21 May 2017

Rainfall on Mars shaped the planet

MARS_Helmets_DLAt one stage in its history rain storms on Mars were so heavy – and the raindrops so large – that they changed the planet’s surface, carving valleys and altering the shape of meteorite impact craters, new research shows.

A paper by geologists Robert Craddock and Ralph Lorenz, published in the journal Icarus, suggests that over billions of years Mars’s atmospheric pressure fell, powering up the nature of its rainfall.

Soon after its formation around 4.5 billion years ago, atmospheric pressure on the red planet was around four bars. To compare, Earth’s is one.

At that pressure, Craddock and Lorenz say, rain would have looked more like mist. Raindrops could not have grown to more than three millimetres in diameter, and would not have penetrated the ground when they hit it.

Over deep time, however, the atmospheric pressure decreased to around 1.5 bars. This, combined with lower gravity than that of Earth, meant that raindrops as large as 7.3 millimetres across could form – substantially bigger than the 6.5 millimetre whoppers sometimes recorded on our own planet.

The geologists calculate that the intensity of big falls would have been only about 70% of those found on Earth, but would still have been easily strong enough to put a dent or two in the ground.

Indeed, they suggest that the falls would have overwhelmed the soil’s ability to absorb moisture, thus creating run-off currents that eventually formed valley networks and reshaped impact craters.

“We have shown that Mars would have seen some pretty big raindrops that would have been able to make more drastic changes to the surface,” comments Lorenz, from Johns Hopkins University in the US.

Craddock, who works at the Smithsonian Institute, adds that their paper represents the first time scientists have used physics to gain insight into the Martian climate.

“There will always be some unknowns, of course, such as how high a storm cloud may have risen into the Martian atmosphere, but we made efforts to apply the range of published variables for rainfall on Earth,” he adds.

“It’s unlikely that rainfall on early Mars would have been dramatically different than what's described in our paper.”

9 May 2017

scientists now want to send a space probe to orbit Pluto

Pluto-01_Stern_03_Pluto_Color_TXTHumanity's first up-close look at Pluto was so intriguing that some researchers want to go back and spend a lot more time studying the icy world.

Late last month, 35 scientists met for 7 hours in Houston to discuss the basic blueprint and science goals of a potential Pluto orbiter mission. Such an effort would build upon the knowledge gained during the epic Pluto flyby performed in July 2015 by NASA's New Horizons probe.

Participants came away from the April 24 workshop fired up and committed to doing their best to make such a project happen, said New Horizons principal investigator Alan Stern, who was there. [Destination Pluto: NASA's New Horizons Mission in Pictures]

The meeting was reminiscent, Stern said, of New Horizons' earliest days: the late 1980s, when he and a few other people first raised the possibility of launching a flyby mission to Pluto.

"It felt a lot like that, but [with] a new generation of people," Stern, who's based at the Southwest Research Institute in Boulder, Colorado, told Space.com.

New Horizons' flyby revealed Pluto to be a stunningly diverse world with vast plains of nitrogen ice, 2-mile-high (3.2 kilometers) mountains of water ice and a wealth of other surface features. But the probe got just a fleeting look at the dwarf planet system while zooming by; an orbiter would linger and lift Pluto's veil even more, Stern said.

"You could map every square inch of the planet and its moons," he said. "It would be a scientific spectacular."

As the possible mission is currently envisioned, the orbiter would cruise around the Pluto system, using gravity assists from the dwarf planet's largest moon, Charon, to slingshot it here and there, Stern said. The strategy would be similar to that employed by NASA's Cassini spacecraft, which has shaped its path through the Saturn system over the years via flybys of the ringed planet's largest moon, Titan.

The current concept is therefore different from one Stern proposed shortly after New Horizons' flyby, which would have put a lander down on Charon.

With a Charon lander, "you're stuck looking at one side of Pluto," Stern said. (Charon and Pluto are tidally locked, meaning each world always shows the same face to the other.)

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"And you can't get in superclose. You can't get down in the atmosphere," he added. "This, I think, is a better mission concept."

Though the mission would be Cassini-like, the Pluto orbiter itself would resemble NASA's Dawn probe, which is currently circling the dwarf planet Ceres, Stern said. Like Dawn, the Pluto probe would likely use electric propulsion and have a half-dozen science instruments, he said.

However, because the Pluto orbiter would be operating so far from the sun, it would rely on nuclear power to generate its electricity, rather than sunlight, as Dawn does, Stern added. And the price tag would be higher than Dawn's $467 million; the Pluto effort would probably qualify as a New Frontiers mission or a small flagship. (New Frontiers missions cost about $1 billion, whereas flagships run about $2 billion.)

Stern said a Pluto orbiter could get off the ground in the late 2020s or so. A 2030 launch would have ceremonial significance, coming on the 100th anniversary of Pluto's discovery, he added. The probe would spend seven or eight years journeying to the dwarf planet, then perhaps four or five years studying Pluto and its moons.

When the probe's work there was done, Stern said, the spacecraft could conceivably use one last Charon flyby to escape the Pluto system and head toward another object in the Kuiper Belt, the ring of frigid bodies beyond Neptune's orbit. (New Horizons is doing something similar; it's now headed for a Jan. 1, 2019, flyby of a small Kuiper Belt object called 2014 MU69.)

But a Pluto orbiter mission is a long way from becoming reality, Stern stressed. He said he and his fellow researchers aim to mature the concept in time for it to be considered during the next Planetary Science Decadal Survey, a U.S. National Research Council effort that sets exploration priorities for NASA every 10 years.

The next decadal survey will start in 2020, finish in 2022 and be published in 2023, Stern said.

"The curtain is opening," he said of the Pluto orbiter idea. "This thing is going to be a topic of discussion now for the next few years."

24 Apr 2017

Scarborough Firm Invests in Pop-Up Planetarium

574016-600x400_scale_type-center_cropExploring the celestial wonders above North Yorkshire is being made easier thanks to a £15,000 investment in a pop-up planetarium and two powerful portable telescopes by a Scarborough firm.

Hidden Horizons, which specialises in science and natural history-based tours including coastal fossil hunting, began running stargazing safaris in 2016 as part of the inaugural Dark Skies Festival run jointly by the North York Moors and Yorkshire Dales National Parks.

The success of the 2016 and this February’s Festivals led to a spike in visitor interest for eyeing the dark skies and a surge in bookings for Hidden Horizons’ celestial exploring events.

Now, aided by a 50% grant from the North York Moors National Park Authority and additional support from the Forestry Commission, Hidden Horizons has purchased an inflatable planetarium, solar telescope and one of the county’s largest publicly-accessible portable telescopes to meet the growing interest.

The portability of the equipment means the company can now bring the wonders of the universe to schools, pubs, hotels and other public and private venues right across the region.

The beauty of the planetarium, which spans four-metres in diameter and can accommodate up to 30 children or 20 adults, means that Hidden Horizons can run sessions even if the weather prevents trips outdoors.

During the day the powerful solar telescope will enable visitors to safely observe sunspots and dramatic flares while the night sky telescope will lead budding astronomers on a journey deep into the universe, with its ability to reveal up to 40,000 objects at any one time.

Andy Exton, director and astronomer for Hidden Horizons comments:

“We’re very fortunate to have a great, expansive dark skies area on our doorstep and people are catching on to this.

