Posted on by Tammy Plotner

Bringing Satellites Out Of Retirement – The DARPA Phoenix Program

Artist's Concept of Phoenix Mission - Credit: DARPA

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It’s the dead zone. Approximately 22,000 miles above the Earth, $300 million worth of retired satellites are simply taking up space in geosynchronous orbit. Like anything a bit elderly, they might have problems, but they’re far from useless. There are a hundred willing volunteers waiting to be retrofitted, and all they need is the wave of a magic wand to come back to life. The DARPA Phoenix program might just be the answer.

Communication satellites in geosynchronous orbit (GEO) enable vital interchanges between warfighters. When one fails, it means an expensive replacement. But what remains isn’t a burned-out shell – it’s still a viable piece of equipment which often contains still usable antennae, solar arrays and other components. The only problem is that we haven’t figured out a way to recycle them. Now DARPA’s Phoenix program is offering an answer by developing the technology necessary to “harvest” these non-working satellites and their working parts. “If this program is successful, space debris becomes space resource,” said DARPA Director, Regina E. Dugan.

However, as easy as the idea might sound, it’s going to take a lot of cooperation from a variety of applied sciences. For example, incorporating the robotics which allows a doctor to perform telesurgery from a remote location to the advanced remote imaging systems used for offshore drilling which views the ocean floor thousands of feet underwater. If this technology could be re-engineered to work at zero gravity, high-vacuum and under an intense radiation environment, it’s entirely possible to re-purpose retired GEO satellites.

“Satellites in GEO are not designed to be disassembled or repaired, so it’s not a matter of simply removing some nuts and bolts,” said David Barnhart, DARPA program manager. “This requires new remote imaging and robotics technology and special tools to grip, cut, and modify complex systems, since existing joints are usually molded or welded. Another challenge is developing new remote operating procedures to hold two parts together so a third robotic ‘hand’ can join them with a third part, such as a fastener, all in zero gravity. For a person operating such robotics, the complexity is similar to trying to assemble via remote control multiple Legos at the same time while looking through a telescope.”

Now enter DARPA’s System F6 – the master satellite. It will host affordable, smaller scale electronics and structural models that provide on-board control. These smaller units will be able to communicate with each other and the master satellite – working together to harness the potential of the retired satellite’s assets. Right now, the Phoenix program is looking for the automation technology for creating a new breed of “satlets,” or nanosatellites. These can be sent into space much more economically through existing commercial satellite launches and then robotically attached to the elderly satellites to create new systems.

Artist Concept of System F6 - Credit: DARPA

System F6 (Future, Fast, Flexible, Fractionated, Free-Flying Spacecraft United by Information Exchange) will be fascinating in itself… a hive of wirelessly-interconnected modules capable of communicating with each other – sharing resources among themselves and utilizing resources found elsewhere within the cluster. “The program is predicated on the development of open interface standards—from the physical wireless link layer through the network protocol stack, including the real-time resource sharing middleware and cluster flight logic—to enable the emergence of a space “global commons” which would enhance the mutual security posture of all participants through interdependence.” says the DARPA team. “A key program goal is the industry-wide promulgation of these open interface standards for the sustainment and development of future fractionated systems.”

Right now the Phoenix program is looking for high tech expertise needed to develop a payload orbital delivery system. The PODS units will be needed to safely house the satlets during launch. The next step is an independent servicing station which will be placed in GEO and connected to PODS. The service module will be home to equipment such as mechanical arms and remote vision systems… the virtual “operating” center to make the DARPA Phoenix program a success.

Original News Source: DARPA News Release.
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Posted on by Tammy Plotner

Quantum Levitation And The Superconductor

Superconductivity and magnetic fields are like oil and water… they don’t mix. When it can, the superconductor will push out any magnetic fields from the interior in a process called the Meissner effect. It happens when a sample is cooled below its superconducting transition temperature, where it then cancels out its magnetic flux. What’s next? A superconductor. Now the fun really begins… Continue reading “Quantum Levitation And The Superconductor”

Posted on by Tammy Plotner

GAIA – A Billion Eyes On The Skies

Artist Concept of GAIA - Credit: ESA

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Its name is GAIA and it’s perhaps the most ambitious project which has ever faced the European Space Agency. Scheduled to launch in 2013, this new breed of space telescope will stately progress to Lagrange Point 2, where it will spend the next five years. Its mission? To create the largest and most precise three dimensional chart of our Galaxy by providing unprecedented positional and radial velocity measurements for about one billion stars in our Galaxy and throughout the Local Group.

