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News Article | April 17, 2017
Site: www.bbc.co.uk

After two decades of development and "heartbreak", scientists are on the verge of sending missions to explore the ocean world of Europa. Could this be our best shot at finding life elsewhere in the Solar System? Orbiting the giant planet Jupiter is an icy world, just a little smaller than Earth's moon. From a distance, Europa appears to be etched with a nexus of dark streaks, like the product of a toddler's chaotic scribbling. Close up, these are revealed to be long linear cracks in the ice, many of which are filled with an unknown contaminant that scientists have dubbed the "brown gunk". Elsewhere, the surface is tortured and irregular, as if massive slabs of ice have drifted, spun and flipped over in slush. Jupiter's immense gravity helps generate tidal forces that repeatedly stretch and relax the moon. But the stresses that created Europa's smashed up terrain are best explained by the ice shell floating on an ocean of liquid water. "The fact that there's liquid water underneath the surface which we know from previous missions, in particular from the magnetometer observations made by the Galileo spacecraft as it flew past [in the 1990s], makes it one of the most exciting potential targets to look for life," says Prof Andrew Coates of UCL's Mullard Space Science Laboratory in Surrey, UK. Europa's dark, briny deep might extend 80-170km into the moon's interior, meaning it could be holding twice as much liquid water as there is in all of Earth's oceans. And while water is one vital prerequisite for life, Europa's ocean might have others - such as a source of chemical energy for microbes. What's more, the ocean may communicate with the surface through a number of means, including warm blobs of ice from below rising up through the ice shell - which could be tens of kilometres thick. So studying the surface could provide clues to what's going on deep below. Now, Nasa is priming two missions to explore this intriguing world. Both have been discussed here at the 48th Lunar and Planetary Science Conference (LPSC) in Houston. The first is a flyby mission called Europa Clipper that would likely launch in 2022. The second is a lander mission that would follow a few years later. "We're really trying to get at Europa's potential habitability, the ingredients for life: water, and whether there's chemical energy for life," he tells me. "We do that by trying to understand the ocean and the ice shell, the composition and the geology. And mixed into those is the level of current activity at Europa." Clipper carries a payload of nine instruments, including a camera that will image most of the surface; spectrometers to understand its composition; ice-penetrating radar to map the ice shell in three dimensions and find water beneath the ice shell; and a magnetometer to characterise the ocean. However, since the Galileo spacecraft provided evidence for an ocean in the 1990s, we've learned that Europa isn't one of a kind. "One of the most amazing and significant discoveries of the past decade or so in planetary exploration is that you can't swing a dead cat in the outer Solar System without hitting an ocean world," says Clipper's programme scientist Curt Niebur, from Nasa headquarters in Washington DC. At Saturn's moon Enceladus, for example, ice from a subsurface ocean gushes into space through fissures at the south pole. The saturnian satellite could also get a dedicated mission in the 2020s, but Dr Niebur believes Europa stands out: "Europa is much larger than Enceladus and has more of everything: more geological activity, more water, more space for that water, more heat, more raw ingredients and more stability in its environment." But there's something else that marks the moon out: its neighbourhood. Europa's orbital path takes it deep into Jupiter's powerful magnetic field, which traps and speeds up particles. The resulting belts of intense radiation fry spacecraft electronics, limiting the durations of missions to months or even weeks. That said, this radiation also drives reactions on Europa's surface, yielding chemicals called oxidants. On Earth, biology exploits the chemical reactions between oxidants and compounds known as reductants to supply the energy needed for life. However, the oxidants made on the surface are only useful to Europan microbes if they can get down into the ocean. Fortunately, the process of convection that pushes warm blobs of ice upwards might also drive surface material down. Once in the ocean, oxidants could react with reductants made by seawater interacting with the rocky ocean floor. "You need both poles of the battery," explains Robert Pappalardo. For scientists like Bob Pappalardo and Curt Niebur, the impending missions are the realisation of a two-decades-long dream. Since the first Europa mission concepts were drawn up in the late 1990s, one promising proposal after another has been thwarted. During the noughties, the US and Europe even pooled resources on a mission that would have sent separate spacecraft to Europa and Jupiter's larger ice moon Ganymede. But the plan was cancelled amid budget cuts, with the European part evolving into the Juice mission. "I don't think there's been a Europa mission over the past 18 years that I have not either had my fingers in or has not passed under my eye," says Curt Niebur. "It's been a long road. The road to launch is always a rocky one, and it's always full of heartbreak. We've experienced that more than most on Europa." Exploring Europa is costly - though no more so than other Nasa "flagship" missions such as Cassini or the Curiosity rover. There are inherent engineering challenges, such as operating within Jupiter's radiation belts. Spacecraft instruments need to be shielded with materials such as titanium metal but, says Dr Pappalardo, "you can only shield them so much because they have to be able to see Europa". So to keep Clipper safe, Nasa is going to stray from the rulebook somewhat. "The assumption always