Posted on by Fraser Cain

Big Dunes on Mars

Image credit: NASA/JPL

Mars has the largest volcano, the deepest canyon, and it’s got the biggest sand dunes. Several conditions on the Red Planet, including its low gravity, air pressure and sand probably contribute to the gigantic sand dunes that can form there. Dunes have been seen by the Mars Global Surveyor which reach twice as tall as they get on Earth. The Mars Exploration Rovers, currently on track to reach Mars in early 2004 will have cameras on board that may help scientists take a closer look at the sand that makes up these gigantic dunes.

Mars is kind of like Texas: things are just bigger there. In addition to the biggest canyon and biggest volcano in the solar system, Mars has now been found to have sand ripples twice as tall as they would be on Earth.

Initial measurements of some of the Red Planet’s dunes and ripples using stereo-images from the Mars Orbiter Camera onboard the Mars Global Surveyor have revealed ripple features reaching almost 20 feet high and dunes towering at 300 feet.

One way to imagine the taller dimension of ripples on Mars is to visualize sand ripples on Earth, then stretch out the vertical dimension to double height, without changing the horizontal dimension.

“They do seem higher in relation to ripples on Earth,” said Kevin Williams of the Smithsonian National Air and Space Museum. Williams will be presenting this latest insight into the otherworldly scale of Marscapes on Monday, Nov. 3 at the annual meeting of the Geological Society of America in Seattle, WA.

Ripples are common on Mars and usually found in low-lying areas and inside craters, says Williams. On Earth they tend to form in long parallel lines from sand grains being pushed by water or air at right angles to the ripple lines. Dunes, on the other hand, are formed when grains of sand actually get airborne and “saltate” (a word based on the Latin verb “to jump”). That leads to cusp-shaped, star-shaped, and other dune arrangements that allow materials to pile sand much higher.

How exactly Martian dunes and ripples form is still unknown, says Williams, since the images from space give us no clues to the grain sizes or whether they are migrating or moving in any way. Though there are Viking spacecraft images from almost 30 years ago to compare with, the images do not have the resolution to confirm whether ripples have moved much in that time. For now, the dimensions of ripple-forms on Mars are the only indications of whether they are large ripples or small dunes. Williams’ results came about from the advantageous combination of image parameters to get the first height measurements of these ripple-like features at the limit of image resolution.

According to Williams, it’s likely the doubled heights of Mars ripples relative to their spacing is made possible by the same thing that makes Mars’ volcanoes so tall: lower gravity. With about one-third the gravity of Earth, sand, silt, and dust can theoretically stack up higher before gravity causes a slope failure.

However, other differences could play roles in making these large piles of sand as well. “It could also be from different wind speeds, air densities or other factors,” said Williams. Mars has a perennially subfreezing, very thin atmosphere in which global dust storms have been known to obscure the surface from view.

The study of Mars dunes and ripples has been underway since Viking spacecraft images of Mars first revealed such features in the late 1970s and early 1980s, says Williams. The primary difficulty of the work continues to be in discerning the close-up details, like the exact heights of features and grain sizes. As with dunes and ripples on Earth, these wind-blown features could reveal a lot about local and regional weather and wind currents ? if more was known about ripple and dune building under the very un-Earthlike conditions of Mars.

So far the only close-encounters humans have ever had with Martian dunes were with the Viking Landers and the Pathfinder mission, which sent the Sojourner rover trundling among Martian boulders. “There were some small dunes in the area of Pathfinder,” Williams said.

There are also likely to be ripples or small dunes within range of the far more mobile Mars Exploration Rovers now enroute to the Red Planet, Williams said. The Mars Exploration Rovers, Spirit and Opportunity, are larger and will be able to travel much further than Sojourner, making it more likely they will be taking a closer look at ripples as well as other geological features of Mars.

Original Source: Geological Society of America News Release

Posted on by Fraser Cain

Envisat Watches an Iceberg Break Up

Image credit: ESA

The European Space Agency’s Envisat Earth observation satellite captured images of a gigantic iceberg as it broke up during an Antarctic storm. The iceberg, called B-15A, was created in March 2000 when a Jamaican-sized chunk of ice broke away from the Ross Ice Shelf. It broke into smaller pieces shortly after that, but the largest chunk, B-15A grounded itself off the coast and stuck around for a few years. Finally in October, 2003, a giant storm helped split the iceberg up.

ESA’s Envisat satellite was witness to the dramatic last days of what was once the world’s largest iceberg, as a violent Antarctic storm cracked a 160-km-long floe in two.

A series of Envisat Advanced Synthetic Aperture Radar (ASAR) instrument images acquired between mid-September and October record how the bottle-shaped iceberg B-15A was split by the onslaught of powerful storms, waves and ocean currents as its own weight kept it fixed on the floor of Antarctica’s Ross Sea.

