- Ukraine Appoints New Chairman of State Space Agency
- Live Fast Die Young: Galaxies Lose the Gas That Keeps Them Alive
- Roscosmos to Replace Ukraine’s Zenith Launchers with Angara Rockets
- Russian Proton-M Rocket Successfully Launches Inmarsat-5 F-2 Satellite
- Japan Launches New Backup Intelligence Satellite
- NASA Successfully Launches Soil Moisture Mapping Satellite
- High-Def Radar Images of Asteroid 2004 BL86 Released
- Meteorite May Represent ‘Bulk Background’ of Mars’ Battered Crust
- Gravitational Waves Remain Elusive
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Posted: 02 Feb 2015 05:19 AM PST
Introduction of the new Chairman of the State Space Agency of Ukraine (SSAU) – Dr. Oleg S. Uruskyi has taken place on Jan. 26, 2015 at the State Space Agency of Ukraine HQ. The Vice Prime-Minister - Minister of Regional Development, Construction, Housing and Utilities of Ukraine – Gennadiy Zubko read out loud the Resolution #26-r of the Cabinet of Ministers of Ukraine as of Jan. 21, 2015 “On the appointment of Dr. Oleg Uruskyi the Chairman of SSAU". In his speech the Vice Prime-Minister emphasized the important tasks facing the space industry and its leader.
Welcoming the new Chairman of SSAU with this appointment, Advisor to the President of Ukraine - Director of the National Institute for Strategic Studies Mr. Volodymyr Gorbulin noted that in 1992-1996 Dr. Uruskyi was a member of the team, which created the Space Agency and started implementation of the first space missions of Ukraine. While presenting his vision of the future as the Head of SSAU Dr. Uruskyi stressed that "Complex challenges are addressed to the Space Agency. However, I'm certain that we can manage them together". SSAU is a minor descendant of the Soviet space program that was majorly passed to the Russian Federal Space Agency. The agency took over all former Soviet defense industrial complex that was located on the territory of Ukraine. Ukraine became officially the tenth space power (country able to launch own satellite by own launcher) on Aug. 31, 1995 (at start of Sich-1 on Tsyklon). Credit: nkau.gov.ua  | ||||
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Posted: 02 Feb 2015 04:50 AM PST
Galaxies can die early because the gas they need to make new stars is suddenly ejected, research published today suggests. Most galaxies age slowly as they run out of raw materials needed for growth over billions of years. But a pilot study looking at galaxies that die young has found some might shoot out this gas early on, causing them to redden and kick the bucket prematurely. Astrophysicist Ivy Wong, from the University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR), said there are two main types of galaxies; ‘blue’ galaxies that are still actively making new stars and ‘red’ galaxies that have stopped growing.
Most galaxies transition from blue to ‘red and dead’ slowly after two billion years or more, but some transition suddenly after less than a billion years—young in cosmic terms. Dr Wong and her colleagues looked for the first time at four galaxies on the cusp of their star formation shutting down, each at a different stage in the transition. The researchers found that the galaxies approaching the end of their star formation phase had expelled most of their gas. Dr Wong said it was initially hard to get time on telescopes to do the research because other astronomers did not believe the dying galaxies would have any gas left to see. The exciting result means the scientists will be able to use powerful telescopes to conduct a larger survey and discover the cause of this sudden shutdown in star formation. Dr Wong said it is unclear why the gas was being expelled. “One possibility is that it could be blown out by the galaxy’s supermassive black hole,” she said. “Another possibility is that the gas could be ripped out by a neighbouring galaxy, although the galaxies in the pilot project are all isolated and don’t appear to have others nearby.” Swiss Federal Institute of Technology Professor Kevin Schawinski said the researchers predicted that the galaxies had to rapidly lose their gas to explain their fast deaths. “We selected four galaxies right at the time where this gas ejection should be occurring,” he said. “It was amazing to see that this is exactly what happens!” The study appeared in the journal Monthly Notices of the Royal Astronomical Society, published by Oxford University Press. Credit: icrar.org  | ||||
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Posted: 02 Feb 2015 04:34 AM PST
Roscosmos won't any longer buy Zenith rockets produced in Ukraine’s Dnipropetrovsk, Izvestia daily writes on Monday referring to representative of Roscosmos Igor Burenkov. He said the agency would not buy any Zenith launchers, and the satellites that were supposed to be launched by them will be orbited by new launchers of the Angara class. "Our industry has just finished work on a modern rocket that can carry out any tasks, and thus we don't need to buy rockets from Ukraine any longer," the newspaper quotes the representative.