was: Galileo flew past Europa, so the next mission has to be an orbiter. That's just how we do business," says Dr Niebur. But rather than orbit Europa, Clipper will instead reduce its exposure to mission-shortening radiation by orbiting Jupiter, and make at least 45 close flybys of the icy moon over three-and-a-half years. "We realised we could avoid those technical challenges of orbiting Europa, make the mission much more achievable and still get the science we want if we fly past it a lot," says Clipper's programme scientist. The strength of sunlight near Europa is about a 30th of what it is at Earth. But Nasa decided it could power Clipper with solar panels rather than the radioactive generators some other outer planet missions have used. "All those years of study forced us to burn away our pre-conceptions and get us to really focus on reality, not on our wish-list... to focus on the best science," says Curt Niebur. In 2011, a National Research Council report re-stated the importance of exploring the icy moon. Even so, Nasa remained wary because of the cost. But the support on Capitol Hill has been pivotal. A Europa venture has bipartisan backing, and in Republican Congressman John Culberson - the chair of the particular House Appropriations Subcommittee with jurisdiction over Nasa's budget - the mission has had a unique champion. The 60-year-old Texan lawmaker has been entranced by Europa ever since observing it through the Celestron 8 telescope he bought himself as a high school graduation present. Over the last four years, the subcommittee he chairs has channelled money to scientists working on Europa, even when the space agency's chief wasn't asking for it. Generous investment means that much more of the technical work has been completed on Clipper than is normal for a mission at its stage (phase B) in the Nasa project cycle. The lander is at an earlier stage of development, called pre-phase A, but a report on the mission's science value was discussed at a workshop here at the LPSC. The lander has received no funding in the President's 2018 budget request for Nasa. But Dr Jim Green, director of planetary science at the agency, tells me: "That mission in particular is tremendously exciting, because it tells us the science we have to do from the surface of a moon that's really hard to get to. "We still have quite the process to go through, do the due diligence, understanding the kind of measurements we need to make. Then we'll work with the administration in the future at the right time to see if, budgetarily, we can move forward with it." Some innovative Europa lander concepts have been proposed over the last two decades, reflecting the scientific bounty to be had by touching down. Dr Geraint Jones of the Mullard Space Science Laboratory has worked on one concept called a penetrator. "They haven't been flown in space before, but it's a really promising technology," he explains. A projectile deployed from a satellite hits the surface "really hard, at about 300m/second, about 700 miles an hour", exposing pristine ice for analysis by onboard instruments, which could be designed to withstand the impact. By contrast, Nasa's forthcoming lander would put down softly with the help of the Sky Crane technology used to drop the Curiosity rover safely on Mars in 2012. During the touchdown, it will use an autonomous landing system to detect and avoid surface hazards in real time. Clipper will provide the reconnaissance for a landing site. "I like to think of it as finding that right oasis, where there might be water close to the surface. Maybe it's warm and maybe it has organic materials," says Bob Pappalardo. The craft would be equipped with a sensitive instrument payload and a counter-rotating saw to help get at fresher samples below the radiation-processed surface ice. "The lander is all about hitting the freshest, most pristine sample possible. One way to do that is to dig deep, another way is going to where there is some kind of eruption on the surface - like a plume - that's dropping very fresh material onto the surface," says Curt Niebur. In recent years, the Hubble telescope has made tentative observations of plumes of water-ice erupting from beneath Europa, much as they do on Enceladus. But there's no point in the lander going to the site of a decades-old eruption, it would need to visit the location of a much more recent plume. So scientists need to understand what's controlling these geysers: for example, Clipper will determine whether the plumes are correlated with any hot spots on the surface. Earth's seas are teeming with life, so it can be hard for us to contemplate the prospect of a sterile, 100km-plus deep ocean on Europa. But the scientific threshold for detecting life is set very high. So will we be able to recognise alien life if it's there? "The goal of the lander mission is not simply to detect life [to our satisfaction], but to convince everyone else that we have done so," Dr Niebur explains. "It does no good for us to invest in this mission if all we create is scientific controversy." Thus, the lander's science definition team came up with two ways to address this. First, any detection of life has to be based on multiple, independent lines of evidence from direct measurements. "There's no silver bullet; you don't do one measurement and say: 'aha, eureka we've found it'. You look at the sum total," says Dr Niebur. Second, the scientists have come up with a framework to interpret those results, some of which might be positive, while others negative: "It creates a decision tree that marches through all the different variables. Following all these different paths, the end result is: yes, we've found life, or no we haven't," he says. At the lander workshop here at the LPSC, Nasa's Kevin Hand described the process as "biosignature bingo". Now, the team will have to see if the scientific community is persuaded. Curt Niebur explains: "I want to have that discussion now, today, years before we launch so that we can all be focused on analysing the data once we land."