Increasing numbers of stargazing bookings are coming from visitors outside the region, from as far afield as Manchester, London and even Singapore, and so this investment will really boost our offer, particularly as it increases our flexibility to stage pop-up astronomy evenings at a huge variety of venues.”

You can contact them here

Catriona McLees, Head of Promotion and Tourism for the North York Moors National Park Authority adds:

“We were delighted to extend grant funding for this initiative as it is a great legacy of the Dark Skies Festival and taps into the nation’s growing enthusiasm for stargazing. It will also help support other tourism businesses by providing a further draw for people to visit and stay in the National Park particularly during those months when footfall tends to drop off.”

23 Apr 2017

Spectacular Aurora display not over yet

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Aurora hunters were treated to an unusually intense and widespread display of the Southern Lights over the weekend, and it's not over yet, says Otago University astronomer Ian Griffin.

The Aurora Australis, or the Southern Lights, were spotted all over the country - and as far north as Auckland.

 

Dr Griffin - who is also the Otago eight_col_18121591_404897046558188_7239403000989958350_oMuseum director - told Morning Report it was a particularly intense display in Otago on Sunday night.

"This was quite an interesting display, I saw mostly greens, but other people who have got better eyes than me were seeing reds, but the photographs showed all the colours much better and there were some lovely purples in there as well. So it was a pretty stunning display, all told."

This week's display was caused by a large coronal hole on the sun, said Dr Griffin.

eight_col_18056316_404896633224896_2691289982670285738_o"It's basically a gap in the sun's magnetic field that starts spewing material towards the Earth - and it races towards the Earth at between 600 and 800 kilometres per second - and it's that material that interacts with the Earth's magnetic field and causes the atmosphere to glow.

"And that glow is the aurora, and the colour of the glow is different gases in the atmosphere, so the green glow is mainly oxygen and if you can see the red colour, that's nitrogen."

He said Sunday was unfortunately cloudy in Otago, but that he had seen some "brilliant' pictures of lights in Christchurch and Wellington, and even further north.

"One of the most amazing things was that somebody photographed it in Auckland, which is pretty incredible really, because to see the aurora that far north is very unusual. You may only see it in Auckland once every couple of years."

Dr Griffin said the current round of lights could continue for a few more days.

"It'll probably tail off, but if it's clear tonight, I would nip out and have a look."

RESEARCHERS PRODUCE DETAILED MAP OF POTENTIAL MARS ROVER LANDING SITE

Ashampoo_Snap_2017.04.22_23h09m43s_001_Brown University researchers have published the most detailed geological history to date for a region of Mars known as Northeast Syrtis Major, a spot high on NASA's list of potential landing sites for its next Mars rover to be launched in 2020.

The region is home to a striking mineral diversity, including deposits that indicate a variety of past environments that could have hosted life. Using the highest resolution images available from NASA's Mars Reconnaissance Orbiter, the study maps the extent of those key mineral deposits across the surface and places them within the region's larger geological context.

"When we look at this in high resolution, we can see complicated geomorphic patterns and a diversity of minerals at the surface that I think is unlike anything we've ever seen on Mars," said Mike Bramble, a Ph.D. student at Brown who led the study, which is published in the journal Icarus. "Within a few kilometres, there's a huge spectrum of things you can see and they change very quickly."

If NASA ultimately decides to land at Northeast Syrtis, the work would help in providing a roadmap for the rover's journey.

"This is a foundational paper for considering this part of the planet as a potential landing site for the Mars 2020 rover," said Jack Mustard, a professor in Brown's Department of Earth, Environmental and Planetary Sciences and a co-author on the paper. "This represents an exceptional amount of work on Mike's part, really going into the key morphologic and spectroscopic datasets we need in order to understand what this region can tell us about the history of Mars if we explore it with a rover."

Northeast Syrtis sits between two giant Martian landforms—an impact crater 2,000 kilometres in diameter called the Isidis Basin, and a large volcano called Syrtis Major. The impact basin formed about 3.96 billion years ago, while lava flow from the volcano came later, about 3.7 billion years ago. Northeast Syrtis preserves the geological activity that occurred in the 250 million years between those two events. Billions of years of erosion, mostly from winds howling across the region into the Isidis lowlands, have exposed that history on the surface.

Within Northeast Syrtis are the mineral signatures of four distinct types of watery and potentially habitable past environments. Those minerals had been detected by prior research, but the new map shows in detail how they are distributed within the region's larger geological context. That helps constrain the mechanisms that may have formed them, and shows when they formed
relative to each other.

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The lowest and the oldest layer exposed at Northeast Syrtis has the kind of clay minerals formed when rocks interact with water that has a fairly neutral pH. Next in the sequence are rocks containing kaolinite, a mineral formed by water percolating through soil. The next layer up contains spots where the mineral olivine has been altered to carbonate—an aqueous reaction that, on Earth, is known to provide chemical energy for bacterial colonies. The upper layers contain sulphate minerals, another sign of a watery, potentially life-sustaining environment.

Understanding the relative timing of these environments is critical, Mustard says. They occurred around the transition between the Noachian and Hesperian epochs—a time of profound environmental change on Mars.

"We know that these environments existed near this major pivot point in Mars history, and in mapping their context we know what came first, what came next and what came last," Mustard said. "So now if we're able to go there with a rover, we can sample rock on either side of that pivot point, which could help us understand the changes that occurred at that time, and test different hypotheses for the possibility of past life."

And finding signs of past life is the primary mission of the Mars2020 rover. NASA has held three workshops in which scientists debated the merits of various landing targets for the rover.

Mustard and Bramble have led the charge for Northeast Syrtis, which has come out near the top of the list at each workshop. Last February, NASA announced that the site is one of the final three under consideration.

Mustard and Bramble hope this latest work might inform NASA's decision, and ultimately help in planning the Mars2020 mission.

"As we turn our eyes to the next target for in situ exploration on the Martian surface," the researchers conclude, "no location offers better access of the gamut of geological processes active at Mars than Northeast Syrtis Major."

21 Apr 2017

McDonald Observatory dedicates $40 million upgrade

McDonald_Observatory-167_Courtesy%20of%20Ethan%20Tweedie%20Photography_0The University’s McDonald Observatory in West Texas dedicated its $40 million telescope upgrade last week and is now performing an in-depth study of a mysterious force known as dark energy.

The upgrade gives McDonald’s 10-meter telescope the ability to create a 3-D map of the universe to study dark energy, a little understood concept that could explain the accelerating expansion of the universe.

Photo Credit: Courtesy of Ethan Tweedie Photography | Daily Texan Staff

The telescope, the world’s third largest in size, can now see light that is close to 12 billion years old and can view 120 times more of the night sky than it previously could. Not even the largest telescope in the world at the Kek Observatory in Hawaii has as large of a field of view.

“It is sort of one of a kind right now,” McDonald Observatory director Taft Armandroff said. “It’s going to allow us to study a lot of areas of astronomy that are on the cutting edge.”

The Observatory received funding from the State of Texas, other universities and private donors to add four new instruments to the telescope along with expanding its view and depth. Two of these instruments, high and low resolution spectrographs, will be used to study the light from both galaxies and individual stars, Armandroff said.

Another new instrument allows the telescope to see high red-shift galaxies, or galaxies that are 10 to 12 billion light years away and were formed shortly after the Big Bang, Armandroff said.

