Posted on by Fraser Cain

Centre of Valles Marineris

This image, taken by the High Resolution Stereo Camera (HRSC) on board ESA?s Mars Express spacecraft, shows the central part of the 4000-kilometre long Valles Marineris canyon on Mars.

The HRSC obtained these images during during orbits 334 and 360 with a resolution of approximately 21 metres per pixel for the earlier orbit and 30 metres per pixel for the latter.

The scene shows an area of approximately 300 by 600 kilometres and was taken from an image mosaic that was created from the two orbit sequences. The image is located between 3? to 13? South, and 284? to 289? East.

Valles Marineris was named after the US Mariner 9 probe, the first spacecraft to image this enormous feature in 1971. Here, the huge canyon which runs east to west is at its widest in the north-south direction.

It remains unclear how this gigantic geological feature, unparalleled in the Solar System, was formed. Tensions in the upper crust of Mars possibly led to cracking of the highlands. Subsequently, blocks of the crust slid down between these tectonic fractures.

The fracturing of Valles Marineris could have occurred thousands of millions of years ago, when the Tharsis bulge (west of Valles Marineris) began to form as the result of volcanic activity and subsequently grew to the dimensions of greater than a thousand kilometres in diameter and more than ten kilometres high. On Earth, such a tectonic process is called ?rifting?, presently occurring on a smaller scale in the Kenya rift in eastern Africa.

The collapse of large parts of the highland is an alternative explanation. For instance, extensive amounts of water ice could have been stored beneath the surface and were then melted as a result of thermal activity, most likely the nearby volcanic Tharsis province.

The water could have travelled towards the northern lowlands, leaving cavities beneath the surface where the ice once existed. The roofs could no longer sustain the load of the overlying rocks, so the area collapsed.

Regardless of how Valles Marineris might have formed, it is clear that once the depressions were formed and the surface was topographically structured, heavy erosion then began shaping the landscape.

Two distinct landforms can be distinguished. On one hand, we see sheer cliffs with prominent edges and ridges. These are erosion features that are typical in arid mountain zones on Earth.

Today, the surface of Mars is bone dry, so wind and gravity are the dominant processes that shape the landscape (this might have been much different in the geological past of the planet when Valles Marineris possibly had flowing water or glaciers winding down its slopes).

In contrast, some gigantic ?hills? (indeed, between 1000 and 2000 metres high) located on the floors of the valleys have a smoother topography and a more sinuous outline. So far, scientists have no definitive explanation for why these different landforms exist.

Below the northern scarp, there are several landslides, where material was transported over a distance of up to 70 kilometres. Also seen in the image there are several structures suggesting flow of material in the past. Therefore, material could have been deposited in the valleys, making the present floor look heterogeneous.

In the centre of the image, there are surface features that appear similar to ice flows. These were previously identified in pictures from the US Viking probes of the 1970s; their origin remains a mystery.

Original Source: ESA News Release

Posted on by Fraser Cain

What’s Up This Week – Feb 14 – 20, 2005

Monday, February 14 – Happy Valentine’s Day! One of the more unusual and ephemeral objects for the northern sky is the elusive IC 1805 – known as the “Heart” nebula in Cassiopeia. Thanks to the presence of the Moon and the constellation’s position, viewing the IC 1805 will be next to impossible, but you can still challenge yourself to Mel 15, the 7th magnitude star cluster associated with the “Heart”. Remember its position for a night with clear, dark skies. The IC 1805 will be your “Valentine” for years to come. You see? Even the stars can hold surprises!

And what could be more romantic than a moonlit evening? Why not take out a scope and tonight let’s study dorsa! Along the terminator you will see 75% of Mare Tranquillitatis, joined at its northern edge by the beginnings of Mare Serenitatis. It is here that you will find our “marker” – the ancient walled plain Posidonius. Inside Serenitatis and running parallel with the terminator are the snake-like lines of the Dorsa Smirnov – a beautiful collection of wrinkle ridges known as “dorsa”. To the south look for the “three ring circus” of craters Theophilus, Cyrillus and Catharina. Focus your attention on the sunlit Mare Nectaris. Cutting across it between Theophilus in the north, and shallow open crater Beaumont in the south you will see a thin, bright line. Congratulations! You have just spotted an officially “unnamed” lunar feature that is often referred to as Dorsa Beaumont.