ASAR is especially useful for polar operations because its radar signal can pierce thick clouds and works through both day and night. Radar imagery charts surface roughness, so can easily differentiate between different ice types. Old ice ? as on the surface of B-15A ? is rougher than newly formed ice.

B-15A began its existence as B-15 in March 2000 – with an area of 11,655 sq km it was the world’s largest known iceberg. This Jamaica-sized floe was created when it broke away from the Ross Ice Shelf. The initial monster berg split into numerous pieces shortly afterwards, with the largest piece designated B-15A.

Like a wall of ice, B-15A remained a stubborn presence for the next two and a half years, diverting ocean currents. This caused increased ice around Ross Island that disrupted breeding patterns for the local penguin colony and required extra icebreaker activity to maintain shipping access to the US base at McMurdo Sound.

B-15A’s end came in sight on 7 October this year, as 120 kph winds buffeted the grounded iceberg during a storm. Two cracks ran into the heart of the iceberg from opposite ends until finally the entire berg gave way.

The larger of the two new pieces has inherited the name B-15A, and the smaller berg named B-15J. They remain largely locked in place, some 3,800 kilometres south of New Zealand. The bergs could persist there for many years ? a GPS station has been placed on the 3,496 sq km B-15A to enable study of its future progress.

Despite events such as these there is so far no conclusive evidence as to whether polar ice is actually thinning. Next year will see the launch of ESA?s CryoSat mission, a dedicated ice-watching satellite designed to map precise changes in the thickness of polar ice-sheets and floating sea-ice.

CryoSat will be the first satellite to be launched as part of the Agency?s Living Planet Programme. This small research mission will carry a radar altimeter that is based on a heritage from existing instruments, but with several major enhancements to improve the measurement of icy surfaces.

By determining rates of ice-thickness change CryoSat will contribute to our understanding of the relationship between the Earth?s ice cover and global climate.

Original Source: ESA News Release

Posted on by Fraser Cain

Desert in Chile Could Help Explain Mars Environment

Image credit: NASA

A team of scientists have traveled to one of the driest places on Earth to help understand why past missions to Mars have failed to detect any life in the soil. The Atacama Desert is located in a region of Chile which is blocked on both sides by high mountain ranges, so it’s incredibly dry. The scientists have studied the soil and realized that organic material is there, it’s just so minimal that the instruments on board the Viking lander, which visited Mars in the 1970s, wouldn’t have been able to sense them. More sophisticated instruments should be installed on future missions to find evidence of life.

A team of scientists from NASA, the Universidad Nacional Autonoma de Mexico, Louisiana State University and several other research organizations has discovered clues from one of Earth’s driest deserts about the limits of life on Earth, and why past missions to Mars may have failed to detect life.

The results were published this week in Science magazine in an article entitled “Mars-like Soils in the Atacama Desert, Chile, and the Dry Limit of Microbial Life.”

NASA’s Viking missions to Mars in the 1970s showed the martian soil to be disappointingly lifeless and depleted in organic materials, the chemical precursors necessary for life. Last year, in the driest part of Chile’s Atacama Desert, the research team conducted microbe-hunting experiments similar to Viking’s, and no evidence of life was found. The scientists called the finding “highly unusual” in an environment exposed to the atmosphere.

“In the driest part of the Atacama, we found that, if Viking had landed there instead of on Mars and done exactly the same experiments, we would also have been shut out,” said Dr. Chris McKay, the expedition’s principal investigator, who is based at NASA Ames Research Center, Moffett Field, Calif. “The Atacama appears to be the only place on Earth Viking would have found nothing.”

During field studies, the team analyzed Atacama’s depleted Mars-like soils and found organic materials at such low levels and released at such high temperatures that Viking would not have been able to detect them, said McKay, who noted that the team did discover a non-biological oxidative substance that appears to have reacted with the organics — results that mimicked Viking’s results.

“The Atacama is the only place on Earth that I’ve taken soil samples to grow microorganisms back at the lab and nothing whatsoever grew,” said Dr. Fred A. Rainey, a co-author from Louisiana State University, who studies microorganisms in extreme environments.

According to the researchers, the Atacama site they studied could serve as a valuable testbed for developing instruments and experiments that are better tailored to finding microbial life on Mars than the current generation. “We think Atacama’s lifeless zone is a great resource to develop portable and self-contained instruments that are especially designed for taking and analyzing samples of the martian soil,” McKay said.