News Article | October 27, 2016
Site: phys.org

"These 18 stars rotate in just a few days on average, while the sun takes nearly a month," said Steve Howell, a senior research scientist at NASA's Ames Research Center in Moffett Field, California, and leader of the team. "The rapid rotation amplifies the same kind of activity we see on the sun, such as sunspots and solar flares, and essentially sends it into overdrive." The most extreme member of the group, a K-type orange giant dubbed KSw 71, is more than 10 times larger than the sun, rotates in just 5.5 days, and produces X-ray emission 4,000 times greater than the sun does at solar maximum. These rare stars were found as part of an X-ray survey of the original Kepler field of view, a patch of the sky comprising parts of the constellations Cygnus and Lyra. From May 2009 to May 2013, Kepler measured the brightness of more than 150,000 stars in this region to detect the regular dimming from planets passing in front of their host stars. The mission was immensely successful, netting more than 2,300 confirmed exoplanets and nearly 5,000 candidates to date. An ongoing extended mission, called K2, continues this work in areas of the sky located along the ecliptic, the plane of Earth's orbit around the sun. "A side benefit of the Kepler mission is that its initial field of view is now one of the best-studied parts of the sky," said team member Padi Boyd, a researcher at NASA's Goddard Space Flight Center in Greenbelt, Maryland, who designed the Swift survey. For example, the entire area was observed in infrared light by NASA's Wide-field Infrared Survey Explorer, and NASA's Galaxy Evolution Explorer observed many parts of it in the ultraviolet. "Our group was looking for variable X-ray sources with optical counterparts seen by Kepler, especially active galaxies, where a central black hole drives the emissions," she explained. Using the X-ray and ultraviolet/optical telescopes aboard Swift, the researchers conducted the Kepler-Swift Active Galaxies and Stars Survey (KSwAGS), imaging about six square degrees, or 12 times the apparent size of a full moon, in the Kepler field. "With KSwAGS we found 93 new X-ray sources, about evenly split between active galaxies and various types of X-ray stars," said team member Krista Lynne Smith, a graduate student at the University of Maryland, College Park who led the analysis of Swift data. "Many of these sources have never been observed before in X-rays or ultraviolet light." For the brightest sources, the team obtained spectra using the 200-inch telescope at Palomar Observatory in California. These spectra provide detailed chemical portraits of the stars and show clear evidence of enhanced stellar activity, particularly strong diagnostic lines of calcium and hydrogen. The researchers used Kepler measurements to determine the rotation periods and sizes for 10 of the stars, which range from 2.9 to 10.5 times larger than the sun. Their surface temperatures range from somewhat hotter to slightly cooler than the sun, mostly spanning spectral types F through K. Astronomers classify the stars as subgiants and giants, which are more advanced evolutionary phases than the sun's caused by greater depletion of their primary fuel source, hydrogen. All of them eventually will become much larger red giant stars. A paper detailing the findings will be published in the Nov. 1 edition of the Astrophysical Journal and is now available online. Forty years ago, Ronald Webbink at the University of Illinois, Urbana-Champaign noted that close binary systems cannot survive once the fuel supply of one star dwindles and it starts to enlarge. The stars coalesce to form a single rapidly spinning star initially residing in a so-called "excretion" disk formed by gas thrown out during the merger. The disk dissipates over the next 100 million years, leaving behind a very active, rapidly spinning star. Howell and his colleagues suggest that their 18 KSwAGS stars formed by this scenario and have only recently dissipated their disks. To identify so many stars passing through such a cosmically brief phase of development is a real boon to stellar astronomers. "Webbink's model suggests we should find about 160 of these stars in the entire Kepler field," said co-author Elena Mason, a researcher at the Italian National Institute for Astrophysics Astronomical Observatory of Trieste. "What we have found is in line with theoretical expectations when we account for the small portion of the field we observed with Swift." The team has already extended their Swift observations to additional fields mapped by the K2 mission. Ames manages the Kepler and K2 missions for NASA's Science Mission Directorate. NASA's Jet Propulsion Laboratory in Pasadena, California, managed Kepler mission development. Ball Aerospace & Technologies Corp. operates the flight system with support from the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. Goddard manages the Swift mission in collaboration with Pennsylvania State University in University Park, the Los Alamos National Laboratory in New Mexico and Orbital Sciences Corp. in Dulles, Virginia. Other partners include the University of Leicester and Mullard Space Science Laboratory in the United Kingdom, Brera Observatory and the Italian Space Agency in Italy, with additional collaborators in Germany and Japan. Explore further: 'Heartbeat stars' unlocked in new study More information: Steve B. Howell et al. RAPIDLY ROTATING, X-RAY BRIGHT STARS IN THEFIELD, The Astrophysical Journal (2016). DOI: 10.3847/0004-637X/831/1/27


