Then, in 1997, came a big step forward. The CNSA invited ESA to participate in the Double Star dual-satellite mission to study the Earth?s magnetic field, from a perspective different but complementary to Cluster’s. The Agreement to carry out this joint mission was signed on 9 July 2001 by ESA?s then Director General Antonio Rodot? and CNSA Administrator Luan Enjie.

For Professor David Southwood, ESA?s Science Programme Director: ?Today?s successful launch marks the culmination of these joint efforts and a further important step forward in this historic collaboration between China and Europe.?

Original Source: ESA News Release

Posted on by Fraser Cain

NASA Fights to Save Budget

Image credit: NASA
Administrator Sean O’Keefe today acknowledged the tough financial decisions that have to be made by Congress in passing the fiscal year 2005 budget, but asked the chairman of the U.S. House Committee on Appropriations to restore more than $1 billion of recommended cuts made Tuesday by the appropriations subcommittee.

“Over the course of the past year, Congress has called for the President to articulate a vision and strategy for space exploration. The President’s budget proposes the means to support the Vision for Space Exploration while the Subcommittee’s position does not provide the resources,” said the Administrator in a letter to Committee Chairman C. W. Bill Young, Republican congressman from Florida’s 10th District. “We are encouraged that the Subcommittee endorsed the Vision for Space Exploration in their markup, indicating they are hopeful that it may be possible to augment NASA funding as the appropriations process moves forward.”

Tuesday, members of the subcommittee recommended to the full Appropriations Committee a $15.1 billion budget for NASA, cutting about $1.1 billion from the President’s 2005 fiscal year submission. The NASA budget is part of a $93 billion spending bill that also provides funding for the Department of Veterans Affairs, the Department of Housing and Urban Development, the National Science Foundation and the Environmental Protection Agency.

“The Subcommittee-recommended funding level for NASA would adversely affect its ongoing science and technology programs, as well as the NASA workforce, and will delay plans for FY 2005 critical technology design efforts needed to better define the architecture in support of the Vision for Space Exploration,” the Administrator continued in his letter. “It is very important that these design efforts go forward in FY 2005 to enable NASA to address the long-lead, high-risk requirements that will form the basis for informed decisions by Congress on next steps in the Exploration plan.”

The Administrator thanked Chairman Young for the Appropriation Committee’s support of the Vision for Space Exploration. Administrator O’Keefe said he would continue to seek Committee and Congressional support for full funding of the President’s 2005 budget as the appropriations process continues.

The entire letter may be found on the Internet at:

http://www.nasa.gov/pdf/62799main_072204_young_letter.pdf

Original Source: NASA News Release

Posted on by Fraser Cain

What Venus and Sunspots Have in Common

Scientists using measurements from NASA’s Solar Radiation and Climate Experiment (SORCE) satellite have discovered that Venus and sunspots have something in common: they both block some of the sun’s energy going to Earth.

Using data from NASA’s SORCE satellite, scientists noticed that, when Venus came between the Earth and the sun on June 8, the other planet reduced the amount of sunlight reaching Earth by 0.1 percent. This Venus transit occurs when, from an earthly perspective, Venus crosses in front of the sun. When it happens, once every 122 years, there are two transits eight years apart. The next crossing happens in 2012 and will be visible to people on the U.S. West Coast.

“Because of its distance from Earth, Venus appeared to be about the size of a sunspot,” said Gary Rottman, SORCE Principal Investigator and a scientist at the Laboratory for Atmospheric and Space Physics (LASP), at the University of Colorado at Boulder. The SORCE team had seen similar reductions in the sun’s energy coming Earthward during the October 2003 sunspot activity.

In October 2003 the Earth-bound sunlight dimmed 0.3 percent for about four days, due to three very large sunspot groups moving across the face of the sun.

“This is an unprecedented large decrease in the amount of sunlight, and it is comparable to the decrease that scientists estimate occurred in the seventeenth century,” Rottman said. That decrease lasted almost 50 years, and was likely associated with the exceptionally cold temperatures throughout Europe at that time, a period from the 1400s to the 1700s known as the “little ice age.”

