Phoenix mission ready to land on Mars

NASA's Phoenix Mars Lander is preparing to begin a three-month mission to taste and sniff fistfuls of Martian soil and buried ice. The lander is scheduled to touch down on the Red Planet May 25. Phoenix will enter the top of the martian atmosphere at almost 13,000 mph. In 7 minutes, the spacecraft must complete a challenging sequence of events to slow to about 5 mph before its three legs reach the ground. Confirmation of the landing could come as early as 7:53 P.M. EDT. "This is not a trip to grandma's house. Putting a spacecraft safely on Mars is hard and risky," said Ed Weiler, associate administrator for NASA's Science Mission Directorate at NASA headquarters in Washington. "Internationally, fewer than half the attempts have succeeded." Rocks large enough to spoil the landing or prevent opening of the solar panels present the biggest known risk. Images from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter, detailed enough to show individual rocks smaller than the lander, have helped lessen that risk. One research goal is to assess whether conditions at the site ever have been favorable for microbial life. The composition and texture of soil above the ice could give clues to whether the ice ever melts in response to long-term climate cycles. Another important question is whether the scooped-up samples contain carbon-based chemicals that are potential building blocks and food for life. Phoenix uses hardware from a spacecraft built for a 2001 launch that was canceled due to the loss of a similar Mars spacecraft during a 1999 landing attempt. Researchers who proposed the Phoenix mission in 2002 saw the unused spacecraft as a resource for pursuing a new science opportunity. Earlier in 2002, NASA's Mars Odyssey orbiter discovered that plentiful water ice lies just beneath the surface throughout much of high-latitude Mars. NASA chose the Phoenix proposal over 24 others to become the first endeavor in the Mars Scout program of competitively selected missions. "Phoenix will land farther north on Mars than any previous mission," said Phoenix Project Manager Barry Goldstein of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California. The solar-powered robotic lander will manipulate a 7.7-foot arm to scoop up samples of underground ice and soil lying above the ice. Onboard laboratory instruments will analyze the samples. Cameras and a Canadian weather station will supply other information about the site's environment. "The Phoenix mission not only studies the northern permafrost region, but takes the next step in Mars exploration by determining whether this region, which may encompass as much as 25 percent of the martian surface, is habitable," said Peter Smith, Phoenix principal investigator at the University of Arizona in Tucson.

Venus Express finds hydroxyl on Venus

Hydroxyl, an important but difficult-to-detect molecule, is made up of a hydrogen and oxygen atom each. It has now been found in the upper reaches of the Venusian atmosphere about 100 kilometers above the surface by Venus Express' Visible and Infrared Thermal Imaging Spectrometer (VIRTIS). The elusive molecule was detected by turning the spacecraft away from the planet and looking along the faintly visible layer of atmosphere surrounding the planet's disc. The instrument detected the hydroxyl molecules by measuring the amount of infrared light that they give off. The band of atmosphere in which the glowing hydroxyl molecules are located is very narrow; it is only about 10 kilometers wide. By looking at the limb of the planet, Venus Express looked along this faint atmospheric layer, increasing the signal strength by about 50. Hydroxyl is thought to be important for any planet's atmosphere because it is highly reactive. On Earth it has a key role in purging pollutants from the atmosphere and is thought to help stabilize the carbon dioxide in the martian atmosphere, preventing it from converting to carbon monoxide. On Mars it is also thought to play a vital role in sterilizing the soil, making the top layers hostile to microbial life. The reactive molecule has been seen around comets, but the method of production there is thought to be completely different from the way it forms in planetary atmospheres. "Because the Venusian atmosphere had not been studied extensively before Venus Express arrived on the scene, we have not been able to confirm much of what our models tell us by observing what is actually happening. This detection will help us refine our models and learn much more," says one of the principal investigators of the VIRTIS experiment, Giuseppe Piccioni, from the Istituto di Astrofisica Spaziale e Fisica Cosmica in Rome, Italy. On Earth, the glow of hydroxyl in the atmosphere has been shown to be closely linked to the abundance of ozone. From this study, the same is thought to be true at Venus. Now, scientists can set about estimating the amount of ozone in the planet's atmosphere. Venus Express has shown that the amount of hydroxyl at Venus is highly variable. It can change by 50 percent from one orbit to the next and this may be caused by differing amounts of ozone in the atmosphere. "Ozone is an important molecule for any atmosphere, because it is a strong absorber of ultraviolet radiation from the Sun," says Piccioni. The amount of the radiation absorbed is a key parameter driving the heating and dynamics of a planet's atmosphere. On Earth, it heats the stratosphere (the third layer of Earth's atmosphere) making it stable and protecting the biosphere from harmful ultraviolet rays. Computer models will now be able to tell how this jump and drop in ozone levels over short intervals affects the restless atmosphere of that world. "Venus Express has already shown us that Venus is much more Earth-like than once thought. The detection of hydroxyl brings it a step closer," says Piccioni. He and his colleagues are only reporting the initial detection from a few orbits in their latest paper. They are working on the analysis of data from about 50 other orbits and more observations will follow.