News Article | October 27, 2016
Site: www.eurekalert.org

Astronomers using observations from NASA's Kepler and Swift missions have discovered a batch of rapidly spinning stars that produce X-rays at more than 100 times the peak levels ever seen from the sun. The stars, which spin so fast they've been squashed into pumpkin-like shapes, are thought to be the result of close binary systems where two sun-like stars merge. "These 18 stars rotate in just a few days on average, while the sun takes nearly a month," said Steve Howell, a senior research scientist at NASA's Ames Research Center in Moffett Field, California, and leader of the team. "The rapid rotation amplifies the same kind of activity we see on the sun, such as sunspots and solar flares, and essentially sends it into overdrive." The most extreme member of the group, a K-type orange giant dubbed KSw 71, is more than 10 times larger than the sun, rotates in just 5.5 days, and produces X-ray emission 4,000 times greater than the sun does at solar maximum. These rare stars were found as part of an X-ray survey of the original Kepler field of view, a patch of the sky comprising parts of the constellations Cygnus and Lyra. From May 2009 to May 2013, Kepler measured the brightness of more than 150,000 stars in this region to detect the regular dimming from planets passing in front of their host stars. The mission was immensely successful, netting more than 2,300 confirmed exoplanets and nearly 5,000 candidates to date. An ongoing extended mission, called K2, continues this work in areas of the sky located along the ecliptic, the plane of Earth's orbit around the sun. "A side benefit of the Kepler mission is that its initial field of view is now one of the best-studied parts of the sky," said team member Padi Boyd, a researcher at NASA's Goddard Space Flight Center in Greenbelt, Maryland, who designed the Swift survey. For example, the entire area was observed in infrared light by NASA's Wide-field Infrared Survey Explorer, and NASA's Galaxy Evolution Explorer observed many parts of it in the ultraviolet. "Our group was looking for variable X-ray sources with optical counterparts seen by Kepler, especially active galaxies, where a central black hole drives the emissions," she explained. Using the X-ray and ultraviolet/optical telescopes aboard Swift, the researchers conducted the Kepler-Swift Active Galaxies and Stars Survey (KSwAGS), imaging about six square degrees, or 12 times the apparent size of a full moon, in the Kepler field. "With KSwAGS we found 93 new X-ray sources, about evenly split between active galaxies and various types of X-ray stars," said team member Krista Lynne Smith, a graduate student at the University of Maryland, College Park who led the analysis of Swift data. "Many of these sources have never been observed before in X-rays or ultraviolet light." For the brightest sources, the team obtained spectra using the 200-inch telescope at Palomar Observatory in California. These spectra provide detailed chemical portraits of the stars and show clear evidence of enhanced stellar activity, particularly strong diagnostic lines of calcium and hydrogen. The researchers used Kepler measurements to determine the rotation periods and sizes for 10 of the stars, which range from 2.9 to 10.5 times larger than the sun. Their surface temperatures range from somewhat hotter to slightly cooler than the sun, mostly spanning spectral types F through K. Astronomers classify the stars as subgiants and giants, which are more advanced evolutionary phases than the sun's caused by greater depletion of their primary fuel source, hydrogen. All of them eventually will become much larger red giant stars. A paper detailing the findings will be published in the Nov. 1 edition of the Astrophysical Journal and is now available online. Forty years ago, Ronald Webbink at the University of Illinois, Urbana-Champaign noted that close binary systems cannot survive once the fuel supply of one star dwindles and it starts to enlarge. The stars coalesce to form a single rapidly spinning star initially residing in a so-called "excretion" disk formed by gas thrown out during the merger. The disk dissipates over the next 100 million years, leaving behind a very active, rapidly spinning star. Howell and his colleagues suggest that their 18 KSwAGS stars formed by this scenario and have only recently dissipated their disks. To identify so many stars passing through such a cosmically brief phase of development is a real boon to stellar astronomers. "Webbink's model suggests we should find about 160 of these stars in the entire Kepler field," said co-author Elena Mason, a researcher at the Italian National Institute for Astrophysics Astronomical Observatory of Trieste. "What we have found is in line with theoretical expectations when we account for the small portion of the field we observed with Swift." The team has already extended their Swift observations to additional fields mapped by the K2 mission. Ames manages the Kepler and K2 missions for NASA's Science Mission Directorate. NASA's Jet Propulsion Laboratory in Pasadena, California, managed Kepler mission development. Ball Aerospace & Technologies Corp. operates the flight system with support from the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. Goddard manages the Swift mission in collaboration with Pennsylvania State University in University Park, the Los Alamos National Laboratory in New Mexico and Orbital Sciences Corp. in Dulles, Virginia. Other partners include the University of Leicester and Mullard Space Science Laboratory in the United Kingdom, Brera Observatory and the Italian Space Agency in Italy, with additional collaborators in Germany and Japan.