While this number represents perhaps only 1% of the Milky Way’s stellar population, the GAIA mission will be “seeing” far more than just stars. Its astrophysical information data base will work hand-in-hand with on-board multi-color photometry… providing an information set which has the precision necessary to quantify the early formation, and subsequent dynamical, chemical and star formation evolution of the Milky Way Galaxy. As a result of its tracking capabilities, GAIA will also capture information on asteroids, comets, extra-solar planets and even low temperature, low mass objects. Its sensitive equipment will sweep over neighboring galaxies and reach out into space for a half million quasars. GAIA will push the boundaries of general relativity and cosmology to the limits.

What’s inside? GAIA will carry twin telescopes complete with two camera arrays incorporating charge coupled devices – each one measuring 45.0mm by 59.0mm and encompassing 1,966 pixels by 4,500 pixels. “The mounting and precise alignment of the 106 CCDs is a key step in the assembly of the flight model focal plane assembly,” said Philippe Gare, ESA’s GAIA Payload Manager.

The diminutive sensors will be placed in rows across a silicon carbide framework and span an area just slightly under half a square meter. It’s a billion little eyes ready to be turned towards the skies…

However, no optical telescope is complete without a mirror assembly and GAIA delivers. It is crafted with a set of 10 mirrors… all with outstanding physical and optical characteristics. “Since the design process began in 2006, the GAIA team has learned how to produce a set of sintered silicon carbide mirrors which is not only extremely strong and ultra-stable – with about twice the rigidity of steel – but also lightweight and with a high thermal conductivity,” said Matthias Erdmann, ESA’s GAIA Payload Systems Engineer responsible for optics and ceramics.

“Although these are not the first silicon carbide mirrors that have been made for a space mission, no mirrors as large as the GAIA primary mirror have previously been coated using the CVD process,” he added. “The degree of similarity of the mirror pairs is also quite unique. This is particularly important for GAIA , since each telescope must have similar optical capabilities, with diffraction limited viewing and minimal wavefront errors. Their outstanding optical characteristics achieve new standards that will be of great value to the development of future space observatories. As a result of this programme, the European industrial team has been able to master all of the processes required for making state-of-the-art space mirrors, and become the world leader in silicon carbide mirror technology.”

GAIA Telescope Array - Credit: ESA

But getting GAIA into space hasn’t been an overnight process. From initial approval of the project to launch encompasses 13 years – and an additional 7 to 8 to analyze the resulting data. Just consider its downlink – about 5 Mbit/s during its daily passes. While that’s comparable to a home broadband system, GAIA isn’t doing it from home. It’s transmitting from a million and a half kilometers away.

“The raw data that has to be collected is about 100 terabytes, and when all the data are processed in the archive we are talking about up to one petabyte,” says Giuseppe Sarri, Esa’s Gaia project manager. “For the analysis, a supercomputer will be needed to get out all the numbers.”

Yet, Gaia is not the first space mission to chart the heavens. In 1989, ESA also took on Hipparcos – a catalog effort well known even to the amateur community. It produced a primary catalogue of about 118 000 stars, and a secondary catalogue, called Tycho, of over 2 million stars. Even these impressive numbers will pale next to GAIA, whose mirrors will collect thirty times more light and measure a star’s position and motion two hundred times more accurately. At the end of its five-year mission, the information will fill over 30,000 CD ROMs – filled with 1000 million celestial objects – and be freely distributed to the astronomical community.

And we’ll be waiting…

For Further Reading: GAIA Mission Pages.