Solar conditions during the little ice age were quite different, as there were essentially no sunspots. Astronomers of the time, like Galileo, kept a good record of sunspot activity before and during the period, encountering only about 50 sunspots in 30 years.

Rottman said, “Something very different was happening during the seventeenth century, and it produced a much more permanent change in the sun’s energy output at that time.” Today, the large sunspots are surrounded by bright areas called “faculae.” Faculae more than compensate for the decrease in sunlight from sunspots, and provide a net increase in sunlight when averaged over a few weeks.

The large number of sunspots occurring in October/November 2003 indicated a very active sun, and indeed many very large solar flares occurred at that time. SORCE observed the massive record-setting solar flares in x-rays. The flares were accompanied by large sunspots, which produced a 0.3 percent decrease in the sun’s energy output. SORCE simultaneously collected the energy from all wavelengths, something that had never been done before.

“The SORCE satellite instruments provide measurements of unprecedented accuracy, so the sun’s energy output is known with great precision, and precise knowledge of variations in the sun’s energy input to Earth is a necessary prerequisite to understanding Earth’s changing climate,” said Robert F. Cahalan, SORCE Project Scientist and Head of the Climate and Radiation Branch at NASA’s Goddard Space Flight Center, Greenbelt, Md.

The SORCE measurements provide today’s atmospheric and climate scientists with essential information on the sun’s energy input to the Earth. These measurements also will be valuable to future scientists, who will be relating their view of the world back to conditions existing today. Likewise Galileo’s findings about the sun almost 400 years ago have increased in value as understanding of the sun and its importance for Earth has advanced.

For more SORCE information and images on the Internet, visit:

hthttp://www.gsfc.nasa.gov/topstory/2004/0730sunblockers.html
and
http://lasp.colorado.edu/sorce/

Original Source: NASA News Release

Posted on by Fraser Cain

Icy Enceladus

Saturn?s brilliant jewel, water-ice-covered Enceladus (499 kilometers, 310 miles across), is the most reflective body in the Solar System. Reflecting greater than 90% of the incident sunlight, this moon was the source of much surprise during the Voyager era. Enceladus exhibits both smooth and lightly cratered terrains that are crisscrossed here and there by linear, groove-like features. It also has characteristics similar to those of Jupiter’s moons, Ganymede and Europa, making one of Saturn’s most enigmatic moons.

Cassini will investigate its rich geologic record in a series of four planned close flybys. The first flyby is scheduled for February 17, 2005.

The image was taken in visible light with the narrow angle camera on July 3, 2004, from a distance of 1.6 million kilometers (990,000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of about 103 degrees. The image scale is 10 kilometers (6 miles) per pixel. The image has not been magnified.

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 Cassini-Huygens mission for NASA’s Office of Space Science, Washington, D.C. The imaging team is based at the Space Science Institute, Boulder, Colorado.

For more information about the Cassini-Huygens mission, visit http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org.

Original Source: CICLOPS News Release

Posted on by Fraser Cain

Eclectic Group of Galaxies Captured by Hubble

Like a photographer clicking random snapshots of a crowd of people, NASA’s Hubble Space Telescope has taken a view of an eclectic mix of galaxies. In taking this picture, Hubble’s Advanced Camera for Surveys was not looking at any particular target. The camera was taking a picture of a typical patch of sky, while Hubble’s infrared camera was viewing a target in an adjacent galaxy-rich region.

The jumble of galaxies in this image, taken in September 2003, includes a yellow spiral whose arms have been stretched by a possible collision [lower right]; a young, blue galaxy [top] bursting with star birth; and several smaller, red galaxies.

But the most peculiar-looking galaxy of the bunch ? the dramatic blue arc in the center of the photo ? is actually an optical illusion. The blue arc is an image of a distant galaxy that has been smeared into the odd shape by a phenomenon called gravitational lensing. This “funhouse- mirror effect” occurs when light from a distant object is bent and stretched by the mass of an intervening object. In this case the gravitational lens, or intervening object, is a red elliptical galaxy nearly 6 billion light-years from Earth. The red color suggests that the galaxy contains older, cooler stars.

