Chaos Plagued the Early Universe

A new theory proposes that the earliest Universe, which formed immediately after the Big Bang, expanded in the space around it in an extremely chaotic manner.

This is not by far a new idea. It was proposed for the first time more than seven years ago, by Adilson E. Motter, who is a physics expert at the Northwestern University.

At the time when the idea was first conjectured, the physicist did not have the tools needed to prove it.

Now, with the help of a colleague, Motter finally managed to present the world with the mathematical utensils needed to demonstrate the theory rigorously.

Details of the work appear in a paper entitled “(Non)Invariance of Dynamical Quantities for Orbit Equivalent Flows,” which is published in the latest issue of the top-rated Journal Communications in Mathematical Physics.

The mathematical tools work extremely well when applied to the most widely-accepted model of how the Universe came to be.

The main conundrum the physicist was trying to crack is whether chaos is absolute or relative inside systems that are in themselves governed by general relativity.

In these systems, time itself is relative. For the purpose of the work, chaos was determined at the phenomenon by which tiny events lead to very large changes in the time evolution of a system.

The Universe therefore becomes a prime example of a chaotic system. An absolute thing, for example, is the speed of light, which remains the same regardless of where an observer is placed in time and space.

“A competing interpretation has been that chaos could be a property of the observer rather than a property of the system being observed,” says Motter, who is an assistant professor of physics and astronomy at the Northwestern Weinberg College of Arts and Sciences.

“Our study shows that different physical observers will necessarily agree on the chaotic nature of the system,” adds the expert, who is also the author of the new journal entry.

“Technically, we have established the conditions under which the indicators of chaos are relativistic invariants. Our mathematical characterization also explains existing controversial result,” Motter goes on to say.

“They were generated by singularities induced by the choice of the time coordinate, which are not present for physically admissible observables,” he concludes.

Santa Fe Was Impacted by Huge Asteroid

Between 1.2 billion and 330 million years ago, the area near Santa Fe, New Mexico, was the site of a major asteroid impact. The conclusion belongs to a new study, which looked at an exposed mountain wall. The feature exposes a number of rock layers that look all the same to the eye of profane individuals, but which provide geologists with a wealth of data about Earth's distant past. It is estimated that the original impact crater was no less than between 6 and 13 kilometers in diameter, Space reports.

The reason why the timing of the impact cannot be determined with more accuracy is an anomaly known as the “Great Unconformity.” This means that the rock layers corresponding to the period stretching between 1.2-1.6 billion years and 330 million years ago are missing. This may have happened for a variety of reasons, but the leading theory is that a sea existed at this location a long time ago. This and other natural factors such as water receding, erosion, winds and so on, destroyed the rocks, which only began depositing ago when seas moved back on, 330 million years ago.

It was then that the first sediments were laid down again. This is why 1.2 billion year old layers of rock now lie directly underneath much newer ones. “We need an army of scientists and graduate students studying this site, over many, many years. It could take several lifetimes to do all the necessary work,” says University of New Mexico Institute of Meteoritics expert Horton Newsom. He conducted the work with colleagues Shawn Wright and Wolf Elston. He says that the team was amazed to learn that the rock layers are exposed directly.

This means that the team no longer needs digs in order to analyze the past events, just a lot of patience. “Such impact crater cross-sections are extremely rare in the world,” the expert says. He adds that the crater has long since been eroded entirely, but argues that additional studies of the site would help experts gain additional insights into how the impact affected the rocks underneath. The group will continue working in Santa Fe, with hopes that the actual size of the impact crater, as well as its age, will be accurately established.

How Binary Star Systems Form

For many years, we have been taught to believe that most stars are similar to our Sun, in the sense that they form the sole core of their systems. This picture now appears to be dismantled piece-by-piece by new scientific evidence, which shows that a great number of cosmic fireballs are in fact members of binary systems. In these setups, two stars spin around each other, bound together by the mutual gravitational pulls they exert on each other. The mechanisms through which these binaries form have fascinated and puzzled astronomers for a long time, and now new data comes to clarify the mystery.

One of the main questions related to their development is whether the two components of the binary develop in separate molecular clouds, or if maybe they are born in the same one. Commonly, experts say that systems featuring stars that are fairly distant from each other appeared when two nearby clouds of gas and dust collapsed. When the stars orbit each other at a close distance, researchers believe that a single cloud was the source for both fireballs. But astronomers were in the dark about how a single source could produce two stars.

Experts at the University of Michigan in Ann Arbor decided to investigate the phenomenon, and used the American space agency's Spitzer Space Telescope, which surveys the sky in infrared wavelengths. Data collected with the sensitive observatory determined the existence of asymmetrical gas and dust envelopes around forming stars. These blob-like structures may promote the development of irregularities inside the clouds, which may in turn lead to the emergence of binary systems. Details of the new work appear in a recent issue of the esteemed publication Astrophysical Journal.

University of Michigan in Ann Arbor expert John Tobin, who is also the lead author of the paper, says that “we see asymmetries in the dense material around these proto-stars on scales only a few times larger than the size of the solar system. This means that the disks around them will be fed unevenly, possibly enhancing fragmentation of the disk and triggering binary star formation. We were really surprised by the prevalence of asymmetrical envelope structures. And because we know that most stars are binary, these asymmetries could be indicative of how they form,” Spitzer is managed by experts at the NASA Jet Propulsion Laboratory (JPL) in Pasadena, California.

New Hubble pictures suggest Milky Way fell together

New infrared images of the Milky Way globular cluster 47 Tucanae (this one recorded at a wavelength of 1.6 micrometers), reveal that both the cluster and the Milky Way's central bulge are 11 billion to 12 billion years old and may have formed simultaneously with the Milky Way’s halo.

BALTIMORE — A preliminary analysis of elderly stars in the Milky Way appears to strike a blow against the prevailing theory of galaxy formation. The study suggests that several large and seemingly disparate chunks of the Milky Way galaxy formed at the same time from the collapse of a single blob of gas and dust.

That’s in direct contrast to the leading galaxy-formation scenario, which holds that the Milky Way and other galaxies began small and grew bit by bit for the most part, gravitationally acquiring intergalactic gas and dust and merging with galaxies in their immediate neighborhood.

The new evidence, which astronomers emphasize is only tentative, comes from a new, ongoing study of a familiar globular cluster — a dense, elderly grouping of more than a million Milky Way stars collectively known as 47 Tucanae. Earlier this year, Harvey Richer of the University of British Columbia in Canada and his colleagues began examining 47 Tucanae with two Hubble Space Telescope cameras — the newly installed Wide Field Camera 3 and the Advanced Camera for Surveys, which stopped working early in 2007 but was revived by astronauts during the servicing mission last year.

The cluster lies near but not inside the Milky Way’s bulge, a massive concentration of stars that surrounds the galaxy’s core. But because the cluster shares several properties with the bulge, such as chemical composition and orbital motion, astronomers consider the age of 47 Tucanae a good proxy for that of the bulge.