Posted on by Tammy Plotner

Rare Mineral Points To Martian Water History

A sample of ther mineral jarosite from a site in Greece. Photo Copyright: Steve Rust

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No. This isn’t an ancient raisin sponge cake you found at the back of your breadbox. It’s a closeup of a rare mineral called jarosite… a hydrated iron sulfate composite which takes on some very specific properties when it is exposed to a wet environment. It was discovered here on Earth in 1852 in ravines in the mountainous coast of southeastern Spain – and it turned up on Mars at a rocky outcropping, dubbed El Capitan, in the crater at Meridiani Planum where Opportunity landed. What makes this ruddy, crystalline structure so exciting is that it can “date” when liquid water may have existed.

If you thought jarosite looked like a left-over, then your assumption is close to correct. It’s actually a byproduct of the weathering of exposed rocks and forms when the right equation of oxygen, iron, sulfur, potassium and water are mixed.

In a recent study published in an October (v. 310) issue of Earth and Planetary Science Letters, Suzanne Baldwin, professor of Earth Sciences in SU’s College of Arts and Sciences; and Joseph Kula, research associate and corresponding author for the study, established the “diffusion parameters” for argon in jarosite. From this, the crystalline structure then produces the noble gas, argon, when certain potassium isotopes in the crystals decay. Like carbon, this potassium decay rate is a radioactive process which has an established rate. By measuring the argon, scientists can then get a close determination on the age when the mineral interacted with liquid water. This bit of information could some day aid scientists in determining Mars’ water history when samples are returned.

“Our experiments indicate that over billion-year timescales and at surface temperatures of 20 degrees Celsius (68 degrees Fahrenheit) or colder, jarosite will preserve the amount of argon that has accumulated since the crystal formed,” Kula says, “which simply means that jarosite is a good marker for measuring the amount of time that has passed since water was present on Mars.”

Since water is critical for most life forms, knowing when, where and how long water might have existed on Mars will help clue us in to potential habitable sites. “Jarosite requires water for its formation, but dry conditions for its preservation,” Baldwin says. “We’d like to know when water formed on the surface of Mars and how long it was there. Studying jarosite may help answer some of these questions.”

But using argon as a “time clock” can still have some potential drawbacks. When exposed to temperature extremes, it is possible for some gas to escape the crystals. To help determine the validity of their hypothesis, the team is currently subjecting jarosite and its argon content to a battery of computer simulations. Fortunately, they have found it to exist over a wide range of conditions – those of which could very well have been a part of Martian history.

“Our results suggest that 4 billion-year-old jarosite will preserve its argon and, along with it, a record of the climate conditions that existed at the time it formed,” Baldwin says. The scientists haven’t stopped their studies yet, and they are conducting further experiments on jarosite that formed less than 50 million years ago in the Big Horn Basin in Wyoming. Through this research they hope to determine the timeline in which the minerals formed and how quickly environmental conditions changed from wet to dry. “The results can be used as a context for interpreting findings on other planets.”

Original Story Source: EurkAlert News Release.

Posted on by Tammy Plotner

Black Hole Secrets… Water Vapor Gives Clues To Star Formation

Artist's Concept of Water Vapor in Black Hole Disk - Credit: Leiden University

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A eye-opening discovery has been made by an international team of scientists led by astronomer Paul van der Werf (Leiden University, The Netherlands). They have discovered a black hole in the early Universe located about 12 billion light years away that’s surrounded by a nearly impenetrable disk of gas and dust. The halo isn’t the surprise, however… but the presence of star formation in dense water vapor is.

Using the sensitive radio telescopes of IRAM (Institut de Radioastronomie Millimétrique) at the Plateau de Bure in the French Alps, the team was searching for the signs of water vapor around a quasar – a distant galaxy which gathers its luminosity from the growth of a black hole which weighs in at hundreds of millions times more mass than Sol.

“Water in cosmic clouds is normally frozen to ice, but the ice can be evaporated by the strong radiation of the quasar or of young stars. Therefore we decided to search for water vapor in this object.” says van der Werf. “It is located so far away that we are looking back in time, to an era where the Universe was only 10% of its present age. This is one of the first searches ever conducted to find water in the early Universe.”

