Posted on by Jenny Winder

BepiColombo – Mission to Mercury

Caption: BepiColombo’s components separating at Mercury. Image Credit: Astrium

BepiColombo, due to launch in 2015, will be only the third spacecraft to visit Mercury and the first to be sent by the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA). Currently undergoing tests at ESA’s European Space Research and Technology Centre (ESTEC) in the Netherlands. Here are the details and objectives of this joint mission to our innermost planet which hopes to give us the best understanding of Mercury to date

As the innermost of the terrestrial planets Mercury has an important role in showing us how planets form, yet it is the least explored planet in the inner Solar System. NASA sent Mariner 10 in 1974–5 and MESSENGER flew passed the planet 3 times in 2008 and 2009, before going into orbit around it last year. Being in close proximity, the Sun’s enormous gravity makes placing a spacecraft into a stable orbit, a challenge.

Professor Giuseppe (Bepi) Colombo (1920–1984) was the Italian mathematician and scientist who developed the gravity-assist maneuver and helped NASA to devise the trajectory of Mariner 10. The spacecraft that bears his name comprises three components: the Mercury Transfer Module (MTM) and the two probes: Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO) It will take 6 years to make the journey from Earth to Mercury using solar-electric propulsion and gravity assists from the Earth and Venus, before eventual gravity capture at Mercury.

The transfer module will then separate and the orbiters will use rocket engines and a technique called ‘weak stability boundary capture’ to enter polar orbits around Mercury. MPO will enter a 2.3 hour period polar orbit and MMO a 9.3 hour period polar orbit. MPO is a 357 kg spacecraft in the shape of a flat prism will carry an imaging system consisting of a wide-angle and narrow angle camera, an infrared spectrometer, an ultraviolet spectrometer, gamma, X-ray, and neutron spectrometers, a laser altimeter, an ion and neutral spectrometer, a near-Earth object telescope and detection system, and radio science experiments. During the 1 year nominal mission it will map the entire surface in different wavelengths, and hopes to find water ice in polar craters permanently in shadow from the Sun’s rays.MMO is a flat cylinder with a mass of about 250 kg and will carry fluxgate magnetometers, charged particle detectors, a wave receiver, a positive ion emitter, and an imaging system.

The main mission objectives are: to investigate the origin and evolution of a planet close to the parent star; study Mercury’s form, interior structure, geology, composition and craters; examine the composition and dynamics of Mercury’s vestigial atmosphere (exosphere); probe the structure and dynamics of Mercury’s magnetized envelope (magnetosphere); determine the origin of Mercury’s magnetic field; investigate the composition and origin of polar deposits and perform a test of Einstein’s theory of general relativity.

In 1845, Urbain-Jean-Joseph Le Verrier, noticed that at perihelion Mercury was moving around the Sun faster than predicted by Newton’s theory of gravity. It was not understood until 1915 when Albert Einstein overhauled the theory of gravity. BepiColombo will measure Mercury’s motion more accurately than ever before and so provide one of the most rigorous tests ever of Einstein’s theory.

Find out more about the mission at ESA

Posted on by Nancy Atkinson

Awesome Map of Space Agencies Around the World

When you think of space agencies around the world, what comes to mind? Probably NASA, ESA, ISRO and JAXA are the acronyms you know; then there’s the Russian Federal Space Agency, the Canadian Space Agency, and the China National Space Agency. But did you know there are dozens of countries with space agencies, with nearly 200 space agencies and centers around the world? Blogger Heather Archuletta has put together a map and list of all the space agencies on the planet, including countries you may not have realized had a space agency such as Argentina, Bulgaria, Pakistan Morocco, and more. The list includes links to all the space agency’s websites and a link to an interactive Google Map. The immediate thought that came to mind, which Heather shared on Twitter was, ROAD TRIP!

For any space nerd, that would be the ultimate global trek, to visit every space agency in the world. With all the NASA and Russian centers and all the various countries in ESA, your trip would include 198 locations around our planet!

Heather is known for her Pillownaut blog which originally detailed her time participating in NASA bedrest studies to simulate long duration spaceflight. The space agency map was a new project, born from a conversation with a friend.

“Overall, I created it to be a tracking tool, and to show how huge the space industry has become,” Heather told Universe Today. “Many people think of the space game as being the US, Russia and a handful of Europeans… but truly, lifestyle in many countries is dependent upon the use of space, even if it’s just as simple as remote sensing or collaborative satellites.”