Finally, Armandroff said the telescope now has a habitable zone planet finder which detects wobbles in the movement of a star to see if it has any orbiting planets.

Together, these devices will help astronomers at the University and elsewhere create a 3-D map they can use to measure how fast the universe’s expansion is accelerating and thereby give them an idea as to what force might be causing it, astrophysics professor Karl Gebhardt said.

“It’s crazy exciting. No one has looked at the universe in this way in the past,” Gebhardt said. “We may redefine what gravity actually is, (or dark energy) could be something like a new type of particle.”

Already, students at the University are analysing the data the telescope collects each night. After nightfall in West Texas, the telescope collects information that is sent to a server that both undergraduate and graduate students have access to.

After a class with Gebhardt last semester, aerospace engineering senior Jamie McCullough began working with the McDonald Observatory data. Most of the time, McCullough analyses the data sent over to adjust the information based on how much light was hitting the telescope. McCullough has also been working on writing a code that will perform these calibrations automatically.

“The upgrade is fantastic, and there’s so much data coming off of it, and there’s so much potential for so much advancement,” McCullough said. “It’ll really just be exciting to see what comes of it.”

19 Apr 2017

NASA Radar Spots Relatively Large Asteroid Prior to Flyby

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Radar images of asteroid 2014 JO25 were obtained in the early morning hours on Tuesday, with NASA's 70-meter (230-foot) antenna at the Goldstone Deep Space Communications Complex in California. The images reveal a peanut-shaped asteroid that rotates about once every five hours. The images have resolutions as fine as 25 feet (7.5 meters) per pixel.

Asteroid 2014 JO25 was discovered in May 2014 by astronomers at the Catalina Sky Survey near Tucson, Arizona -- a project of NASA's Near-Earth Objects Observations Program in collaboration with the University of Arizona. The asteroid will fly safely past Earth on Wednesday at a distance of about 1.1 million miles (1.8 million kilometres), or about 4.6 times the distance from Earth to the moon. The encounter is the closest the object will have come to Earth in 400 years and will be its closest approach for at least the next 500 years.

"The asteroid has a contact binary structure - two lobes connected by a neck-like region," said Shantanu Naidu, a scientist from NASA's Jet Propulsion Laboratory in Pasadena, California, who led the Goldstone observations. "The images show flat facets, concavities and angular topography."

The largest of the asteroid's two lobes is estimated to be 2,000 feet (620 meters) across.

Radar observations of the asteroid also have been conducted at the National Science Foundation's Arecibo Observatory in Puerto Rico. Additional radar observations are being conducted at both Goldstone and Arecibo on April 19 20, and 21, and could provide images with even higher resolution.

Radar has been used to observe hundreds of asteroids. When these small, natural remnants of the formation of the solar system pass relatively close to Earth, deep space radar is a powerful technique for studying their sizes, shapes, rotation, surface features, and roughness, and for more precise determination of their orbital path.

NASA's Jet Propulsion Laboratory, Pasadena, California, manages and operates NASA's Deep Space Network, including the Goldstone Solar System Radar, and hosts the Center for Near-Earth Object Studies for NASA's Near-Earth Object Observations Program within the agency's Science Mission Directorate.

18 Apr 2017

Do Meteors Hiss, Sizzle, and Pop?

imageFor hundreds of years there have been reports of people hearing the sound of meteors—shooting stars—as they streak across the sky. As early as 1714, astronomy Edmond Halley (yes, that Halley, of comet fame) dismissed these accounts of hissing, sizzling, and popping as figments of the imagination. After all, sound travels much more slowly than light—see: every thunderstorm ever—so any sound from the meteor breaking up in the atmosphere would arrive long after the streak of ionized gas has faded from the sky. But hearing and seeing a meteor at the same time is not a scientific impossibility. A new hypothesis published in Geophysical Research Letters might explain just how it happens, and why the described noises sound a lot like radio static.

When a meteor hits the atmosphere, at between 25,000 and 160,000 miles per hour, it releases electromagnetic radiation, including both light and what are known as very low frequency radio waves. Twenty-five years ago, scientists demonstrated that these waves, which travel just as fast as light, can cause objects, especially metal ones, to vibrate in a way that produces sound.

“The conversion from electromagnetic waves to sound waves … is exactly how your radio works,” Colin Price of Tel Aviv University, co-author of the new study, told Science. The study proposes that these waves come from an electrical current generated as the meteor interacts with the atmosphere. Though it involves coma ions, an am bipolar electric field, and Hall current, it’s the simplest explanation for the phenomenon yet.

Telescope project makes progress on radio-quiet zone

untitledThe Square Kilometre Array (SKA) SA project office has acquired half of the land it needs to create a radio-quiet zone around the large radio telescope and is on track to complete the process by the end of 2018, says spokesman Lorenzo Raynard.

It is an important milestone in a sensitive process as, if the farmers in the area refuse to sell their land, the government can expropriate it. The SKA is an international science project located in SA and Australia and will be the world’s most powerful radio telescope once completed. The South African core is 90km from Carnarvon in the Northern Cape.

About 131,500ha of land surrounding the telescope’s 176-dish core needs to be free from radio-frequency interference. The project acquired 13,500ha of this land in 2008. In 2016 it embarked on a process to acquire another 118,000ha comprising 36 parcels of land close to the core as well as access rights to servitudes that will hold another 21 dishes.

The SKA SA project office has acquired 14 parcels of land, comprising 61,000ha and needs to buy another 18 parcels of land totalling 57,000ha. Four parcels of land originally earmarked for purchase no longer needed to be bought, but would provide access rights to servitudes, said Raynard. The land-acquisition project is one of three SKA processes under way in SA. The Department of Science and Technology has been driving the implementation of legislation to protect the site from radio interference.

17 Apr 2017

Why Sending Stephen Hawking to Space Matters

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Despite having been told he would not make it past his 25th birthday, now 75-year-old renowned cosmologist and science author Stephen Hawking is being sent to space on billionaire Richard Branson’s Virgin Galactic ship. While confined to a wheelchair and communicating via a speech generator attached to a single cheek muscle, Stephen Hawking continues to contribute to the advancement of science in incredible ways. Over the course of his career, Hawking has also been a fierce advocate of disability rights and has shattered the glass ceiling of what people with disabilities are perceived to be capable of time and time again.

While the physical and intellectual capabilities of human beings differ greatly, they do not necessarily define us nor do they render us incapable of accomplishing significant feats. Stephen Hawking has visited one of Earth’s last thresholds, Antarctica, and has experienced weightlessness on a sub-orbital space flight. He is the Director of Research at the Centre for Theoretical Cosmology at the University of Cambridge and has written several novels, of which A Brief History of Time was a record-breaking best-seller. The physicist famously theorized that black holes emit radiation and is a recipient of the Presidential Medal of Freedom, the greatest award for civilians available in the United States. These are just a few of his accomplishments.

Hawking’s incredible career signifies the extent to which the empowerment of people with disabilities through increased accessibility and technological advancement can provide greater opportunities for everyone to pursue their dreams regardless of their circumstances. At age 21, Hawking was diagnosed with a rare early-onset form of amyotrophic lateral sclerosis (ALS) that has slowly paralyzed him. While this disease is generally fatal within five years, Hawking has lived more than five decades since his initial diagnosis. While not everyone diagnosed with ALS may have access to the same treatment and care as this academic celebrity, the longevity and success of Hawking’s career demonstrates that investing in people with disabilities is a worthy pursuit.