Izvestia writes that Roscosmos planned three launches of Zenith rockets for 2016-2018, and two more were due this year - meteorology satellites Elector-L and scientific apparatuses, like the Spektr-RG Observatory. Engines for Zenith rockets are produced in Russia, not far from Moscow, where Izvestia learned the company has five ready engines for Zeniths - they were produced in 2013-2014. Head of the Energia Space Corporation, producing the engines, Vladimir Solntsev, told the newspaper the company suggests using the engines for a new launcher of the super-heavy class. Credit: TASS  | ||||
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Posted: 01 Feb 2015 01:59 PM PST
International Launch Services (ILS) opened their 2015 campaign Sunday with the launch of the Russian Proton-M launch vehicle, from the Baikonur cosmodrome in Kazakhstan, carrying British Inmarsat-5 F-2 communications satellite – part of the Inmarsat Global Xpress (GX) system – on a multi-hour flight to its transfer orbit. "The launch took place at 15:31 Moscow time [7:31 a.m. EST]," the Russian Federal Space Agency (Roscosmos) spokesperson said. Separation of I-5 F2 and release into geosynchronous orbit is scheduled to occur 15 hours and 31 minutes after blast-off, at which point control of the satellite will pass to Inmarsat’s mission team.
Once operational, I-5 F2 will deliver Global Xpress services to the Americas and the Atlantic Ocean Region, complementing Inmarsat-5 F1 coverage in the Indian Ocean Region. The third satellite in the constellation is scheduled for launch early in 2015, enabling the Global Xpress network to become globally available – expected early in the second half of this year.
“Global Xpress is a truly transformational technology and, as we complete its global roll-out, 2015 promises to be one of the most significant chapters in our company’s history,” said Rupert Pearce, CEO of Inmarsat.
The Boeing Space and Intelligence Systems built Inmarsat-5 F2 communications satellite is based on the BSS-702HP Platform.
This was Russia's first launch of 2015. Earlier this month, the launch was moved to February 1 due to the client's request, the Russian Federal Space Agency spokesperson said.
The Proton-M is the largest carrier rocket in Russia's fleet of space launch vehicles. The rocket has lifted dozens of Russian-made and foreign satellites since it was first launched in 2001.
This is the second Inmarsat satellite to be launched using the Proton carrier rocket. The first Global Xpress satellite, Inmarsat-5 F1, blasted off from the Baikonur Cosmodrome on 8 December 2013.
Credit: inmarsat.com, sputnikn
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Posted: 01 Feb 2015 01:00 PM PST
Mitsubishi Heavy Industries Ltd. and the Japan Aerospace Exploration Agency (JAXA), successfully launched a backup information-gathering radar satellite on an H-2A rocket on Sunday. The H-2A Launch Vehicle No. 27 lifted off from JAXA’s Tanegashima Space Center on Tanegashima island in Kagoshima Prefecture, southwestern Japan, at 10:21 a.m. The satellite was put into orbit after being separated from the rocket and was confirmed to be functioning properly, according to Mitsubishi Heavy and JAXA, a government-affiliated body.
Following the successful launch, Prime Minister Shinzo Abe said in a statement that the government will build a reliable system for gathering information in order to boost Japan’s national security and enhance its crisis management capabilities.
Koji Shimohira, head of the space center, told a news conference, “We will appropriately operate the satellite to gather information that is truly needed.”
The information gathering satellite is equipped with a radar spy instrument capable of peering through clouds, darkness and camouflage to obtain high-resolution imagery of the Earth's surface.
The launch was supposed to take off on Jan. 29, but was delayed due to adverse weather conditions.