Heather noted that the map includes one site in India that is not operational yet, but built.

But consider how many jobs around the world have been created because of space exploration… and these jobs employ some of the best and brightest minds in forward-thinking, global-enriching ways. And even more, there’s now the burgeoning private space industry that is employing even more people with jobs that focus on the future.

Check out http://pillownaut.com/spacemap/spacemap.html and plan your space-nerd road trip today!

Posted on by Paul Scott Anderson

Hayabusa 2 Mission Approved by Japanese Government

Artist's conception of Hayabua 2 approaching the asteroid 1999 JU3. Credit: Akihiro Ikeshita/JAXA

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In 2010, the Japanese spacecraft Hayabusa completed an exciting although nail-biting mission to the asteroid Itokawa, successfully returning samples to Earth after first reaching the asteroid in 2005; the mission almost failed, with the spacecraft plagued by technical problems. The canister containing the microscopic rock samples made a soft landing in Australia, the first time that samples from an asteroid had been brought back to Earth for study.

Now, the Japanese government has approved a follow-up mission, Hayabusa 2. This time the probe is scheduled to be launched in 2014 and rendezvous with the asteroid known as 1999 JU3 in mid-2018. Samples would again be taken and returned to Earth in late 2020.

1999 JU3 is approximately 914 metres (3,000 feet) in diameter, a little larger than Itokawa, and is roughly spherical in shape, whereas Itokawa was much more oblong.

As is common for any space agency, the Japanese Aerospace Exploration Agency (JAXA) is working with tight budgets and deadlines to make this next mission happen. There is a possibility of a back-up launch window in 2015, but if that deadline is also not met, the mission will have to wait another decade to launch.

The asteroid Itokawa, visited by Hayabusa in 2005. Credit: JAXA

One of the main problems with Hayabusa was the failure of the sampling mechanism during the “landing” (actually more of a brief contact with the surface with the sample capturing device) to retrieve the samples for delivery back to Earth. Only a small amount of material made it into the sample capsule, but which was fortunate and ultimately made the mission a limited success. The microscopic grains were confirmed to have primarily come from Itokawa itself and are still being studied today.

To avoid a repetition of the glitches experienced by Hayabusa, some fundamental changes needed to be made.

This next spacecraft will use an updated ion propulsion engine, the same propulsion system used by Hayabusa, as well as improved guidance and navigation systems, new antennas and a new altitude control system.

For Hayabusa 2’s sample-collecting activities, a slowly descending impactor will be used, detonating upon contact with the surface, instead of the high-speed projectile used by Hayabusa. Perhaps not quite as dramatic, but hopefully more likely to succeed. Like its predecessor, the main objective of the mission is to collect as much surface material as possible for delivery back home.

Hopefully Hayabusa 2 will not be hampered by the same problems as Hayabusa; if JAXA can achieve this, it will be exciting to have samples returned from a second asteroid as well, which can only help to further our understanding of the history and formation of the solar system, and by extrapolation, even other solar systems as well.

Posted on by Ray Sanders

Best-Ever Topographic Map of Earth from NASA and Japan

At 4.4 kilometers in elevation, California's Mt. Whitney is the highest point in the continental United States. Image credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

[/caption]NASA and Japan recently announced a new and improved digital topographic map of Earth, which was produced with detailed measurements from NASA’s Terra spacecraft.

The new data covers over 99 percent of Earth’s landmass and spans from 83 degrees north latitude to 83 degrees south. Each elevation measurement point in the data is only 30 meters apart.

How were scientists able to improve on previous generations of detailed topographic maps?


The new model, known as a global digital elevation model, was created from images collected by the Japanese Advanced Spaceborne Thermal Emission and Reflection Radiometer, or ASTER, instrument aboard NASA’s Terra spacecraft. To create a “stereo pair” image,scientists can take two slightly offset images and combine them to create a three-dimensional effect of depth.

The previous version of the global digital elevation model was released in June of 2009 by NASA and Japan’s Ministry of Economy, Trade and Industry.

“The ASTER global digital elevation model was already the most complete, consistent global topographic map in the world,” said ASTER program scientist Woody Turner, “With these enhancements, its resolution is in many respects comparable to the U.S. data from NASA’s Shuttle Radar Topography Mission, while covering more of the globe.”

The ASTER team added 260,000 stereo-pair images to improve the previous model, which improved spatial resolution, increased horizontal and vertical accuracy, and provided the ability to identify lakes as small as 1 kilometer in diameter.