The distant object whose image is smeared into the long blue arc is about 10 billion light-years away. This ancient galaxy existed just a few billion years after the Big Bang, when the universe was about a quarter of its present age. The blue color indicates that the galaxy contains hot, young stars.

Gravitational lenses can be seen throughout the sky because the cosmos is crowded with galaxies. Light from distant galaxies, therefore, cannot always travel through space without another galaxy getting in the way. It is like walking through a crowded airport. In space, a faraway galaxy’s light will travel through a galaxy that is in the way. But if the galaxy is massive enough, its gravity will bend and distort the light.

Long arcs, such as the one in this image, are commonly seen in large clusters of galaxies because of their huge concentrations of mass. But they are not as common in isolated galaxies such as this one. For the gravitational lens to occur, the galaxies must be almost perfectly aligned with each other.

Gravitational lenses yield important information about galaxies. They are a unique and extremely useful way of directly determining the amount of mass, including dark matter, in a galaxy. Galaxies are not just made up of stars, gas, and dust. An invisible form of matter, called dark matter, makes up most of a galaxy’s mass. A study of this newly discovered system, dubbed J033238-275653, was published in the Astrophysical Journal Letters. This study, together with similar observations, may allow astronomers to make the first direct measurements of the masses of bright, nearby galaxies.

Original Source: Hubble News Release

Posted on by Fraser Cain

Chandra Sees a Star Flare Up

Observations with NASA’s Chandra X-ray Observatory captured an X-ray outburst from a young star, revealing a probable scenario for the intermittent brightening of the recently discovered McNeil’s Nebula. It appears the interaction between the young star’s magnetic field and an orbiting disk of gas can cause dramatic, episodic increases in the light from the star and disk, illuminating the surrounding gas.

“The story of McNeil’s Nebula is a wonderful example of the importance of serendipity in science,” said Joel Kastner of the Rochester Institute of Technology in Rochester, New York, lead author of a paper in the July 22 issue of Nature describing the X-ray results. “Visible-light images were made of this region several months before Jay McNeil made his discovery, so it could be determined approximately when and by how much the star flared up to produce McNeil’s Nebula.”

The small nebula, which lies in the constellation Orion about 1300 light years from Earth, was discovered with a 3-inch telescope by McNeil, an amateur astronomer from Paducah, Kentucky, in January 2004. In November 2002, a team led by Ted Simon of the Institute for Astronomy in Hawaii had observed the star-rich region with Chandra in search of young, X-ray emitting stars, and had detected several objects. Optical and infrared astronomers had, as part of independent surveys, also observed the region about a year later, in 2003.

After the announcement of McNeil’s discovery, optical, infrared and X-ray astronomers rushed to observe the region again. They found that a young star buried in the nebula had flared up, and was illuminating the nebula. This star was coincident with one of the X-ray sources discovered earlier by Simon.

Chandra observations obtained by Kastner’s group just after the optical outburst showed that the source had brightened fifty-fold in X-rays when compared to Simon’s earlier observation. The visible-light eruption provides evidence that the cause of the X-ray outburst is the sudden infall of matter onto the surface of the star from an orbiting disk of gas.

In general, the coupling of the magnetic field of the star and the magnetic field of its circumstellar disk regulates the inflow of gas from the disk onto the star. This slow, steady inflow suddenly can become much more rapid if a large amount of gas accumulates in the disk, and the disk and the star are rotating at different rates.

The differing rotation rates would twist and shear the magnetic field, storing up energy. This energy is eventually released in an energetic, X-ray producing outburst as the magnetic field violently rearranges back to a more stable state. During this period, a large amount of gas can fall onto the star, producing the observed optical and infrared outburst.

A new buildup of gas in the disk could lead to a new outburst in the future. Such a scenario may explain why the brightness of McNeil’s Nebula appears to vary with time. It is faintly present in surveys of this region of Orion in images taken in the 1960s, but absent from images taken in the 1950s and 1990s.

NASA’s Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for NASA’s Office of Space Science, Washington. Northrop Grumman of Redondo Beach, Calif., formerly TRW, Inc., was the prime development contractor for the observatory. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass.

Original Source: Chandra News Release