Very cool…

Tuesday, February 15 – Happy 441st Birthday to Galileo Galilei! He was the first scientist to use a telescope for astronomical observation. I wonder if Galileo could have ever dreamed when he first saw the Moon that mankind would one day walk on its surface? Let’s celebrate his achievements by a look into lunar history…

Tonight, all of Mare Tranquillitatis, and the majority of Mare Serenitatis will be revealed just north of the terminator’s mid-point. On the northwestern shore of Serenitatis, you will see the eastern portion Caucasus Mountains emerging in the sunlight. Tonight let us take an historic journey to the southwest edge of Tranquillitatis and visit with the Apollo 11 landing area. Although we can never see the “Eagle” telescopically, we can find where it landed! Tracing along the western wall, look for the small circles of craters Sabine and Ritter. Once you have located them, go to your highest power! To the east in the smooth sands you will see a parallel line of three tiny craters. From west to east, these are Aldrin, Collins and Armstrong – the only craters to be named for the living! It is just south of these three tiny punctuations that Apollo 11 touched down, forever changing our perceptions of space exploration.

Galileo would have been proud!

Sunday, February 26 – Fran?ois Jean Dominique Arago was born on this day in 1786. Arago was the pioneer scientist in the wave nature of light and the inventor of the polarimeter and other optical devices. In February 1948, Gerard Kuiper discovered Uranus’s moon, Miranda. And speaking of moons, did you see Selene during the daylight today? Spectacular, isn’t it? Have you ever wondered if there was any place on the lunar surface that has not seen the light? Then let’s go exploring for one tonight…

Our first order of business will be to identify crater Albategnius. Directly in the center of the Moon is a dark floored area known as the Sinus Medii. South of it will be two conspicuously large craters – Hipparchus to the north and ancient Albategnius to the south. Trace along the terminator toward the south until you have almost reached its point (cusp) and you will see a black oval. This normal looking crater with the brilliant west wall is equally ancient crater Curtius. Because of its high latitude, we shall never see the interior of this crater – and neither has the Sun! It is believed that the inner walls are quite steep and the crater Curtius’ interior has never been illuminated since its formation billions of years ago. Because it has remained dark, we can speculate that there may be “lunar ice” pocketed inside its many cracks and rilles that date back to the Moon’s formation!

Because our Moon has no atmosphere, the entire surface is exposed to the vacuum of space. When sunlit, the surface reaches up to 385 K, so any exposed “ice” would vaporize and be lost because the Moon’s gravity cannot hold it. The only way for “ice” to exist would be in a permanently shadowed area. Near Curtius is the Moon’s south pole and Clementine imaging showed around 15,000 square kilometers of area where such conditions could exist. So where did this “ice” come from? The lunar surface never ceases to be pelted by meteorites – most of which contain water ice. As we know, many craters were formed by just such an impact. Once hidden from the sunlight, this “ice” could go on to exist for millions of years!

Thursday, February 17 – So… would you like to do a little lunar “prospecting” tonight? Then let’s explore a crater similar to last night’s Curtius. In the north, identify previous study crater Plato. North of Plato you will see a long horizontal area of gray floor – Mare Frigoris. North of it you will note a “double crater”. This is elongated diamond-shape is Goldschmidt and the crater which cuts across its western border is Anaxagoras. The lunar “north pole” isn’t far from Goldschmidt and since Anaxagoras is just about one degree outside of the Moon’s theoretical “arctic” area, the lunar sunrise will never go high enough to clear the southernmost rim. As proposed with yesterday’s study, this “permanent darkness” must mean there is ice! For that very reason, NASA’s Lunar Prospector probe was sent to explore. Did it find what it was looking for? Answer – Yes!

The probe discovered vast quantities of cometary ice which have hidden inside the crater’s depths untouched for millions of years. If this sounds rather boring to you, then realize this type of resource will colour our plans to eventually establish a manned “base” on the lunar surface! On March 5, 1998 NASA announced that Lunar Prospector’s neutron spectrometer data showed that water ice was discovered at both lunar poles. The first results showed the “ice” mixed in with lunar regolith (soil, rocks and dust), but long term data confirmed near pure pockets hidden beneath about 40 cm of surface material – with the results being strongest in the northern polar region. It is estimated there may be as much as 6 trillion kg (6.6 billion tons) of this valuable resource! If this still doesn’t get your motor running, then realize we can never establish a manned lunar base because of the tremendous expense involved in transporting our most basic human need – water. The presence of lunar water could also mean a source of oxygen, another vital material we need to survive! And if we wanted to return home or onward, these same deposits could provide hydrogen which could be used as rocket fuel. So as you view Anaxagoras tonight, realize that you may be viewing one of mankind’s future “homes” on a distant world!

Friday, February 18 – Today in 1930 Clyde Tombaugh discovered Pluto during a search with photographic plates taken on the Lowell Observatory’s 13″ telescope. Although we might not make such a monumental contribution, we can still do a little “mountain climbing”! Tonight the most outstanding feature on the Moon will be Copernicus, but since we’ve delved into the deepest areas of the lunar surface, why not climb to some of its peaks?