An analysis of the Hubble portrait, which includes one of the deepest infrared views ever recorded, reveals that 47 Tucanae, and therefore the Milky Way’s bulge, formed between 11 billion and 12 billion years ago, Richer reported May 4 at a symposium on stellar evolution at the Space Telescope Science Institute in Baltimore. He said previous age estimates that did not use the new Hubble camera and put the cluster at a more youthful 9 billion years old are simply not correct.

“This is not a young cluster. That’s definitive,” Richer said. But he cautioned that both the analysis and observations of 47 Tucanae are ongoing, so the precise age determination is still “very preliminary.”

The new age determination places the bulge at roughly the same vintage as the halo of the Milky Way, a vast spherical region that extends to the outskirts of the galaxy and envelops the flattened disk containing the Milky Way’s signature spiral arms,.

Researchers had previously determined the halo’s age by studying several globular clusters that lie within it. The similarity in age of 47 Tucanae and the galactic halo suggests that the two structures may have formed simultaneously, in one giant monolithic gravitational collapse of material, Richer said. “It may have been that major components of the galaxy pretty much formed everywhere at the same time very early on and other bits and pieces came along later,” he noted.

A younger age for the bulge would have indicated that the galaxy grew more gradually and from the outside in, with the halo forming first and the central bulge arising a few billion years later.

But if the age estimate holds up, it would appear to be in conflict with the prescription for galaxy formation dictated by the cold dark matter theory, which holds that galaxies began as small fry that built themselves up by stealing gas and stars from their neighbors.

Evidence that the halo and the bulge of the Milky Way formed together could be seen either as a cosmic coincidence or a finding that suggests some previously unknown episode of violence early in the galaxy’s history, commented Rosie Wyse of Johns Hopkins University in Baltimore, who was not a collaborator on the study.

One possibility, she notes, is that the Milky Way suffered a major collision not long after its birth that drove material from the halo into the central part of the galaxy, forming the bulge. That could also explain why the mass of stars in the bulge is about 10 times heavier than that in the halo, she said.

The finding does not rule out the possibility that parts of the Milky Way grew by accreting, or gravitationally accumulating material, from neighbors, Richer said. Indeed, the Milky Way today continues to grow by pulling in small neighboring galaxies, such as the Sagittarius dwarf galaxy.

NASA To Probe First Moments Of The Universe

This graphic shows the universe as it evolved from the big bang to now. Goddard scientists believe that the universe expanded from subatomic scales to the astronomical in a fraction of a second after its birth. They now building, along with their university partner, an instrument that searches for clues that the inflation did, in fact, occur. Credit: NASA/WMAP Science Team

Sophisticated new technologies created by NASA and university scientists are enabling them to build an instrument designed to probe the first moments of the universe's existence.

Former NASA scientist Chuck Bennett, now an astrophysicist at Johns Hopkins University (JHU) in Baltimore, Md., won a $5-million National Science Foundation grant to build a new ground-based instrument, the Cosmology Large Angular Scale Surveyor (CLASS). Bennett is building CLASS with his collaborators at the NASA Goddard Space Flight Center in Greenbelt, Md.

Goddard will provide most of the instrument's sophisticated detectors and other state-of-the-art technologies that will allow the scientists to test the "inflation theory" of the universe's origin.

Staggering Idea
Considered a staggering idea just 30 years ago, the inflation theory postulates that the universe expanded far faster than the speed of light and grew exponentially almost instantaneously after the big bang, the moment the universe sprang into existence 13.7 billion years ago.

In particular, the telescope will search for a unique polarization pattern in the cosmic background radiation - the remnant light from the first moment of the universe's creation that bathes the sky in all directions. Because of the size and expansion of the universe, scientists can study this ancient light only if their instruments are tuned to microwave frequencies.

If the cosmic growth spurt from inflation really happened, scientists say the event could have created gravitational waves, which are ripples in the fabric of space. The theory also predicts that these gravitational waves would have caused the background light to be polarized in a particular pattern. The telescope, therefore, will look for this signature pattern.

"Miraculously enough, it is within our ability to probe back into the first moments of the universe and learn what happened then," Bennett said.

The CLASS team, which also includes other partner institutions, will complete the instrument in 2014, equipping it with detectors sensitive to microwave light. The team then will ship the instrument to the Atacama Desert in northern Chile where it will observe large swaths of the microwave sky in search of the polarized signature.

Tantalizing Clues
Although scientists have yet to find the polarization pattern, they have uncovered tantalizing clues that inflation did, in fact, happen. Scientific results from the Goddard-developed Cosmic Background Explorer (COBE) found tiny temperature differences in the cosmic background radiation. These differences varied by only a few millionths of a degree and pointed to density differences that eventually gave rise to the stars and galaxies seen today.

COBE's successor, the Goddard-led Wilkinson Microwave Anisotropy Probe (WMAP), examined the tiny temperature differences in more detail and discovered new evidence for inflation. Among other things, WMAP showed that the geometry of the universe is close to flat - a physical dimension attributable to inflation. However, other theories explain these dynamics. What the scientific community needs is definitive proof of the primordial gravity waves - phenomena that could have been produced only by inflation.

Another Goddard Mission Complements CLASS
CLASS is not the only effort aimed at finding the same telltale evidence. Another Goddard team is now building a balloon-based instrument, the Primordial Inflation Polarization Exploration (PIPER) that Principal Investigator Al Kogut hopes to launch in 2012. "CLASS and PIPER are perfect partners," said Goddard scientist Ed Wollack, who is involved in the CLASS project. "They share many technologies while spanning a wide frequency range. They will do great science while demonstrating the technologies for a space mission."

Although both CLASS and PIPER are looking for the same polarization signature, they will approach the challenge using different detector technologies to study different microwave frequencies. Both detector technologies were developed at Goddard.

"The more frequencies you study, the better your chance of detecting the pattern of inflation," said David Chuss, a Goddard scientist working on CLASS.

The ultimate goal for the Goddard-JHU team is leveraging its expertise with CLASS and PIPER and winning a possible follow-on space observatory that would examine the primordial background light with even greater precision. "What we're doing is very much what we need to do to be competitive for an observatory if NASA decides to launch one," Chuss said.

Japan to launch 'space yacht' propelled by solar particles

Japan is to launch a "space yacht" propelled by solar particles that bounce off its kite-shaped sails, the country's space agency said Tuesday.

A rocket carrying the Ikaros -- an acronym for Interplanetary Kite-craft Accelerated by Radiation of the Sun -- will blast off from the Tanegashima space centre in southern Japan on May 18.

"Ikaros is a 'space yacht' that gets propulsion from the pressure of sunlight particles bouncing off its sail," Yuichi Tsuda, space systems expert at the Japan Aerospace Exploration Agency (JAXA), told journalists.

The flexible sails, which are thinner than a human hair, are also equipped with thin-film solar cells to generate electricity to create "a hybrid technology of electricity and pressure", Tsuda said.