A shocking revelation? Not really. Water vapor has been discovered before. In this instance, however, the water amounted to about 1,000 trillion times the volume found on Earth. What’s more… it’s forming stars. It’s a dense disk, so thick that light barely escapes, and star propagation is rapid.

“Water molecules are sensitive to infrared radiation, so we could use the water vapor detected as a cosmic infrared light meter. With this method we found that essentially all radiation is locked up in the gas disk surrounding the black hole.” team member Marco Spaans (University of Groningen, The Netherlands) explains. “This trapped radiation is so intense that it will build up enormous pressure and eventually blow away the gas and dust clouds surrounding the black hole.”

These findings add a new complexity to our understanding of black holes and the galaxies which hold them. Team member Alicia Berciano Alba (ASTRON, The Netherlands) says: “There is a mysterious relation between the masses of black holes in the centers of galaxies and the masses of the galaxies themselves, as if the formation of both is regulated by the same process. Our results show that these opaque gas disks, which will be ultimately blown away by the intense pressure of the trapped radiation, probably play a key role in this process.” IRAM director Pierre Cox, co-author of the paper, adds: “This discovery opens new possibilities for studying galaxies in the early Universe, using water molecules that probe regions closest to the central black hole, that are otherwise difficult to explore.”

Keep on going, because the IRAM team is up to the task and continuing to look for other sources of water vapor in the early Universe!

Original Story Source: Leiden University New Release. For Further Reading: Water vapor emission reveals a highly obscured, star forming nuclear region in the QSO host galaxy APM 08279+5255 at z=3.9.

Posted on by Tammy Plotner

Two New Globular Star Clusters Discovered By VISTA

This image from VISTA is a tiny part of the VISTA Variables in the Via Lactea (VVV) survey that is systematically studying the central parts of the Milky Way in infrared light. On the right lies the globular star cluster UKS 1 and on the left lies a much less conspicuous new discovery, VVV CL001 — a previously unknown globular, one of just 160 known globular clusters in the Milky Way at the time of writing. The new globular appears as a faint grouping of stars about 25% of the width of the image from the left edge, and about 60% of the way from bottom to top. Credit: ESO/D. Minniti/VVV Team

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Where there once was 158, there is now more… Globular clusters, that is. Thanks to ESO’s VISTA survey telescope at the Paranal Observatory in Chile, the Via Lactea (VVV) survey has cut through the gas and dust of the Milky Way to reveal the first star cluster that is far beyond our center. But keep your eyes on the prize, because as dazzling as the cluster called UKS 1 is on the right is, the one named VVV CL001 on the left isn’t as easy to spot.

Need more? Then keep on looking, because VVV CL001 isn’t alone. The next victory for VISTA is VVV CL002, which is shown in the image below. What makes it special? It’s quite possible that VVV CL002 is the closest of its type to the center of our galaxy. While you might think discoveries of this type are commonplace, they are actually out of the ordinary. The last was documented in 2010 and it’s only through systematically studying the central parts of the Milky Way in infrared light that new ones turn up. To add even more excitement to the discovery, there is a possibility that VVV CL001 is gravitationally bound to UKS 1, making it a binary pair! However, without further study, this remains unverified.

This image from VISTA is a tiny part of the VISTA Variables in the Via Lactea (VVV) survey that is systematically studying the central parts of the Milky Way in infrared light. In the centre lies the faint newly found globular star cluster, VVV CL002. This previously unknown globular, which appears as an inconspicuous concentration of faint stars near the centre of the picture, lies close to the centre of the Milky Way. Credit: ESO/D. Minniti/VVV Team

Thanks to the hard work of the VVV team led by Dante Minniti (Pontificia Universidad Catolica de Chile) and Philip Lucas (Centre for Astrophysics Research, University of Hertfordshire, UK) we’re able to feast our eyes on even more. About 15,000 light years away on the other side of the Milky Way, they’ve turned up VVV CL003 – an open cluster. Due the intristic faintness of these new objects, it’s a wonder we can see them at all… In any light!

Original Story Source: ESO Press Release.