News Article | October 31, 2016
Site: www.rdmag.com

Earth will not be the only place with pumpkins this Halloween. Recently, astronomers using observations from NASA’s Kepler and Swift missions have unveiled a batch of 18 rapidly spinning stars that spin so fast they’ve been squashed into “pumpkin-like” shapes. The stars produce X-rays at more than 100 times the peak levels ever seen from the sun and are thought to be the result of close binary systems where two sun-like stars’ merge. Steve Howell, a senior research scientist at NASA's Ames Research Center in Moffett Field, California and leader of the team, explained the behavior of the stars. “These 18 stars rotate in just a few days on average, while the sun takes nearly a month,” he said in a statement. “The rapid rotation amplifies the same kind of activity we see on the sun, such as sunspots and solar flares and essentially sends it into overdrive.” Astronomers dubbed the most extreme member of the group KSw 71, a K-type orange giant that is more than 10 times larger than the sun, rotates in just 5.5 days and produces X-ray emission 4,000 times greater than the sun does at solar maximum. The rare stars were found as part of the Kepler–Swift Active Galaxies and Stars Survey (KSwAGS ) of the original Kepler field of view, which measured the brightness of more than 150,000 stars between 2009 and 2013 to detect the regular dimming from planets passing in front of their host stars. “A side benefit of the Kepler mission is that its initial field of view is now one of the best-studied parts of the sky,” team member Padi Boyd, a researcher at NASA's Goddard Space Flight Center in Greenbelt, Md., who designed the Swift survey, said in a statement. “Our group was looking for variable X-ray sources with optical counterparts seen by Kepler, especially active galaxies, where a central black hole drives the emissions.” Using X-ray and ultraviolet/optical telescopes aboard Swift, the researchers conducted the survey, imaging about 6 square degrees or 12 times the apparent size of a full moon, in the Kepler field. “With KSwAGS we found 93 new X-ray sources, about evenly split between active galaxies and various types of X-ray stars,” team member Krista Lynne Smith, a graduate student at the University of Maryland, who led the analysis of Swift data, said in a statement. “Many of these sources have never been observed before in X-rays or ultraviolet light.” The researchers determined the rotational periods and size of 10 of the stars, which range from 2.9 to 10.5 times larger than the sun, using Kepler measurements. Ames manages the Kepler and K2 missions for NASA’s Science Mission Directorate. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed Kepler mission development. Ball Aerospace & Technologies Corp. operates the flight system with support from the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. Goddard manages the Swift mission in collaboration with Pennsylvania State University in University Park, the Los Alamos National Laboratory in New Mexico and Orbital Sciences Corp. in Dulles, Va. Other partners include the University of Leicester and Mullard Space Science Laboratory in the United Kingdom, Brera Observatory and the Italian Space Agency in Italy, with additional collaborators in Germany and Japan. A paper detailing the findings will be published in the Nov. 1 edition of the Astrophysical Journal and is now available online.


News Article | November 30, 2016
Site: www.eurekalert.org

A team led by Roberto Mignani from INAF Milan (Italy) and from the University of Zielona Gora (Poland), used ESO's Very Large Telescope (VLT) at the Paranal Observatory in Chile to observe the neutron star RX J1856.5-3754, about 400 light-years from Earth [1]. Despite being amongst the closest neutron stars, its extreme dimness meant the astronomers could only observe the star with visible light using the FORS2 instrument on the VLT, at the limits of current telescope technology. Neutron stars are the very dense remnant cores of massive stars -- at least 10 times more massive than our Sun -- that have exploded as supernovae at the ends of their lives. They also have extreme magnetic fields, billions of times stronger than that of the Sun, that permeate their outer surface and surroundings. These fields are so strong that they even affect the properties of the empty space around the star. Normally a vacuum is thought of as completely empty, and light can travel through it without being changed. But in quantum electrodynamics (QED), the quantum theory describing the interaction between photons and charged particles such as electrons, space is full of virtual particles that appear and vanish all the time. Very strong magnetic fields can modify this space so that it affects the polarisation of light passing through it. Mignani explains: "According to QED, a highly magnetised vacuum behaves as a prism for the propagation of light, an effect known as vacuum birefringence." Among the many predictions of QED, however, vacuum birefringence so far lacked a direct experimental demonstration. Attempts to detect it in the laboratory have not yet succeeded in the 80 years since it was predicted in a paper by Werner Heisenberg (of uncertainty principle fame) and Hans Heinrich Euler. "This effect can be detected only in the presence of enormously strong magnetic fields, such as those around neutron stars. This shows, once more, that neutron stars are invaluable laboratories in which to study the fundamental laws of nature." says Roberto Turolla (University of Padua, Italy). After careful analysis of the VLT data, Mignani and his team detected linear polarisation -- at a significant degree of around 16% -- that they say is likely due to the boosting effect of vacuum birefringence occurring in the area of empty space surrounding RX J1856.5-3754 [2]. Vincenzo Testa (INAF, Rome, Italy) comments: "This is the faintest object for which polarisation has ever been measured. It required one of the largest and most efficient telescopes in the world, the VLT, and accurate data analysis techniques to enhance the signal from such a faint star." "The high linear polarisation that we measured with the VLT can't be easily explained by our models unless the vacuum birefringence effects predicted by QED are included," adds Mignani. "This VLT study is the very first observational support for predictions of these kinds of QED effects arising in extremely strong magnetic fields," remarks Silvia Zane (UCL/MSSL, UK). Mignani is excited about further improvements to this area of study that could come about with more advanced telescopes: "Polarisation measurements with the next generation of telescopes, such as ESO's European Extremely Large Telescope, could play a crucial role in testing QED predictions of vacuum birefringence effects around many more neutron stars." "This measurement, made for the first time now in visible light, also paves the way to similar measurements to be carried out at X-ray wavelengths," adds Kinwah Wu (UCL/MSSL, UK). [1] This object is part of the group of neutron stars known as the Magnificent Seven. They are known as isolated neutron stars (INS), which have no stellar companions, do not emit radio waves (like pulsars), and are not surrounded by progenitor supernova material. [2] There are other processes that can polarise starlight as it travels through space. The team carefully reviewed other possibilities -- for example polarisation created by scattering off dust grains -- but consider it unlikely that they produced the polarisation signal observed. This research was presented in the paper entitled "Evidence for vacuum birefringence from the first optical polarimetry measurement of the isolated neutron star RX J1856.5?3754", by R. Mignani et al., to appear in Monthly Notices of the Royal Astronomical Society. The team is composed of R.P. Mignani (INAF - Istituto di Astrofisica Spaziale e Fisica Cosmica Milano, Milano, Italy; Janusz Gil Institute of Astronomy, University of Zielona Góra, Zielona Góra, Poland), V. Testa (INAF - Osservatorio Astronomico di Roma, Monteporzio, Italy), D. González Caniulef (Mullard Space Science Laboratory, University College London, UK), R. Taverna (Dipartimento di Fisica e Astronomia, Università di Padova, Padova, Italy), R. Turolla (Dipartimento di Fisica e Astronomia, Università di Padova, Padova, Italy; Mullard Space Science Laboratory, University College London, UK), S. Zane (Mullard Space Science Laboratory, University College London, UK) and K. Wu (Mullard Space Science Laboratory, University College London, UK). ESO is the foremost intergovernmental astronomy organisation in Europe and the world's most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world's most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world's largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become "the world's biggest eye on the sky".