“This updated version of the ASTER global digital elevation model provides civilian users with the highest-resolution global topography data available,” said ASTER science team lead Mike Abrams. “These data can be used for a broad range of applications, from planning highways and protecting lands with cultural or environmental significance, to searching for natural resources.”

Arguably one of America's most magnificent national parks is the Grand Canyon in northern Arizona. Image credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

Joining together in a collaborative effort, NASA and METI are contributing data for the ASTER topographic map to the Group on Earth Observations, for use in the group’s Global Earth Observation System of Systems. No, the previous statement wasn’t a typo – the “system of systems” is an international effort, which uses shared Earth observation data to help monitor and forecast global environmental changes.

One of five instruments launched on Terra in 1999, ASTER acquires images from visible to thermal infrared wavelengths, with spatial resolutions ranging from about 15 to 90 meters. ASTER’s science team is a joint effort between the United States and Japan.

The ASTER data was validated by NASA, METI, Japan’s Earth Remote Sensing Data Analysis Center (ERSDAC), and the U.S. Geological Survey, with additional support from the U.S. National Geospatial-Intelligence Agency and other collaborators. NASA’s Land Processes Distributed Active Archive Center is handling the distribution of the new ASTER global digital elevation model.

If you’d like to download the ASTER global digital elevation model to study at no cost, you can do so at: https://lpdaac.usgs.gov/ or http://www.ersdac.or.jp/GDEM/E/4.html

To learn more about ASTER, or NASA’s Terra mission, visit: http://asterweb.jpl.nasa.gov/ and http://www.nasa.gov/terra

Source: NASA/JPL Press Release

Posted on by Jason Rhian

Book Review: The Space Shuttle: Celebrating Thirty Years of NASA’s First Space Plane

The Space Shuttle: Celebating Thirty Years Of NASA's First Space Plane is chocked full of great imagery and works to cover each of the shuttle's 135 missions. Photo Credit: Zenith Press

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The space shuttle program is over. The orbiters are being decommissioned, stripped of the components that allowed them to travel in space. For those that followed the program, those that wished they did and those with only a passing interest in what the program accomplished a new book has been produced covering the entirety of the thirty years that comprised NASA’s longest human space flight program. The Space Shuttle: Celebrating Thirty Years of NASA’s First Space Plane is written by aerospace author Piers Bizony and weighs in at 300 pages in length.

Bizony is a prolific author who has focused a lot of his work on space flight. Some of the books that he has written include (but definitely are not limited to) include: One Giant Leap: Apollo 11 Remembered, Space 50, The Man Who Ran the Moon: James E. Webb, NASA, and the Secret History of Project Apollo and Island in the Sky: The International Space Station.

Bizony pulls out all the stops in detailing the shuttle era. From thunder and light - to tragedy, the full spectrum of the shuttle program is highlighted here. Photo Credit: NASA

The book contains 900 color images, detailing the entire history of NASA’s fleet of orbiters. From the first launches and the hope that those initial flights were rich in, to the Challenger tragedy and the subsequent realization that the space shuttles would never be what they were intended to be.

The next phase of the book deals with the post-Challenger period and how NASA worked to find a balance with its fleet of orbiters, while at the same time worked to regain the trust of the America public. The path was both hindered and helped by a single payload – the Hubble Space Telescope.

The Space Shuttle: Celebrating Thirty Years of NASA’s First Space Plane - has stunning imagery on every page, allowing the reader to once again view the majesty that the shuttle program provided. Photo Credit: NASA

When the images the orbiting telescope beamed back turned out fuzzy, NASA was a laughing stock. Hubble would become a sensation and NASA redeemed its name after the first servicing mission to Hubble corrected the problem with the telescope’s mirror.

Hubble was not the only telescope or probe that the shuttle placed in the heavens. It would however, be the only one that NASA’s fleet of orbiters would visit during several servicing missions. Besides Hubble the shuttle also sent the Chandra X-Ray telescope, Galileo probe to Jupiter and the Magellan probe to Venus during the course of the program’s history.

It is currently unknown when the U.S. will launch crews into orbit again. Some aerospace experts have even suggested that the shuttles be pulled out of retirement to help fill this gap - but this is highly unlikely to happen. Photo Credit: NASA

NASA was now on course to begin construction of the most ambitious engineering feat in human history – the International Space Station. The Space Shuttle: Celebrating Thirty Years of NASA’s First Space Plane details this period, as well as the tragic loss of the shuttle Columbia in 2003 with great care and attention to detail. Many never-before-seen images are contained within and Bizony uses them to punctuate the history that the space shuttle accomplished with every flight.