Using Copernicus as our guide, to the north and northwest of this ancient crater lay the Carpathian Mountains ringing the southern edge of the Mare Imbrium. As you can see, they begin well east of the terminator, but look into the shadow! Extending some 40 km (25 miles) beyond the line of daylight, you will continue to see bright peaks – some of which reach 2072 meters (6600 feet) high! When the area is fully revealed tomorrow, you will see the Carpathian Mountains eventually disappear into the lava flow that once formed them. Continuing onward to Plato, which sits on the northern shore of Imbrium, we will look for the singular peak of Pico. It is between Plato and Mons Pico that you will find the scattered peaks of the Teneriffe Mountains. It is possible that these are the remnants of much taller summits of a once stronger range, but only around 1890 meters (6200 feet) still survives above the surface. Time to power up! To the west of the Teneriffes, and very near the terminator, you will see a narrow “pass” cut through the region, very similar to the Alpine Valley. This is known as the Straight Range and some of its peaks reach up to 2072 meters (6600 feet)! Although this doesn’t sound particularly impressive, that’s over twice as tall as the Vosges Mountains in central western Europe and on the average very comparable to the Appalachian Mountains in the eastern United States. Not bad!

Saturday, February 19 – Nicholas Copernicus was born on this day in 1473. Copernicus advanced our understanding of earth’s relation to the motions of the solar system. He was a man who could see the “big picture”!

Tonight let’s continue our Moon mountain climbing expedition and look at the “big picture” on the lunar surface. Tonight all of Mare Imbrium is bathed in sunlight and we can truly see its shape. Appearing as a featureless ellipse bordered by mountain ranges, let’s identify them again. Starting at Plato and moving east to south to west you will find the Alps, the Caucasus, the Apennine and the Carpathians mountains. Look at the form closely… Doesn’t this appear that perhaps once upon a time an enormous impact created the entire area? Compare it to the younger Sinus Iridium. Ringed by the Juras Mountains, it may have also been formed by a much later and very similar impact.

And you thought they were just mountains…

Sunday, February 20 – Today in 1962 John Glenn became the first American to orbit the Earth three times aboard Friendship 7. Only 32 years later, the Clementine Lunar Explorer also went in orbit – but this time around the Moon! Let’s get out the scopes…

Tonight’s most prominent lunar feature will be the graceful Gassendi towards the south, but it is a crater in the Oceanus Procellarum that we will be studying tonight. Within the “Ocean of Storms” you will find the bright point of Class 1 crater Kepler, just slightly above the terminator. The sprawling Oceanus Procellarum has low reflectivity (albedo) because the mare lavas are primarily dark minerals like iron and magnesium. Bright young Kepler (32 km/2.6 km) will show a wonderfully developing ray system, but there is so much information there! The very hills that Kepler’s initial impact drove into are part of the Alpes Formation – the inner ejecta from the Imbrium area which we noted last night. At high power you will see that the hills themselves have been filled with lava flow before Kepler was formed. The crater rim itself is very bright, consisting mostly of a pale mineral called anorthosite. The lunar rays extending from Kepler are anorthosite fragments that literally were splashed out and flung across the lunar surface during the impact that formed this crater. The region is also home to lunar feature known as “domes” – seen between the crater and the Carpathian Mountains. So unique is Kepler’s geological formation that it became the first crater to mapped by U.S. Geological Survey in 1962. This fantastic chart was labeled I-355 and was the work of R.J. Hackman.

Kepler… Not just another boring crater!

Until next week? “May you all shine on… like the Moon, the stars, and the Sun…”

May your journey be at light speed! ~Tammy Plotner

Posted on by Fraser Cain

Safe Havens for Planetary Formation

A new theory of how planets form finds havens of stability amid violent turbulence in the swirling gas that surrounds a young star. These protected areas are where planets can begin to form without being destroyed. The theory will be published in the February issue of the journal Icarus.

“This is another way to get a planet started. It marries the two main theories of planet formation,” said Richard Durisen, professor of astronomy and chair of that department at Indiana University Bloomington. Durisen is a leader in the use of computers to model planet formation.

Watching his simulations run on a computer monitor, it’s easy to imagine looking down from a vantage point in interstellar space and watching the process actually happen.

A green disk of gas swirls around a central star. Eventually, spiral arms of yellow begin to appear within the disk, indicating regions where the gas is becoming denser. Then a few blobs of red appear, at first just hints but then gradually more stable. These red regions are even denser, showing where masses of gas are accumulating that might later become planets.

The turbulent gases and swirling disks are mathematical constructions using hydrodynamics and computer graphics. The computer monitor displays the results of the scientists’ calculations as colorful animations.

“These are the disks of gas and dust that astronomers see around most young stars, from which planets form,” Durisen explained. “They’re like a giant whirlpool swirling around the star in orbit. Our own solar system formed out of such a disk.”