News Article | February 23, 2017
Site: www.newscientist.com

We could have spotted the majestic icy plumes of Saturn’s moon Enceladus 25 years earlier than we did, if only we’d known to look. The vast fountains of icy material erupting from Enceladus’s south pole enthralled planetary scientists when they were first spotted in images returned by NASA’s Cassini spacecraft in 2005. Further observations suggest that the moon hosts a subsurface sea that could be one of the best places in the solar system to look for life. Now a space image-processing enthusiast from Tennessee, in the US, believes he’s made a ‘pre-discovery’ of those plumes in archive image data from the Voyager 1 probe, which raced past the Saturn system in 1980. Ted Stryk – an associate professor of philosophy and English at Roane State Community College who has recently worked with the NASA New Horizons team – processed Voyager 1 data that is publicly available from NASA’s online Planetary Data System to reveal a faint protrusion emanating from the frozen moon’s southern hemisphere. In order to spot Enceladus’ plumes in the old Voyager data, Stryk needed images taken when the moon was illuminated at a certain angle. But the probe didn’t capture any deliberately targeted shots at those key moments. So he had to search the archive for where the moon cropped up, under those conditions, in Voyager 1 pictures of other Saturnian subjects. “There was one set where there was a series of eight images that contained Enceladus, just a few pixels across, at a not optimal but useful phase-angle for this kind of work,” he says. By stacking together and averaging those images, taken in November of 1980, Stryk was able to boost the signal-to-noise ratio of the final picture and so reveal the feature he argues are the plumes found by Cassini decades later. Stryk’s work will be published in the proceedings of the Lunar and Planetary Science Conference, which will take place in The Woodlands, Texas next month. “It’s remarkable to be able to go back to data taken almost a quarter of a century before Cassini arrived and, armed with the discovery information from Cassini, produce this remarkable processed Voyager image which seems to reveal the plume at that time,” says Andrew Coates, a Cassini scientist at the Mullard Space Science Laboratory in the UK. If Stryk’s processed image does indeed show the plume from Enceladus’ jets, that could supply researchers with an intriguing new data point, he adds. “Another detection from 1980 if confirmed has the potential, once the data are fully understood and calibrated, to tell us something about how long the activity has been going on for.”