With a chance of catastrophic failure estimated by some as being as high as one chance in 53 - the shuttle was a risky endeavor. However, given all of the program's accomplishments - it is not a stretch to say that the shuttle made fact out of last century's science fiction. Photo Credit: NASA

The book also contains a detailed diagram of the orbiter (it is long and therefore was produced as a pull-out section. This element is included near the end and acts as a nice punctuation mark to the stream of imagery contained within.

While it required the combined effort of 16 different nations to make the International Space Station work - the space shuttle made the orbiting laboratory a reality. Photo Credit: NASA

The book is not perfect (but what book is). If one did not know better, upon reading this book one would assume that the Delta Clipper (both DC-X and DC-XA) flew once and upon landing caught fire. DC-X flew eight times – not once. Bizony also describes the lunar element of the Vision for Space Exploration (VSE) as being a repeat of Apollo. Apollo 17 was the longest duration that astronauts roamed the Moon’s surface – they were there for about three days. The VSE called for a permanent crewed presence on the moon.

For those out there that consider themselves “shuttle huggers” this book is simply a must-have. It is perfect to take to autograph shows to be signed by astronauts (as every mission is detailed, it is a simple matter to have crew members sign on the pages that contain their missions). It is also a perfect gift for space aficionados this holiday season. Published by Zenith Press and retailing for $40.00, The Space Shuttle: Celebrating Thirty Years of NASA’s First Space Plane is a welcome addition to your home library.

How will the shuttle be remebered? According to Bizony, given the technological restraints and the numerous accomplishments that the orbiter accomplished - it will be remembered in a positive light. Photo Credit: NASA
Posted on by Jason Rhian

NASA Facing Astronaut Deficit

A National Research Council report states that NASA's ability to conduct normal human space flight operations could be hampered if it cannot maintain a robust astronaut corps. Photo Credit: Jason Rhian

[/caption]This past December the White House directed the National Academies to review how many astronauts that NASA actually needed to conduct its operations in the post-shuttle era. New findings in a new report are showing that rather than the space agency having too many astronauts – it will have too few to meet mission objectives. The National Research Council (NRC) has released a report showing that NASA is entering into a period where low numbers of qualified astronauts will affect the agency’s ability to conduct human space flight operations.

NASA once had a strong, stable astronaut corps but the agency has slowly but surely saw those numbers dwindle. In 1999 NASA had 150 astronauts today it has 61 – with more leaving the space agency every month. NASA needs to have a stable corps of space flyers for not only International Space Station operations but also to help develop the Orion Multi-Person Crew Vehicle (MPCV).

With the shuttle program over and the fleet of orbiters on their way to museums, many astronauts are opting to leave the space agency. Photo Credit: Jason Rhian

Moreover NASA needs its astronaut corps to remain stable so as to maintain its agreements with the Russian Federal Space Agency, European Space Agency, Japanese Aerospace Exploration Agency and Canadian Space agency. Fewer astronauts weakens NASA’s ability to fulfill operations that are required under these arrangements.

NASA is losing astronauts at approximately the rate of one every two months. If this exodus is allowed to continue the agency’s ability to conduct normal operations will be dramatically impaired. The NRC report highlights many of the nuances that space flight requires – most of which are missed when one considers space flight. Ground operations, emergency response, training and other elements that are involved with crewed space flight operations.

Astronaut Mark Kelly, who commanded the final flight of the space shuttle Endeavour has announced that he will leave NASA effective Oct. 1, the commander of STS-133, the final flight of Discovery, has already departed the space agency. Photo Credit: Jason Rhian

For many astronauts however the appeal of working for the space agency is fading. NASA no longer has clear-cut objectives as it once did. In 2004 plans were announced for NASA to go to the Moon, Mars and then other points in the solar system after the shuttle was retired. In 2010 NASA had the so-called ‘Vision for Space Exploration’ cancelled and the space agency was directed to assist commercial entities in developing technology to reach low-Earth-orbit. It is hoped that once these firms become viable NASA will be freed to fly to an asteroid and then Mars sometime in the 2030s.

NASA is experiencing what some might call a “brain drain” not only are astronauts departing the agency in large numbers – so too are other NASA officials. In recent months NASA’s Chief Technologist Bobby Braun, Safety Chief Bryan O’Connor and the Associate Administrator for Exploration Douglas Cooke (who has been with NASA for 38 years) have either left NASA or signaled their intent to do so.