Tokyo put spy satellites into operation in the early 2000s after its erratic neighbour North Korea fired a mid-range ballistic missile over the Japanese mainland and into the western Pacific in 1998.
Credit: the-japan-news.com
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Posted: 01 Feb 2015 11:19 AM PST
NASA successfully launched its first Earth satellite designed to collect global observations of the vital soil moisture hidden just beneath our feet. The Soil Moisture Active Passive (SMAP) observatory, a mission with broad applications for science and society, lifted off at 6:22 a.m. PST (9:22 a.m. EST) Saturday from Vandenberg Air Force Base, California, on a United Launch Alliance (ULA) Delta II rocket. "The launch of SMAP completes an ambitious 11-month period for NASA that has seen the launch of five new Earth-observing space missions to help us better understand our changing planet," said NASA Administrator Charles Bolden. "Scientists and policymakers will use SMAP data to track water movement around our planet and make more informed decisions in critical areas like agriculture and water resources."
About 57 minutes after liftoff, SMAP separated from the rocket's second stage into an initial 411- by 425-mile (661- by 685-kilometer) orbit. After a series of activation procedures, the spacecraft established communications with ground controllers and deployed its solar array. Initial telemetry shows the spacecraft is in excellent health.
“All subsystems are being powered on and checked out as planned,” Kent Kellogg, the SMAP project manager, announced during a post-launch press conference. “Communications, guidance and control, computers and power are all operating nominally.”
The observatory’s instruments won’t be turned on until 11 days after launch, in keeping with the mission’s timeline.
The Educational Launch of Nanosatellite (ELaNa) initiative X auxiliary payload that flew aboard the Delta II also was deployed on time.
“All four ELaNa CubeSats were ejected from the second stage per the mission timeline, and are flying free,” said Scott Higginbotham, NASA ELaNa X mission manager from NASA’s Kennedy Space Center.
The FIREBIRD-II (A and B) payload has also been deployed. This is a two-Cubesat space weather project that will study electron microbursts in the Van Allen radiation belts.
“Congratulations to the NASA Launch Services Program team, JPL and all of our mission partners on today’s successful launch of the SMAP satellite,” said Jim Sponnick, ULA vice president, Atlas and Delta Programs. “It is our honor to launch this important Earth science mission to help scientists observe and predict natural hazards, and improve our understanding of Earth’s water, energy and carbon cycles.”
SMAP now begins a three-year mission that will figuratively scratch below Earth's surface to expand our understanding of a key component of the Earth system that links the water, energy and carbon cycles driving our living planet. SMAP’s combined radar and radiometer instruments will peer into the top 2 inches (5 centimeters) of soil, through clouds and moderate vegetation cover, day and night, to produce the highest-resolution, most accurate soil moisture maps ever obtained from space.
The mission will help improve climate and weather forecasts and allow scientists to monitor droughts and better predict flooding caused by severe rainfall or snowmelt -- information that can save lives and property. In addition, since plant growth depends on the amount of water in the soil, SMAP data will allow nations to better forecast crop yields and assist in global famine early-warning systems.
SMAP also will detect whether the ground is frozen or thawed. Detecting variations in the timing of spring thaw and changes in the length of the growing season will help scientists more accurately account for how much carbon plants are removing from Earth's atmosphere each year.
"The next few years will be especially exciting for Earth science thanks to measurements from SMAP and our other new missions," said Michael Freilich, director of the Earth Science Division of NASA’s Science Mission Directorate in Washington. "Each mission measures key variables that affect Earth’s environment. SMAP will provide new insights into the global water, energy, and carbon cycles. Combining data from all our orbiting missions will give us a much better understanding of how the Earth system works."
SMAP will orbit Earth from pole to pole every 98.5 minutes, repeating the same ground track every eight days. Its 620-mile (1,000-kilometer) measurement swath allows SMAP to cover Earth’s entire equatorial regions every three days and higher latitudes every two days. The mission will map global soil moisture with about 5.6-mile (9-kilometer) resolution.