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While Stephen Hawking’s physical capabilities have continued to decline over the decades, his mind and intellect have remained intact. By providing Hawking with a vehicle to communicate his brilliance, the pursuit of science has benefited as a whole. People with disabilities are often erased in both science and science fiction. Becoming a spacefaring species was one of the greatest defining moments for human beings. Now, we look to colonizing other terrestrial bodies in the event that one day our own planet can no longer harbour life.

In a visit to London’ Space Museum in 2015, Stephen Hawking stated that space travel “represents an important life insurance for our future survival, as it could prevent the disappearance of humanity by colonizing other planets.” One of the cosmologist’s biggest dreams has been to travel to space himself which will, in the near future, become a reality. As an icon for disability rights activism, Hawking’s journey will allow people with disabilities to see themselves represented in the voyage to the stars.

In science fiction, writers imagine future worlds in which anything is possible. In these imaginings of tomorrow, be they utopian, dystopian or complex, nuanced worlds with problems like our own, disability is often perceived as something to be cured, fixed or erased altogether. In pathologizing disability or removing it entirely from futurist contexts, people with disabilities often do not find themselves represented or as fitting into the grand scheme. As a result, Stephen Hawking’s projected spaceflight matters immensely as it exemplifies that he, like anyone else, is an individual with his own physical and intellectual capacities, of which having a disability is not his sole-defining characteristic.

It is evident that Hawking’s career has been greatly empowered due to his intelligence and access to economic capital which others with his disease may not be as fortunate to have. However, he is a shining example of the potential that can be realized when society works to develop technology and increase accessibility for everyone. Today, accessibility can take on the form of ensuring all stations on public transit lines have elevators or that all new buildings use levers instead of door knobs. The shift towards accessibility in urban planning and the design of all things means that people with disabilities have a bright future ahead.

The rise of space tourism by private companies like Virgin Galactic and SpaceX are disrupting the entire space exploration industry. The CEO of SpaceX, founder of PayPal and Tesla Motors’ Elon Musk has launched private vehicles into space and enabled them to return to Earth with reusable rockets. In doing so, Musk has greatly reduced the cost of spaceflight and in turn made it more accessible. As these companies continue to develop space technology, the goal of taking humans to other planets becomes more realistic. Not only this but also sending human beings to space from all walks of life including those, like Stephen Hawking, with disabilities.

Stephen Hawking being sent so space matters for every dreamer who has imagined themselves leaving Earth to gaze down in wonder upon the curvature of the pale blue dot. It has traditionally only been astronauts with unparalleled physical and intellectual ability who have had the enormous privilege of leaving our planet’s atmosphere. Now, the extremely wealthy can purchase a ticket to the stars via private space travel companies. However, as evidenced by this change and while it may take centuries, it is only a matter of time before space travel becomes available to everyone.

Supermassive black holes found in two tiny galaxies

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Three years ago, a University of Utah-led team discovered that an ultra-compact dwarf galaxy contained a supermassive black hole, then the smallest known galaxy to harbour such a giant black hole. The findings suggested that the dwarfs were likely tiny leftovers of larger galaxies that were stripped of their outer layers after colliding into other, larger galaxies.

Now, the same group of U astronomers and colleagues have found two more ultra-compact dwarf galaxies with supermassive black holes. Together, the three examples suggest that black holes lurk at the centre of most of these objects, potentially doubling the number of supermassive black holes known in the universe. The black holes make up a high percentage of the compact galaxies' total mass, supporting the theory that the dwarfs are remnants of massive galaxies that were ripped apart by larger galaxies.

"We still don't fully understand how galaxies form and evolve over time. These objects can tell us how galaxies merge and collide," says Chris Ahn, doctoral candidate in the Department of Physics & Astronomy, and lead author of the international study that published Monday in The Astrophysical Journal. "Maybe a fraction of the centres of all galaxies are actually these compact galaxies stripped of their outer parts."

Measuring galaxies
 
The authors measured two ultra-compact dwarf galaxies, named VUCD3 and M59cO, that lie far beyond the spiral arms of our Milky Way, orbiting massive galaxies in the Virgo galaxy cluster. They detected a supermassive black hole in both galaxies; VUCD3's black hole has a mass equivalent to 4.4 million suns, making up about 13 percent of the galaxy's total mass, and M59cO's black hole has a mass of 5.8 million suns, making up about 18 percent of its total mass.

By comparison, the monstrous black hole at the centre of the Milky Way has a mass of 4 million suns, but makes up less than .01 percent of the galaxy's total mass.

"It's pretty amazing when you really think about it. These ultra-compact dwarfs are around 0.1 percent the size of the Milky Way, yet they host supermassive black holes that are bigger than the black hole at the centre of our own galaxy," marvels Ahn.

To calculate the ultra-compact dwarf galaxies' mass, the astronomers measured the movement of the stars using the Gemini North telescope located on Mauna Kea volcano in Hawaii. The astronomers have to correct for the distortions caused by Earth's atmosphere. They shot a laser into the sky to make a fake little star, and moved a mirror around hundreds of times a second to undo the distortion. They then applied the technique to the ultra-compact dwarf galaxies, which are so small that the corrections are necessary to measure the motions inside the object. The technique, known as adaptive optics, brings the once blurry galaxy into focus.

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They also analysed images from the Hubble Space Telescope to measure the distribution of the stars in each galaxy, and created a computer simulation that best fit their observations.

They found that the motion of the stars at the centre of the galaxies moved much faster than those on the outside, a classic signature of a black hole. VUCD3 and M59cO are the second and third ultra-compact dwarf galaxies found to contain a supermassive black hole, suggesting that all such dwarfs may harbour similarly massive light-sucking objects.

Ultra-compact dwarf galaxy mysteries
 
Astronomers discovered ultra-compact dwarf galaxies in the late 1990s. The objects are made up of hundreds of millions of stars densely packed together on an average of 100 light years across. Scientists took measurements to see what was happening inside the galaxies, and something didn't add up; the ultra-compact dwarf galaxies had more mass than their stars alone could account for. Senior author Anil Seth, assistant professor in the Department of Physics & Astronomy at the U, led the 2014 study that found the first ultra-compact dwarf galaxy with a supermassive black hole. The two U-led studies make a strong case that supermassive black holes at the centre of the galaxies are responsible for the extra mass.

An alternate theory of the dwarfs is that they are just really massive star clusters -- groups of a hundred thousand stars born at the same time. The largest star cluster in the Milky Way is three million stars, and ultra-compact dwarf galaxies are 10 to 100 times bigger than that. "The question was, 'Is that because they form bigger star clusters with the same process? Or are they different in some way?' This work shows that they are different," Seth continues.

"It's obvious in retrospect, because the centre of a regular galaxy looks almost exactly like these objects, but that wasn't what most people thought they were. I wasn't convinced that we were going to find a black hole when I took the observations," says Seth. "This is a cool example of scientific discovery and how quickly you can reorient our understanding of the universe."