"Solar sails are the technology that realises space travel without fuel as long as we have sunlight. The availability of electricity would enable us to navigate farther and more effectively in the solar system."

Ikaros, which has cost 1.5 billion yen (16 million dollars) to develop, will be the first use of the technology in deep space, as past experiments have been limited to unfolding its sails in orbits around the Earth, said Tsuda.

JAXA plans to control the path of Ikaros by changing the angle at which sunlight particles bounce off the silver-coloured sail.

Ikaros will be a short cylindrical shape when it is released into space and will then extend its 14-metre (46 foot) sail, JAXA said.

The name of the spacecraft alludes to Icarus, the figure from Greek mythology who flew too close to the sun and fell into the sea, but Tsuda promised that "this Ikaros will not fly into the sun".

The same rocket will also launch Japan's first satellite bound for Venus, called the Akatsuki, or PLANET-C, which will work closely with Venus Express, a satellite sent earlier by the European Space Agency.

In coming years, JAXA may launch other bold projects.

An expert panel to the government has proposed Japan send a wheeled robot to the moon in five years and build the world's first lunar base by 2020, a Strategic Headquarters for Space Policy official said Tuesday.

Under the plan, the robot's tasks would include setting up an observation device, gathering geological samples and sending data back to Earth. The robot would also set up solar panels to generate energy, the official said.

The expert panel initially considered sending a two-legged humanoid but judged a "rover-type" robot more practical. "It is still difficult for a biped robot to walk on a bumpy surface, even on Earth," the official said.

The team also envisions building the world's first station on the moon by about 2020, which would be staffed by advanced wheeled robots, he said.

The group estimates the unmanned mission would cost Japan 200 billion yen (two billion dollars) over the next 10 years.

The 20-member team -- made up of experts from JAXA as well as business and academia -- advises Transport Minister Seiji Maehara.

It plans to submit a report to Maehara, the minister in charge of space exploration, by late June, which would be discussed at the Strategic Headquarters for Space Policy, chaired by Prime Minister Yukio Hatoyama.

First Serious Study Looks for the Sun's 'Brothers'

Like all other stars before it, and all those that will come after it, the Sun was born in a nebula, surrounded by thick, massive clouds of cosmic dust and hydrogen gas. It first ignited some 5 billion years ago, alongside tens to thousands of other stars, all of which must be of similar age and chemical makeup. Now, in the first-ever complex study on the issue, astronomers begin looking for the Sun's siblings, in a research that could ultimately provide us with more clues as to how the solar system evolved over time, Technology Review reports.

Finding the birthplace of our star could also assist astronomers in answering fundamental questions about the origin of the solar system, in addition to providing information as to which direction the Sun has been traveling in for the past 5 billion years, when reported to the center of the Milky Way. This knowledge could then better inform us in understanding the conditions that eventually led to the appearance of life on Earth billions of years ago. Mysteries related to sudden changes in the planet's climate could also be revealed by studying stars formed from the same nebula as the Sun.

When compared with other yellow dwarfs, as well as with other objects in this part of the Milky Way, the Sun exhibits an unusually-high concentration of metallic elements. This abnormality has puzzled astronomers for many years, and it's now believed that identifying the star's birthplace could help unravel this enigma as well. For all these reasons, researchers at the Missouri State University, led by expert Anthony Brown, conducted the first serious astronomical search for the stars that appeared at the same time our own celestial fireball did. Unfortunately, the results are not encouraging.

The main issue plaguing such an effort is the magnitude of the needed search. Recent data on how nebulae function reveal that some stars may be ejected from within their nurseries as if sprayed from a cosmic hose. This means that their formation process is very chaotic, and also implies that our star's siblings may be spread apart over distances exceeding 3,000 light-years. Covering such vast distances is like looking for a needle in a haystack, given that the area contains an estimated 100 million stars. Of these objects, astronomers have accurate information on just 100,000 of them, which is a small portion of our solar system's neighborhood.

There is no reason to disappoint, however. Though a Sun sibling has not been found within 100 parsecs from our star, astronomers take comfort in the fact that the year 2012 will see the launch of the Gaia spacecraft. The instrument will be the successor of the Hipparcos space probe, which is responsible for providing experts with most data on the 100,000 stars analyzed until now. Gaia will conduct the first decent-quality 3D investigation of the Milky Way, and will map more than 1 billion stars. However, we will have to wait until 2020 for this census to be done.

Creating a 'Perpetual Eclipse' in Space

StarTiger-2 external coronagraph demonstrator during testing

In September 2009, a group of prominent scientists was convened by the European Space Agency (ESA) at one of its research facilities with a single objective – produce a space-based setup that would allow for the continuous analysis of a portion of the Sun hiding in plain sight. The results of the investigation were announced yesterday, April 27, as the six-month-long research project was officially closed down on time, at the agency's European Space Research and Technology Center (ESTEC), in the Netherlands.

The StarTiger project is one of ESA's latest endeavors, and it was developed at the Laboratoire Astrophysique d’Marseille (LAM), where the science team was convened. Inside a clean room at the facility, the researchers constructed a scale-model prototype of the new mission, whose main goal is to create a perpetual eclipse in space. Usually, the edges of the Sun are only visible from Earth during a full eclipse by the Moon, but the astronomical event happens rather rare. What ESA wanted to achieve is the capability to conduct eclipse study around the clock.

The solution its research team proposed was constructing a double-satellite system. The instruments would fly in a close, tight formation, where the one in front would cast a perennial shadow on the one in the back. This approach raises monumental engineering problems, given that both spacecraft would be flying at high speeds through space. The navigation and control systems are the most difficult aspects to set up, but the endeavor is not impossible, scientists say.

“ESA’s StarTiger is a new R&D approach, one that has paid off handsomely here. This integrated ‘breadboard’ demonstrator has been completed in just six months, including all necessary subsystems, mathematical models and software, to not only validate the external coronagraph concept but assess its performance in practical terms,” explained at yesterday's ceremony the supervisor of the initiative, expert Peter de Maagt.

“The main objective was achieved together with several secondary objectives. The idea was to perform relative positioning between the two satellites and absolute positioning with respect to the Sun. Working face-to-face in the same room was our key to success, considering the schedule we faced. We combined our various competences to solve the many problems that arose along the way,” added LAM team leader Sebastien Vives. He managed the main research group of seven experts, who were supported by 20 other investigators.

Explanation: Supermassive Black Hole Formation

Image comment: This illustration of the black hole in Andromeda shows an old lopsided stellar disk (red) orbiting a black hole (black dot)
Image credits: NASA / ESA / A. Field

One of the greatest mysteries in the fields of astronomy and astrophysics was until recently figuring out how supermassive black holes get so big. These impressively-large formations can be found at the cores of equally-massive galaxies, and they can grow continuously until their reach masses a billion times larger than that of the Sun. For many years, various explanations have been proposed and dismissed, but now a new idea appears to hold up to thorough scientific scrutiny.