More sophisticated instruments on future sample-return Mars missions are a necessity if scientists are to avoid contaminating future martian samples, McKay noted. “We’re still doing the first steps of instrument development for Mars.” Recently, researchers have developed a method to extract DNA from soil without humans getting involved in processing the data, which is “a step in the right direction,” according to McKay.

The reason Chile’s Atacama Desert is so dry and virtually sterile, researchers say, is because it is blocked from moisture on both sides by the Andes mountains and by coastal mountains. At 3,000 feet, the Atacama is 15 million years old and 50 times more arid than California’s Death Valley. The scientists studied the driest part of the Atacama, an area called the ‘double rain shadow.’ During the past four years, the team’s sensor station has recorded only one rainfall, which shed a paltry 1/10 of an inch of moisture. McKay hypothesizes that it rains in the arid core of the Atacama on average of only once every 10 years.

The Atacama research was funded by NASA’s Astrobiology Science and Technology for Exploring Planets program, by Louisiana State University, the National Science Foundation and by several other organizations.

The article was also authored by Dr. Rafael Navarro-Gonzalez, Dr. Paola Molina and Dr .Jose de la Rosa from the Universidad Nacional Autonoma de Mexico, Mexico City, MX; Danielle Bagaley, Becky Hollen and Alanna Small, Louisiana State University, Baton Rouge, LA.; Dr. Richard Quinn, the SETI Institute, Mountain View, Calif.; Dr. Frank Grunthaner, NASA Jet Propulsion Laboratory, Pasadena, Calif.; Dr. Luis Caceres, Instituto del Desierto y Departameno de Ingenieria, Quimica; and Dr. Benito Gomez-Silva, Instituto del Desierto y unidad de Bioquimica, Universidad de Antofagasta, Antofagasta, Chile.

For images of the field experiments, please go to: http://www.sciencemag.org

Original Source: NASA News Release

Posted on by Fraser Cain

Three New Astronauts Added For Next Shuttle Mission

Image credit: NASA

NASA announced that three additional astronauts will fly into space aboard the space shuttle when it returns to flight some time after September 2004. STS-114 will consist of Mission Commander Eileen Collins, Pilot James Kelly, and Mission Specialists Stephen Robinson, Soichi Noguchi, Andrew Thomas, Wendy Lawrence and Charles Camarda. The mission objectives for the flight will be to test the new safety procedures developed as part of the Columbia accident investigation including shuttle inspection and repair techniques.

The STS-114 crew, augmented by three new members, is in place for the Space Shuttle’s Return to Flight mission. Three Mission Specialists have been added to the four astronauts already in training for the STS-114 mission planned for launch no earlier than September 2004.

The new crewmembers, Andrew Thomas (Ph.D.), Wendy Lawrence (Capt., USN) and Charles Camarda (Ph.D.) join mission commander Eileen Collins (Col., USAF), Pilot James Kelly (Lt. Col., USAF), Mission Specialists Stephen Robinson (Ph.D) and Soichi Noguchi, of the Japan Aerospace Exploration Agency, who were named to this flight in 2001.

“STS-114 is going to be a complex developmental test flight, and this crew has the right set of skills and experience to help get the Space Shuttles safely flying again,” said NASA’s Associate Administrator for Space Flight William Readdy. “STS-114 was always slated to have a crew of seven. But now, instead of three crew rotating on-and-off the International Space Station, all crew members will be dedicated to the STS-114 mission objectives,” Readdy said.

The major mission objectives of the STS-114 flight have shifted from International Space Station logistics and crew rotation to testing and evaluating new procedures for flight safety. This includes Shuttle inspection and repair techniques. It also includes a smaller set of Space Station tasks from what was scheduled before the Shuttle Columbia accident in February.

“This is a demanding mission and the addition of Andy, Wendy and Charlie, to this already well-qualified crew, ensures they have all the skills necessary to meet the challenge of Return to Flight and the resumption of Space Shuttle support of the International Space Station,” said Bob Cabana, Director of Flight Crew Operations at NASA’s Johnson Space Center.

“Andy brings a wealth of experience in all areas of operations from his previous Shuttle flights and Mir space station mission. Wendy is a superb robotics operator with detailed knowledge of all the Shuttle systems. Charlie has been actively involved with the thermal protection system repair activities and has trained as a backup Space Station crewmember. He is thoroughly familiar with the systems on board the International Space Station,” Cabana said.

“When coupled with Eileen, Jim, Steve and Soichi, who were already trained to perform the assembly tasks on this mission, the full crew will have the expertise and crew time to accomplish all mission objectives,” Cabana said.