"SMAP will improve the daily lives of people around the world,” said Simon Yueh, SMAP project scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California. "Soil moisture data from SMAP has the potential to significantly improve the accuracy of short-term weather forecasts and reduce the uncertainty of long-term projections of how climate change will impact Earth's water cycle.”
The SMAP team is engaged with many organizations and individuals that see immediate uses for the satellite’s data. Through workshops and tutorials, the SMAP Applications Working Group is collaborating with 45 “early adopters” to test and integrate the mission's data products into many different applications. Early adopters include weather forecasters from several nations, as well as researchers and planners from the U.S. Department of Agriculture, U.S. Geological Survey, U.S. Centers for Disease Control and Prevention, and the United Nations World Food Programme.
During the next 90 days, SMAP and its ground system will be commissioned to ensure they are fully functional and are ready to begin routine science data collection. A key milestone will be the deployment of the spacecraft’s instrument boom and 20-foot- (6-meter)-diameter reflector antenna. The observatory will be maneuvered to its final 426-mile (685-kilometer), near-polar operational orbit, and the antenna will spin up to 14.6 revolutions per minute.
SMAP science operations will then begin, and SMAP data will be calibrated and validated. The first release of SMAP soil moisture data products is expected within nine months. Fully validated science data are expected to be released within 15 months.
SMAP is managed for NASA's Science Mission Directorate in Washington by JPL, with instrument hardware and science contributions made by NASA's Goddard Space Flight Center in Greenbelt, Maryland. JPL built the spacecraft and is responsible for project management, system engineering, radar instrumentation, mission operations and the ground data system. Goddard is responsible for the radiometer instrument and science data products. Both centers collaborate on science data processing and delivery to the Alaska Satellite Facility, in Fairbanks, and the National Snow and Ice Data Center at the University of Colorado in Boulder. NASA's Launch Services Program at the agency's Kennedy Space Center in Florida was responsible for launch management. JPL is managed for NASA by the California Institute of Technology in Pasadena.
ULA's next launch is the Atlas V Magnetospheric Multiscale (MMS) mission for NASA, scheduled for March 12 from Space Launch Complex-41 from Cape Canaveral Air Force Station, Florida.
Credit: NASA, ulalaunch.com
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Posted: 01 Feb 2015 10:45 AM PST
A team of astronomers using the National Science Foundation's Green Bank Telescope (GBT) in West Virginia and NASA's Deep Space Network radar transmitter at Goldstone, California, has made the most detailed radar images yet of asteroid 2004 BL86. The images, which were taken early in the morning on Jan. 27, 2015, reveal the asteroid's surface features in unprecedented clarity. At the time of the observations, the asteroid was traveling away from the Earth, so its distance varied from 1.3 million to 1.6 million kilometers, or about three-and-a-half to four times the distance from the Earth to the Moon. To make these images, a continuous radar signal was sent from the transmitter at Goldstone to the asteroid. The reflected signal was then received by the 100-meter diameter dish of the GBT in a process known as bistatic radar imaging.
The GBT images also confirmed the presence of a small moon-like companion zipping around the asteroid, which was previously detected with ground-based optical telescopes by Joe Pollock of Appalachian State University in Boone, North Carolina, and Petr Pravec of Ondrejov Observatory in the Czech Republic.
Radar images are particularly valuable in studying asteroids because they enable very high-resolution imaging. At the distance of the GBT observations, ground-based optical telescopes would produce images with a resolution of about 100 meters per pixel, so the asteroid would appear as a smudgy blob. The resolution of radar images, however, depends on how the signal is coded and the strength of the return signal, not the size of a telescope lens or mirror. With the GBT's newly installed data acquisition equipment, the astronomers were able to create images with a resolution as fine as a few (3.75) meters, revealing distinct surface features.
"There are a lot of fascinating features in these images, including possible evidence for several ridges at different latitudes," said Lance Benner, a scientist with NASA’s Jet Propulsion Laboratory in Pasadena, California, and a member of the observing team.
The images also clearly establish that 2004 BL86 is a rounded object with an apparent equatorial bulge, which was also seen in the earlier Goldstone observations. In the latest images, the orientation reveal more of the asteroid’s equator, providing a clearer picture of that region. The collage of images also shows the rapid motion of the asteroid’s moon relative to its companion.