It's a widely-known fact that black holes grow by accumulating mass from their surroundings. They attract various materials, such as cosmic gas and dust, in their surroundings, and then make them a part of their accretion disks. These are the circular structures that can be found around most large black holes, from which the dark behemoth continuously draws matter. But, in the case of gas being gobbled up by these structures, astrophysicists ran into a dilemma, PhysOrg reports.

The gas has a large angular momentum, which means that it basically moves too fast to allow for the black holes to trap it into their accretion disks. So experts have been pondering on the mechanisms the formations employ in slowing the gas down sufficiently. University of California in Berkeley (UCB) astrophysicists Philip Hopkins and Eliot Quataert recently published a new study, in which they propose that old lopsided stellar disks, such as the one noticed around the black hole at the core our neighboring galaxy, Andromeda, may play a pivotal part in slowing down the swirling gas.

These disks can grow to a diameter of dozens of light-years, and, due to their lopsided nature, they tend to exert an uneven gravitational attraction on the incoming gas. This in turn causes various gas filaments within the larger clouds to collide with each other, creating friction, and reducing speed sufficiently to allow for the black hole that traps the gas with its own gravitational pull. In spite of popular belief, the dark behemoths can only gobble up gas if it passes within one light-year of their event horizon. Through this mechanism, the investigators propose, a black hole such as Andromeda's could gain several solar mass-worth of matter each year, helping to account for its current mass.

Galaxy Clusters Enveloped by Cigar-Shaped Dark Matter Halos

Image comment: A photo of the Bullet Cluster, one of the 20 such structures that was analyzed for the new investigation
Image credits: NASA / STScI / Magellan / U.Arizona / D.Clowe et al

A series of recent experiments has revealed that, more often than not, the halos of dark matter surrounding massive galaxy clusters are flattened and shaped like a cigar. Until now, astrophysicists believed that the mysterious stuff, which is believed to be five times more abundant than regular matter around the Universe, would clump up in rounded spheres. However, observations appear to paint a different picture, and experts are currently working on models that would help explain that. The discovery could finally lead to studies that would result in the direct detection of the peculiar type of matter, whose existence can only be inferred from the gravitational pull it exerts on normal matter around it. “There are clear theoretical predictions that we expect dark mater halos to be flattened like this. It's a very beautiful, very clean and direct measurement of that,” explains expert Graham P. Smith, who is based at the University of Birmingham, in the United Kingdom. He is also a coauthor of the new study, which will appear in an upcoming issue of the esteemed scientific publication Monthly Notices of the Royal Astronomical Society. In the new studies, the investigators looked at about 20 galaxy clusters, which are massive collections of galaxies, held together by strong gravitational interactions. In order to see the effect dark matter has on the largest organized structures in the Universe, the researchers used gravitational lensing. This observations technique analyzes how much light is bent when mass wraps time-space in order to determine the mass of celestial objects beyond. The Mauna Kea, Hawaii-based Subaru Telescope was used for the study, and the team took advantage of the Prime Focus Camera above all other instruments. “What we're probing with these gravitational lensing observations is the dark matter distribution, because the dark matter dominates the mass on these large scales,” Smith says. The research team in charge of the study was led by National Astronomical Observatory of Japan expert Masamune Oguri and University of Tokyo scientist Masahiro Takada. The cigar-like shapes of these dark matter halos have been predicted in computer models of the cold dark matter theory, but thus far they have not been evidenced in practice in such a large number of galaxy clusters, Space reports.

NASA's Spitzer Space Telescope Discovers Extrasolar Planet Lacking Methane

PASADENA, Calif. - NASA's Spitzer Space Telescope has discovered something odd about a distant planet -- it lacks methane, an ingredient common to many of the planets in our solar system.

"It's a big puzzle," said Kevin Stevenson, a planetary sciences graduate student at the University of Central Florida in Orlando, lead author of a study appearing tomorrow, April 22 in the journal Nature. "Models tell us that the carbon in this planet should be in the form of methane. Theorists are going to be quite busy trying to figure this one out."

The discovery brings astronomers one step closer to probing the atmospheres of distant planets the size of Earth. The methane-free planet, called GJ 436b, is about the size of Neptune, making it the smallest distant planet that any telescope has successfully "tasted," or analyzed. Eventually, a larger space telescope could use the same kind of technique to search smaller, Earth-like worlds for methane and other chemical signs of life, such as water, oxygen and carbon dioxide.

"Ultimately, we want to find biosignatures on a small, rocky world. Oxygen, especially with even a little methane, would tell us that we humans might not be alone," said Stevenson.

"In this case, we expected to find methane not because of the presence of life, but because of the planet's chemistry. This type of planet should have cooked up methane. It's like dipping bread into beaten eggs, frying it, and getting oatmeal in the end," said Joseph Harrington of the University of Central Florida, the principal investigator of the research.

Methane is present on our life-bearing planet, manufactured primarily by microbes living in cows and soaking in waterlogged rice fields. All of the giant planets in our solar system have methane too, despite their lack of cows. Neptune is blue because of this chemical, which absorbs red light. Methane is a common ingredient of relatively cool bodies, including "failed" stars, which are called brown dwarfs.

In fact, any world with the common atmospheric mix of hydrogen, carbon and oxygen, and a temperature up to 1,000 Kelvin (1,340 degrees Fahrenheit) is expected to have a large amount of methane and a small amount of carbon monoxide. The carbon should "prefer" to be in the form of methane at these temperatures.

At 800 Kelvin (or 980 degrees Fahrenheit), GJ 436b is supposed to have abundant methane and little carbon monoxide. Spitzer observations have shown the opposite. The space telescope has captured the planet's light in six infrared wavelengths, showing evidence for carbon monoxide but not methane.

"We're scratching our heads," said Harrington. "But what this does tell us is that there is room for improvement in our models. Now we have actual data on faraway planets that will teach us what's really going on in their atmospheres."

GJ 436b is located 33 light-years away in the constellation Leo, the Lion. It rides in a tight, 2.64-day orbit around its small star, an "M-dwarf" much cooler than our sun. The planet transits, or crosses in front of, its star as viewed from Earth.

Spitzer was able to detect the faint glow of GJ 436b by watching it slip behind its star, an event called a secondary eclipse. As the planet disappears, the total light observed from the star system drops -- this drop is then measured to find the brightness of the planet at various wavelengths. The technique, first pioneered by Spitzer in 2005, has since been used to measure atmospheric components of several Jupiter-sized exoplanets, the so-called "hot Jupiters," and now the Neptune-sized GJ 436b.

"The Spitzer technique is being pushed to smaller, cooler planets more like our Earth than the previously studied hot Jupiters," said Charles Beichman, director of NASA's Exoplanet Science Institute at NASA's Jet Propulsion Laboratory and the California Institute of Technology, both in Pasadena, Calif. "In coming years, we can expect that a space telescope could characterize the atmosphere of a rocky planet a few times the size of the Earth. Such a planet might show signposts of life."

This research was performed before Spitzer ran out of its liquid coolant in May 2009, officially beginning its "warm" mission.

