From BBC: “ViaSat-2: Satellite goliath goes into orbit”

BBC

6.1.17
Jonathan Amos

The Ariane lifted away from its pad during a tropical rain shower.

The most powerful commercial broadband satellite ever built has just gone into orbit on an Ariane rocket.

ViaSat-2, which is to be stationed above the Americas, has a total throughput capacity of about 300 gigabits per second.

The spacecraft was part of a dual payload on the Ariane flight. It was joined by Eutelsat 172B, a UK/French-built platform to go over the Pacific.

Both satellites will be chasing the rampant market for wi-fi on aeroplanes.

Airlines are currently in a headlong rush to equip their fleets with connections that will allow passengers to use their mobile devices in mid-air.

More than 6,000 commercial aircraft worldwide were offering an onboard wi-fi service in 2016; it is expected more than 17,000 will be doing so by 2021.

In-flight internet has traditionally had a terrible reputation, but there is a feeling now that the latest technology really can give passengers a meaningful slice of bandwidth and at a competitive price.

Inmarsat rides SpaceX Falcon

Intelsat rolls out next-gen system

Artwork: ViaSat-2 will be positioned 36,000km above the equator at 69 degrees West

The Ariane left the Kourou spaceport in French Guiana at 20:45 local time, Thursday (23:45 GMT), ejecting the satellites into their transfer orbits about half an hour later.

Both must now get themselves into their final positions. Noteworthy is the fact that ViaSat-2 and 172B will be using electric engines to do this.

These work by accelerating and expelling ions at high speed. The process provides less thrust than a standard chemical engine, but saves substantially on propellant mass.

Eutelsat-172B is the first satellite from Airbus to use all-electric propulsion for orbit-raising and station-keeping

That saving can be traded to get either a lower-priced launch ticket, or to pack even greater capacity into the satellite’s communications payload for no additional weight.

The US, Boeing-built ViaSat-2 uses a mix of chemical and electric propulsion, but Eutelsat’s platform is all-electric – the first such design to come from Europe’s biggest space manufacturer, Airbus.

ViaSat-2 will be providing broadband services to fixed customers across North America, Central America, the Caribbean, and a portion of northern South America.

But the satellite is also configured to service planes and ships, and in particular it is looking to grab a significant share of business out over the Atlantic.

The aviation sector currently is a key battleground for satellite operators; it is where they are seeing double-digit growth.

In the US, working with airlines such as JetBlue, ViaSat has already found success through its existing high-throughput ViaSat-1 spacecraft.

With the extra capacity on ViaSat-2, it aims to do better still.

“We think people want to use their devices in the air the way they do on the ground; that’s the bet we’ve made,” said ViaSat Chief Operating Officer Rick Baldridge.

“JetBlue delayed their in-flight wi-fi offering, waiting for us, and now they’re giving it away for free and we’re providing 12 megabits per second to every seat, including streaming video,” he told BBC News.

ViaSat-2’s “footprint” touches the western coast of Europe, but aeroplanes travelling further east will be handed seamlessly to a better-positioned Eutelsat spacecraft, which should enable passengers to stay connected all the way across to Turkey if needs be.

This is one of the benefits of the strategic alliance that the two satellite companies have formed. And in time this will see the pair operate a ViaSat-3 platform together over Europe. This spacecraft is being built to have a total throughput capacity of one terabit per second.

172B has a 3D printed bracket (far right) holding an antenna to the satellite. This component is 35% lighter than the conventionally produced bracket (far left). AIRBUS DS.

From its position very close to the International Date Line, Eutelsat’s 172B spacecraft is going to target – amongst other business – the flight corridors of the Asia-Pacific region. And it has some very smart British technology to do this in the form of a multi port amplifier.

This can flexibly switch power between the satellite’s 11 spot beams to make sure the available bandwidth is always focused where it is needed most – whether that be on the planes moving east-west from Japan to California, say, or when they go in the other direction as a cluster at a different time of day.

“To oversimplify, in-flight connectivity has mostly been restricted to the US. But now it is expanding into the Asia-Pacific region and it’s also coming to Europe,” said Rodolphe Belmer, Eutelsat’s chief executive officer.

“We see spontaneous demand from airlines and it’s booming. It’s true the technology hasn’t always delivered, but you will see with the introduction of very high throughput satellites in the next few years that we will be able to… bring a massive quantity of bandwidth onboard the plane, meaning you can stream Netflix in HD. That’s a game-changer.”

In-flight connectivity is a key battleground for the satellite operators. Getty Images.

Euroconsult is one of the world’s leading analyst groups following the satellite industry. Its research confirms the rapid growth now taking place, and says this will only accelerate.

Euroconsult’s recent report on in-flight-connectivity (IFC) predicted nearly half of all commercial planes would be enabled by 2021, pushing revenues for the suppliers of onboard services from $1bn to $6.5bn inside 10 years. But Euroconsult’s CEO, Pacôme Revillon, said there will be winners and losers in this IFC race and this would likely be decided in the very near future.

“Going to 2020, approximately 50% of aircraft could have opted for their chosen connectivity solutions, and certainly all of the major airlines will have made that choice. By that stage the market share could decide who are the winners and losers, and we anticipate seeing some consolidation in this sector, with two to three companies coming to dominate the market,” he told BBC News.

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From BBC: “The Obsecure Religion that shaped the West” A Little Diversion on Easter and Passover

BBC

6 April 2017
Joobin Bekhrad

It has influenced Star Wars and Game of Thrones – and characters as diverse as Voltaire, Nietzsche and Freddie Mercury have cited it as an inspiration. So what is Zoroastrianism? Joobin Bekhrad finds out.