News Article | November 11, 2016
Site: www.bbc.co.uk

Beagle 2, the failed British mission to Mars in 2003, came "excruciatingly close" to succeeding, a study shows. A new analysis of pictures of the Beagle 2 spacecraft shows that it did not crash-land on the Martian surface. Instead, it indicates that the landing went to plan and at least three of its four solar panels opened successfully. The analysis also suggests that the probe may even have worked for several months, but was unable to send its data back to Earth. Prof Mark Sims of Leicester University, who commissioned the study, told BBC News that there is an extremely small possibility that Beagle 2 might still be working on the Martian surface. "It may have worked for hundreds of days depending on how much dust was deposited on the solar panels and whether any dust devils were cleaning the panels - as happened with Nasa's Mars Exploration Rovers," he said. "One possibility is that it could still be working today - but it is extremely unlikely and I doubt that it is." Dr Manish Patel, of the Open University, was among the hundreds of UK scientists who worked on the Beagle 2 mission. He agrees that the new evidence suggests that Beagle 2 took lots of scientific data but was unable to send it back. "If Beagle 2 went into surface operations mode, it could have continued for some time performing the initial pre-programmed operations, happily taking data and waiting for a response from the orbiters. It turned out to be a very lonely time for the lander at the surface," he said. Those views are backed by Prof Jan-Peter Muller of the Mullard Space Science Laboratory, which is part of University College London - who has no ties with the Beagle-2 mission. "Given that (Nasa's) exploration rover Opportunity is going strong since January 2004 when it was due to last only until March 2004 and that Mars Express is going strong 13 years after orbit insertion when it was due to last only 3 years, the possibility that Beagle 2 could still be collecting data after 13 years is remotely possible." The British built Beagle 2 Spacecraft was due to land on the Martian surface on Christmas Day in 2003. The mission was charismatically led by the late Prof Colin Pillinger. The spacecraft was capable of collecting soil samples and analysing them for signs of organic molecules associated with life in a miniaturised on-board laboratory. Disappointingly, no signal was received on Christmas Day. The search for a response from Beagle 2 continued for several months but the spacecraft was never heard from again. In 2014, Nasa's Mars Reconnaissance Orbiter (MRO) found Beagle 2 on the Martian surface. The spacecraft took pictures which seemed to indicate that the spacecraft landed as planned and some of its solar panels had opened. In the new detailed analysis, Nick Higgett and his team at De Montfort University not only confirmed this but also indicated that Beagle 2 had deployed at least three of its solar panels - with the fourth and final panel possibly beginning to open. The technique is based on simulating possible configurations of the lander on the surface and comparing the amount of sunlight that reflects off the simulated lander with real pictures taken from Nasa's Mars Reconnaissance Orbiter. The researchers then identified which landing configuration of one, two, three or four solar panels opened was the best fit. "Hopefully these results help to solve a long held mystery and will benefit any future missions to Mars," said Mr Higgett. "We got so close," says Prof Sims, adding: "We succeeded in so many elements. It is a great pity the communications didn't work and we didn't get the science back." Prof Sims, who worked on Beagle 2, says that he and others who worked on the mission take satisfaction from the fact that the system did seem to work so well. "It shows that the Beagle 2 team did an amazing job. It shows that the design was sound. It got there. It landed on Mars at the first attempt." The analysis suggests that Beagle 2 fell at the very final hurdle. It was unable to send back data or receive instructions from Earth. This may have been because the fourth solar panel may have partially opened and shielded the radio antenna. Alternatively, the receiver might have malfunctioned. Another possibility is that internal electrical systems were damaged by a heavy landing. After studying the analysis, Dr Patel says he feels "incredibly frustrated" but also "incredibly proud" that the Beagle 2 team came so close. "Previously, I assumed it was in pieces. But now I feel very proud to know that it's there, intact, and was (likely) ready to do some great science," he explained. "This kind of tantalising result on a long held mystery is the kind of thing that keeps us going, that really inspires me to persist in the challenge of exploring Mars. "I like to think that in every failure there is a success hidden somewhere that teaches us and motivates us. This is a perfect example." The new results will be discussed by Mark Sims and Geraint Morgan at the Colin Pillinger Memorial Talk at Bristol University next Wednesday 16 November


News Article | June 21, 2016
Site: www.techtimes.com

Earth's twin planet Venus is a blistering planet filled with streaks of acidic clouds, a runaway greenhouse effect and a surface hot enough to melt lead. This second planet from the sun is considered the closest semblance to our own planet because it is slightly smaller, but it's completely different. For instance, the atmosphere of Venus consists mainly of carbon dioxide, little nitrogen and small traces of sulfur oxide and other gases. Its atmosphere is much thicker than that of Earth and can reach pressures of more than 90 times that of our planet at sea level. It is also extremely dry, with a comparative abundance of water 100 times lower. But it wasn't always this way. Scientists believe that Venus once contained large amounts of water 4 billion years ago. However, as the planet heated up, much of the water evaporated into the atmosphere. They suspect that the planet's "electric wind" may have helped strip all the water out of the atmosphere. Astronomers have long been wondering whether all planets with atmospheres have an electric field generated by a layer of particles located in the ionosphere. But so far, in every planet that they looked, they have been unable to detect it. Their theory is that the electric field is just very, very weak. They even postulate that Earth's electric field is only at a range of 1 to 2 volts. The electric field of Venus, however, is quite enormous, says Glyn Collinson. "It's a monster lurking in the sky," says Collinson, who is a NASA scientist and lead author of a new paper that measures Venus' electric field. The planet's electric field is five times larger than that of Mars, Earth or Saturn's natural satellite Titan. Because it is so strong, scientists say the electric field produces its own "wind." It's very different from the gusts of air we experience, however, as it is more akin to solar wind - a stream of particles coming from the sun. Researchers say that when molecules of water go up into the atmosphere, light from the sun separates the water into hydrogen ions that easily escape and oxygen ions that are heavier. On Venus, the electric wind is so ferocious that it can accelerate these oxygen ions and cause them to escape the atmosphere. Co-author Professor Andrew Coates of the University College London Mullard Space Science Laboratory says the ions dragged away into space are lost forever, and that more than 100 metric tons of oxygen ions per year are actually removed from Venus. Collinson says although they do not know why the electric field is much stronger in Venus, they think its distance to the sun, as well as the ultraviolet sunlight being double in brightness, may be affecting it. The team used a large instrument aboard the European Space Agency's Venus Express to measure the planet's electric field. Details of the study are published in the journal Geophysical Research Letters on June 20. © 2016 Tech Times, All rights reserved. Do not reproduce without permission.