Further analysis of the images could provide important insights into the formation and evolution of this object.
"Capturing an object this small, about half a kilometer across, at such a tremendous distance with this clarity is truly amazing," said Michael Busch, a research scientist at the SETI Institute in Mountain View, California, and a member of the observing team. "This level of detail is similar to fly-by observations obtained by spacecraft," he noted.
Concurrently with the radar imaging, the scientists also used the radar transmitter at the Arecibo Observatory in Puerto Rico and a portion of the antennas that are part of the National Radio Astronomy Observatory’s (NRAO) Very Long Baseline Array (VLBA) to perform an observation known as radar speckle tracking. This technique uses the seemingly chaotic radar pattern reflected by the uneven surface of an asteroid as it sweeps across the surface of the Earth to determine how fast and in what direction it's tumbling. Once analyzed, these data will also reveal important details about its internal physical properties and future trajectory.
The asteroid 2004 BL86 is approximately 300 meters across and its moon is a mere 70 meters across. This size comparison is not evident in the radar images because of the way they were processed. Approximately one-sixth of asteroids in this size range (200 meters or larger) sport at least one companion.
"It was enjoyable and a great privilege to participate in this experiment," remarked NRAO astronomer Frank Ghigo who assisted with the GBT portion of the observations.
The 100-meter Green Bank Telescope is the world's largest fully steerable radio telescope. Its location in the National Radio Quiet Zone and the West Virginia Radio Astronomy Zone protects the incredibly sensitive telescope from unwanted radio interference, enabling it to perform unique observations.
The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.
Credit: nrao.edu
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Posted: 01 Feb 2015 10:17 AM PST
NWA 7034, a meteorite found a few years ago in the Moroccan desert, is like no other rock ever found on Earth. It’s been shown to be a 4.4 billion-year-old chunk of the Martian crust, and according to a new analysis, rocks just like it may cover vast swaths of Mars. In a new paper, scientists report that spectroscopic measurements of the meteorite are a spot-on match with orbital measurements of the Martian dark plains, areas where the planet’s coating of red dust is thin and the rocks beneath are exposed. The findings suggest that the meteorite, nicknamed Black Beauty, is representative of the “bulk background” of rocks on the Martian surface, says Kevin Cannon, a Brown University graduate student and lead author of the new paper. The research, co-authored by Jack Mustard from Brown and Carl Agee from the University of New Mexico, is in press in the journal Icarus.
When scientists started analyzing Black Beauty in 2011, they knew they had something special. Its chemical makeup confirmed that it was a castaway from Mars, but it was unlike any Martian meteorite ever found. Before Black Beauty, all the Martian rocks found on Earth were classified as SNC meteorites (shergottites, nakhlites, or chassignites). They’re mainly igneous rocks made of cooled volcanic material. But Black Beauty is a breccia, a mashup of different rock types welded together in a basaltic matrix. It contains sedimentary components that match the chemical makeup of rocks analyzed by the Mars rovers. Scientists concluded that it is a piece of Martian crust — the first such sample to make it to Earth.
Cannon and Mustard thought Black Beauty might help to clear up a longstanding enigma: the spectral signal from SNC meteorites never quite match with remotely sensed specra from the Martian surface. “Most samples from Mars are somewhat similar to spacecraft measurements,” Mustard said, “but annoyingly different.”
So after acquiring a chip of Black Beauty from Agee, Cannon and Mustard used a variety of spectroscopic techniques to analyze it. The work included use of a hyperspectral imaging system developed by Headwall photonics, a Massachusetts-based company. The device enabled detailed spectral imaging of the entire sample.
“Other techniques give us measurements of a dime-sized spot,” Cannon said. “What we wanted to do was get an average for the entire sample. That overall measurement was what ended up matching the orbital data.”
The researchers say the spectral match helps put a face on the dark plains, suggesting that the regions are dominated by brecciated rocks similar to Black Beauty. Because the dark plains are dust-poor regions, they’re thought to be representative of what hides beneath the red dust on much of the rest of the planet.