Posted on by Jason Rhian

Book Review: A Dictionary of the Space Age

A Dictionary of the Space Age covers most aspects of space flight but is somewhat lacking in detail. Image Credit: John Hopkins University & Alan Walters/awaltersphoto.com

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Writing a dictionary is not the same as writing a novel. While it might seem difficult to mess up a dictionary, even one with terminology that is as complicated as that used within the space industry – getting it right can be challenging. For those that follow space flight having such a dictionary can be invaluable. While A Dictionary of the Space Age does meet the basic requirements easily it fails somewhat in terms of its comprehensiveness.

When normal folks, even space enthusiasts watch launches and other space-related events (EVAs, dockings, landings and such) there are so many acronyms and jargon thrown about – that it is extremely hard to follow. With A Dictionary of the Space Age on hand, one can simply thumb through and find out exactly what is being said, making it both easier to follow along and making the endeavor being witnessed far more inclusive. That is as long if you are only looking for the most general of terms. The book is far from complete – but given the complex nature of the topic – this might not have been possible.

Crewed, unmanned, military space efforts and satellites – all have key terms addressed within the pages of this book.

The book is published by The Johns Hopkins University Press and was compiled and written by aerospace expert Paul Dickson. One can purchase the book on the secondary market (Amazon.com) for around $12 (new for around $25). The dictionary also has a Kindle edition which is available for $37.76. Dickson’s previous works on space flight is Sputnik: The Shock of the Century.

Weighing in at 288 pages, the book briefly covers the primary terms used within the space community. In short, if you are interested in learning more about space flight – or wish to do so – this is a good book for you.

Posted on by Tammy Plotner

MAXI Peers Into Black Hole Binaries

X-ray all-sky image obtained by MAXI's first 10-month observation Bright X-ray sources (mainly binaries comprising neutron stars and black holes) exist in large numbers around the Galactic Center (in the direction of Sagittarius) and along the Galactic Plane (Milky Way) and change from day to day. Colors indicate the "hardness" of X-ray spectrum. More than 200 X-ray sources including weak ones have been identified. Credit: JAXA

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The Monitor of All-sky X-ray Image, or MAXI for short, spends its time aboard the ISS conducting a full sky survey every 92 minutes. Its sole purpose is to monitor X-ray source activity and report. Unlike stars seen in visible light, X-ray sources aren’t evenly distributed and can exhibit some highly unusual behavior. What causes these erratic moments? Read on…

“Most visible stars shine with energies generated by nuclear fusion in their cores. In these stars, if the energy generated in their core increases more than usual, the whole object expands and eventually lowers the core temperature. In this way, negative feedback is activated to stabilize the nuclear reaction. For this reason, these stars shine very stably for most of their lifetime.” says Nobuyuki Kawai of the Tokoyo Institute of Technology. “On the other hand, the energy source of most intense X-ray sources is gravitational energy released when the gas surrounding extremely compact bodies like black holes and neutron stars is accreted onto them. The normal stars’ stabilizing mechanism does not work in this process, and accordingly, X-ray intensity fluctuates in response to changes in the supply of gas from the surrounding area.”

This means MAXI needs to keep a close watch on both known and unknown X-ray sources for activity. Catching it as it happens allows an alert to be posted to other observatories for monitoring and study. Right now the focus has been on MAXI’s 18 month study of black hole binaries – the most famous of which is Cygnus X-1. It is well-known this famous source shines brilliantly in the X-ray spectrum, but it switches between a “hard” and “soft” state. These periods of high and low energy may be directly related to the density of gas which surrounds it.

“We can get a clue to estimate the mass of a black hole by examining the X-ray intensity and radiation spectrum in the soft state. As a result of analysis of the motion of the companion star rotating the center of gravity of the binary system, we found that Cygnus X-1 is a remarkably smaller object than normal stars, with an X-ray source mass about 10 times the solar mass but which emits hardly any visible light.” says Professor Kawai. “If applying star theory, such an object must be a black hole.”