News Article | March 24, 2016
Site: www.rdmag.com

In the New World, one of the first recorded sightings of the aurora borealis—on Dec. 11, 1719—didn’t elicit positive responses from the New Englanders who spotted it. Instead, it dredged up apocalyptic fear. Reports of a face appearing in the iridescent night sky lights brought portents of Judgement Day. Today, the aurora borealis is a tourist attraction. The phenomenon is seen when ejected energetic particles from the sun interact with the Earth’s magnetosphere. But what’s the phenomenon like on other planets? Well curious reader, wonder no more. The American Geophysical Union has released composite images of Jupiter’s own Northern Lights. The distant planetary phenomenon is the subject of a new study published in the organization’s Journal of Geophysical Research—Space Physics. According to the researchers, the spectacular aurora is eight times brighter and hundreds of times more energetic than Earth’s aurora borealis. The observations were recorded in October 2011. “The sun constantly ejects streams of particles into space in the solar wind,” according to the American Geophysical Union. “When giant storms erupt, the winds become much stronger and compress Jupiter’s magnetosphere, shifting its boundary with the solar wind (1.25 million miles) through space. The new study found that this interaction at the boundary triggers the high energy X-rays in Jupiter’s Northern Lights, which cover an area bigger than the surface of the Earth.” Over the course of 11 hours, the researchers monitored the solar storms’ impact on the planet. Since X-rays aren't visible to the human eye, the researchers were able to use their instruments to produce a composite image of Jupiter's Northern Lights. “In 2000, one of the most surprising findings was a bright ‘hot spot’ of X-rays in the aurora, which rotated with the planet,” said William Dunn, of the Univ. College London's Mullard Space Science Laboratory, in a statement. “It pulsed with bursts of X-rays every 45 minutes, like a planetary lighthouse. When the solar storm arrived in 2011, we saw that the hot spot pulsed more rapidly, brightening every 26 minutes. We’re not sure what causes this increase in speed but, because it quickens during the storm, we think the pulsations are also connected to the solar wind, as well as the bright new aurora.” Scientists hope NASA's Juno spacecraft, slated for arrival this year, will help shed some light on this phenomenon. Scientists have known of Jupiter's auroras for decades. They’ve even been referred to by one scientist as the "Northern Lights on steroids." They were first discovered by NASA's Voyager 1 in 1979. Establish your company as a technology leader! For more than 50 years, the R&D 100 Awards have showcased new products of technological significance. You can join this exclusive community! Learn more.


News Article | March 22, 2016
Site: motherboard.vice.com

Jupiter has its own version of the Northern Lights, and it can be hundreds of times more energetic than the earthly phenomenon. For the first time, scientists have studied Jupiter’s X-ray aurora during a solar storm. They found that it was eight times brighter than usual under these conditions, and that its brightest spot “pulsed” more quickly—every 26 minutes as opposed to 45 minutes. The researchers don’t know exactly why this is, but ultimately understanding these kind of processes could help identify habitable planets elsewhere in the Universe. Here, the image on the left shows the aurora as a coronal mass ejection (solar flare) reached Jupiter in October 2011; the image on the right shows it two days later when the solar wind had subsided. As the aurora is made of X-rays—which are more energetic than the light in our aurora borealis—they’re not visible, but the brightness in the colouring is based on the data collected with NASA’s Chandra observatory. The study was published Tuesday in the Journal of Geophysical Research. William Dunn, a PhD student at University College London’s Mullard Space Science Laboratory and lead author, explained in a phone call that this research will help demystify the relationship between Jupiter’s massive magnetosphere (the area controlled by its magnetic field) and solar wind. “We have a vague idea of what’s going on between the Earth’s magnetic field and the solar wind, but we don’t really understand what happens elsewhere in the Solar System,” he explained. Jupiter is particularly interesting because its magnetic field and magnetosphere are very different from Earth’s. For a start, Jupiter is much bigger than Earth (and every other planet combined) and its magnetic field is magnitudes stronger. It also spins faster with a full rotation every 10 hours, as opposed to 24 hours, and is affected by volcanic material from the moon Io. As it’s so different to Earth, it could help inform which processes connecting Earth to the solar wind are shared among other celestial objects, and which may be unique. “Because Jupiter presents a very different set of circumstances, Jupiter and Earth kind of provide us with two benchmarks against which we can understand all these other places and all these other features across the Universe,” said Dunn. One reason this is particularly cool: We think magnetic fields are crucial to support complex life. The fact that Mars’s atmosphere was, we believe, stripped away by solar winds owing to its lack of a strong magnetic field, is a major reason many don’t expect it to host life anywhere near its surface. Knowing more about how magnetospheres relate to the Sun and solar winds could therefore inform our search for potentially habitable exoplanets. “By having a magnetic field, you get this protective boundary that prevents the solar wind sweeping away your atmosphere,” said Dunn. “And so understanding the signatures that are associated with that protective boundary, and that interaction with the Sun, will help us to understand how well-protected the planet is from the solar wind.” For now, the researchers don’t know exactly how the interplay between solar winds and Jupiter’s magnetosphere works, but given the effect of the solar storm on the aurora, they know there is a relationship there. Luckily for them, NASA’s Juno orbiter is scheduled to reach Jupiter in July, and one of its goals is to specifically investigate the gas giant’s magnetic field.

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