Talk of ‘us’ and ‘them’ has long dominated Iran-related politics in the West. At the same time, Christianity has frequently been used to define the identity and values of the US and Europe, as well as to contrast those values with those of a Middle Eastern ‘other’. Yet, a brief glance at an ancient religion – still being practised today – suggests that what many take for granted as wholesome Western ideals, beliefs and culture may in fact have Iranian roots.

It is generally believed by scholars that the ancient Iranian prophet Zarathustra (known in Persian as Zartosht and Greek as Zoroaster) lived sometime between 1500 and 1000 BC. Prior to Zarathustra, the ancient Persians worshipped the deities of the old Irano-Aryan religion, a counterpart to the Indo-Aryan religion that would come to be known as Hinduism. Zarathustra, however, condemned this practice, and preached that God alone – Ahura Mazda, the Lord of Wisdom – should be worshipped. In doing so, he not only contributed to the great divide between the Iranian and Indian Aryans, but arguably introduced to mankind its first monotheistic faith.

The idea of a single god was not the only essentially Zoroastrian tenet to find its way into other major faiths, most notably the ‘big three’: Judaism, Christianity and Islam. The concepts of Heaven and Hell, Judgment Day and the final revelation of the world, and angels and demons all originated in the teachings of Zarathustra, as well as the later canon of Zoroastrian literature they inspired. Even the idea of Satan is a fundamentally Zoroastrian one; in fact, the entire faith of Zoroastrianism is predicated on the struggle between God and the forces of goodness and light (represented by the Holy Spirit, Spenta Manyu) and Ahriman, who presides over the forces of darkness and evil. While man has to choose to which side he belongs, the religion teaches that ultimately, God will prevail, and even those condemned to hellfire will enjoy the blessings of Paradise (an Old Persian word).

How did Zoroastrian ideas find their way into the Abrahamic faiths and elsewhere? According to scholars, many of these concepts were introduced to the Jews of Babylon upon being liberated by the Persian emperor Cyrus the Great. They trickled into mainstream Jewish thought, and figures like Beelzebub emerged. And after Persia’s conquests of Greek lands during the heyday of the Achaemenid Empire, Greek philosophy took a different course. The Greeks had previously believed humans had little agency, and that their fates were at the mercy of their many gods, who often acted according to whim and fancy. After their acquaintance with Iranian religion and philosophy, however, they began to feel more as if they were the masters of their destinies, and that their decisions were in their own hands.

Though it was once the state religion of Iran and widely practised in other regions inhabited by Persian peoples (eg Afghanistan, Tajikistan and much of Central Asia), Zoroastrianism is today a minority religion in Iran, and boasts few adherents worldwide. The religion’s cultural legacy, however, is another matter. Many Zoroastrian traditions continue to underpin and distinguish Iranian culture, and outside the country, it has also had a noted impact, particularly in Western Europe.

Zoroastrian rhapsody

Centuries before Dante’s Divine Comedy, the Book of Arda Virafdescribed in vivid detail a journey to Heaven and Hell. Could Dante have possibly heard about the cosmic Zoroastrian traveller’s report, which assumed its final form around the 10th Century CE? The similarity of the two works is uncanny, but one can only offer hypotheses.

Elsewhere, however, the Zoroastrian ‘connection’ is less murky. The Iranian prophet appears holding a sparkling globe in Raphael’s 16th Century School of Athens. Likewise, the Clavis Artis, a late 17th/early 18th-Century German work on alchemy was dedicated to Zarathustra, and featured numerous Christian-themed depictions of him. Zoroaster “came to be regarded [in Christian Europe] as a master of magic, a philosopher and an astrologer, especially after the Renaissance,” says Ursula Sims-Williams of the School of Oriental and African Studies at the University of London.

Today, mention of the name Zadig immediately brings to mind the French fashion label Zadig & Voltaire. While the clothes may not be Zoroastrian, the story behind the name certainly is. Written in the mid-18th Century by none other than Voltaire, Zadigtells the tale of its eponymous Persian Zoroastrian hero, who, after a series of trials and tribulations, ultimately weds a Babylonian princess. Although flippant at times and not rooted in history, Voltaire’s philosophical tale sprouted from a genuine interest in Iran also shared by other leaders of the Enlightenment. So enamoured with Iranian culture was Voltaire that he was known in his circles as ‘Sa’di’. In the same spirit, Goethe’s West-East Divan, dedicated to the Persian poet Hafez, featured a Zoroastrian-themed chapter, while Thomas Moore lamented the fate of Iran’s Zoroastrians in Lalla Rookh.

It wasn’t only in Western art and literature that Zoroastrianism made its mark; indeed, the ancient faith also made a number of musical appearances on the European stage.

In addition to the priestly character Sarastro, the libretto of Mozart’s The Magic Flute is laden with Zoroastrian themes, such as light versus darkness, trials by fire and water, and the pursuit of wisdom and goodness above all else. And the late Farrokh Bulsara – aka Freddie Mercury – was intensely proud of his Persian Zoroastrian heritage. “I’ll always walk around like a Persian popinjay,” he once remarked in an interview, “and no one’s gonna stop me, honey!” Likewise, his sister Kashmira Cooke in a 2014 interview reflected on the role of Zoroastrianism in the family. “We as a family were very proud of being Zoroastrian,” she said. “I think what [Freddie’s] Zoroastrian faith gave him was to work hard, to persevere, and to follow your dreams.”