Black holes and the formation of galaxies
 
Black holes are areas with such strong gravity that not even light can escape. They form when stars collapse, leaving behind a black hole with dense mass that exerts gravitational force on the objects around it. Supermassive black holes have a mass of more than 1 million suns, and are thought to be at the centre of all big galaxies.

One explanation for the supermassive black hole inside the ultra-compact dwarf galaxies is that the galaxies were once made up of billions of stars. The authors believe that the dwarfs were "swallowed up" and ripped apart by the gravity of much larger galaxies. The ultra-compact dwarf black hole is the remnant of its formerly massive size. The findings change the way that astronomers can piece together how galaxies form and evolve over time.

"We know that galaxies merge and combine all the time -- that's how galaxies evolve. Our Milky Way is eating up galaxies as we speak," says Seth. "Our general picture of how galaxies form is that little galaxies merge to form big galaxies. But we have a really incomplete picture of that. The ultra-compact dwarf galaxies provide us a longer timeline to be able to look at what's happened in the past."

28 Mar 2017

Unprecedented Fine Structure of a Solar Flare Revealed by the 1.6 m New Big Bear Solar Telescope

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Scientists from NJIT's Center for Solar-Terrestrial Research are providing some of the first detailed views of the mechanisms that may trigger solar flares, colossal releases of magnetic energy in the Sun's corona that dispatch energized particles capable of penetrating Earth's atmosphere within an hour and disrupting orbiting satellites and electronic communications on the ground.

Recent images captured by the university's 1.6-meter New Solar Telescope at Big Bear Solar Observatory (BBSO) have revealed the emergence of small-scale magnetic fields in the lower reaches of the corona the researchers say may be linked to the onset of a main flare. The study also includes the first scientific contributions from NJIT's newly commissioned Extended Owens Valley Solar Array (EOVSA).

"These smaller magnetic fields appear as precursors to the flare by reconnecting with each other -- breaking apart and forming new connections -- in an already stressed magnetic environment. This sets the stage for a larger energy release," notes Haimin Wang, distinguished professor of physics at NJIT and the leading author of a paper published this week in the magazine Nature Astronomy. The study, funded by the National Science Foundation and NASA, was conducted in collaboration with colleagues in Japan and China.

"Through our measurements, we are able to see the emergence of fine magnetic channel structures prior to the flare, which contain mixed positive and negative magnetic polarities," Wang adds. "We then see a strong twist in the magnetic lines that creates instability in the system and may trigger the eruption."

While solar flares are generally believed to be powered by what is known as free energy -- energy stored in the corona that is released by twisting magnetic fields -- the authors suggest that the build-up of coronal energy in the upper atmosphere alone may not be sufficient to trigger a flare. In their study of a prolonged flare on June 22, 2015, they observed in unprecedented detail the emergence in the lower atmosphere of what they call precursors, or "pre-flare brightening's," in various wavelengths.

There are well-documented periods in which flares occur more frequently than the norm, but it has been difficult thus far to determine exactly when and where a particular flare might be initiated. The BBSO's recent study of a flare's magnetic evolution, enhanced by simultaneous microwave observations from EOVSA, has been able to pin down the time and location of the magnetic reconnection prior to the flare.

"Our study may help us predict flares with more precision," Wang says.

A co-author of the article, Kanya Kusano of Nagoya University, compared BBSO's observations with his numerical simulation of the triggering process of solar flares.

"I found that the observational result is very well consistent with the simulation," he notes. "This clearly indicates that these mixed-polarity magnetic channel structures are typical of the stressed magnetic field that triggers solar flares."

27 Mar 2017

Large-scale planetary waves found on the sun

ig115_13_soho_02Scientists at the National Center for Atmospheric Research have discovered Rossby waves on the sun. The large-scale planetary waves were first discovered on Earth.

On Earth, Rossby waves are correlated with local weather events. On the sun, scientists suggest the waves could influence solar activity and related phenomena, like sunspots and solar flares.

"The discovery of magnetized Rossby waves on the Sun offers the tantalizing possibility that we can predict space weather much further in advance," lead researcher Scott McIntosh said in a news release.

Rossby wave patterns are unique to rotating fluids, like the atmosphere and the ocean. The sun's upper layers are mostly plasma and rotate. Scientists have previously hypothesized that the sun could host Rossby waves, but observing wave patterns on the sun is difficult.

Researchers are able to pick out wave patterns on Earth using dozens of satellites and instruments, which observe physical phenomena from a variety of vantage points. Solar scientists are able to observe the sun from a single vantage point.

Recently, a trio of satellites and spacecraft offered astronomers varied solar perspectives. Researchers supplemented data collected by NASA's Solar Dynamics Observatory, a probe circling halfway between the sun and Earth, with observation from a pair of satellites with NASA's Solar TErrestrial RElations Observatory mission.

"By combining the data from all three satellites we can see the entire sun and that's important for studies like this because you want the measurements to all be at the same time," explained Dean Pesnell, SDO project scientist at NASA's Goddard Space Flight Center. "They're pushing the boundary of how we use solar data to understand the interior of the sun and where the magnetic field of the sun comes from."

In tracing the movements of coronal bright points on the sun's surface, researchers identified cohesive bands of magnetized activity -- Rossby-like waves moving across the solar surface. Researchers shared their discovery in the journal Nature Astronomy.

Scientists believe the waves could be linked with the 11-year solar cycle, as well as solar phenomena like coronal mass ejections and solar flares.

"It's possible that it's all tied together, but we needed to have a global perspective to see that," McIntosh said. "We believe that people have been observing the impacts of these Rossby-like waves for decades, but haven't been able to put the whole picture together."

Further research is needed to explore the predictive abilities of the newly discovered patterns. But first, scientists say they need better data.

"To connect the local scale with the global scale, we need to expand our view," McIntosh said. "We need a constellation of spacecraft that circle the Sun and monitor the evolution of its global magnetic field."

Electrification of sand on Titan and its influence on sediment movement

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Experiments led by researchers at the Georgia Institute of Technology suggest the particles that cover the surface of Saturn's largest moon, Titan, are "electrically charged." When the wind blows hard enough (approximately 15 mph), Titan's non-silicate granules get kicked up and start to hop in a motion referred to as saltation. As they collide, they become frictionally charged, like a balloon rubbing against your hair, and clump together in a way not observed for sand dune grains on Earth -- they become resistant to further motion. They maintain that charge for days or months at a time and attach to other hydrocarbon substances, much like packing peanuts used in shipping boxes here on Earth.

The findings have just been published in the journal Nature Geoscience.

"If you grabbed piles of grains and built a sand castle on Titan, it would perhaps stay together for weeks due to their electrostatic properties," said Josef Dufek, the Georgia Tech professor who co-led the study. "Any spacecraft that lands in regions of granular material on Titan is going to have a tough time staying clean. Think of putting a cat in a box of packing peanuts."

The electrification findings may help explain an odd phenomenon. Prevailing winds on Titan blow from east to west across the moon's surface, but sandy dunes nearly 300 feet tall seem to form in the opposite direction.

"These electrostatic forces increase frictional thresholds," said Josh Méndez Harper, a Georgia Tech geophysics and electrical engineering doctoral student who is the paper's lead author. "This makes the grains so sticky and cohesive that only heavy winds can move them. The prevailing winds aren't strong enough to shape the dunes."