Scientists now know of more than 130 planets around other stars, and almost all of them are at least as massive as Jupiter. “Gas giant planets are more common than we could have guessed even 10 years ago,” he said. “Nature is pretty good at making these planets.”

The key to understanding how planets are made is a phenomenon called gravitational instabilities, according to Durisen. Scientists have long thought that if gas disks around stars are massive enough and cold enough, these instabilities happen, allowing the disk’s gravity to overwhelm gas pressure and cause parts of the disk to pull together and form dense clumps, which could become planets.

However, a gravitationally unstable disk is a violent environment. Interactions with other disk material and other clumps can throw a potential planet into the central star or tear it apart completely. If planets are to form in an unstable disk, they need a more protected environment, and Durisen thinks he has found one.

As his simulations run, rings of gas form in the disk at an edge of an unstable region and grow more dense. If solid particles accumulating in a ring quickly migrate to the middle of the ring, the core of a planet could form much faster.

The time factor is important. A major challenge that Durisen and other theorists face is a recent discovery by astronomers that giant gas planets such as Jupiter form fairly quickly by astronomical standards. They have to — otherwise the gas they need will be gone.

“Astronomers now know that massive disks of gas around young stars tend to go away over a period of a few million years,” Durisen said. “So that’s the chance to make gas-rich planets. Jupiter and Saturn and the planets that are common around other stars are all gas giants, and those planets have to be made during this few-million-year window when there is still a substantial amount of gas disk around.”

This need for speed causes problems for any theory with a leisurely approach to forming planets, such as the core accretion theory that was the standard model until recently.

“In the core accretion theory, the formation of gas giant planets gets started by a process similar to the way planets such as Earth accumulate,” Durisen explained. “Solid objects hit each other and stick together and grow in size. If a solid object grows to be about 10 times the mass of Earth, and there’s also gas around, it becomes massive enough to grab onto a lot of the gas by gravity. Once that happens, you get rapid growth of a gas giant planet.”

The trouble is, it takes a long time to form a solid core that way — anywhere from about 10 million to 100 million years. The theory may work for Jupiter and Saturn, but not for dozens of planets around other stars. Many of these other planets have several times the mass of Jupiter, and it’s very hard to make such enormous planets by core accretion.

The theory that gravitational instabilities by themselves can form gas giant planets was first proposed more than 50 years ago. It’s recently been revived because of problems with the core accretion theory. The idea that vast masses of gas suddenly collapse by gravity to form a dense object, perhaps in just a few orbits, certainly fits the available time frame, but it has some problems of its own.

According to the gravitational instability theory, spiral arms form in a gas disk and then break up into clumps that are in different orbits. These clumps survive and grow larger until planets form around them. Durisen sees these clumps in his simulations — but they don’t last long.

“The clumps fly around and shear out and re-form and are destroyed over and over again,” he said. “If the gravitational instabilities are strong enough, a spiral arm will break into clumps. The question is, what happens to them?”

Co-authors of the paper are IU doctoral student Kai Cai and two of Durisen’s former students: Annie C. Mejia, postdoctoral fellow in the Department of Astronomy, University of Washington; and Megan K. Pickett, associate professor of physics and astronomy, Purdue University Calumet.

Original Source: Indiana University News Release

Posted on by Fraser Cain

Swift’s First Burst Pinpointed

Cosmic gamma-ray bursts produce more energy in the blink of an eye, than the Sun will release in its entire lifetime. These short-lived explosions appear to be the death throes of massive stars, and, many scientists believe, mark the birth of black holes. Testing these ideas has been difficult, however, because the bursts fade so quickly and rapid action is required. Now a team of Carnegie and Caltech astronomers, led by Carnegie-Princeton and Hubble fellow Edo Berger, has made crucial strides toward answering these cosmic quandaries. The team was able to discover and study burst afterglows thanks to the exquisite performance of NASA’s new Swift satellite and rapid follow-up with telescopes in both the southern and northern hemispheres.

“I’m thrilled,” said Berger. “We’ve shown that we can chase the Swift bursts at a moment’s notice, even right before Christmas! This is a great sign of exciting advances down the road.” The discoveries herald a new era in the study of gamma-ray bursts, hundreds of which are expected to be discovered and scrutinized in the next several years.

The Swift satellite detected the first of the four bursts on December 23, 2004, in the constellation Puppis, and Carnegie astronomers used telescopes at the Las Campanas Observatory in Chile to pinpoint the visual afterglow within several hours. This was the first burst detected solely by the new Swift satellite to be pinpointed with sufficient accuracy to study the remains. The next three bursts came in quick succession between January 17 and 26 and were immediately pinpointed by a team of Carnegie and Caltech astronomers using the Palomar Mountain 200-inch Hale telescope in California and the Keck Observatory 10-meter telescopes in Hawaii.