Other authors include: Sarah Nymeyer, William C. Bowman, Ryan A. Hardy and Nate B. Lust from the University of Central Florida; Nikku Madhusudhan and Sara Seager of the Massachusetts Institute of Technology, Cambridge; Drake Deming of NASA's Goddard Space Flight Center, Greenbelt, Md.; and Emily Rauscher of Columbia University, New York.

JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech. Caltech manages JPL for NASA. For more information about Spitzer, visit http://www.spitzer.caltech.edu/spitzer and http://www.nasa.gov/spitzer.

Dark matter may give neutron stars black hearts

DARK matter may be prompting black holes to appear spontaneously in the hearts of distant exotic stars. If so, this could hint at the nature of dark matter.

Arnaud de Lavallaz and Malcolm Fairbairn of King's College London wondered what would happen when dark matter - which makes up most of the mass of galaxies - is sucked into the heart of neutron stars. These stars, the remnants of supernova explosions, are the densest known stars in the universe. It turns out that the outcome depends on the nature of dark matter.

Most of the favoured theories of dark matter suggest each particle of the stuff is also an antiparticle, meaning that they should annihilate each other when they meet. But Fairbairn and de Lavallaz considered a dark matter particle of a different type, which is not also its antiparticle.

The pair calculated what would happen if dark matter particles like these were attracted by the intense gravity of neutron stars. Because they would not annihilate each other, the dark matter particles would end up forming a smaller, dense star at the heart of the neutron star. If the neutron star were near the centre of the galaxy, for example, and surrounded by an abundance of dark matter, then it would continue to accrete dark matter.

Eventually, the mass of the dark matter star would exceed its "Chandrashekar limit" - beyond which a star cannot withstand gravitational pressure. The dark matter star would collapse into a black hole. "Then the neutron star won't be able to survive anymore, and it'll collapse too," says Fairbairn. "It would be pretty catastrophic."

Their calculations show that if a neutron star collapsed in this way the result would be a burst of gamma rays, which could be spotted from Earth (arxiv.org/abs/1004.0629).

Various underground experiments back on Earth have been trying to detect dark matter, using different techniques. While none of the major experiments have seen anything yet, physicists running the Dark Matter (DAMA) experiment inside the Gran Sasso mountain in Italy have been saying for some time that dark matter particles are hitting their detector. Most physicists are sceptical of the DAMA results because it doesn't sit well with favoured theories on the nature of dark matter.

Fairbairn says that the DAMA experiment could be sensitive to dark matter particles that do not self-annihilate, which might explain why it is seeing something and others are not.

Source: NewScientist.com

NRL Researchers Study Galaxy Mergers

The University of Hawaii 2.2-meter telescope.

Scientists at the Naval Research Laboratory have solved a long-standing dilemma about the mass of infrared bright merging galaxies. Because galaxies are the largest directly observable objects in the universe, learning more about their formation is key to understanding how the universe works.

Dr. Barry Rothberg and Dr. Jacqueline Fischer, both of the Infrared-Submillimeter Astrophysics & Techniques Section in the Remote Sensing Division, used new data from the 8-meter Gemini-South telescope in Chile along with earlier results from the W. M. Keck-2 10-meter and University of Hawaii 2.2-meter telescopes in Hawaii and archival data from the Hubble Space Telescope, to solve the problem. They have published a paper on their research findings on galaxy evolution in the Astrophysical Journal (March 20, 2010 Volume 712).

Galaxies in the Universe generally come in two shapes, spiral, like our own Milky Way, and elliptical, in which the stars move in random orbits, Rothberg explains. The largest galaxies in the Universe are elliptical in shape and how they formed is central to our understanding how the Universe has evolved over the last 15 billion years. The long-standing theory has been that spiral galaxies merge with each other forming most of the elliptical galaxies in the Universe. Spiral galaxies contain significant amounts of cold hydrogen gas. When they merge, the beautiful spiral patterns are destroyed and the gas is converted into new stars. The more gas present in the spiral galaxies, the more stars are formed and with it, large amounts of dust. The dust is heated by the young stars and radiates energy at infrared wavelengths.

Until recently scientists thought that these infrared bright merging galaxies were not massive enough to be the precursors of most elliptical galaxies in the Universe. The problem lay in the method of measuring their mass. The conventional method of measuring mass in dusty IR-bright galaxies uses near-infrared light to measure the random motions of old-stars. The larger the random motions, the more mass is present. Using near-infrared light makes it possible to penetrate the dust and see as many of the old stars as possible. However, a complication occurs when spiral galaxies merge, because most of their gas is funneled to the gravitational center of the system and forms a rotating disk. This rotating disk of gas is transformed into a rotating disk of young stars that is also very bright at near-infrared wavelengths. The rotating disk of young stars both outshines the old stars and makes it appear as if the old stars have significantly less random motion. In contrast to this conventional method, Rothberg and Fischer instead observed the random motions of old stars at shorter wavelengths effectively using the dust to their advantage to block the light from the young stars. Their new results showed that the old stars in merging galaxies have large random motions, which means they will eventually become very massive elliptical galaxies.

The next step for NRL researches is to directly observe the stellar disks in IR luminous mergers using three-dimensional spectroscopy. Each pixel is a spectrum, and from this the researchers can make two-dimensional maps of stellar motion and stellar age. This will allow them to measure the size, rotation, luminosity, mass and age of the central disk.

Source:- NRL

Craters Around Lunar Poles Could Be Electrified

Illustration on LADEE probe in orbit around the Moon. More about Lunar Electric Craters

As the solar wind flows over natural obstructions on the moon, it may charge polar lunar craters to hundreds of volts, according to new calculations by NASA's Lunar Science Institute team.

Polar lunar craters are of interest because of resources, including water ice, which exist there. The moon's orientation to the sun keeps the bottoms of polar craters in permanent shadow, allowing temperatures there to plunge below minus 400 degrees Fahrenheit, cold enough to store volatile material like water for billions of years.

"However, our research suggests that, in addition to the wicked cold, explorers and robots at the bottoms of polar lunar craters may have to contend with a complex electrical environment as well, which can affect surface chemistry, static discharge, and dust cling," said William Farrell of NASA's Goddard Space Flight Center, Greenbelt, Md.

"This important work by Dr. Farrell and his team is further evidence that our view on the moon has changed dramatically in recent years," said Gregory Schmidt, deputy director of the NASA Lunar Science Institute at NASA's Ames Research Center, Moffett Field, Calif. "It has a dynamic and fascinating environment that we are only beginning to understand."

Solar wind inflow into craters can erode the surface, which affects recently discovered water molecules. Static discharge could short out sensitive equipment, while the sticky and extremely abrasive lunar dust could wear out spacesuits and may be hazardous if tracked inside spacecraft and inhaled over long periods.