Two New Ways to Explore the Virtual Universe, in Vivid 3-D

The skies may be the next frontier in travel, yet not even the wealthiest space tourist can zoom out to, say, the Crab Nebula, the Trapezium Cluster or Eta Carinae, a star 100 times more massive than the Sun and 7,500 light-years away. But those galactic destinations and thousands of others can now be toured and explored at the controls of a computer mouse, with the constellations, stars and space dust displayed in vivid detail and animated imagery across the screen. The project, the WorldWide Telescope, is the culmination of years of work by researchers at Microsoft, and the Web site and free downloadable software are available starting on Tuesday, at www.WorldWideTelescope.org. There are many online astronomy sites, but astronomers say the Microsoft entry sets a new standard in three-dimensional representation of vast amounts data plucked from space telescopes, the ease of navigation, the visual experience and features like guided tours narrated by experts. “Exploring the virtual universe is incredibly smooth and seamless like a top-of-the-line computer game, but also the science is correct,” said Alexander Szalay, a professor of astronomy and physics at Johns Hopkins. “No sacrifices have been made. It just feels as if you are in it.” The WorldWide Telescope project spans astronomy, education and computing. Educators hope its rich images, animation and design for self-navigation will help entice computer-gaming young people into astronomy and science in general. The space service, astronomers say, could also become valuable in scientific discovery, especially with a professional version being developed with the Harvard-Smithsonian Center for Astrophysics. Like many fields of science, astronomy has become digitized and data rich in recent years, making it an ideal proving ground for advanced computing techniques in data mining, visualization and searching. So it is scarcely surprising that the other major company with an ambitious astronomy service online is Google. The Internet search giant first layered astronomical data and images onto Google Earth last August. The switch to astronomy in Google Sky amounts to looking out into space instead of down on Earth. Two months ago, Google introduced a Web-based version of Google Sky, layering space images on its searchable map service. Microsoft and Google are spirited competitors and antagonists in the rough-and-tumble commercial markets of Internet search and software. Yet in online astronomy, both sides proclaim mutual respect and say their sole rivalry is in scientific discovery and public education. They say they have no plans to sell advertising on the astronomy sites. Scientists and educators applaud the interest and investment by the two. “It’s really encouraging that both Microsoft and Google are there, pushing these powerful tools for science education forward,” said Daniel Atkins, director of the National Science Foundation’s Office of Cyberinfrastructure, which focuses on using new technology in learning and research. There may be no space war between Microsoft and Google, but their offerings reflect their different cultures. The WorldWide Telescope results from careful planning and lengthy development in a research division. It has the richer graphics and it created special software to present the images of spherical space objects with less polar distortion. WorldWide Telescope requires downloading a hefty piece of software, and it runs only on Microsoft Windows. Google Sky started as a Google “20 percent” project, in which engineers can spend time on anything they choose. Google Earth, where Google Sky began, requires a software download, but its Web-based version, which came out in March, does not. The Google culture encourages engineers to put new things onto the Internet quickly and keep improving them, a philosophy geared to constant evolution instead of finished products. Despite differences, the companies share motivations. Lior Ron, Google Sky product manager, said the astronomy focus “says a lot about the interests of the people in both companies.” At Google, Mr. Ron, 31, is one of a group of astronomy enthusiasts. He built his own telescope as a teenager and went to astronomy camps in his native Israel. He said he almost joined private space industry last year instead of Google. A personal fascination in astronomy has also energized work at Microsoft. Jonathan Fay, 42, the lead software engineer on the project, has built an observatory, with a dome eight feet in diameter, in his backyard in suburban Seattle. The inspiration for the WorldWide Telescope, and much of the early work, came from Jim Gray, a renowned computer scientist who disappeared last year while sailing alone off northern California. Mr. Gray had long been intrigued by the computing challenges of presenting map and satellite images online. His project to show aerial map images of the world, TerraServer, went up in June 1998, a few months before Google was founded. Mr. Gray then worked for years with astronomers on the concept he presented in Science in September 2001, “The World-wide Telescope.” Mr. Szalay was co-author. Mr. Gray’s vision was largely about making the flood of astronomical data accessible and usable for scientists. The project began to take on its current look and design in fall 2006, when Curtis Wong started working on it full time. Mr. Wong, another amateur astronomer, heads a new media research group at Microsoft, which he joined in 1998. He is the creator of award-winning multimedia CD-ROMs on subjects like the Barnes art collection, Leonardo da Vinci and the making of the atomic bomb. When he came to the astronomy project, Mr. Wong recalled telling Mr. Gray, “This is great, but let’s bring all this data and make it available, accessible and engaging to the public.” A conversation with Mr. Wong, 54, is different from most around the Microsoft campus in Redmond, Wash., which is mainly populated by engineers, marketers and business managers. Mr. Wong speaks of the WorldWide Telescope’s allowing citizen explorers to make and post virtual tours. One tour on the site is by a 6-year-old boy from Toronto. “What we’re starting with is just a foundation,” Mr. Wong said. “When it really gets interesting is when more and more stories populate the WorldWide Telescope.” Young people today are used to sharing stories, on MySpace, Facebook, YouTube and elsewhere. Educators hope that the WorldWide Telescope can entice them to take an interest in astronomy. “Science has a bad rap because it is seen as a dry accumulation of facts,” said Roy R. Gould, a science education expert at the Harvard-Smithsonian Center for Astrophysics. “But this is a visually beautiful environment where you can explore, create and share.”