Ice and fire

When it comes to music, though, perhaps no single example best reflects the influence of Zoroastrianism’s legacy than Richard Strauss’ Thus Spoke Zarathustra, which famously provided the booming backbone to much of Stanley Kubrick’s 2001: A Space Odyssey. The score owes its inspiration to Nietzsche’s magnum opus of the same name, which follows a prophet named Zarathustra, although many of the ideas Nietzsche proposes are, in fact, anti-Zoroastrian. The German philosopher rejects the dichotomy of good and evil so characteristic of Zoroastrianism – and, as an avowed atheist, he had no use for monotheism at all.

Freddie Mercury and Zadig & Voltaire aside, there are other overt examples of Zoroastrianism’s impact on contemporary popular culture in the West. Ahura Mazda served as the namesake for the Mazda car company, as well as the inspiration for the legend of Azor Ahai – a demigod who triumphs over darkness – in George RR Martin’s Game of Thrones, as many of its fans discovered last year. As well, one could well argue that the cosmic battle between the Light and Dark sides of the Force in Star Wars has, quite ostensibly, Zoroastrianism written all over it [cf. also the Essenic Dead Sea Scrolls for Sons of Light and Sons of Darkness and the battle of Armegeddon, the coming of the Messiah].

For all its contributions to Western thought, religion and culture, relatively little is known about the world’s first monotheistic faith and its Iranian founder. In the mainstream, and to many US and European politicians, Iran is assumed to be the polar opposite of everything the free world stands for and champions. Iran’s many other legacies and influences aside, the all but forgotten religion of Zoroastrianism just might provide the key to understanding how similar ‘we’ are to ‘them’.

Zoroastrians believe there is one God called Ahura Mazda (Wise Lord) and He created the world.

Zoroastrians believe that the elements are pure and that fire represents God’s light or wisdom.

Ahura Mazda revealed the truth through the Prophet, Zoroaster.

Zoroastrians traditionally pray several times a day.

Zoroastrians worship communally in a Fire Temple or Agiary.

The Zoroastrian book of Holy Scriptures is called The Avesta.

The Avesta is the oldest and core part of the scriptures, which contains the Gathas. The Gathas are seventeen hymns thought to be composed by Zoroaster himself.

The Younger Avesta – commentaries to the older Avestan written in later years. It also contains myths, stories and details of ritual observances.

Zoroaster consistently contrasts these two peoples as the People of Righteousness ( asha ) and the People of the Lie ( druj ).

This expression is repeated many times in the Hasidic text The Tanya by Rabbi Schneur Zalmon of Liadi, the founder of Chabad

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From BBC: “Gravity probe exceeds performance goals”

BBC

2.18.17
Jonathan Amos

ESA/LISA Pathfinder

The long-planned LISA space mission to detect gravitational waves looks as though it will be green lit shortly.

Scientists working on a demonstration of its key measurement technologies say they have just beaten the sensitivity performance that will be required.

The European Space Agency (Esa), which will operate the billion-euro mission, is now expected to “select” the project, perhaps as early as June.

The LISA venture intends to emulate the success of ground-based detectors.

Caltech/MIT Advanced aLigo Hanford, WA, USA installation

Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

These have already witnessed the warping of space-time that occurs when black holes 10-20 times the mass of the Sun collide about a billion light-years from Earth.

LISA, however, aims to detect the coming together of truly gargantuan black holes, millions of times the mass of the Sun, all the way out to the edge of the observable Universe.

Researchers will use this information to trace the evolution of the cosmos, from its earliest structures to the complex web of galaxies we see around us today.

The performance success of the measurement demonstration was announced here in Boston at the annual meeting of the American Association for the Advancement of Science (AAAS).

It occurred on Esa’s LISA “Pathfinder” (LPF) spacecraft that has been flying for just over a year.

This probe is trialling parts of the laser interferometer that will eventually be used to detect passing gravitational waves.

When Pathfinder’s instrumentation was set running it was hoped it would get within a factor of 10 of the sensitivity that would ultimately be needed by the LISA mission, proper.

In the event, LPF not only matched this mark, but went on to exceed it after 12 months of experimentation.

“You can do the full science of LISA just based on what LPF has got. And that’s thrilling; it really is beyond our dreams,” Prof Stefano Vitale, Pathfinder’s principal investigator, told BBC News.

LIGO

Gravitational waves are a prediction of the Theory of General Relativity
It took decades to develop the technology to directly detect them
They are ripples in the fabric of space and time produced by violent events
Accelerating masses will produce waves that propagate at the speed of light
Detectable sources ought to include merging black holes and neutron stars
LIGO fires lasers into long, L-shaped tunnels; the waves disturb the light
Detecting the waves opens up the Universe to completely new investigations

The first detection of gravitational waves at the US LIGO laboratories in late 2015 has been described as one of the most important physics breakthroughs in decades.

Being able to sense the subtle warping of space-time that occurs as a result of cataclysmic events offers a completely new way to study the Universe, one that does not depend on traditional telescope technology.

Rather than trying to see the light from far-off events, scientists would instead “listen” to the vibrations these events produce in the very fabric of the cosmos.

LIGO achieved its success by discerning the tiny perturbations in laser light that was bounced between super-still mirrors suspended in kilometres’ long, vacuum tunnels.

LISA would do something very similar, except its lasers would bounce between free-floating gold-platinum blocks carried on three identical spacecraft separated by 2.5 million km.