The solar wind is a thin gas of electrically charged components of atoms - negatively charged electrons and positively charged ions - that is constantly blowing from the surface of the sun into space. Since the moon is only slightly tilted compared to the sun, the solar wind flows almost horizontally over the lunar surface at the poles and along the region where day transitions to night, called the terminator.

The researchers created computer simulations to discover what happens when the solar wind flows over the rims of polar craters. They discovered that in some ways, the solar wind behaves like wind on Earth - flowing into deep polar valleys and crater floors. Unlike wind on Earth, the dual electron-ion composition of the solar wind may create an unusual electric charge on the side of the mountain or crater wall; that is, on the inside of the rim directly below the solar wind flow.

Since electrons are over 1,000 times lighter than ions, the lighter electrons in the solar wind rush into a lunar crater or valley ahead of the heavy ions, creating a negatively charged region inside the crater. The ions eventually catch up, but rain into the crater at consistently lower concentrations than that of the electrons. This imbalance in the crater makes the inside walls and floor acquire a negative electric charge.

The calculations reveal that the electron/ion separation effect is most extreme on a crater's leeward edge - along the inside crater wall and at the crater floor nearest the solar wind flow. Along this inner edge, the heavy ions have the greatest difficulty getting to the surface. Compared to the electrons, they act like a tractor-trailer struggling to follow a motorcycle; they just can't make as sharp a turn over the mountain top as the electrons.

"The electrons build up an electron cloud on this leeward edge of the crater wall and floor, which can create an unusually large negative charge of a few hundred Volts relative to the dense solar wind flowing over the top," says Farrell.

The negative charge along this leeward edge won't build up indefinitely. Eventually, the attraction between the negatively charged region and positive ions in the solar wind will cause some other unusual electric current to flow.

The team believes one possible source for this current could be negatively charged dust that is repelled by the negatively charged surface, gets levitated and flows away from this highly charged region. "The Apollo astronauts in the orbiting Command Module saw faint rays on the lunar horizon during sunrise that might have been scattered light from electrically lofted dust," said Farrell.

"Additionally, the Apollo 17 mission landed at a site similar to a crater environment - the Taurus-Littrow valley. The Lunar Ejecta and Meteorite Experiment left by the Apollo 17 astronauts detected impacts from dust at terminator crossings where the solar wind is nearly-horizontal flowing, similar to the situation over polar craters."

Next steps for the team include more complex computer models. "We want to develop a fully three-dimensional model to examine the effects of solar wind expansion around the edges of a mountain. We now examine the vertical expansion, but we want to also know what happens horizontally," said Farrell. As early as 2012, NASA will launch the Lunar Atmosphere and Dust Environment Explorer (LADEE) mission that will orbit the moon and could look for the dust flows predicted by the team's research.

Farrell is lead author of a paper on this research published March 24 in the Journal of Geophysical Research. The research is part of the Lunar Science Institute's Dynamic Response of the Environment at the moon (DREAM) project. The team includes researchers from NASA Goddard, the University of California, Berkeley, and the University of Maryland, Baltimore County.

Study Counters Clovis Comet Theory

A team of researchers from the University of Arizona has revisited evidence pointing to a cataclysmic event thought by many scientists to have wiped out the North American megafauna - such as mammoths, saber tooth cats, giant ground sloths and Dire wolves - along with the Clovis hunter-gatherer culture some 13,000 years ago.

The team obtained their findings following an unusual, multidisciplinary approach and published them in the Proceedings of the National Academy of Sciences (PNAS).

"The idea of an extraterrestrial impact driving the Pleistocene extinction event has recently caused a stir in the scientific community," said C. Vance Haynes, a professor emeritus at UA's School of Anthropology and the department of geosciences, who is the study's lead author. "We systematically revisited the evidence for an impact scenario and discovered it just does not hold up."

Haynes has dedicated his scientific career to the study of the Clovis people - the first well-defined culture in the New World - and discovered many sites with evidence of their presence in Arizona.

One of the most prominent and most studied of those sites is the Murray Springs Clovis site in southeastern Arizona, where archaeologists and anthropologists have unearthed hundreds of artifacts such as arrowheads, spear points and stone tools.

The site includes the remains of a Clovis hunters' camp close to a mammoth and a bison kill site, allowing the researchers to reconstruct the daily life of the Clovis culture to a certain extent.

When the last ice age came to an end approximately 13,000 years ago and the glaciers covering a large portion of the North American continent began melting and retreating toward the north, a sudden cooling period known as the "Big Freeze" or, more scientifically, the Younger Dryas, reversed the warming process and caused glaciers to expand again.

Even though this cooling period lasted only for 1,300 years, a blink of an eye in geologic timeframes, it witnessed the disappearance of an entire fauna of large mammals.

The big question, according to Haynes, is 'Why did those animals go extinct in a very short geological timeframe?'"

"When you go out and look at the sediments deposited during that time, you see this black layer we call the Black Mat. It contains the fossilized remains of a massive algae bloom, indicating a short period of water table rise and cool climate that kept the moisture in the soil. Below the Black Mat, you find all kinds of fossils from mammoths, bison, mastodons, Dire wolves and so forth, but when you look right above it - nothing."

Scientists have suggested several scenarios to account for the rapid Pleistocene extinction event. Some ascribe it to the rapid shift toward a cooler and dryer during the "Big Freeze," causing widespread droughts.

Haynes disagrees. "We find evidence of big changes in climate throughout the geologic record that were not associated with widespread extinctions."

Others have blamed the demise of the North American megafauna on pathogens brought onto the North American continent by animals from the Old World crossing the Bering Strait.

"The disease hypothesis does not hold up well in the light of natural selection and evolution," Haynes said, "because some individuals would have been immune to the pathogens and survived."

The two attempts to account for the mass extinction event prevailing at this point include humans and celestial bodies. Many deem it possible that humans such as the Clovis culture hunted the Pleistocene mammals to extinction, as proposed by UA Professor Emeritus Paul S. Martin.

Alternatively, it is thought that a comet or asteroid slammed into the glaciers covering the Great Lakes area, unleashing firestorms that consumed large portions of vegetation. In addition, the dust and molten rock kicked up high into the atmosphere during the impact could have shrouded the Earth in a nuclear winter-like blanket of airborne dust, blocking sunlight and causing temperatures to plummet.

In the present study, Haynes and his coworkers set out to put the evidence for an impact scenario to the test: Unusually high concentrations of spherical magnetic particles in the soil samples taken at the Murray Springs Clovis site had been interpreted as indication of an extraterrestrial source.

Another hint in this direction was a spike in the Black Mat's iridium content - an element rarely encountered on Earth but quite abundant in meteorites. In addition, the occurrence of nanodiamonds had been suggested as evidence of an extraterrestrial origin. Finally, a supposedly abundant charcoal content in the soil samples had been cited as evidence of widespread wildfires ravaging the land in the aftermath of the impact.

To ensure their samples were comparable, Haynes collected at the same locations in the Black Mat layer as the team proposing the impact scenario: "I sampled where they sampled and at the same times they sampled."