“The Las Campanas telescopes are ideal for their flexibility to follow up targets like gamma-ray bursts, which quickly fade out of view,” said Carnegie Observatories director Wendy Freedman. “This is a wonderful example of science that comes from the synergy between telescopes on the ground and in space, and between public and private observatories.”

Because Swift allows a response to new gamma-ray bursts within minutes, astronomers hope to use the intense light from gamma-ray bursts as cosmic “flashlights.” They plan to use the bright visual afterglows to trace the formation of the first galaxies, only a few hundred million years after the Big Bang, and the composition of the gas that permeates the universe. “This is much like using a flashlight to study the contents of a dark room,” said Berger. “But because the flashlight is on for only a few hours, we have to act quickly.”

“Swift’s rapid response is opening a new window on the universe. I can’t wait to see what we catch,” remarked Neil Gehrels of Goddard Space Flight Center, principal investigator for Swift.

Swift, launched on November 20, 2004, is the most sensitive gamma-ray burst satellite to date, and the first to have X-ray and optical telescopes on-board, allowing it to relay very accurate and rapid positions to astronomers on the ground. The satellite is a collaboration between NASA’s Goddard Space Flight Center, Penn State University, Leicester University and the Mullard Space Science Laboratory (both in England), and the Osservatorio Astronomico di Brera in Italy.

In the next few years the Swift satellite is expected to find several hundred gamma-ray bursts. Follow-up observations on-board Swift and using telescopes on the ground should move us a few steps closer to answering some of the most fundamental puzzles in astronomy, such as the birth of black holes, the first stars, and the first galaxies.

The team that identified and studied the afterglows of the first Swift bursts?in addition to Berger, Freedman and Gehrels?includes Mario Hamuy, Wojtek Krzeminski, and Eric Persson from Carnegie Observatories, Shri Kulkarni, Derek Fox, Alicia Soderberg, and Brad Cenko from Caltech, Dale Frail from the National Radio Astronomy Observatory, Paul Price from the University of Hawaii, Eric Murphy from Yale University, and Swift team members David Burrows, John Nousek, and Joanne Hill from Penn State University, Scott Barthelmy from Goddard Space Flight Center, and Alberto Moretti from Osservatorio Astronomico di Brera.

Original Source: Carnegie News Release

Posted on by Fraser Cain

Enhanced Ariane 5 Blasts Off

The latest version of Ariane 5, designed to loft payloads of up to 10 tonnes to geostationary transfer orbit, successfully completed its initial qualification flight on 12 February. After a perfect liftoff from Europe?s Spaceport in French Guiana, at 18:03 local time (22:03 CET), the launcher on Ariane Flight 164 injected its payload into the predicted transfer orbit.

This success paves the way for the commercial introduction of this ‘Ariane 5 ECA’ version, which is due to replace the current Ariane 5G ‘Generic’ configuration and is designed to maintain the competitiveness of European launch systems on the world launch services market. Starting from the second flight scheduled for mid-year, Ariane 5 ECA will become the new European workhorse for lifting heavy payloads to geostationary orbit and beyond.

Ariane 5 ECA features upgraded twin solid boosters, each loaded with an extra 2.43 tonnes of propellant, increasing their combined thrust on liftoff by a total of 60 tonnes compared to the Generic configuration. The cryogenic main stage has also been upgraded to carry 15 tonnes of additional propellant. It is powered by the new Vulcain 2 engine, derived from Vulcain 1, which provides 20% more thrust. The Ariane 5 ECA introduces the new high-performance “ESC-A” cryogenic upper stage, powered by the same HM-7B engine as on the Ariane 4 third stage.

Ariane 5 ECA has enough lift capacity to take most combinations of commercial satellites to geostationary transfer orbit and will enable Arianespace to reinstate the systematic dual-launch policy that spelled the success of previous generations of Ariane launchers.

On this flight, the Ariane 5 ECA launcher carried three payloads. The first released 26 minutes into flight, was XTAR-EUR, a 3600-kg commercial X-band communication satellite flown on behalf of XTAR LLC. This will subsequently use its onboard propulsion system to achieve circular orbit. After an initial period of in-orbit testing, it will be deployed to provide secure communications to government customers.

The other two satellites onboard, the Sloshsat FLEVO minisatellite and the Maqsat B2 instrumented model, stored inside the Sylda dual launch adapter, were flown on behalf of ESA.

Next released, 31 minutes after liftoff, the Sloshsat Facility for Liquid Experimentation and Verification in Orbit is a 129-kg satellite developed for ESA by the Dutch National Aerospace Laboratory (NRL). It will investigate fluid physics in microgravity to understand how propellant-tank sloshing affects spacecraft control. Its mission is planned to last 10 days.