“This is showing that if you went to Mars and picked up a chunk of crust, you’d expect it to be heavily beat up, battered, broken apart and put back together,” Cannon said.
That the surface of Mars would be rich in Black Beauty-like breccias makes a lot of sense, given what we know about Mars, the researchers say.
“Mars is punctured by over 400,000 impact craters greater than 1 km in diameter ...,” they write. “Because brecciation is a natural consequence of impacts, it is expected that material similar to NWA 7034 has accumulated on Mars over time.”
In other words, Mustard says, the bulk of rocks on the surface of Mars probably look a lot like Black Beauty: “dark, messy and beautiful.”
Credit: brown.edu
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Posted: 01 Feb 2015 09:48 AM PST
Despite earlier reports of a possible detection, a joint analysis of data from ESA’s Planck satellite and the ground-based BICEP2 and Keck Array experiments has found no conclusive evidence of primordial gravitational waves. The Universe began about 13.8 billion years ago and evolved from an extremely hot, dense and uniform state to the rich and complex cosmos of galaxies, stars and planets we see today. An extraordinary source of information about the Universe’s history is the Cosmic Microwave Background, or CMB, the legacy of light emitted only 380 000 years after the Big Bang. "By analyzing both sets of data together, we could get a more definitive picture of what's going on than we could with either dataset alone," says Charles Lawrence, the U.S. project scientist for Planck at NASA's Jet Propulsion Laboratory, Pasadena, California. "The joint analysis shows that much of the signal detected by BICEP2/Keck is coming from dust in the Milky Way, but we cannot rule out a gravitational wave signal at a low level. This is a good example of how progress is made in science, one step at a time."
ESA’s Planck satellite observed this background across the whole sky with unprecedented accuracy, and a broad variety of new findings about the early Universe has already been revealed over the past two years.
But astronomers are still digging ever deeper in the hope of exploring even further back in time: they are searching for a particular signature of cosmic ‘inflation’ – a very brief accelerated expansion that, according to current theory, the Universe experienced when it was only the tiniest fraction of a second old.
This signature would be seeded by gravitational waves, tiny perturbations in the fabric of space-time, that astronomers believe would have been generated during the inflationary phase.
Interestingly, these perturbations should leave an imprint on another feature of the cosmic background: its polarisation.
"The swirly polarization pattern, reported by BICEP2, was also clearly seen with new data from the Keck Array," says Jamie Bock of the California Institute of Technology in Pasadena, and JPL, a member of both the BICEP2/Keck and Planck teams.
When light waves vibrate preferentially in a certain direction, we say the light is polarised.
The CMB is polarised, exhibiting a complex arrangement across the sky. This arises from the combination of two basic patterns: circular and radial (known as E-modes), and curly (B-modes).
Different phenomena in the Universe produce either E- or B-modes on different angular scales and identifying the various contributions requires extremely precise measurements. It is the B-modes that could hold the prize of probing the Universe’s early inflation.
"The noise in the instruments limits how deeply we can search for a signal from inflation," said Bock. "BICEP2/Keck measured the sky at one wavelength. To answer how much of the signal comes from the galaxy, we used Planck's measurements in multiple wavelengths. We get a big boost by combining BICEP2/Keck and Planck measurements together, the best data currently available."
“Searching for this unique record of the very early Universe is as difficult as it is exciting, since this subtle signal is hidden in the polarisation of the CMB, which itself only represents only a feeble few percent of the total light,” says Jan Tauber, ESA’s project scientist for Planck.
Planck is not alone in this search. In early 2014, another team of astronomers presented results based on observations of the polarised CMB on a small patch of the sky performed 2010–12 with BICEP2, an experiment located at the South Pole. The team also used preliminary data from another South Pole experiment, the Keck Array.
They found something new: curly B-modes in the polarisation observed over stretches of the sky a few times larger than the size of the full Moon.
The BICEP2 team presented evidence favouring the interpretation that this signal originated in primordial gravitational waves, sparking an enormous response in the academic community and general public.
However, there is another contender in this game that can produce a similar effect: interstellar dust in our Galaxy, the Milky Way.