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To test particle flow under Titan-like conditions, the researchers built a small experiment in a modified pressure vessel in their Georgia Tech lab. They inserted grains of naphthalene and biphenyl -- two toxic, carbon and hydrogen bearing compounds believed to exist on Titan's surface -- into a small cylinder. Then they rotated the tube for 20 minutes in a dry, pure nitrogen environment (Titan's atmosphere is composed of 98 percent nitrogen). Afterwards, they measured the electric properties of each grain as it tumbled out of the tube.

"All of the particles charged well, and about 2 to 5 percent didn't come out of the tumbler," said Méndez Harper. "They clung to the inside and stuck together. When we did the same experiment with sand and volcanic ash using Earth-like conditions, all of it came out. Nothing stuck."

Earth sand does pick up electrical charge when it's moved, but the charges are smaller and dissipate quickly. That's one reason why you need water to keep sand together when building a sand castle. Not so with Titan.

"These non-silicate, granular materials can hold their electrostatic charges for days, weeks or months at a time under low-gravity conditions," said George McDonald, a graduate student in the School of Earth and Atmospheric Sciences who also co-authored the paper.

Visually, Titan is the object in the solar system most like Earth. Data gathered from multiple flybys by Cassini since 2005 have revealed large liquid lakes at the poles, as well as mountains, rivers and potentially volcanoes. However, instead of water-filled oceans and seas, they're composed of methane and ethane and are replenished by precipitation from hydrocarbon-filled clouds. Titan's surface pressure is a bit higher than our planet -- standing on the moon would feel similar to standing 15 feet underwater here on Earth.

"Titan's extreme physical environment requires scientists to think differently about what we've learned of Earth's granular dynamics," said Dufek. "Landforms are influenced by forces that aren't intuitive to us because those forces aren't so important on Earth. Titan is a strange, electrostatically sticky world."

25 Mar 2017

Astronomers find unexpected, dust-obscured star formation in distant galaxy

Pushing the limits of the largest single-aperture millimetre telescope in the world, and coupling it with gravitational lensing, University of Massachusetts Amherst astronomer Alexandra Pope and colleagues report that they have detected a surprising rate of star formation, four times higher than previously detected, in a dust-obscured galaxy behind a Frontier Fields cluster.

170323125453_1_900x600As Pope explains, "This very distant, relatively typical galaxy is known to us, and we knew it was forming stars, but we had no idea what its real star-formation rate was because there is so much dust surrounding it. Previous observations couldn't reach past that. Finding out that 75 percent of its star formation was obscured by dust is remarkable and intriguing. These observations clearly show that we have more to learn."

She adds, "Historians want to know how civilizations were built up, and we astronomers want to know where and how the elements in the universe were formed and where everything is made of, came from." The study is accepted for publication in The Astrophysical Journal.

The new tool that has made such revelations possible is the 50-meter Large Millimeter Telescope (LMT) which has been observing as a 32-meter telescope located on an extinct volcano in central Mexico in "early science mode" since 2013. Operated jointly by UMass Amherst and Mexico's Instituto Nacional de Astrofísica, Optical y Electronica (INAOE), it offers astonishing new power to peer into dusty galaxies, the astrophysicist says.

Pope, an expert at analysing how dust masks star formation, says tracing dust-obscured galaxies at early epochs offers good signposts for understanding how the universe became enriched with metals over time. "We know at the basic level that metals are formed in stars, but the rate of build-up over cosmic time we don't know," she points out. "We know what we see today but we don't know how it came about, and we want to fill in that picture."

Overall, she and colleagues write, "This remarkable lower-mass galaxy showing signs of both low metallicity and high dust content may challenge our picture of dust production in the early universe."

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Before the AzTEC camera on the LMT took observations of this galaxy, astronomers relied on Hubble Space Telescope images to study star formation, Pope says. But most star formation is obscured by dust, so the Hubble images could not make a complete census of the build-up of stars in this galaxy. "Previous millimetre observations have been limited to the most extreme dusty galaxies. With this study, we have detected a surprisingly high rate of dust-obscured star formation in a typical galaxy in the early universe."

With gravitational lensing, researchers use a foreground mass -- another galaxy or a galaxy cluster -- as a lens. As light from very distant, background galaxies passes through, it is magnified. "This technique offers a way to see things that are much fainter than your telescope can see," she notes. As traced in Hubble images, the lensed galaxy they studied in the Frontier Fields cluster showed it forming only about four solar masses of new stars per year, which is a "fairly typical" observation and unsurprising to astronomers today, Pope says. "But then the LMT observations revealed another 15 solar masses per year, which means we had been missing about three-quarters of the star formation going on."

She adds, "We are not yet at the level of detecting all of the star formation going on, but we are getting better. One of the big goals for us is to push observations at longer wavelengths and to trace these very dusty galaxies at early epochs. We are pushing observations in this direction and the fact that Hubble found only one quarter of the star formation in this distant normal galaxy is a huge motivation for doing a lot more studies like this."

As early as next year, Pope and her colleague Grant Wilson will install on the LMT a new state-of-the-art imaging system he is building, dubbed TolTEC. It will offer mapping speed 100 times faster than the LMT's current capability making it the fastest millimetre-wavelength polarimetric camera on Earth for conducting deep surveys of the universe, Wilson says. It should allow astronomers to create a census of star-forming galaxies, and observations that require five years to complete today will be done in a little over one week.

Pope says, "Currently, our census of dust-obscured star formation activity in galaxies is severely incomplete, especially in the distant universe. With TolTEC on the LMT, we will be able to make a complete census of dust-obscured star formation activity in galaxies over 13 billion years of cosmic time.

24 Mar 2017

NASA to slam a spaceship into an asteroid for practice

2-aidadoublemiNASA and the European Space Agency want to ram into an asteroid in a bid to save humanity from a “Deep Impact”-style catastrophe.

They want to see whether it’s possible to deflect a space rock from its course as part of a planetary defence mission.

Fears over potentially deadly asteroids are at an all time high after the White House issued an “emergency defence plan” in the event of a collision late last year.

Esteemed British astrophysicist and cosmologist Lord Martin Rees recently warned that the government should be spending “millions” on planetary defence.

The proposed mission will use two spacecraft, one to be launched by the ESA in 2020 and the other by NASA in 2021.

The first spaceship, dubbed AIM (for Asteroid Impact Mission) will orbit around 65803 Didymos, which was discovered in 1996.

The NASA spacecraft, called DART (Double Asteroid Redirection Test) will be timed to hit the rock a few months later, at a speed of nearly four miles per second.

AIM’s telescopes will monitor where stray pieces of rock end up.

The mission is to figure out whether deflection is the best defence from a stray space rock.

There’s a danger that crashing into the asteroid could cause fragments to break off and potentially speed up its trajectory.

untitledThe shrapnel could pose a risk to Earth, too.

“When we have a high-speed impact on an asteroid, you create a crater,” explained Andrew Cheng, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland said.

Cheng, who is lead investigator for the NASA side of the project, told Cosmos: “You blow pieces back in the direction you came from.”

The mission is yet to get the green light as it waits to confirm funding.

But planetary defence is a hot topic among scientists.

NASA have previously warned that Earth is “due an extinction level attack”.

But there’s little in place to stop one from causing absolute mayhem.

On the bright side, asteroids fly by Earth regularly and most are small enough to burn up in the atmosphere, completely unnoticed.