In order to limit the proliferation of space debris, the third passenger, Maqsat B2, will remain attached to the launcher’s upper stage. This 3500-kg instrumented model was designed to simulate the dynamic behaviour of a commercial satellite inside the Ariane 5 payload fairing. An autonomous telemetry system transmitted data on the payload environment during all the flight phases, from liftoff to in-orbit injection. Fitted with a set of cameras, Maqsat B2 also provided dramatic onboard views of several key flight phases, including separation of the solid boosters and jettisoning of the Sylda upper-half payload.

?Less than one month after the descent of Huygens on Titan, this launch marks another great achievement for Europe in space and a further demonstration of European skills in this highly demanding technological field? said Jean-Jacques Dordain, Director General of ESA, after the flight. ?Today?s success is also just reward for all the people, in industry and at agencies all over Europe, who have been working so hard to bring this launcher back into operational use.

“Guaranteed access to space is a pre-requisite for our success in all space activities and so it is our duty to maintain this capacity to the full.?

Original Source: ESA News Release

Posted on by Fraser Cain

Astrophoto: NGC-253 Spiral Galaxy by John Chumack

Amateur photographer John Chumack took this picture of Spiral Galaxy NGC-253, which is located in the constellation of Sculptor. The telescope was a Takahashi Epsilon 250mm and ST8XE CCD camera, on a Software Bisque Paramount ME, taken on Mount Joy, New Mexico, New Mexico Skies Resort. John operated the telescope remotely from Dayton, Ohio using Arnie Rosner’s Rent-A-Scope setup. John has been imaging the sky for 2 decades, and has an amazing collection of pictures at his website: Galactic Images. If you’re an amateur astrophotographer, visit the Universe Today forum and post your pictures, we might feature it in the newsletter.

Posted on by Fraser Cain

Life Might Have Started in Fresh Water

A geomicrobiologist at Washington University in St. Louis has proposed that evolution is the primary driving force in the early Earth’s development rather than physical processes, such as plate tectonics.

Carrine Blank, Ph.D., Washington University assistant professor of geomicrobiology in the Department of Earth & Planetary Sciences in Arts & Sciences, studying Cyanobacteria – bacteria that use light, water, and carbon dioxide to produce oxygen and biomass – has concluded that these species got their start on Earth in freshwater systems on continents and gradually evolved to exist in brackish water environments, then higher salt ones, marine and hyper saline (salt crust) environments.

Cyanobacteria are organisms that gave rise to chloroplasts, the oxygen factory in plant cells. A half billion years ago Cyanobacteria predated more complex organisms like multi-cellular plants and functioned in a world where the oxygen level of the biosphere was much less than it is today. Over their very long life span, Cyanobacteria have evolved a system to survive a gradually increasing oxidizing environment, making them of interest to a broad range of researchers.

Blank is able to draw her hypothesis from family trees she is drawing of Cyanobacteria. Her observations are likely to incite debate among biologists and geologists studying one of Earth’s most controversial eras – approximately 2.1 billion years ago, when cyanobacteria first arose on the Earth. This was a time when the Earth’s atmosphere had an incredible, mysterious and inexplicable rise in oxygen, from extremely low levels to 10 percent of what it is today. There were three – some say four – global glaciations, and the fossil record reflects a major shift in the number of organisms metabolizing sulfur and a major shift in carbon cycling.

“The question is: Why?” said Blank.

“My contribution is the attempt to find evolutionary explanations for these major changes. There were lots of evolutionary movements in Cyanobacteria at this time, and the bacteria were making an impact on the Earth’s development. Geologists in the past have been relying on geological events for transitions that triggered change, but I’m arguing that a lot of these things could be evolutionary.”

Blank presented her research at the 2004 annual meeting of the Geological Society of America, held, Nov. 7-10 in Denver.

Blank’s finding that Cyanobacteria emerged first in fresh water lakes or streams is counterintuitive.

“Most people have the assumption that Cyanobacteria came out of a marine environment – after all, they are still important to marine environments today, so they must always have been,” Blank said. “When Cyanobacteria started to appear, there was no ozone shield, so UV light would have killed most things. They either had to have come up with ways to deal with the UV light – and there is evidence that they made UV-absorbing pigments – or find ways of growing under sediments to avoid the light.”

To study the evolution of Cyanobacteria, Blank drew up a backbone tree using multiple genes from whole genome sequences. Additional species were added to the tree using ribosomal RNA genes. Morphological characters, for instance, the presence or absence of a sheath, unicellular or filamentous growth, the presence or absence of heterocysts ? a thick-walled cell occurring at intervals ? were coded and mapped on the tree. The distribution of traits was compared with those found in the fossil record.

Cyanobacteria emerging some two billion years ago were becoming complex microbes that had larger cell diameters than earlier groups – at least 2.5 microns. Blank’s tree shows that several morphological traits arose independently in multiple lines, among them a sheath structure, filamentous growth, the ability to fix nitrogen, thermophily (love of heat), motility and the use of sulfide as an electron donor.