Collins served as pilot on STS-63 in 1995 and STS-84 in 1997. She flew as commander in 1999 on STS-93. Kelly piloted his first mission aboard STS-102 in 2001. Robinson was on STS-85 in 1997 and STS-95 in 1998. He served as a backup crewmember for Expedition 4. Thomas, a long-duration Russian Space Station Mir veteran, also served aboard STS-77 in 1996, STS-89 and 91 to and from the Mir in 1998, and STS-102 in 2001. Lawrence, another space veteran, brings experience from STS-67 in 1995, STS-86 in 1997, and STS-91 in 1998. Noguchi and Camarda, both selected as astronauts in 1996, will make their first flight to space on STS-114.

For biographical information about the STS-114 crew and other astronauts on the Internet, visit the NASA astronaut biography page at:

http://www.jsc.nasa.gov/Bios/
For more information about NASA’s Return to Flight efforts on the Internet, visit:

http://www.nasa.gov/news/highlights/returntoflight.html

Original Source: NASA News Release

Posted on by Fraser Cain

Total Lunar Eclipse Was a Treat on Saturday Night

Skywatchers from Alaska to Eastern Europe were treated to a total lunar eclipse on Saturday night, when the Moon dipped behind the Earth’s shadow. Chunks of the Moon began to disappear at 2332 Universal Time (6:32 pm EST), and then it turned a coppery red about two hours later. And then four hours after it started, the eclipse was over. Many observers said it was one of the brightest eclipses they’d seen in recent years. If you missed this show, don’t worry, there are two more lunar eclipses coming in 2004. Then a break; there won’t be another total lunar eclipse visible until 2007.

Posted on by Fraser Cain

ESA Cancels Eddington

Image credit: ESA

The European Space Agency announced this week that it has canceled Eddington, a space-based observatory designed to search for extrasolar planets. They’re also going to be scaling back the BepiColombo mission to Mercury by removing the lander that was supposed to accompany the spacecraft. The agency blamed the cuts on budget overruns with other missions, such as Rosetta. One new mission was announced, however. The LISA Pathfinder will serve as a prototype to help search for gravity waves.

Today, at its 105th meeting, ESA’s Science Programme Committee (SPC) has made important decisions concerning the Cosmic Vision programme. Due to the current financial exigencies and an outlook with no budget increase or other relief, the SPC was forced to cancel the Eddington mission and rescope the BepiColombo mission.

Eddington had two aims, both remarkable and very pertinent to front-line astronomical interests. The first aim was to look for Earth-like planets outside our solar system – one of the key goals in the search to understand how life came to be, how we came to live where we do in the universe and whether there are other potential life supporting environments ‘out there’. At the same time it was going to follow on the path blazed by the ESA-NASA mission SOHO had taken with the Sun of using astroseismology to look ‘inside’ stars. In the longer term, the loss of this one mission will not stop us pursuing the grand quests for which it is a step.

The loss of the BepiColombo lander is also scientifically hard to take. ESA, in conjunction with the Japanese space agency, JAXA, will still put two orbiters around Mercury but the ?ground truth? provided by the lander is a big loss. However, to land on a planet so near the Sun is no small matter and was a bridge too far in present circumstances, and this chance for Europe to be first has probably been lost.

The origins of the problems were recognized at the ESA Council, held in June 2003. Several sudden demands on finance occurred in the spring, the most obvious and public being the unforeseen Ariane 5 grounding in January. A loan of 100 million Euro was temporarily granted, that must be paid back out of present resources by the end of 2006.

ESA’s SPC were therefore caught in a vice. Immediate mission starts had to be severely limited and the overall envelope of the programme kept down.

By making today’s decision, the SPC has brought down the scope of the Cosmic Vision programme to a level that necessarily reflects the financial conditions rather than the ambitions of the scientific community.

A long and painful discussion during the SPC meeting resulted in the conclusion that only one new mission can be started at this time, namely LISA Pathfinder. The mission is the technical precursor to the world?s first gravitational wave astronomical observatory, LISA. The LISA mission itself (to be made in cooperation with the United States) is scheduled for launch in 2012.

ESA’s Cosmic Vision, set to last until 2012, is a living programme. It has to be able to constantly adapt to to the available funding as well as respond to the expectations of the scientific community, to technological developments. Within these boundaries, the decisions made by the SPC try to maximize the outcome of Cosmic Vision across disciplines, keeping it at the same time challenging and affordable. Nonetheless, there are many European scientists with ambitions that exceed the programme?s ability to respond.

Original Source: ESA News Release

Posted on by Fraser Cain

NASA Selects Five Potential New Missions

Image credit: NASA

NASA has selected five proposals as part of its Small Explorer (SMEX) missions – these are low-cost, highly specialized missions to help advance science in a specific area. The candidates are: the Normal-incidence Extreme Ultraviolet Spectrometer, the Dark Universe Observatory, the Interstellar Boundary Explorer, the Nuclear Spectroscopic Telescope Array, and the Jupiter Magnetospheric Explorer. Two finalists will eventually be chosen for launch by 2007-2008.