Right now astronomers are studying gas properties and estimate there are about 20 binary X-ray sources other than Cygnus X-1. Most of these black hole binaries are considered to be “X-ray nova” – showing activity anywhere from every few years to only once in the four decades we’ve been studying them in this light. With the help of MAXI’s sensitive all-sky monitoring, researchers now stand a chance of being able to monitor activity from beginning to end. Has it been successful? You bet. When black hole binary, XTE J1752-223, was discovered by the routine patrol of RXTE, MAXI also detected the emergence of this new X-ray nova and was able to observe all the activities until it disappeared in April 2010. On September 25, 2010 MAXI and the Swift satellite discovered black hole binary MAXI J1659-152 almost simultaneously allowing it to be observed by researchers and amateur astronomers around the world.

“In addition to these black hole binaries, MAXI has achieved many interesting observations including: detection of the largest flare from active galactic nuclei in X-ray observation history; discovery of a new binary X-ray pulsar, MAXI J1409-619; and detection of a number of intense star flares.” says Kawai. “As long as the ISS is operating, we will use MAXI to monitor the X-ray sky, which changes restlessly and violently.”

Original Story Source: Japan Aerospace Exploration Agency.

Posted on by Nancy Atkinson

Japan’s Trash-laden HTV-2 Undocks from ISS

Japan's Kounotori 2 –or ‘White Stork’ – cargo carrier as it arrived at the ISS in January. Credit: Paolo Nespol/NASA

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Japan’s HTV-2 Kounotori resupply ship undocked from the International Space Station at 15.45 GMT on March 28, and will burn up in Earth’s atmosphere sometime early Wednesday March 31. Back in January, the craft brought five metric tons of equipment and supplies to the station, but now it is loaded with trash and unneeded equipment and packing materials. Most of the HTV will likely disintegrate as it passes through the atmosphere, but any pieces left over will find a watery grave in a remote area in the Central Pacific. But sensors on board the HTV-2 will provide data on how the craft behaves during its fiery demise.

The Re-entry Breakup Recorder (REBR) will record temperature, acceleration, rotational rate and other data.

The second HTV from Japan arrived at the ISS on January 27 carrying its cargo of food, water supplies, and equipment. Japan expects to send another seven cargo ships to the station by 2015, with the next one scheduled to arrive in January 2012.

The ISS crew grappled HTV-2 with the Canadarm 2, undocked it from the station and then maneuvered the HTV into a release position about 30 feet below the station. The Space Station Integration and Promotion Center in Tsukuba, Japan was able to handle the commands to activate and check out the freighter’s guidance, navigation and control systems. Because of the March 11 earthquake in Japan, controls of the HTV and Japan’s Kibo laboratory was temporarily handed over to NASA in Houston, but the center is now fully restored for full commanding, telemetry and voice capabilities for the ISS.

The cargo ship will enter the atmosphere on Wednesday at 03.09 GMT, and any remaining fragments will fall into the Pacific Ocean 31 minutes later.

So long Konotori, and we thank you.

Posted on by Anne Minard

Perseus Cluster Thicker Around the Middle Than Thought

Credits: NASA/ISAS/DSS/A. Simionescu et al.; inset: NASA/CXC/A. Fabian et al.

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The Japanese Suzaku X-ray telescope has just taken a close look at the Perseus galaxy cluster, and revealed it’s got a bit of a spare tire.

Suzaku explored faint X-ray emission of hot gas across two swaths of the Perseus Galaxy Cluster. The resulting images, which record X-rays with energies between 700 and 7,000 electron volts in a combined exposure of three days, are shown in the two false-color strips above. Bluer colors indicate less intense X-ray emission. The dashed circle is 11.6 million light-years across and marks the so-called virial radius, where cold gas is now entering the cluster. Red circles indicate X-ray sources not associated with the cluster.

The results appear in today’s issue of Science.

The Perseus cluster (03hh 18m +41° 30‘) is the brightest extragalactic source of extended X-rays.

Lead author Aurora Simionescu, an astrophysicist at Stanford, and her colleagues note that until now, most observations of galaxy clusters have focused on their bright interiors. The Suzaku telescope was able to peer more closely at the outskirts of the Perseus cluster. The resulting census of baryonic matter (protons and neutrons of gas and metals) compared to dark matter offers some surprising observations.

It turns out the fraction of baryonic matter to dark matter at Perseus’s center was consistent with measurements for the universe as a whole, but the baryonic fraction unexpectedly exceeds the universal average on the cluster’s outskirts.

“The apparent baryon fraction exceeds the cosmic mean at larger radii, suggesting a clumpy distribution of the gas, which is important for understanding the ongoing growth of clusters from the surrounding cosmic web,” the authors write in the new paper.

Source: Science. See also JAXA’s Suzaku site