Supernova Remnant Is Young and Quick

About a century ago, the light from the explosion of a star within our galaxy swept past Earth. No one noticed. Such explosions, called supernovas, can shine brightly in the night sky. But this dying star was close to the center of the galaxy, where thick dust and gas blocked most of the light, and astronomers of the era saw nothing. Now radio telescopes on Earth and the Chandra X-ray Observatory in orbit have taken pictures of the stellar debris, revealing it to be the youngest supernova remnant known in the Milky Way galaxy. The observations, reported in a telephone news conference Wednesday, show that it is still expanding outward at an unexpectedly quick pace of perhaps 30 million miles an hour, or about 5 percent of the speed of light. The rapid expansion means the interstellar gas around the star was thin and did not slow the remnant as much as usual. In addition to that quick expansion, the remnant is growing brighter at radio frequencies: being so young, it is still getting warmer. “It’s doing things we have never seen before,” said Stephen P. Reynolds, a professor of physics at North Carolina State University, who led the Chandra study. While the dust and gas at the galactic core block visible light, other frequencies of light can make it through. David A. Green of the University of Cambridge in England originally identified the supernova remnant in 1985 using the Very Large Array, a Y-shaped configuration of 27 radio telescopes in New Mexico. At the time, he estimated the age at 400 to 1,000 years. Last year Dr. Reynolds pointed Chandra at the same remnant, known as G1.9+0.3. The new X-ray image indicated that G1.9+0.3 had become considerably larger since Dr. Green first looked at it. Dr. Green then took another radio image of the remnant with the Very Large Array and found that the remnant was now about 16 percent wider than in 1985. “We can extrapolate backwards for the age of the object,” Dr. Green said. The star was about 26,000 light-years away. So the actual explosion occurred about 26,000 years ago, and the light from the blast traveled that long to arrive at Earth no more than 150 years ago. The findings will appear in two scientific articles, one in The Astrophysical Journal and one in Monthly Notices of the Royal Astronomical Society. The G1.9+0.3 remnant is still mostly debris from the exploded star. In older remnants, the glow comes from interstellar gases heated by the shock waves rather than pieces of the dead star. “You are actually getting to see the rock that made the splash, not the wave that’s going out into the pond,” said Robert P. Kirshner, a professor of astronomy at Harvard who was not connected with the research. “This is a stellar death, and the corpse is still warm.” The discovery helps fill in the deficit of supernovas for the Milky Way, where the rate of explosions appears much lower than in similar spiral galaxies. “This lack is a significant puzzle,” Dr. Reynolds said. Either astronomers have not been able to identify the remnants, or the Milky Way is somehow different. “Either way,” he said, “is very interesting.”

Chasing the green flash

Solar phenomena are revealed at Paranal.

Provided by European Southern Observatory

The green flash is a rare phenomenon seen at sunrise or sunset, but only
when conditions are just right. Justin Branam [View Larger Image]

May 6, 2008
Cerro Paranal, Chile, home of the European Southern Observatory's (ESO) Very Large Telescope (VLT), is one of the best sites for observation on Earth.