2 Mar 2017

There's a Massive, Glowing Blob in the Universe, and a Mystery Source Is Lighting It Up

lya-nebula_1024Astronomers have discovered a vast, glowing blob of gas in the distant Universe, and they can't figure out what's actually lighting it up.

This glowing nebula is located at the centre of an enormous 'protocluster' of early galaxies some 10 billion light-years from Earth, and is the brightest cosmic object of its kind ever found. And yet, there's no obvious source of its power.

The object, called an 'enormous Lyman-alpha nebula' (ELAN), is not only the brightest object of its kind found in the Universe - it's also one of the biggest, rivalling even the 'Slug Nebula', which stretches 2 million light-years through intergalactic space.

"It's extremely bright, and it's probably larger than the Slug Nebula, but there's nothing else visible except the faint smudge of a galaxy," says one of team, J. Xavier Prochaska, from the University of California, Santa Cruz.

"So it's a terrifically energetic phenomenon without an obvious power source."

Only a handful of ELANs have been discovered so far, and these accumulations of gas are thought to be part of a network of filaments that connect neighbouring galaxies to each other in the vast cosmic web of the Universe.

While other ELANs appear to be powered by the intense radiation given off by quasars, star formation, or supernovae, no such events could be found near this latest example, dubbed the MAMMOTH-1 nebula.

What we do know is the light has the same wavelength that's absorbed and emitted by hydrogen atoms as they cool down - a discharge known as Lyman-alpha radiation - but it's not clear what's been heating them up.

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The find recalls a discovery in 2000 of another ELAN, known as the Lyman-alpha blob 1, located in the southern constellation of Aquarius, some 11.5 billion light-years from Earth.

Stretching three times larger than our own Milky Way galaxy, this thing is ginormous and extremely green, but to this day, no one can say what's illuminating it.

Scientists have suggested that supermassive black holes swallowing matter in galaxies within the central region of the blob could be responsible, and now the team behind this new discovery suspect the same thing is happening to the MAMMOTH-1 nebula.

The MAMMOTH-1 nebula was found by a survey called Mapping the Most Massive Over densities Through Hydrogen (MAMMOTH), which was also responsible for finding the Slug Nebula back in 2014.

The protocluster it's found in is massive, hosting an unusually high concentration of galaxies in an area of about 50 million light-years across - all bound together by gravity.

While the galaxies are now mature, our telescopes are only just seeing them as they would have looked a mere 3 billion years after the Big Bang - the peak of galaxy formation in our Universe.

Several hypotheses have been put forward for how the MAMMOTH-1 nebula at the heart of this great protocluster got so bright, but the most likely ones revolve around radiation or discharges coming from something called an active galactic nucleus (AGN).

AGNs are compact regions at the centre of galaxies that have a much higher than normal luminosity. The team explains that AGNs are powered by a supermassive black hole actively feeding on gas in the centre of a galaxy, and are known for being extremely bright sources of light.

The intense radiation emitted by AGNs ionise the hydrogen gas in the space around it, and this could prompt the ELANs to emit super-bright Lyman-alpha radiation.

Quasars - the brightest objects in the Universe - are known for being the most luminous AGNs in visible light, except the MAMMOTH-1 nebula is not associated with a quasar, as far as the researchers can tell.

But that doesn't mean there isn't one lurking in the background.

"It has all the hallmarks of an AGN, but we don't see anything in our optical images. I expect there's a quasar that is so obscured by dust that most of its light is hidden," Prochaska says.

The team has its work cut out for it in trying to spot a single quasar some 10 billion light-years from Earth, and until then, the brightest known ELAN will remain a cosmic mystery.

The research has been accepted for publication in the Astrophysical Journal, and you can read it in full at the pre-print website, arXiv.org.

What Cassini's Daring Ring-Dive Around Saturn Could Tell Us About Uranus

Ashampoo_Snap_2017.03.02_02h17m12s_001_Glowing in pale blue, Uranus looks like a ghostly planet in pictures taken from the only spacecraft to ever visit it: Voyager 2. Due to the planet's great distance from Earth, follow-up studies of the planet began only in the late 1990s when telescope optics improved. Since then, Uranus has remained a low priority for observational institutions.

That's unfortunate for scientists looking to learn more about the faint rings of Uranus, discovered 40 years ago this year. Two airborne campaigns were set up to watch Uranus pass in front of a star in 1977. And both were taken aback when they found rings circling the planet. One of the teams missed three of the rings because they were so surprised by the find.

There are hopes that a spacecraft will fly to Uranus or Neptune in the 2020s or 2030s. NASA is undertaking early-stage feasibility studies. So it will remain to the plucky Cassini spacecraft, in orbit around Saturn since 2004, to show scientists what it can about the rings of Uranus by analogy with Saturn.

"At the time of the Uranian discovery, we had never seen narrow, dense rings before," said Mark Showalter, a planetary astronomer at the Search for Extra terrestrial Intelligence Institute. "The narrow rings of Saturn behave similarly to the rings of Uranus," he added, "so that has enabled us to understand dense rings a little bit better."

Cassini is in the final year of its epic mission, and is taking a rare close look at Saturn's rings in the coming weeks. The spacecraft is in the midst of performing 20 "ring-grazing orbits" that will allow for the best views of them since Cassini's arrival in 2004. The manoeuvres began in November and run through April.

"[W]e expect to see the rings, along with the small moons and other structures embedded in them, as never before," Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory in California, said in a statement. "The last time we got this close to the rings was during arrival at Saturn in 2004, and we saw only their backlit side. Now we have dozens of opportunities to examine their structure at extremely high resolution on both sides."

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Following completion of the ring orbits, Cassini will perform unprecedented dives between Saturn and its rings between April and September. Then, on September 15, Cassini will make a suicidal plunge into Saturn itself to protect icy worlds like Enceladus from the small chance of Cassini crashing into and contaminating their surfaces.

But before that, Showalter points out, Cassini will provide more insights on what is happening within the Uranus system, even though the spacecraft is surveying a completely different planet. The wobbles in Saturn's narrow rings appear to move in similar ways that Uranian rings do, for example.

But there are still several mysteries that may take another Uranian mission to resolve.

For example, images from Voyager 2 depicted dust rings surrounding the main ring system of. Then, when Uranus reached its equinox (closest point in its orbit) in 2008, observations from the Keck Telescope imaged the rings when they were edge-on from Earth, making it easier to identify the presence of any dust. It appears that the dust has shifted 3,100 miles between the two observations, Showalter said. The reason for the shift remains poorly understood.

Another open question is the role that the moons Cornelia and Ophelia play in shepherding the outer ring of Uranus — a phenomena also seen around Saturn. But the rings around Uranus are more difficult to observe right now because the planet is in an area of the sky with fewer stars, Showalter said, meaning the planet remains obscure more than it did in the 1970s and 1980s.

Showalter has been very busy in the past few years working on both the New Horizons mission, which passed by Pluto in 2015, as well as Cassini. He says he hopes to pull out some older data on Uranus soon to learn more about the planet's ring system, and to provide some insight for whenever a spacecraft does visit the Blue World again.
 

28 Feb 2017

NASA study hints at possible change in water 'fingerprint' of comet

134387_webA trip past the sun may have selectively altered the production of one form of water in a comet - an effect not seen by astronomers before, a new NASA study suggests.