Using highly sensitive and sophisticated analytical methods, Haynes' coworkers at the department of geosciences and UA's Lunar and Planetary Lab then analyzed their samples for the evidence that had been presented in support of the impact scenario.

The team did find abundant magnetic spherules. But where did they come from? Was a meteorite the only possible source?

"Researchers have only begun to study those magnetic spherules recently, so we still don't know much about them," Haynes said. "What we do know is that they occur in exhaust from vehicles and power plants."

To determine whether the magnetic spherules found at Murray Springs could be of terrestrial origin, Haynes followed a tip from UA Geosciences Professor Anthony Jull, who suggested taking a sample of dirt from the rooftop of his house and examining it under the microscope.

Haynes remembers looking at the soil samples on a microscope slide, and "sure enough, there they were - among all the dust and grains and grit

"We did confirm the other authors' findings that the magnetic spherules are concentrated in the samples at the Clovis site, but when you study the topography on which the sediments were laid down, you immediately see why: Rainwater washed them down into a river bed, where they accumulated over time. Since this is where the samples with the increased spherule content came from, we were not surprised to find more of the spherules there. The samples we took from the slopes do not have higher than normal concentrations of spherules."

What about the charcoal indicating vegetation burning?

"The only places we found charcoal were the campsites of the Clovis people, where they build their fires."

But where could the nanodiamonds come from?

Again, Haynes' colleague, Anthony Jull, had the answer. A common ingredient of cosmic dust, nanodiamonds are constantly raining down onto the earth's surface, rendering them unsuitable as unequivocal evidence of an extraterrestrial impact. "Something happened 13,000 years ago that we do not understand," said Haynes. "What we can say, though, is that all of the evidence put forth in support of the impact scenario can be sufficiently explained by earthly causes such as climate change, overhunting or a combination of both."

Does this mean the results obtained by Haynes and his coworkers rule out the possibility of a cosmic event?

"No, it doesn't," Haynes said. "It just doesn't make it very likely."

New Technique Can Spot Smaller Exoplanets

Image comment: This image of the planets in the HR8799 system were found using vortex coronagraph
Image credits: NASA / JPL-Caltech / Palomar Observatory

Up until now, methods of detecting exoplanets beyond our solar system could only see space rocks that were very large, and also fairly far away from their parent stars. These limitations occur on account of the fact that the brightness of exoplanets can rarely be observed directly, due to the light the stars they orbit emit. This means that small planets, about the size of Earth, can only be detected with incredible difficulties. However, this class of celestial objects is thought to be the most likely to support alien life. Now, a new observations technology could surpass the previous limitations.

According to the investigators behind the new method, the technique is especially suitable for detecting small exoplanets, that orbit their parent star closer to, or even within, their respective habitable zones. The method can also detect these bodies at larger distances from our solar system than ever before, which could significantly increase the chances of astronomers finding planets that have temperatures suitable for maintaining liquid water on their surface. Experts plan to find these objects using a small instrument called a “vortex coronagraph.”

Unlike other detection methods, which rely on the use of impressively-large telescopes, this device only uses a small portion of an observatory. In a demonstrative study, the technique was used on the 1.5-meter (5-foot) Hale Telescope, located at the Palomar Observatory, in San Diego. The study team, led by NASA Jet Propulsion Laboratory (JPL) expert Gene Serabyn, managed to find three already-discovered planets using this small telescope. The space rocks orbit the star called HR 8799, and they are all gas giants similar to Jupiter, though more massive.

Initially, these bodies were found using the Mauna Kea, Hawaii-based 10-meter (33-foot) telescopes of the W.M. Keck Observatory, and the 8.0-meter (26-foot) Gemini North Observatory. “We managed to see these planets with a telescope that's smaller than one panel on the Keck telescope. What this [vortex coronagraphy] does is it allows you to consider using a much smaller telescope, and something that's much more affordable, to look for Earth-like planets,” the JPL expert tells Space. Details of how the device works can be found in the April 15 issue of the esteemed scientific publication Nature.

New Method of Classifying Planets Proposed

Image comment: Artist's drawing depicting the dwarf planet Haumea, with its tow moons. The body has a prolonged shape that puzzles astronomers

Image credits: A. Feild (Space Telescope Science Institute)

The way the International Astronomical Union (IAU) goes about defining planets is a topic that many are uncomfortable with. A large proportion of all astronomers in the organization do not agree with the definitions by which the IAU decided which space object is classified as a planet, and which as a dwarf planet. This was made very obvious in 2006, when the organization voted – with only a few members in attendance – that Pluto was a dwarf planet, and not a real, full-size one. Now, experts propose a new method of defining what planets are, Technology Review reports.

The international scientific community has been trying to determine the best possible way of defining a planet for many ears, but most propositions on how to do that have thus far fallen short of their original goal. For instance, experts cannot classify an object on a planet based only on size, as throughout the Universe, size varies widely among planets. The IAU currently employs three criteria. The first is that the body needs to be orbiting the Sun, the second is that it must have sufficient mass to have formed a nearly spherical shape, and the third is that it needs to have cleared its orbit.

Pluto was deemed to be meeting the first two criteria, but not the third, because it passes through the orbit of Neptune. But critics say that, if Pluto was not deemed a planet because of this, then neither should Neptune be considered a planet, as it also failed the third criteria. Australian National University in Canberra expert Charles Lineweaver and Marc Norman decided to investigate the matter on their own, and the team now proposes a new approach to defining what a planet is. They basically suggest that any body which is not potato-shaped, and which has a diameter of more than 200 kilometers, can be considered a dwarf planet.

The problem with their approach is the fact that this definition raises the number of dwarf planets in the solar system considerably, while at the same time making the asteroid Vesta – a potato-shaped space rock much larger than 200 kilometers – a cosmic oddity. This method of defining space objects again puts Pluto as the number one dwarf planet, but it's unlikely to sit well with those who want to see the body established to its former “glory”. The main issue here remains elevating interest in this type of research, as more often than not, this translates into increased funding for this type of studies.

Source;- http://www.technologyreview.com/blog/arxiv/25034/

Analyzing the Sun's 'Magnetic Flux Ropes'

Image comment: The three images reveal gases trapped in the flux rope at different temperatures, from 1.5 million degrees Celsius in the image on the left through to 2.5 million degrees Celsius in the right hand image
Image credits: JAXA / ISAS / NASA / STFC

Coronal mass ejections (CME) are some of the most interesting and important phenomena going on on the surface of our Sun. As the years pass, astronomers and astrophysicists gain a deeper and deeper understanding of how these structures form and develop. This is of tremendous importance, as the CME have the potential to create secondary events that can fry power grids and satellites, radiate our planet, and jeopardize the lives of people working aboard the International Space Station (ISS). It would now appear that one of the keys to learning more of CME is analyzing magnetic flux ropes.