The Earth's atmosphere is a gigantic prism that disperses sunlight. In the most ideal atmospheric conditions, such as those found regularly above Cerro Paranal, this leads to the appearance of green and blue flashes at sunset. The phenomenon is so popular that it is tradition for the Paranal staff to gather daily on the telescope platform to observe the sunset before starting their long night of observations.

The green and blue flashes are fleeting events that require an unobstructed view of the setting Sun, and a very stable atmosphere. These conditions are very often met at Paranal, a mountain in Chile's Atacama Desert, where the sky is cloudless more than 300 days a year.

ESO staff member Stephane Guisard has been chasing green flashes for many years and has captured them on many occasions. "The most challenging is to capture the green flash while still seeing the rest of the Sun with all its colors," he says.

His colleague Guillaume Blanchard was even luckier. On Christmas Eve, while following the tradition of looking at the sunset, he immortalized a blue flash using his hobby telescope.

ESO astronomer Yuri Beletsky also likes to take photographs from Paranal, but prefers night views. This allows him to make use of the unique conditions above the site to make stunning images. On some of these, he has captured other extremely interesting effects related to the Sun: the so-called zodiacal light and the Gegenschein.

Both the zodiacal light and the Gegenschein (German for "counter shine") are due to reflected sunlight by interplanetary dust. These are so faint that they are only visible in places free from light pollution.

Most of the interplanetary dust in the solar system lies in the ecliptic, the plane close to which the planets are moving around the Sun. The zodiacal light and Gegenschein are seen in the region centered around the ecliptic. While the zodiacal light is seen in the vicinity of the Sun, the Gegenschein is seen in the direction opposite the Sun.

Each of the small dust particles, left over from comets and asteroids, acts as a small Moon reflecting the light coming from our host star. "If you could see the individual dust particles then you would see the ones in the middle of the Gegenschein looking like very tiny full moons, while the ones hidden in the faint part of the dust band would look like tiny crescent moons," explains ESO astronomer Colin Snodgrass. "But even the VLT cannot see such tiny individual dust particles out in space. Instead, we see the combined effect, in photos like these, of millions of tiny dust particles reflecting light back to us from the Sun."


Posted by Mikey Pannier
More at: http://www.astronomy.com/asy/default.aspx?c=a&id=6922

Big Stars Need the Help From the Little Guys

We know that there are massive stars out there that can be 10 to 150 times larger than the mass of the sun. These massive stars are rare but produce most the heavy elements in the galaxy when they explode in supernovas. Astrophysicists have been looking at the condition inside cold clouds of molecular hydrogen that favor the formation of massive stars over low-mass stars like the sun. They believe that the early formation of a low mass star in a cloud paves the way for the formation for larger stellar big stars rather than the cloud breaking down into smaller clouds that would produce a bunch of low mass stars. It is when the cloud is cold that it tends to break up into smaller stars but as it gets warmer it can form larger and larger objects. When a star forms in a hydrogen cloud it has a zone of influence around it that it heats up. If it is a low density cloud the influence is small and its effect is unimportant and causes the system to break up. As the density of the cloud increases that influence of the low mass stars warms up the gas and eventually a few low mass stars have heated up the entire cloud causing it to collapse into a massive star. The density of the cloud must be roughly around a million hydrogen molecules per cubic centimeter which is roughly about 10 trillions time greater than earth's atmosphere. scientist also believe that it is possible for low mass stars to form in the outer regions of these clouds where densities are a little less. But this is hard to observe seeings that from earth we can only see the big, bright stars.

http://www.spacedaily.com/reports/Small_Helper_Stars_Needed_For_Massive_Star_Formation_999.html

Oxygen Factory In a Nearby Galaxy

Roughly 160,000 light years away in the Large Megellanic Cloud is the debris of a massive star explosion that was captured by the Chandra X-ray Observatory. This picture is of the brightest of the supernova remnants in the Magellanic clouds, N132D, and is a rare class of oxygen-rich remnants. These type of remnants are thought to be were the oxygen that we breath today has come from. This x-ray image shows low energy x-rays, which appear red, intermediate energy x-rays that appear green and high energy x-rays that appear blue. The majority of the oxygen appears in the green regions of the cloud which are near the center. What is interesting to this cloud is that unlike other oxygen rich debris clouds N132D has an expanding ellipse shaped shell of oxygen. Theoretical work believes that this might be the result of a 'nickel bubble' which occurs shortly after the supernova explosion and is caused by radioactive energy input from nickel that was generated be the explosion. The goal of looking at this star is to further understand the mass of the star that exploded and to learn how these massive stars explode heavy elements like oxygen into space.