NASA recently selected candidate mission proposals that would study the universe, from Jupiter and the sun to black holes and dark matter. The proposals are candidates for missions in NASA’s Explorer Program of lower cost, highly focused, rapid-development scientific spacecraft.

Following detailed mission concept studies, NASA intends to select two of the mission proposals by fall 2004 for full development as Small Explorer (SMEX) missions. The two missions developed for flight will be launched in 2007 and 2008.

NASA has also decided to fund as a “Mission of Opportunity” a balloon-borne experiment to detect high-energy neutrinos, ghostly particles that fill the universe.

“The Small Explorer mission proposals we received show that the scientific community has a lot of innovative ideas on ways to study some of the most vexing questions in science, and to do it on a relatively small budget,” said Dr. Ed Weiler, associate administrator for space science at NASA Headquarters, Washington. “It was difficult to select only a few from among the many great proposals we received, but I think the selected proposals have a great chance to really push back the frontiers of knowledge,” he said.

The selected proposals were judged to have the best science value among 36 submitted to NASA in February 2003. Each will receive $450,000 ($250,000 for the Mission of Opportunity) to conduct a five-month implementation feasibility study. The selected SMEX proposals are:

  • The Normal-incidence Extreme Ultraviolet Spectrometer (NEXUS): a solar spectrometer with major advances in sensitivity and resolution to reveal the cause of coronal heating and solar wind acceleration. Joseph M. Davila of NASA’s Goddard Space Flight Center (GSFC), Greenbelt, Md., would lead NEXUS at a total mission cost to NASA of $131 million.
  • The Dark Universe Observatory (DUO): seven X-ray telescopes to measure the dark matter and dark energy that dominate the content of the universe with 100 times the sensitivity of previous X-ray studies. Richard E. Griffiths of Carnegie Mellon University, Pittsburgh, would lead DUO at a total mission cost to NASA of $132 million.
  • The Interstellar Boundary Explorer (IBEX): a pair of cameras to image the boundary between the solar system and interstellar space with 100 times the sensitivity of previous experiments. David J. McComas of the Southwest Research Institute, San Antonio, would lead IBEX at a total mission cost to NASA of $132 million.
  • The Nuclear Spectroscopic Telescope Array (NuSTAR): a telescope to carry out a census of black holes with 1000 times more sensitivity than previous experiments. NuSTAR would be lead by Fiona Anne Harrison of the California Institute of Technology, Pasadena, at a total mission cost to NASA of $132 million.
  • The Jupiter Magnetospheric Explorer (JMEX): a telescope to study Jupiter’s aurora and magnetosphere from Earth orbit. Nicholas M. Schneider of the University of Colorado at Boulder would lead JMEX, at a total mission cost to NASA of $133 million.

NASA selected a long-duration balloon payload as the mission of opportunity. The Antarctic Impulsive Transient Antenna (ANITA) would detect radio waves emitted when high-energy neutrinos interact in the Antarctic ice shelf. ANITA would be led by Peter W. Gorham of the University of Hawaii at Manoa in Honolulu, at a total mission cost to NASA of $35 million.

In addition, NASA selected a proposed mission for technology-development funding of the proposed instrument. Jean Swank of GSFC will develop a polarization sensitive X-ray detector. Swank will receive up to $300,000 over the next two years for her study.

The five selected SMEX proposals are vying to be the tenth and eleventh SMEX missions selected for full development. Recent selections include the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), launched in February 2002; the Galaxy Evolution Explorer (GALEX), launched in April 2003; and the Aeronomy of Ice in the Mesosphere mission (AIM), to be launched in 2006. The Explorer Program, managed by GSFC for NASA’s Office of Space Science, is designed to provide frequent, low-cost access to space for physics and astronomy missions with small to mid-sized spacecraft.

Original Source: NASA News Release

Posted on by Fraser Cain

Construction on Alma Radio Telescope Begins

Image credit: ESO

Workers in Chile broke ground today in the construction of the Atacama Large Millimeter Array (ALMA) – a giant radio telescope made up of 64 high-precision radio antennas. ALMA is scheduled to be completed in 2012, but radio astronomers will be able to start using it in 2007, when some of the antennas have been completed. Using interferometry, the radio signals from the individual 12-metre dishes will be combined to act like a single radio telescope 14 kilometres across. Needless to say, it will help astronomers push much deeper into the cosmos when viewing the radio spectrum.

Scientists and dignitaries from Europe, North America and Chile are breaking ground today (Thursday, November 6, 2003) on what will be the world’s largest, most sensitive radio telescope operating at millimeter wavelengths.