As some experts put it, almost nothing happens on the Sun without the presence of very strong magnetic fields. These structures can take on various shapes and sizes, and they can trigger solar tsunamis, sunspots, coronal mass emissions and so on. Given the perilous nature of some of these events, it stands to reason that experts want to learn more about how they form. That is why scientists at the University College London (UCL), in the United Kingdom, used the Hinode satellite to gain more data on how these extremely large magnetic fields form.

Magnetic flux ropes are a type of field that can be readily detected in the interplanetary space as CME approach our planet. This led experts to assume that they play an important role in stimulating the emissions. “Magnetic flux ropes have been observed in interplanetary space for many years now and they are widely invoked in theoretical descriptions of how CME are produced. We now need observations to confirm or reject the existence of flux ropes in the solar atmosphere before an eruption takes place to see whether our theories are correct,” explains UCL expert Dr Lucie Green, the lead researcher on the investigation.

“Flux ropes are thought to play a vital role in the evolution of the magnetic field of the Sun. However, the physics of flux ropes is applied across the Universe. For example, a solar physics model of flux rope ejection was recently used to explain the jets driven by the accretion disks around the supermassive black holes found in the center of galaxies,” the scientist adds. Details of the work conducted at UCL were presented today, April 12, at the RAS National Astronomy Meeting, in Glasgow, Scotland, AlphaGalileo reports.

Life on Titan

Methane-ethane lakes on Titan. (c) 2008 Karl Kofoed

Research by astrobiologist William Bains suggests that if life has evolved on the frozen surface of Saturn's moon, Titan, it would be strange, smelly and explosive compared to life on Earth. Dr Bains will present his work at the National Astronomy Meeting in Glasgow on Tuesday 13th April.

'Hollywood would have problems with these aliens' says Dr Bains. 'Beam one onto the Starship Enterprise and it would boil and then burst into flames, and the fumes would kill everyone in range. Even a tiny whiff of its breath would smell unbelievably horrible. But I think it is all the more interesting for that reason. Wouldn't it be sad if the most alien things we found in the galaxy were just like us, but blue and with tails?'

Dr Bains, whose research is carried out through Rufus Scientific in Cambridge, UK, and MIT in the USA, is seeking to work out just how extreme the chemistry of life can be. Life on Titan, Saturn's largest moon, represents one of the more bizarre scenarios being studied. Titan is twice as large as our Moon and has a thick atmosphere of frozen, orange smog. At ten times our distance from the Sun, it is a frigid place, with a surface temperature of -180 degrees Celsius. Water is permanently frozen into ice and the only liquid available is liquid methane and ethane, which the Cassini/Huygens mission has shown is present in ponds and lakes on the surface of the moon.

'Life needs a liquid; even the driest desert plant on Earth needs water for its metabolism to work. So, if life were to exist on Titan, it must have blood based on liquid methane, not water. That means its whole chemistry is radically different. The molecules must be made of a wider variety of elements than we use, but put together in smaller molecules. It would also be much more chemically reactive,' said Dr Bains.

The solubility of chemicals in liquid methane is very limited, and strongly dependent on molecular weight. With a few exceptions, molecules with more than 6 heavy (non-hydrogen) atoms are essentially insoluble. So a metabolism running in liquid methane will have to be built of smaller molecules than terrestrial biochemistry, which is typically built of modules of around 10 heavy atoms. However you can only build around 3400 molecules from such a small number of atoms if you are limited to the chemistry that terrestrial life uses i.e. carbon, nitrogen, oxygen, and sulphur and phosphorus in very limited chemical contexts.

Dr Bains explained, 'Terrestrial life uses about 700 molecules, but to find the right 700 there is reason to suppose that you need to be able to make 10 million or more. The issue is not how many molecules you can make, but whether you can make the collection you need to assemble a metabolism. It is like trying to find bits of wood in a lumber-yard to make a table. In theory you only need 5. But you may have a lumber-yard full of offcuts and still not find exactly the right five that fit together. So you need the potential to make many more molecules than you actually need. Thus the 6-atom chemicals on Titan would have to include much more diverse bond types and probably more diverse elements, including sulphur and phosphorus in much more diverse and (to us) unstable forms, and other elements such as silicon.'

Energy is another factor that would affect the type of life that could evolve on Titan. With Sunlight a tenth of a percent as intense on Titan's surface as on the surface of Earth, energy is likely to be in short supply.

'Rapid movement or growth needs a lot of energy, so slow-growing, lichen-like organisms are possible in theory, but velociraptors are pretty much ruled out,' said Bains.

Source: Royal Astronomical Society

Sandcastles On The Moon

Robots are coming to a Moon near you very soon. Aside from a new fleet of orbiters, some will be landing within three years. There will be rovers deployed on the Moon, and sample return missions. This new wave of missions is brought to you by the governments of the USA, China, India and a collection of private ventures.

With so much attention focused on revisiting the Moon, it's time to re-explore a basic task that's never really been practiced before. Can we work effectively with the lunar regolith?

Any serious talk of working or staying on the Moon includes ways of using lunar materials to our advantage. In its most crude form, this means shoveling lunar soil on top of a lunar base, to protect it from radiation and meteorite impacts. Other uses would be more sophisticated, such as making concrete from the soil, or refining the soil to extract metals, oxygen and other useful things.

Landing areas for spacecraft would need to be built, free from the debris that's normally kicked up by rocket exhaust. Berms of lunar soil would protect fragile structures from nearby launches and landings. We may even want to dig deep underground, to bury certain items.

All of this sounds simple in theory. Just take a big shovel or some type of construction gear, and dig. But is it really this straightforward? We don't properly understand the mechanical properties of the regolith, dust and rocks. We don't know how well equipment and techniques that work well on Earth will perform on the Moon.

During the Apollo missions, astronauts were surprised by the behavior of the lunar soil. It adhered quickly to their spacesuits and equipment. The regolith was also more difficult to penetrate than mission planners had suspected. Planting a rod for a flag was tricky.

During an attempt to drill a core sample, Apollo 15 astronaut James Irwin apparently suffered a minor cardiac problem, according to biometric telemetry.

We will need to gather more data on the handling of lunar soil if we want to do anything ambitious on the Moon, and the best way to do it is with machines, long before astronauts return.

Some private companies are already proposing small robotic lunar dump trucks, which could excavate and move the soil. Over a long period of time, these could steadily build up large structures. But how long would it take, and how effective would it be? That's not known right now.

Doing something as simple as getting a robot to build sandcastles on the Moon would be a step forward. It would be an exercise in mechanical engineering, and a test of how disturbed regolith behaves.

Can we make lunar bricks by fusing the soil with heat? Is it better to build up a berm of raw soil, then "cook" the exterior for strength? These are also unresolved issues.

Other tests we need to perform include placing radiation dosimeters under artificial lunar mounds, to test their shielding properties. Firing mortar shells or pellets at structures would also simulate meteorite strikes.

These questions can only be answered with a lot of missions, and a lot of testing. It will take time, but it needs to be done. Without this knowledge, we will never be able to use the Moon to its full advantage.

Dr Morris Jones is the author of The New Moon Race, available from Rosenberg Publishing.