“We will need lots of analyses of the micro-fossil record by serious paleobiologists to see how sound this hypothesis is,” Blank said. “This time frame is one of the biggest puzzles for biologists and geologists alike. A huge amount of things are happening then in the geological record.”

Original Source: WUSTL News Release

Posted on by Fraser Cain

Mighty Ariane 5 Readied for Launch

Preparations are well underway for the qualification flight of Europe?s latest launcher, the Ariane 5 ECA, from Europe’s Spaceport in French Guiana. The launch window opens on the evening of 12 February at 16:49 (20:49 CET) and will extend until 18:10 (22:10 CET).

Ariane 5 ECA will be able to place heavy payloads of up to 10 tonnes into geostationary transfer orbit (GTO) in comparison to the 6-tonne payloads placed into GTO by the Ariane 5 Generic launchers. The increased performance of the Ariane 5 ECA is due to two main differences:

* a more powerful Vulcain-2 first stage engine developed from the Ariane 5 generic Vulcain 1 engine
* a cryogenic upper stage (ESCA) using the tried and tested Ariane 4 HM7B engine that made over 130 successful launches

Since the failure of the first Ariane 5 ECA Flight in December 2002, the Vulcain-2 nozzle extension has been redesigned and tested, and an exhaustive review of the whole launcher has been conducted.

Flight 164 will carry three payloads on its journey into space:
* an XTAR-EUR telecommunications satellite: to be placed into GTO
* Sloshsat-FLEVO, an experimental mini-satellite to investigate the dynamics of fluids in weightlessness, jointly developed by ESA and NIVR, the Dutch Agency for Aerospace Programmes: to be placed into GTO
* Maqsat B2 telemetry/video imaging package: to remain mated to the upper stage of the launcher for recording flight data

A successful rehearsal of the entire launch countdown – including final fuelling and countdown but stopping short of ignition – took place on 12 January. This enabled mission team members to validate launch procedures, and test all launcher equipment and ground facilities.

Original Source: ESA News Release

Posted on by Fraser Cain

Air Pollution Linked to Growth of Life in Oceans

A surprising link may exist between ocean fertility and air pollution over land, according to Georgia Institute of Technology research reported in the Feb. 16 issue of the Journal of Geophysical Research – Atmospheres. The work provides new insight into the role that ocean fertility plays in the complex cycle involving carbon dioxide and other greenhouse gases in global warming.

When dust storms pass over industrialized areas, they can pick up sulfur dioxide, an acidic trace gas emitted from industrial facilities and power plants. As the dust storms move out over the ocean, the sulfur dioxide they carry lowers the pH (a measure of acidity and alkalinity) level of dust and transforms iron into a soluble form, said Nicholas Meskhidze, a postdoctoral fellow in Professor Athanasios Nenes’ group at Georgia Tech’s School of Earth and Atmospheric Sciences and lead author of the paper “Dust and Pollution: A Recipe for Enhanced Ocean Fertilization.”

This conversion is important because dissolved iron is a necessary micronutrient for phytoplankton – tiny aquatic plants that serve as food for fish and other marine organisms, and also reduce carbon dioxide levels in Earth’s atmosphere via photosynthesis. Phytoplankton carry out almost half of Earth’s photosynthesis even though they represent less than 1 percent of the planet’s biomass.

In research funded by the National Science Foundation, Meskhidze began studying dust storms three years ago under the guidance of William Chameides, Regents’ Professor and Smithgall Chair at Georgia Tech’s School of Earth and Atmospheric Sciences and co-author of the paper.

“I knew that large storms from the Gobi deserts in northern China and Mongolia could carry iron from the soil to remote regions of the northern Pacific Ocean, facilitating photosynthesis and carbon-dioxide uptake,” Meskhidze said. “But I was puzzled because the iron in desert dust is primarily hematite, a mineral that is insoluble in high-pH solutions such as seawater. So it’s not readily available to the plankton.”

Using data obtained in a flight over the study area, Meskhidze analyzed the chemistry of a dust storm that originated in the Gobi desert and passed over Shanghai before moving onto the northern Pacific Ocean. His discovery: When a high-concentration of sulfur dioxide mixed with the desert dust, it acidified the dust to a pH below 2 – the level needed for mineral iron to convert into a dissolved form that would be available to phytoplankton.

Expanding on this discovery, Meskhidze studied how variations in air pollution and mineral dust affect iron mobilization.

Obtaining in-flight data from two different Gobi-desert storms – one occurring on March 12, 2001, and the other on April 6, 2001 — Meskhidze analyzed the pollution content and then modeled the storms’ trajectory and chemical transformation over the North Pacific Ocean. Using satellite measurements, he determined whether there had been increased growth of phytoplankton in the ocean area where the storms passed.