ALMA – the “Atacama Large Millimeter Array” – will be a single instrument composed of 64 high-precision antennas located in the II Region of Chile, in the District of San Pedro de Atacama, at the Chajnantor altiplano, 5,000 metres above sea level. ALMA’s primary function will be to observe and image with unprecedented clarity the enigmatic cold regions of the Universe, which are optically dark, yet shine brightly in the millimetre portion of the electromagnetic spectrum.

The Atacama Large Millimeter Array (ALMA) is an international astronomy facility. ALMA is an equal partnership between Europe and North America, in cooperation with the Republic of Chile, and is funded in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC), and in Europe by the European Southern Observatory (ESO) and Spain. ALMA construction and operations are led on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI), and on behalf of Europe by ESO.

“ALMA will be a giant leap forward for our studies of this relatively little explored spectral window towards the Universe”, said Dr. Catherine Cesarsky, Director General of ESO. “With ESO leading the European part of this ambitious and forward-looking project, the impact of ALMA will be felt in wide circles on our continent. Together with our partners in North America and Chile, we are all looking forward to the truly outstanding opportunities that will be offered by ALMA, also to young scientists and engineers”.

“The U.S. National Science Foundation joins today with our North American partner, Canada, and with the European Southern Observatory, Spain, and Chile to prepare for a spectacular new instrument,” stated Dr. Rita Colwell, director of the U.S. National Science Foundation. “ALMA will expand our vision of the Universe with “eyes” that pierce the shrouded mantles of space through which light cannot penetrate.”

On the occasion of this groundbreaking, the ALMA logo was unveiled.

Science with ALMA
ALMA will capture millimetre and sub-millimetre radiation from space and produce images and spectra of celestial objects as they appear at these wavelengths. This particular portion of the electromagnetic spectrum, which is less energetic than visible and infrared light, yet more energetic than most radio waves, holds the key to understanding a great variety of fundamental processes, e.g., planet and star formation and the formation and evolution of galaxies and galaxy clusters in the early Universe. The possibility to detect emission from organic and other molecules in space is of particularly high interest.

The millimetre and sub-millimetre radiation that ALMA will study is able to penetrate the vast clouds of dust and gas that populate interstellar (and intergalactic) space, revealing previously hidden details about astronomical objects. This radiation, however, is blocked by atmospheric moisture (water molecules) in the Earth’s atmosphere. To conduct research with ALMA in this critical portion of the spectrum, astronomers thus need an exceptional observation site that is very dry, and at a very high altitude where the atmosphere above is thinner. Extensive tests showed that the sky above the high-altitude Chajnantor plain in the Atacama Desert has the unsurpassed clarity and stability needed to perform efficient observations with ALMA.

ALMA operation
ALMA will be the highest-altitude, full-time ground-based observatory in the world, at some 250 metres higher than the peak of Mont Blanc, Europe’s tallest mountain.

Work at this altitude is difficult. To help ensure the safety of the scientists and engineers at ALMA, operations will be conducted from the Operations Support Facility (ALMA OSF), a compound located at a more comfortable altitude of 2,900 metres, between the cities of Toconao and San Pedro de Atacama.

Phase 1 of the ALMA Project, which included the design and development, was completed in 2002. The beginning of Phase 2 happened on February 25, 2003, when the European Southern Observatory (ESO) and the US National Science Foundation (NSF) signed a historic agreement to construct and operate ALMA, cf. ESO PR 04/03.

Construction will continue until 2012; however, initial scientific observations are planned already from 2007, with a partial array of the first antennas. ALMA’s operation will progressively increase until 2012 with the installation of the remaining antennas. The entire project will cost approximately 600 million Euros.

Earlier this year, the ALMA Board selected Professor Massimo Tarenghi, formerly manager of ESO’s VLT Project, to become ALMA Director. He is confident that he and his team will succeed: “We may have a lot of hard work in front of us”, he said, “but all of us in the team are excited about this unique project. We are ready to work for the international astronomical community and to provide them in due time with an outstanding instrument allowing trailblazing research projects in many different fields of modern astrophysics”.

How ALMA will work
ALMA will be composed of 64 high-precision antennas, each 12 metres in diameter. The ALMA antennas can be repositioned, allowing the telescope to function much like the zoom lens on a camera. At its largest, ALMA will be 14 kilometers across. This will allow the telescope to observe fine-scale details of astronomical objects. At its smallest configuration, approximately 150 meters across, ALMA will be able to study the large-scale structures of these same objects.