A cutaway impression of the laser interferometer system inside Lisa Pathfinder. ESA.

Lisa Pathfinder’s payload is a laser interferometer, which measures the behaviour of two free-falling blocks made from a platinum-gold alloy
Placed 38cm apart, these “test masses” are inside cages that are very precisely engineered to insulate them against all disturbing forces
When this super-quiet environment is maintained, the falling blocks will follow a “straight line” that is defined only by gravity
It is under these conditions that a passing gravitational wave would be noticed by ever so slightly changing the separation of the blocks
Lisa Pathfinder has demonstrated sub-femtometre sensitivity, but the satellite cannot itself make a detection of the ripples
To do this, a space-borne observatory would need to reproduce the same performance with blocks positioned 2.5 million km apart

In both cases, the demand is to characterise fantastically small accelerations in the measurement apparatus as it squeezed and stretched by the passing gravitational waves.

For LISA the projected standard is to characterise movements down below the femto-g level – a millionth of a billionth of the acceleration a falling apple experiences at Earth’s surface; and to do that over periods of minutes to hours.

LISA Pathfinder has just succeeded in achieving sub-femto sensitivity over timescales of half a day. Getting stability at the lowest frequencies is very important.

“The lower the frequency to which you go, the bigger are the bodies that generate gravitational waves; the more intense are the gravitational waves; and the more far away are the bodies. So, the lower the frequencies, the deeper into the Universe you go,” explained Prof Vitale, who is affiliated to Italian the Institute for Nuclear Physics and University of Trento.

To be clear, LPF cannot itself detect gravitational waves because the “arm length” of the system has been shrunk down from 2.5 million km to just 38 cm – to be able to fit inside a single demonstration spacecraft – but it augurs well for the full system.

ESA/eLISA

Esa recently issued a call for proposals to fly a gravitational science mission in 2034. The BBC understands the agency received only one submission – from the LISA Consortium.

This is unusual. Normally such calls attract a number of submissions from several groups all with different ideas for a mission. But in this instance, it is maybe not so surprising given that the LISA concept has been investigated for more than two decades.

Prof Karsten Danzmann, co-PI on LPF and the lead proposer of LISA, hopes a way can be found to fly his consortium’s three-spacecraft detection system earlier than 2034, perhaps as early as 2029. But that requires sufficient money being available.

“The launch date is only programatically dominated, not technically,” Prof Danzmann told BBC News.

“And with all the interest in gravitational waves building up right now, ways will be found to fly almost simultaneously with Athena (Europe’s next-generation X-ray telescope slated to launch in 2028).

ESA/Athena spacecraft

“This would make perfect sense because we can tell the X-ray guys where to look, because we get the alert of any bright (black hole) merger immediately, and then we can tell them, ‘look in the next hour and you’ll see an X-ray flash’.”

“That would be tremendously exciting to do multi-messenger astronomy with LISA and Athena at the same time.”

LISA could be selected as a confirmed project at Esa’s Science Programme Committee in June. There would then be a technical review followed by parallel industrial studies to assess the best, most cost-effective way to construct the mission.

Agreement will also be sought with the Americans to bring them onboard. They are likely to contribute about $300-400m of the overall cost in the form of components, such as the lasers that will be fired between LISA’s trio of spacecraft.

The LPF demonstration experiments are due to end in May, or June at the latest.

See the full article here .

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From BBC: “Event Horizon Telescope ready to image black hole”

BBC

2.16.17
Jonathan Amos

The EHT team has produced simulations of what Einstein’s theories predict the hole should look like. Hotaka Shiokawa/CFA/HARVARD

Scientists believe they are on the verge of obtaining the first ever picture of a black hole.

They have built an Earth-sized “virtual telescope” by linking a large array of radio receivers – from the South Pole, to Hawaii, to the Americas and Europe.

There is optimism that observations to be conducted during 5-14 April could finally deliver the long-sought prize.

In the sights of the so-called “Event Horizon Telescope” will be the monster black hole at the centre of our galaxy.

Here is the Event Horizon Telescope Array

The locations of the radio dishes that will be part of the Event Horizon Telescope array. Image credit: Event Horizon Telescope sites, via University of Arizona at https://www.as.arizona.edu/event-horizon-telescope.

Arizona Radio Observatory/Submillimeter-wave Astronomy (ARO/SMT)

Atacama Pathfinder EXperiment (APEX)

Combined Array for Research in Millimeter-wave Astronomy (CARMA)

Atacama Submillimeter Telescope Experiment (ASTE)

Caltech Submillimeter Observatory (CSO)

Institut de Radioastronomie Millimetrique (IRAM) 30m

James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA

Large Millimeter Telescope Alfonso Serrano

Submillimeter Array Hawaii SAO

Future Array/Telescopes

ESO/NRAO/NAOJ ALMA Array, Chile

Plateau de Bure interferometer

South Pole Telescope SPTPOL

Sag A* NASA Chandra X-Ray Observatory 23 July 2014, the supermassive black hole at the center of the Milky Way

Although never seen directly, this object, catalogued as Sagittarius A*, has been determined to exist from the way it influences the orbits of nearby stars.

These race around a point in space at many thousands of km per second, suggesting the hole likely has a mass of about four million times that of the Sun.

But as colossal as that sounds, the “edge” of the black hole – the horizon inside which an immense gravity field traps all light – may be no more than 20 million km or so across.

And at a distance of 26,000 light-years from Earth, this makes Sagittarius A* a tiny pinprick on the sky.