Astronomers from NASA's Goddard Space Flight Center in Greenbelt, Maryland, observed the Oort cloud comet C/2014 Q2, also called Lovejoy, when it passed near Earth in early 2015. Through NASA's partnership in the W. M. Keck Observatory on Mauna Kea, Hawaii, the team observed the comet at infrared wavelengths a few days after Lovejoy passed its perihelion - or closest point to the sun.

The team focused on Lovejoy's water, simultaneously measuring the release of H2O along with production of a heavier form of water, HDO. Water molecules consist of two hydrogen atoms and one oxygen atom. A hydrogen atom has one proton, but when it also includes a neutron, that heavier hydrogen isotope is called deuterium, or the "D" in HDO. From these measurements, the researchers calculated the D-to-H ratio - a chemical fingerprint that provides clues about exactly where comets (or asteroids) formed within the cloud of material that surrounded the young sun in the early days of the solar system. Researchers also use the D-to-H value to try to understand how much of Earth's water may have come from comets versus asteroids.

The scientists compared their findings from the Keck observations with another team's observations made before the comet reached perihelion, using both space- and ground-based telescopes, and found an unexpected difference: After perihelion, the output of HDO was two to three times higher, while the output of H2O remained essentially constant. This meant that the D-to-H ratio was two to three times higher than the values reported earlier.

"The change we saw with this comet is surprising, and highlights the need for repeated measurements of D-to-H in comets at different positions in their orbits to understand all the implications," said Lucas Paganini, a researcher with the Goddard Center for Astrobiology and lead author of the study, available online in the Astrophysical Journal Letters.

Changes in the water production are expected as comets approach the sun, but previous understanding suggested that the release of these different forms of water normally rise or fall more-or-less together, maintaining a consistent D-to-H value. The new findings suggest this may not be the case.

"If the D-to-H value changes with time, it would be misleading to assume that comets contributed only a small fraction of Earth's water compared to asteroids," Paganini said, "especially, if these are based on a single measurement of the D-to-H value in cometary water."

The production of HDO in comets has historically been difficult to measure, because HDO is a much less abundant form of water. Lovejoy, for example, released on the order of 1,500 times more H2O than HDO. Lovejoy's brightness made it possible to measure HDO when the comet passed near Earth, and the improved detectors that are being installed in some ground-based telescopes will permit similar measurements in fainter comets in the future.

The apparent change in Lovejoy's D-to-H may be caused by the higher levels of energetic processes - such as radiation near the sun - that might have altered the characteristics of water in surface layers of the comet. In this case, a different D-to-H value might indicate that the comet has "aged" into a different stage of its lifecycle. Alternatively, prior results might have ignored possible chemical alteration occurring in the comet's tenuous atmosphere.

"Comets can be quite active and sometimes quite dynamic, especially when they are in the inner solar system, closer to the sun," said Michael Mumma, director of the Goddard Center for Astrobiology and a co-author of the study. "The infrared technique provides a snapshot of the comet's output by measuring the production of H2O and HDO simultaneously. This is especially important because it eliminates many sources of systematic uncertainty."

27 Feb 2017

Black History Month: Benjamin Banneker (1731-1806)

rglogo1_SHARPEN projectsFor some years, Benjamin seems to have served as an indentured labourer on the Prince George’s County plantation of Mary Welsh, who had dealings with the Bannaky family and in 1773 executed her dead husband’s instructions to release several of her labour force, including “Negro Ben, born free age 43”.

Welsh was surely not Banneker’s grandmother, as argued by many biographers, but she did leave him a substantial legacy. He then lived alone as a tobacco farmer near the Patapsco River.

By tradition, Banneker received only a brief education from a Quaker schoolmaster. But he showed an early talent for mathematics and construction when, aged 21, he built a model of a striking clock, largely out of wood, which became renowned in his neighbourhood. He read widely and recorded his researches. His skills drew him into contact with a wealthy white family, the Ellicotts, who had established flour mills and an iron foundry on the outskirts of Baltimore in the mid-1770s.

In 1788, George Ellicott, a keen amateur astronomer, lent Banneker books and instruments that enabled him to construct tables predicting the positions of the stars and future solar and lunar eclipses. Three years later, Andrew Ellicott hired Banneker to assist him in surveying the boundaries of the ten-mile-square site of the future federal capital of Washington, DC.

In that year, too, Banneker won the backing of several Philadelphia supporters of the anti-slavery cause to print his work in the popular form of an almanac. Its 1792 publication, introduced by letters pointing out how Banneker’s accomplishments disproved the myth of Negro inferiority, was a considerable success and produced 27 further editions of Banneker’s Almanac over the next five years.

Banneker sent a manuscript copy of his work to Secretary of State Thomas Jefferson, along with a plea against the continuance of black slavery, and received a courteous, if evasive, reply. But Jefferson praised Banneker as “a very respectable mathematician” in forwarding the manuscript to the notice of the French Academy of Sciences. Banneker continued to live on his farm, in declining health, and died on October 9, 1806. Only fragments of his later writings survive, as most perished in a fire after his death. His life and work have become enshrouded in legend and anecdote.

But his achievements ranked him among other American scientists of the time, and they were the more remarkable as the product of patient, lifelong self- education, emerging out of humble origins.

Sources: Silvio Bedini, The Life of Benjamin Banneker (New York: Scribner’s, 1972); Charles A. Cerami, Benjamin Banneker: Surveyor, Astronomer, Publisher, Patriot (New York: Wiley, 2002); George Ely Russell, “Molly Welsh: Alleged Grandmother of Benjamin Banneker,” National Genealogical Society Quarterly, 94 (December 2006): 305-14

Radio telescope in Pune to detect faint objects from distant worlds

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The fully upgraded system of the Giant Metre wave Radio Telescope (GMRT), one of the largest telescopes in the world located near Pune, will be powerful enough to detect fainter objects in the universe that are yet to be observed, said Yashwant Gupta, dean, GMRT Observatory and senior professor, National Centre for Radio Astrophysics, on Sunday.

Speaking on the side-lines of the Science at the Sabha, organised by the Institute of Mathematical Sciences in the city, he said the up gradation of the GMRT by the end of this year will see its sensitivity increased threefold enabling astronomers to observe more objects and phenomena in the universe. "We are upgrading it to see over a much larger range of frequencies at any given time. It means we can get more data and see more details of the universe," he said.

Built in 1995, the GMRT is an array of 30 telescopes that observes radiation coming in from space with a wavelength in the order of radio frequencies. The resolution with which objects can be observed depends on the size of the telescope's antenna. "We are replacing the entire electronics of the antennas from the top all the way down to the end where the data is collected through receivers and analysed," he said.

The GMRT, which is used by astronomers in India and abroad, can study distant galaxies, black holes, high energy objects and events happening billions of light years away. "The upgrade is largely being carried out in India by experts who have gathered knowledge over the years. We are installing, testing and validating the systems." With GMRT, India has found new, highly magnetized, rapidly rotating neutron stars and identified new galaxies and their properties.

On the recent detection of seven earth-sized planets orbiting a star by NASA telescopes, Gupta said more such planets that are habitable would be found. "There are millions of stars like the sun in the galaxy and a solar system is expected to develop around each of them. With powerful transmitters and receivers, we may be able to establish communication with these planets," he said.