ALMA will function as an interferometer (according to the same basic principle as the VLT Interferometer (VLTI) at Paranal). This means that it will combine the signals from all its antennas (one pair of antennas at a time) to simulate a telescope the size of the distance between the antennas.

With 64 antennas, ALMA will generate 2016 individual antenna pairs (“baselines”) during the observations. To handle this enormous amount of data, ALMA will rely on a very powerful, specialized computer (a “correlator”), which will perform 16,000 million million (1.6 x 1016) operations per second.

Currently, two prototype ALMA antennas are undergoing rigorous testing at the NRAO’s Very Large Array site, near Socorro, New Mexico, USA.

International collaboration
For this ambitious project, ALMA has become a joint effort among many nations and scientific institutions. In Europe, ESO leads on behalf of its ten member countries (Belgium, Denmark, France, Germany, Italy, The Netherlands, Portugal, Sweden, Switzerland and the United Kingdom) and Spain. Japan may join in 2004, bringing enhancements to the project. Given the participation of North America, this will be the first truly global project of ground-based astronomy, an essential development in view of the increasing technological sophistication and the high costs of front-line astronomy installations.

The first submillimeter telescope in the southern hemisphere was the 15-m Swedish-ESO Submillimetre Telescope (SEST) which was installed at the ESO La Silla Observatory in 1987. It has since been used extensively by astronomers, mostly from ESO’s member states. SEST has now been decommissioned and a new submillimetre telescope, APEX, is about to commence operations at Chajnantor. APEX, which is a joint project between ESO, the Max Planck Institute for Radio Astronomy in Bonn (Germany), and the Onsala Space Observatory (Sweden), is an antenna comparable to the ALMA antennas.

Original Source: ESO News Release

Posted on by Fraser Cain

Hubble Looks at Erupting Star’s Neighborhood

Image credit: Hubble

The newest image released from the Hubble Space Telescope shows a turbulent region of space surrounding an ultra-luminous star called Eta Carinae. The strand-like nature of the nebula was caused by a series of stars that blew off their outer shells – some of the brighter areas in the nebula may eventually turn into new star systems. This picture is only a three light-year chunk of the whole Carina Nebula, which is 200 light-years across and visible to the naked eye in the southern sky.

A small portion of the rough-and-tumble neighborhood of swirling dust and gas near one of the most massive and eruptive stars in our galaxy is seen in this NASA Hubble Space Telescope image. This close-up view shows only a three light-year-wide portion of the entire Carina Nebula, which has a diameter of over 200 light-years. Located 8,000 light-years from Earth, the nebula can be seen in the southern sky with the naked eye.

Dramatic dark dust knots and complex structures are sculpted by the high-velocity stellar winds and high-energy radiation from the ultra-luminous variable star called Eta Carinae, or Eta Car (located outside the picture). This image shows a region in the Carina Nebula between two large clusters of some of the most massive and hottest known stars.

The filamentary structure is caused by turbulence in the circumstellar gas, which in turn was caused by several stars shedding their outer layers. Cold gas mixes with hot gas, leaving a veil of denser, opaque material in the foreground. The chemical elements in the surroundings create a potential reservoir for new star formation. Areas in the brightest parts of the image at the top show elephant-trunk shaped dust clouds that may form into embryonic solar systems.

This Hubble image was taken in July 2002 as part of a parallel observing program. The Hubble telescope has several instruments that can be simultaneously used to look at slightly different portions of the sky. In this case, the Space Telescope Imaging Spectrograph was used to study Eta Carinae itself, while the Wide Field Planetary Camera 2 was used to take this image of the nebulosity near Eta Car. This parallel observing mode increases Hubble’s efficiency and allows astronomers to probe parts of the sky that they would not otherwise be able to investigate.

Produced by the Hubble Heritage team, this color image is a composite of ultraviolet, visible, and infrared filters that have been assigned the colors blue, green, and red, respectively.

Original Source: Hubble News Release

Posted on by Fraser Cain

Mapping the Hidden Dark Matter

Image credit: Berkeley

Dark matter is an invisible halo of material that seems to surround every galaxy. Astronomers can’t see it, but they know it’s there by the effect of its gravity; there seems to be 10 times as much dark matter as regular matter. Until now, astronomers believed that dark matter probably formed an even mist of particles in space, but researchers from UC Berkeley and MIT have created a computer simulation of how dark matter might clump together into larger chunks of material.

The “dark matter” that comprises a still-undetected one-quarter of the universe is not a uniform cosmic fog, says a University of California, Berkeley, astrophysicist, but instead forms dense clumps that move about like dust motes dancing in a shaft of light.

In a paper submitted this week to Physical Review D, Chung-Pei Ma, an associate professor of astronomy at UC Berkeley, and Edmund Bertschinger of the Massachusetts Institute of Technology (MIT), prove that the motion of dark matter clumps can be modeled in a way similar to the Brownian motion of air-borne dust or pollen.