The Event Horizon Telescope (EHT) team is nonetheless bullish.

“There’s great excitement,” said project leader Sheperd Doeleman from the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

“We’ve been fashioning our virtual telescope for almost two decades now, and in April we’re going to make the observations that we think have the first real chance of bringing a black hole’s event horizon into focus,” he told BBC News.

EHT map

The eventual EHT array will have 12 widely spaced participating radio facilities

The EHT’s trick is a technique called very long baseline array interferometry (VLBI).

This combines a network of widely spaced radio antennas to mimic a telescope aperture that can produce the resolution necessary to perceive a pinprick on the sky.

The EHT is aiming initially to get down to 50 microarcseconds. Team-members talk in analogies, describing the sharpness of vision as being the equivalent of seeing something the size of a grapefruit on the surface of the Moon.

They emphasise the still complex years of work ahead, but also trail the prospect of an imminent breakthrough.

The scientists certainly have an expectation of what they ought to see, if successful.

Simulations rooted in Einstein’s equations predict a bright ring of light fringing a dark feature.

The light would be the emission coming from gas and dust accelerated to high speed and torn apart just before disappearing into the hole.

The dark feature would be the shadow the hole casts on this maelstrom.

“Now, it could be that we will see something different,” Doeleman said.

“As I’ve said before, it’s never a good idea to bet against Einstein, but if we did see something that was very different from what we expect we would have to reassess the theory of gravity.

“I don’t expect that is going to happen, but anything could happen and that’s the beauty of it.”

Over the years, more and more radio astronomy facilities have joined the project. A key recent addition is the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile.

Its extraordinary state-of-the-art technology has at a stroke increased the EHT’s sensitivity by a factor of 10. Hence, the optimism ahead of April.

Even so, scientists have had to install special equipment at all the radio facilities involved in the observations.

This includes big hard drives to store colossal volumes of data, and atomic clocks to precisely timestamp it all.

Nothing happens on the spot – the hard drives must first be flown to a large computing facility at MIT Haystack Observatory in Westford, just outside Boston, Massachusetts.

“Our hard-drive modules hold the capacity of about 100 standard laptops,” said Haystack’s Vincent Fish.

“We have multiple modules at each telescope and we have numerous telescopes in the array. So, ultimately, we’re talking about 10,000 laptops of data.”

It is in Haystack’s correlator computer that the synthesis will begin.

Some very smart imaging algorithms have had to be developed to make sense of the EHT’s observations, but it will not be a quick result.

It could be the end of the year, perhaps the start of 2018, before the team releases an image in public.

All the data from the telescopes will be brought to MIT Haystack to be ingested in its correlator computer.

Looking to the future, the scientists are already thinking about how to extend their techniques.

For example, the matter closest to the event horizon and about to disappear into Sagittarius A* should take about 30 minutes to complete an orbit.

Katie Bouman, from MIT’s Computer Science and Artificial Intelligence Laboratory, thinks it might be possible to capture this movement.

“We want to push boundaries and to try to make movies from the data,” she told BBC News.

“Maybe we can actually see some of the gas flowing around the black hole. That’s really the next stage of what we’re trying to accomplish with these imaging algorithms.”

First and foremost, the team needs good weather at the participating observing stations in April.

The strategy is to view the galactic centre at a wavelength of 1.3mm (230GHz). This has the best chance of piercing any obscuring gas and dust in the vicinity of the black hole. But if there is too much water vapour above the array’s receivers, the EHT will struggle even to see through Earth’s atmosphere.

Just getting a resolved view of Sagittarius A* would be a remarkable triumph in itself. But the real objective here is to use the imaging capability to go test aspects of general relativity.

If there are flaws to be found in Einstein’s ideas – and scientists suspects there are more complete explanations of gravity out there waiting to be discovered – then it is in the extreme environment of black holes that limitations should be exposed.

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From BBC: “Disturbing the peace: Can America’s quietest town be saved?”

BBC

26 November 2016
Dave Lee

There’s a town in West Virginia where there are tight restrictions on mobile signal, wifi and other parts of what most of us know as simply: modern life. It means Green Bank is a place unlike anywhere else in the world. But that could be set to change.

“Do you ever sit awake at night and wonder, what if?” I asked.

Mike Holstine’s eyes twinkled like the stars he had spent his life’s work observing.

“The universe is so huge,” he began.

“On the off chance we do get that hugely lucky signal, when we look in the right place, at the right frequency. When we get that… can you imagine what that’s going to do to humankind?”

Holstine is business manager at the Green Bank Observatory, the centrepiece of which is the colossal Green Bank Telescope. On a foggy Tuesday morning, I’m standing in the middle of it, looking up, feeling small.

Though the GBT has many research tasks, the one everyone talks about is the search for extra-terrestrial intelligence. The GBT listens out for signs of communication or activity by species that are not from Earth.

Unique people

I am not the first BBC reporter to pop in here. In fact, Green Bank is a source of constant fascination for journalists all over the world. Recently, several people in the town told me, a Japanese crew baffled everyone when it appeared to set up a game show-style challenge in the area.

Outsiders come here for two reasons. One, to marvel at the science. Two, to ogle at the unique people who have chosen to live here.

Green Bank sits at the heart of the National Radio Quiet Zone, a 13,000 square mile (33,669 sq km) area where certain types of transmissions are restricted so as not to create interference to the variety of instruments set up in the hills – as well as the Green Bank Observatory, there is also Sugar Grove, a US intelligence agency outpost.