The Milky Way is pervaded by a mixture of gas and dust shining at similar frequencies to those of the CMB, and this foreground emission affects the observation of the most ancient cosmic light. Very careful analysis is needed to separate the foreground emission from the cosmic background.
Critically, interstellar dust also emits polarised light, thus affecting the CMB polarisation as well.
“When we first detected this signal in our data, we relied on models for Galactic dust emission that were available at the time,” says John Kovac, a principal investigator of BICEP2 at Harvard University, in the USA.
“These seemed to indicate that the region of the sky chosen for our observations had dust polarisation much lower than the detected signal.”
The two ground-based experiments collected data at a single microwave frequency, making it difficult to separate the emissions coming from the Milky Way and the background.
On the other hand, Planck observed the sky in nine microwave and sub-millimetre frequency channels, seven of which were also equipped with polarisation-sensitive detectors. By careful analysis, these multi-frequency data can be used to separate the various contributions.
The BICEP2 team had chosen a field where they believed dust emission would be low, and thus interpreted the signal as likely to be cosmological.
However, as soon as Planck’s maps of the polarised emission from Galactic dust were released, it was clear that this foreground contribution could be much higher than previously expected.
In fact, in September 2014, Planck revealed for the first time that the polarised emission from dust is significant over the entire sky, and comparable to the signal detected by BICEP2 even in the cleanest regions.
So, the Planck and BICEP2 teams joined forces, combining the satellite’s ability to deal with foregrounds using observations at several frequencies – including those where dust emission is strongest – with the greater sensitivity of the ground-based experiments over limited areas of the sky, thanks to their more recent, improved technology. By then, the full Keck Array data from 2012 and 2013 had also become available.
“This joint work has shown that the detection of primordial B-modes is no longer robust once the emission from Galactic dust is removed,” says Jean-Loup Puget, principal investigator of the HFI instrument on Planck at the Institut d’Astrophysique Spatiale in Orsay, France.
“So, unfortunately, we have not been able to confirm that the signal is an imprint of cosmic inflation.”
Another source of B-mode polarisation, dating back to the early Universe, was detected in this study, but on much smaller scales on the sky.
This signal, first discovered in 2013, is not a direct probe of the inflationary phase but is induced by the cosmic web of massive structures that populate the Universe and change the path of the CMB photons on their way to us.
This effect is called ‘gravitational lensing’, since it is caused by massive objects bending the surrounding space and thus deflecting the trajectory of light much like a magnifying glass does. The detection of this signal using Planck, BICEP2 and the Keck Array together is the strongest yet.
As for signs of the inflationary period, the question remains open.
“While we haven’t found strong evidence of a signal from primordial gravitational waves in the best observations of CMB polarisation that are currently available, this by no means rules out inflation,” says Reno Mandolesi, principal investigator of the LFI instrument on Planck at University of Ferrara, Italy.
In fact, the joint study sets an upper limit on the amount of gravitational waves from inflation, which might have been generated at the time but at a level too low to be confirmed by the present analysis.
“This analysis shows that the amount of gravitational waves can probably be no more than about half the observed signal,” says Clem Pryke, a principal investigator of BICEP2 at University of Minnesota, in the USA.
“The new upper limit on the signal due to gravitational waves agrees well with the upper limit that we obtained earlier with Planck using the temperature fluctuations of the CMB,” says Brendan Crill, a leading member of both the Planck and BICEP2 teams from NASA’s Jet Propulsion Laboratory in the USA.
“The gravitational wave signal could still be there, and the search is definitely on.”
“A Joint Analysis of BICEP2/Keck Array and Planck Data” by the BICEP2/Keck and Planck collaboration has been submitted to the journal Physical Review Letters. A draft of the manuscript is available here.
The study combines data from ESA’s Planck satellite and from the US National Science Foundation ground-based experiments BICEP2 and the Keck Array, at the South Pole.
The analysis is based on observations of the CMB polarisation on a 400 square degree patch of the sky. The Planck data cover frequencies between 30 GHz and 353 GHz, while the BICEP2 and Keck Array data were taken at a frequency of 150 GHz.
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