Their findings should provide astrophysicists with a new way to calculate the evolution of this ghost universe of dark matter and reconcile it with the observable universe, Ma said.

Dark matter has been a nagging problem for astronomy for more than 30 years. Stars within galaxies and galaxies within clusters move in a way that indicates there is more matter there than we can see. This unseen matter seems to be in a spherical halo that extends probably 10 times farther than the visible stellar halo around galaxies. Early proposals that the invisible matter is comprised of burnt-out stars or heavy neutrinos have not panned out, and the current favorite candidates are exotic particles variously called neutrilinos, axions or other hypothetical supersymmetric particles. Because these exotic particles interact with ordinary matter through gravity only, not via electromagnetic waves, they emit no light.

“We’re only seeing half of all particles,” Ma said. “They’re too heavy to produce now in accelerators, so half of the world we don’t know about.”

The picture only got worse four years ago when “dark energy” was found to be even more prevalent than dark matter. The cosmic account now pegs dark energy at about 69 percent of the universe, exotic dark matter at 27 percent, mundane dark matter – dim, unseen stars – at 3 percent, and what we actually see at a mere 1 percent.

Based on computer models of how dark matter would move under the force of gravity, Ma said that dark matter is not a uniform mist enveloping clusters of galaxies. Instead, dark matter forms smaller clumps that look superficially like the galaxies and globular clusters we see in our luminous universe. The dark matter has a dynamic life independent of luminous matter, she said.

“The cosmic microwave background shows the early effects of dark matter clumping, and these clumps grow under gravitational attraction,” she said. “But each of these clumps, the halo around galaxy clusters, was thought to be smooth. People were intrigued to find that high-resolution simulations show they are not smooth, but instead have intricate substructures. The dark world has a dynamic life of its own.”

Ma, Bertschinger and UC Berkeley graduate student Michael Boylan-Kolchin performed some of these simulations themselves. Several other groups over the past two years have also showed similar clumping.

The ghost universe of dark matter is a template for the visible universe, she said. Dark matter is 25 times more abundant than mere visible matter, so visible matter should cluster wherever dark matter clusters.

Therein lies the problem, Ma said. Computer simulations of the evolution of dark matter predict far more clumps of dark matter in a region than there are clumps of luminous matter we can see. If luminous matter follows dark matter, there should be nearly equivalent numbers of each.

“Our galaxy, the Milky Way, has about a dozen satellites, but in simulations we see thousands of satellites of dark matter,” she said. “Dark matter in the Milky Way is a dynamic, lively environment in which thousands of smaller satellites of dark matter clumps are swarming around a big parent dark matter halo, constantly interacting and disturbing each other.”

In addition, astrophysicists modeling the motion of dark matter were puzzled to see that each clump had a density that peaked in the center and fell off toward the edges in the exact same way, independent of its size. This universal density profile, however, appears to be in conflict with observations of some dwarf galaxies made by Ma’s colleague, UC Berkeley professor of astronomy Leo Blitz, and his research group, among others.

Ma hopes that a new way of looking at the motion of dark matter will resolve these problems and square theory with observation. In her Physical Review article, discussed at a meeting earlier this year of the American Physical Society, she proved that the motion of dark matter can be modeled much like the Brownian motion that botanist Robert Brown described in 1828 and Albert Einstein explained in a seminal 1905 paper that helped garner him the 1921 Nobel Prize in Physics.

Brownian motion was first described as the zigzag path traveled by a grain of pollen floating in water, pushed about by water molecules colliding with it. The phenomenon refers equally to the motion of dust in air and dense clumps of dark matter in the dark matter universe, said Ma.

This insight “let’s us use a different language, a different point of view than the standard view,” to investigate the movement and evolution of dark matter, she said.

Other astronomers, such as UC Berkeley emeritus professor of astronomy Ivan King, have used the theory of Brownian motion to model the movement of hundreds of thousands of stars within star clusters, but this, Ma said, “is the first time it has been applied rigorously to large cosmological scales. The idea is that we don’t care exactly where the clumps are, but rather, how clumps behave statistically in the system, how they scatter gravitationally.”

Ma noted that the Brownian motion of clumps is governed by an equation, the Fokker-Planck equation, that is used to model many stochastic or random processes, including the stock market. Ma and collaborators are currently working on solving this equation for cosmological dark matter.

“It is surprising and delightful that the evolution of dark matter, the evolution of clumps, obeys a simple, 90-year-old equation,” she said.

The work was supported by the National Aeronautics and Space Administration.

Original Source: UC Berkeley