Joel Bradshaw, 28 October 2009

For those in the immediate vicinity of the GBT, the rules are more strict. Your mobile phone is useless here, you will not get a TV signal and you can’t have strong wi-fi  - though they admit this is a losing battle. Modern life is winning, gradually. And newer wi-fi standards do not interfere with the same frequencies as before.

But this relative digital isolation has meant that Green Bank has become a haven for those who feel they are quite literally allergic to electronic interference.

The condition is referred to as electromagnetic hypersensitivity disorder. Opinion is split on whether it is real, with the majority of medical opinion erring on the side that it is more psychological than physical.

But when I met with Diane Schou, one sufferer, I realised it did not matter whether the condition was “real” or not  –  for a growing number of people, modern technology has them feeling trapped.

The knock-on effects from the global recession have led to the Green Bank Telescope being on the chopping block.

The National Science Foundation (NSF) is consulting right now on whether they can justify the expense of the telescope. To make things more precarious for Green Bank, other telescopes with similar abilities have been built in other parts of the world, including Chile.

The NSF is not going to just pull the rug from underneath the GBT. As it stands, funding is going to be gradually removed. Not a slow death, but rather a chance for Mr Holstine to court private investment money to keep the telescope operational.

It is working so far  –  the Breakthrough Listen project, backed with Silicon Valley money, is focused solely on finding other intelligent life. Over 10 years, its investors are planning to spend $100m (£80.3m) on the quest. They are using the GBT as part of an effort to survey the one million stars closest to Earth.

For the locals in Green Bank, the survival of the telescope is not just about seeking ET. It is also the largest employer in the entire county.

The big questions

When I asked Chuck and Heather Niday, who host a weekly show on the charming Allegheny Mountain Radio, whether the town would change if restrictions were lifted, they were reserved.

Sure, the kids would love access to Snapchat. But the fabric of the town would not be affected. It is a rural community and no amount of mobile phone signal will change the nature of this tight-knit town.

If like me you find it unfathomable that we are alone in the universe, then Green Bank is an utterly essential utility. When I asked Mr Holstine to justify the money the US government spends on the facility, he dug deep.

“How many of us have walked out into the night and looked up at the stars and stood there in wonder?

“We don’t produce widgets. We don’t produce something that you go to the store and buy. But we do produce education. We do produce research. We do produce answers to questions we haven’t even asked ourselves yet.

“Those questions are the basis of what it means for us to be human. That constant search is done right here every day.”

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From BBC: “Pressure grows for price on carbon ahead of UN signing”

BBC

4.21.16
Matt McGrath

India is calling for a tax on coal to help adaptation to climate change

A group of world leaders and international finance chiefs has urged the world to rapidly expand the pricing of carbon pollution.

They argue that more than half of emissions of CO2 should be covered by a carbon price within a decade.

India has also called on rich countries to put a tax on coal to help poorer nations adapt to climate change.

These calls came ahead of a UN ceremony where some 155 countries are expected to sign the Paris Climate Agreement.

Race to ratify the Paris climate deal

Putting an effective price on carbon has long been the favourite method of most economists in dealing with climate change.

In 2006 Sir Nicholas Stern’s landmark review of the costs of climate change found that establishing a carbon price was essential to dealing effectively with the problem.

Cap, trade or tax

Since then attempts have been made, with mixed success. These have included cap and trade schemes in many parts of the world, where a limit on emissions is established by governments and permits are issued to heavy carbon users. If they cut back on their emissions they can trade the permits on the market.

Schemes like this have been criticised for being too generous to polluters, often issuing them with free permits. The European Union’s flagship Emissions Trading Scheme almost collapsed because of this practice in recent years.

Other countries have adopted a more straightforward carbon tax as a means of getting polluters to cut back.

So far around 12% of the world’s emissions are covered by such schemes. This new coalition of political leaders and financiers says that has to improve significantly if the world is to keep global temperature rises below 2 degrees.

The group includes the Prime Ministers of Canada and Ethiopia, the Presidents of Chile, France and Mexico, the Chancellor of Germany and the head of the IMF and World Bank.

They believe that the world can achieve 25% of emissions covered by carbon pricing by 2020 while half the world’s output could be covered by 2025.

“There is a growing sense of inevitability about putting a price on carbon pollution,” said World Bank President Jim Yong Kim in a statement.

“Prices for producing renewable energy are falling fast, and putting a price on carbon has the potential to make them even cheaper than fuels that pollute our planet.”

Without giving too many details, the leaders believe that carbon pricing can be expanded in three ways – by increasing the number of governments putting a price on carbon, by deepening existing carbon pricing programs, and by promoting global cooperation.

“We should now follow up the Paris Agreement with adequate actions, national policies, investment schemes and regional and international initiatives and partnerships, said Ethiopia’s Prime Minister Dessalegn.

“I iterate Ethiopia’s commitment to the global efforts to overcome dangerous climate change and ensure sustainable development. We will use every policy instrument, including carbon pricing, which is found to be effective, efficient and fair.”
Global coal tax?

India was also keen to promote the idea of carbon pricing before the UN signing ceremony here in New York . They are promoting the idea of a tax on coal.

The country recently increased its tax on mined coal to $6 a tonne, a significant increase from $1. India’s environment minister Prakasj Javadekar believes the world, especially the wealthier countries, should now follow suit.

“If they follow India and levy a tax of $5-$6 a tonne on coal production, $100 billion can easily be mobilised,” he said, speaking to news agencies.