Posted on by Tammy Plotner

Meteorite Impact Sites Treated To CSI Techniques

Meteorite impact ejecta (left) compared with volcanic deposits (right) showing closely similar structures made of dust particles. The top two photos show accretionary lapilli in density current deposits, whereas bottom two photos show pellets that formed when dust in the atmosphere clumped together and simply fell onto the land surface. Credit: From Branney and Brown 2011 (Journal of Geology 199, 275-292

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Over the last several years, we’ve been treated to television programs which have awakened us to how a crime scene is investigated. It’s a very precise science and one that could very well deepen our understanding of other types of occurrences. Now, new research done by Mike Branney, of the University of Leicester’s Department of Geology, and Richard Brown, University of Durham, are giving us insights as to how massive meteorite strikes in Earth’s past may have reacted much like certain types of volcanic activity.

The two volcanologists have forensically reconstructed an impact event to determine how the ejecta registered on the environment surrounding the scene. Although meteorite strikes are common, direct observation isn’t. However, by carefully sifting through the remains of an event that hasn’t been completely eroded, the scientists were able to forensically reconstruct what happened. Brown and Branney’s findings revealed that a large encounter may have behaved like pryroclastic flow – a devastating cloud of gas and debris from an explosive volcano which speeds across the landscape.

“In particular, the way that ash and dust stick together seems identical. Moist ash from explosive volcanoes sticks together in the atmosphere to fall out as mm-sized pellets.” explains Dr. Branney. “Where these drop back into a hot pyroclastic density current, they grow into larger layered structures, known as accretionary lapilli.”

In this case, the meteorite impact CSI investigation took place in northwest Scotland. There a well-preserved deposit still exists from an event which occurred about a billion years ago. It is very fortunate the site was so pristine, because it still held evidence of both ‘volcanic’ particles – pellets and lapilli. Findings like these will help us to further understand the ramifications of these type of events and how it could affect us, either in the past or the future.

Dr. Brown added: “This reveals that that the 10 meter-thick layer, which has been traced for over 50 km along the Scottish coast, was almost entirely emplaced as a devastating density current that sped outwards from the point of impact – just like a density current from a volcano. Only the uppermost few centimetres actually fell out through the atmosphere.”

Original Story Source: EurkAlert News Release.

Posted on by Tammy Plotner

Are The Milky Way’s First Stars Responsible For Destroying Its Satellite Galaxies?

About a decade ago, standard cosmological models encountered a slight problem when applied to the Milky Way… missing satellite galaxies. While the calculations predicted as many as 500, only 10 are documented and modern figures state as many as 20. So what happened to the other 480 that should be out there? Either they don’t exist – or we can’t see them for some reason. Thanks to research done by the LIDAU project and two researchers from Observatoire Astronomique de Strasbourg, we might just have an answer.

About 150 million years after the Big Bang, the Universe’s first stars began to appear out of the cold, electrically neutral hydrogen and helium gas which filled it. As their intense light cut through the hydrogen atoms, it returned them to their plasma state in a process called reionisation. Things really began to heat up from there… gas began escaping the gravity of low-mass galaxies and as a consequence, they lost their star-forming abilities. By computing the observable consequences of this process, Pierre Ocvirk and Dominique Aubert demonstrated that the Milky Way’s first stars had the power of reionisation and it “is indeed an essential process in the standard model of galaxy formation.” This photo-evaporation state neatly explains the sparsity and age of Milky Way companions and offers up the reason satellite galaxies are rare in this neighborhood.

“On the other hand, their sensitivity to UV radiation means satellite galaxies are good probes of the reionisation epoch. Moreover, they are relatively nearby, from 30000 to 900000 light-years, which allows us to study them in great details, especially with the forthcoming generation of telescopes.” says Ocvirk. “In particular, the study of their stellar content with respect to their position could give us precious insight into the structure of the local UV radiation field during the reionisation.”

Current theory states this photo-evaporation was simply caused by nearby galaxies, resulting in a uniform event – but the new model built by the two French researchers proves this assumption wrong. Their high resolution numerical simulation accounts for the dynamics of the dark matter haloes from beginning to end, as well as their resultant gas impacted star formation and UV radiation.