The results were surprising, he said. Although the April storm was a large one, with three sources of dust colliding and traveling as far as the continental United States, there was no increased phytoplankton activity. Yet the March storm, albeit smaller, significantly boosted the production of phytoplankton.

The differing results can be attributed to the concentration of sulfur dioxide existing in dust storms, Meskhidze said. Large storms are highly alkaline because they contain a higher proportion of calcium carbonate. Thus, the amount of sulfur dioxide picked up from pollution is not enough to bring down the pH below 2.

“Although large storms can export vast amounts of mineral dust to the open ocean, the amount of sulfur dioxide required to acidify these large plumes and generate bioavailable iron is about five to 10 times higher than the average springtime concentrations of this pollutant found in industrialized areas of China,” Meskhidze explained. “Yet the percentage of soluble iron in small dust storms can be many orders of magnitude higher than large dust storms.”

So even though small storms are limited in the amount of dust they transport to the ocean and may not cause large plankton blooms, small storms still produce enough soluble iron to consistently feed phytoplankton and fertilize the ocean. This may be especially important for high-nitrate, low-chlorophyll waters, where phytoplankton production is limited because of a lack of iron.

Natural sources of sulfur dioxide, such as volcanic emissions and ocean production, may also cause iron mobilization and stimulate phytoplankton growth. Yet emissions from human-made sources normally represent a larger portion of the trace gas. Also, human-made emission sites may be closer to the storm’s course and have a stronger influence on it than natural sulfur dioxide, Meskhidze said.

This research deepens scientists’ understanding of the carbon cycle and climate change, he added.

“It appears that the recipe of adding pollution to mineral dust from East Asia may actually enhance ocean productivity and, in so doing, draw down atmospheric carbon dioxide and reduce global warming,” Chameides said.

“Thus, China’s current plans to reduce sulfur dioxide emissions, which will have far-reaching benefits for the environment and health of the people of China, may have the unintended consequence of exacerbating global warming,” he added. “This is perhaps one more reason why we all need to get serious about reducing our emissions of carbon dioxide and other greenhouse gases.”

Original Source: Georgia Tech News Release

Posted on by Fraser Cain

Diamond Worlds Could Exist

Image credit: NASA
Some extrasolar planets may be made substantially from carbon compounds, including diamond, according to a report presented this week at the conference on extrasolar planets in Aspen, Colorado. Earth, Mars and Venus are “silicate planets” consisting mostly of silicon-oxygen compounds. Astrophysicists are proposing that some stars in our galaxy may host “carbon planets” instead.

“Carbon planets could form in much the same way as do certain meteorites in our solar system, the carbonaceous chondrites,” said Dr. Marc J. Kuchner of Princeton University, making the report in Aspen together with Dr. Sara Seager of the Carnegie Institute of Washington. “These meteorites contain large quantities of carbon compounds such as carbides, organics, and graphite, and even the occasional tiny diamond.” Imagine such a meteorite the size of a planet, and you are picturing a carbon planet.

Planets like the Earth are thought to condense from disks of gas orbiting young stars. In gas with extra carbon or too little oxygen, carbon compounds like carbides and graphite condense out instead of silicates, possibly explaining the origin of carbonaceous chondrites and suggesting the possibility of carbon planets. Any condensed graphite would change into diamond under the high pressures inside the carbon planets, potentially forming diamond layers inside the planets many miles thick.

Some of the already known low- and intermediate-mass extrasolar planets may be carbon planets, which should easily survive at high temperatures near a star if they have the mass of Neptune. Carbon planets would probably consist mostly of carbides, thought they may have iron cores and substanial atmospheres. Carbides are a kind of ceramic used to line the cylinders of motorcycle engines among other things.

The planets orbiting the pulsar PSR 1257+12 are good candidates for carbon planets; they may have formed from the disruption of a star that produced carbon as it aged. So are planets located near the center of the Galaxy, where stars are more carbon-rich than the sun, on average. Slowly, the galaxy as a whole is becoming more carbon-rich; in the future, all planets formed may be carbon planets.

“There’s no reason to think that extrasolar planets will be just like the planets in the solar system.” says Kuchner. “The possibilities are startling.”

Kuchner added, “NASA’s future Terrestrial Planet Finder (TPF) mission may be able to spot these planets.” The spectra of these planets should lack water, and instead reveal carbon monoxide, methane, and possibly long-chain carbon compounds synthesized photochemically in their atmospheres. The surfaces of carbon planets may be covered with a layer of long-chain carbon compounds–in other words, something like crude oil or tar.

The first TPF telescope, an optical telescope several times the size of the Hubble Space Telescope is scheduled to launch in 2015. The TPF missions are designed to search for planets like the Earth and determine whether they might be suitable for life.

Original Source: NASA Astrobiology Story