Mr Javadekar said this would be a highly effective way of funding climate adaption in poor countries around the world while incentivising a transition to greener energy sources.

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From BBC: “Gravitational wave mission passes ‘sanity check’ “

BBC

18 April 2016
Jonathan Amos

ESA/LISA Pathfinder

A European Space Agency [ESA] effort to try to detect gravitational waves in space is not only technically feasible but compelling, a new report finds.

A panel of experts was asked to perform a “sanity check” on the endeavour, which is likely to cost well in excess of one billion euros.

The Gravitational Observatory Advisory Team says it sees no showstoppers.

It even suggests ESA try to accelerate the project from its current proposed launch date in 2034 to 2029.

Whether that is possible is largely a question of funding. Space missions launch on a schedule that is determined by a programme’s budget.

“But after submitting our report, ESA came back to us and asked what we thought might be technically possible, putting aside the money,” explained Goat chairman, Dr Michael Perryman.

“We are in the process of finalising a note on that, which will suggest the third quarter of 2029. So, 13 years from now,” he told BBC News.

The agency has stated its intention to build a mission that investigates the “gravitational Universe”, and is set to issue a call to the scientific community to submit a detailed proposal.

Ripples in the fabric of space-time

Artwork: Advanced Ligo detected coalescing black holes more than a billion light-years from Earth. NSF

Caltech/MIT Advanced aLigo detector in Livingston, Louisiana

Gravitational waves are a prediction of the Theory of General Relativity
Their existence had been inferred by science but only recently directly detected
They are ripples in the fabric of space and time produced by violent events
Accelerating masses will produce waves that propagate at the speed of light
Detectable sources ought to include merging black holes and neutron starsGravity mission passes ‘sanity check’
Advanced Ligo fires lasers into long, L-shaped tunnels; the waves disturb the light
Detecting the waves opens up the Universe to completely new investigations

Gravitational waves – ripples in space-time – have become the big topic of conversation since their first detection last year by the ground-based Advanced LIGO facilities in the US.

Using a technique known as laser interferometry, the labs sensed the fantastically small disturbance at Earth generated by the merger of two black holes more than a billion light-years away.

The discovery opens up a completely new way to do astronomy, allowing scientists to probe previously impenetrable regions of the cosmos and to test some of the fundamental ideas behind general relativity – Einstein’s theory of gravity.

The Goat says the stunning detection by aLIGO is a game-changer: “In a single step, gravitational wave astronomy has been placed on a secure observational footing, opening the panorama to the next robust steps in a space-based gravitational wave observatory.”

That was not the case when the panel started its work. Then, there were many people who thought a detection might be beyond our measurement capability.

The Goat believes that any space-borne observatory ESA might pursue should proceed using the same technical approach as aLigo – laser interferometry.

aLIGO employs laser interferometers – the technology suggested also for a space mission. LIGO

The agency is currently doing experiments in orbit that will prove some of the equipment needed on a future gravitational wave observatory. But the Goat also identifies critical additional developments that must now be prioritised to take the laser approach into space.

That said, there is also encouraging support in the report for an alternative detection concept called atom interferometry. This is too immature at the moment to be a contender, the Goat says, but it could benefit from a technology demonstration mission in the near future.

Since the 1980s, scientists have been working on a system to detect gravitational waves from orbit called LISA – the Laser Interferometer Space Antenna.

It would fly a network of satellites separated by a few million kilometres.

Lasers fired between these spacecraft would sense ripples in space-time generated by much more massive objects than the black holes seen by LIGO. LISA’s targets would be the monster black holes, millions of times the mass of our Sun, that coalesce when galaxies collide, for example.

Future LISA: How many lasers can you fly?

ESA is set to fly a mission dedicated to gravitational astronomy in the 2030s

The available budget will determine the architecture of an operational Lisa mission. eLISA

The current LISA design proposes a two-arm laser interferometer (left)
But scientists would prefer to fly an architecture that has three arms (right)
The latter could more easily locate gravitational wave sources in the sky
Whether two or three arms are flown will depend on the available budget
At present, ESA rules only permit a maximum 20% involvement from NASA
But it may require a bigger US participation to get the full architecture

LISA was previously proposed as a joint venture between Europe and the US.

When the Americans then ran into funding difficulties and pulled out, scientists on the European side “de-scoped” the mission to try to make it fit within the financial envelope available at the time. Many commentators thought this revised design compromised the science to an unacceptable degree.

Researchers on both sides of the Atlantic are now pushing hard to go back to the old arrangement.

This potentially represents something of a headache for ESA’s hierarchy.

Following the American withdrawal, the European Space Agency instigated a “rule” that foreign contributions to its missions should in future represent no more than 20% of the overall cost.

The restriction was designed to ensure that no mission could be scuppered by a sudden change of heart from an international partner.

But this financial ceiling may have to be broken if the US is to come back onboard and participate in the type of space mission that gravitational wave scientists most want to see fly.

The Goat “suggests that such a mission will be more robust, and provide a greater science return per euro, if the US could consider a larger contribution, including a re-establishment of a meaningful collaboration.”

The call to formally propose a new mission and its architecture should go out within the next 12 months.

“It is to be determined precisely when, but within the year,” confirmed Dr Fabio Favata, head of ESA’s Science Planning and Community Coordination Office.

“The call will ask the community to define a realistic mission in detail. In the meantime, we are already in discussions with our member states and NASA about who could do what, at least in the study phase. The implementation phase would take more time, of course.”

ESA is already developing some technologies, but the Goat says others must now be prioritised. AIRBUS DS.