“It is the first time that a model accounts for the effect of the radiation emitted by the first stars formed at the center of the Milky way, on its satellite galaxies. Indeed, contrary to previous models, the radiation field produced in this configuration is not uniform, but decreases in intensity as one moves away from the source.” explains Ocvirk. “On one hand, the satellite galaxies close to the galactic center see their gas evaporate very quickly. They form so few stars that they can be undetectable with current telescopes. On the other hand, the more remote satellite galaxies experience on average a weaker irradiation. Therefore they manage to keep their gas longer, and form more stars. As a consequence they are easier to detect and appear more numerous.”

Where did initial assumptions fall short? In previous models reionisation was thought to occur over an evenly distributed UV background, but the MIlky Way’s first stars had already done its damage by consuming its satellites. As the study suggests, our own galaxy is responsible for the lack of smaller companions.

Says Ocvirk; “This new scenario has deep consequences on the formation of galaxies and the interpretation of the large astronomical surveys to come. Indeed, satellite galaxies are affected by our galaxy’s tidal field, and can be slowly digested into our galaxy’s stellar halo. They can also be stretched into filaments and form stellar streams.”

It’s a very interesting new concept and will be one of the main science goals of the Gaia space mission, scheduled for launch in 2013. Until then, the Observatoire Astronomique de Strasbourg team will continue in their efforts to further understand radiative processes during reionisation.

Original Story Source: Observatoire Astronomique de Strasbourg Press Release. For Further Reading: A signature of the internal reionisation of the Milky Way and LIDAU collaboration (Light In the Dark Ages of the Universe).

Posted on by Tammy Plotner

Wake Up! The Orionid Meteor Shower Peaks On October 20…

Orionid Meteor Shower: The above image shows brilliant multiple meteor streaks that can all be connected to a single point in the sky just above the belt of Orion, called the "radiant." The Orionids take place in mid-October and the parent comet is Halley. Comet Halley is actually responsible for two known meteor showers: The other is the Eta Aquarids, which are visible every May. Image Credit and Copyright: Tunc Tezel

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Do you hate to get up early? Then stay up late, because it’s infrequent that both the northern and southern hemispheres have a chance to catch an annual meteor shower. Right now the Earth is heading into the complex Orionid stream, and while the skies won’t be perfectly dark, they aren’t going to be bad. Where and when do you watch? Follow me…

As the Earth slowly orbits the Sun, it passes into one of the debris streams left by Comet Halley and the material returns as the Orionid meteor shower. While it won’t be a “meteor storm”, what you can expect to see is one of the most predictable and reliable meteor showers of the year. Even if it’s a few days early (or late), take advantage of any clear skies and begin your observations because activity is up.

The Orionids produce an average of 10-20 meteors per hour maximum, and best activity begins before local midnight on October 20th, and reaches its peak as Orion stands high to the south about two hours before local dawn on October 21st. With only partial slice of Moon in the late evening/early morning, this looks to be the year’s last, best meteor shower!

“Every year around this time Earth glides through a cloud of dusty debris from Halley’s Comet,” explains Bill Cooke of the NASA Marshall Space Flight Center. “Bits of dust, most no larger than grains of sand, disintegrate in Earth’s atmosphere and become shooting stars.”

“It’s not an intense shower,” he says, “but it is a pretty one.”

Although Comet Halley has now departed the inner Solar System, its debris trail remains well organized – allowing us to predict when this meteor shower will occur. The Earth first enters the stream at the beginning of October and does not leave until the beginning of November. This makes your chances of “catching a falling star” above average!

“Earth comes close to the orbit of Halley’s Comet twice a year, once in May and again in October,” explains Don Yeomans, manager of NASA’s Near-Earth Object Program at the Jet Propulsion Laboratory. Orionid meteoroids strike Earth’s atmosphere traveling 66 km/s or 148,000 mph,” he continued. These meteors are very fast, and although faint (average magnitude 3), occasional fireballs do leave persistent trails that shimmer in the upper atmosphere. It’s the “Oooooh!” effect!

For best success, get away from city lights. Face south-southeast in the northern hemisphere and almost overhead in the southern – then relax and enjoy the stars of the Winter Milky Way. The radiant is near Betelguese, but may occur from any part of the sky. When the Moon rises, try positioning yourself so a house, tree, or other obstruction helps to reduce the glare. The meteor watching experience is much more comfortable if you include a reclining lawn chair, blanket, and thermos of your favorite beverage. Nothing spoils watching quicker than “meteor neck”.

Clouded out? Don’t despair. You don’t always need eyes or perfect weather to keep the watch. Tune an FM radio to the lowest frequency that doesn’t receive a clear signal. An outdoor FM antenna pointed to the zenith increases your chances – but isn’t essential. Simply turn up the static and listen. Those hums, whistles, beeps, bongs, and occasional snatches of signals are distant transmissions being reflected off a meteor’s ion trail!

Posted on by Tammy Plotner

Digging Deeper For Dark Matter

This artist's conception shows a dwarf galaxy seen from the surface of a hypothetical exoplanet. A new study finds that the dark matter in dwarf galaxies is distributed smoothly rather than being clumped at their centers. This contradicts simulations using the standard cosmological model known as lambda-CDM. Credit: David A. Aguilar (CfA)

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Dark matter… If it can’t be seen, then how do we know it’s there? If it wasn’t for the effects of gravity, we wouldn’t. We’d have a galaxy filled with runaway stars and no galaxy would exist for long. But how it behaves and how it is distributed in one of the biggest cosmic cryptograms of all. Even with new research, there seems to be more questions than answers!

“After completing this study, we know less about dark matter than we did before,” said lead author Matt Walker, a Hubble Fellow at the Harvard-Smithsonian Center for Astrophysics.

It is generally accepted that our Universe is predominately composed of dark matter and dark energy. Of the former, it is considered to be “cold”, stately exotic particles which coalesce through gravitation. As they evolve, these dark matter “clumps” then attract “normal” matter which forms present day galaxy structures. Through computer modeling, astronomers have simulated this growth process which concludes that galactic centers should be dense with dark matter. However, these models aren’t consistent with findings. By measuring two dwarf galaxies, scientists have found a even distribution instead.

“Our measurements contradict a basic prediction about the structure of cold dark matter in dwarf galaxies. Unless or until theorists can modify that prediction, cold dark matter is inconsistent with our observational data,” Walker stated.

Why study a dwarf instead of a spiral? In this case, the dwarf galaxy is a perfect candidate because of its composition – 99% dark matter and 1% stars. Walker and his co-author Jorge Penarrubia (University of Cambridge, UK) chose two nearby representatives – the Fornax and Sculptor dwarfs – for their study. In comparison to the Milky Way’s estimated 400 billion stars, this pair averages around 10 million instead. This allowed the team to take a comprehensive sample of around 1500 to 2500 stars for location, speed and basic chemical composition. But even at a reduced amount, this type of stellar accounting isn’t exactly easy picking.

“Stars in a dwarf galaxy swarm like bees in a beehive instead of moving in nice, circular orbits like a spiral galaxy,” explained Penarrubia. “That makes it much more challenging to determine the distribution of dark matter.”

What the team found was somewhat surprising. According to the modeling techniques, dark matter should have clumped at the core. Instead they found it evenly distributed over a distance measuring several hundred light years across.

“If a dwarf galaxy were a peach, the standard cosmological model says we should find a dark matter ‘pit’ at the center. Instead, the first two dwarf galaxies we studied are like pitless peaches,” said Penarrubia.

It is hypothesized that interactions between normal and dark matter might be responsible for the distribution, but the computer simulations say it shouldn’t happen to a dwarf. New queries to new findings? Yes. This revelation may suggest that dark matter isn’t always “cold” and that it could be impacted by normal matter in unexpected ways.

Original Story Source: Harvard Smithsonian Center for Astrophysics News Release. For Further Reading: A Method Of Measuring (Slopes Of) the Mass Profiles of Dwarf Spheroidal Galaxies.