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From BBC: “Jodrell Bank Observatory celebrates 70 years of radio astronomy”

BBC

14 December 2015

The observatory originally used Army radar equipment, with the radio telescope being built later. University of Manchester

The 70th anniversary of an astronomer’s first steps into a “whole new science” at one of Britain’s most important stargazing sites has been marked.

Sir Bernard Lovell began using radio astronomy in 1945 at the opening of the fledgling Jodrell Bank Observatory.

The Cheshire site would later become home to the iconic radio telescope which bears the astrophysicist’s name.

Its director Prof Tim O’Brien said his work had given astronomers the chance to look at “the invisible universe”.

The anniversary has been marked with the launch of a year-long programme of events celebrating “the past, present and future of Jodrell Bank’s science, engineering and heritage”, a spokeswoman said.

In April, the site was chosen as the worldwide headquarters for the Square Kilometre Array project, which will probe the early universe, test the theory of gravity and even search for alien life.

Prof O’Brien said that achievement was a direct result of Sir Bernard’s work, as he pioneered a “whole new science [through which] we discovered a whole new universe out there, full of super massive black holes, exploding stars and the fading glow of the Big Bang.

Sir Bernard Lovell initially set up the observatory for a two-week period in 1945.

The Mark I Telescope, which was renamed the Lovell Telescope in 1987, was built in the 1950s. University of Manchester

The radio telescope, which is still used by astronomers, towers over the surrounding countryside. Mike Peel/University of Manchester

Sir Bernard, who died in 2012, set up old Army radar equipment on the site to detect cosmic-rays and investigate meteors and began work on 14 December 1945.

The huge Lovell Telescope was completed in 1957 and, during its first year, it was the only facility in the West able to track the rocket carrying the Russians’ first satellite, the Sputnik, into space.

It went on to confirm the existence of pulsars – dying stars that send out pulses of electromagnetic radiation – in 1968 and, in 1979, was instrumental in proving Einstein’s theory of relativity for the first time.

In 2006, it was named as Britain’s greatest unsung landmark in a BBC poll.

What is radio astronomy?

Radio astronomy is the observation of radio waves that are emitted from celestial bodies, such as distant galaxies or stars
Many strong sources of radio waves are invisible in normal light, so looking at radio waves reveals a completely different picture of the universe, with even objects like the Sun and planets revealing new features when viewed with radio telescopes
Radio waves are better at travelling long distances than shorter wavelengths, so can provide a clearer ‘view’ of very distant objects than can be gathered using normal light
Though the information gathered by radio telescopes is not in a visible form, it can be processed by computers to create images

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From BBC: “Supernova ‘stream’ in neutrino lab’s sights”

BBC

2 October 2015
Paul Rincon

A global collaboration will aim to unravel the mysteries of neutrinos – also known as “ghost particles”.

The Dune collaboration might observe neutrinos from a supernova in our galaxy – if luck is on their side

Among the goals of the venture, formed earlier this year, will be to catch neutrino particles streaming towards us from a supernova – an exploding star.

Such events occur about every 30 years, but the neutrino streams they produce have not been studied in detail.

Dune (Deep Underground Neutrino Experiment) will be hosted at Fermilab in Batavia, Illinois.

It will involve the development of the world’s most high-intensity beam of neutrinos, which will travel 1,300km (800mi) underground from Fermilab towards a massive detector instrument based at the Sanford Underground Research Facility [SURF] in South Dakota.

SURF

The venture is the product of a merger between European and US projects with similar aims. The international collaboration held its inaugural meeting at Fermilab in April.

“There has been a process since last summer to prepare the ground for this collaboration, based on bringing together the US and European projects. There are now 700 people signed up,” said Prof Stefan Söldner-Rembold, from the University of Manchester.

“The step forward is a new collaboration with a new name that has commitments from the US, Europe, India and other regions to go forward.”

Neutrinos are one of some 17 elementary cosmic building blocks that make up the Universe. But they are also a source of intrigue for particle physicists.

They are extremely light particles, with no electric charge and pass harmlessly through other matter. This property makes them very difficult to observe and is responsible for them being nicknamed “ghost particles”. Neutrinos may also play a role in the mystery of why the Universe came to consist mostly of matter rather than antimatter.

LBNF/DUNE

They are found in three different states, or flavours, and the particles can flip from one flavour to another. Dune aims to carry out a detailed investigation of this three-flavour model of neutrino physics.

The project will make use of an existing particle accelerator at Fermilab as a proton source, and then smash the beam into a so-called “target” made of a material that will engender the production of short-lived particles. These will travel about 200m through a decay pipe, and as they do, a large proportion will transform into neutrinos.

Another potential scientific pay-off of the collaboration might be the opportunity to observe an exploding star in closer detail than ever before. But the team will need luck on their side, as it is dependent on a suitable event taking place during the lifetime of the project. It’s a game of chance, but scientists are hopeful the detector will catch one.

The four 10-kilotonne detector modules will be filled with liquid argon. FNAL

“If a supernova happens in our galaxy, which should happen once every 30 years or so, this experiment should – within seconds – see thousands of neutrino interactions,” said Prof Söldner-Rembold.

“There was a supernova in 1987 and there were some neutrino detectors online – they saw something, which spurred a lot of interest at the time.

This image shows the remnant of Supernova 1987A seen in light of very different wavelengths. ALMA data (in red) shows newly formed dust in the centre of the remnant. Hubble (in green) and Chandra (in blue) data show the expanding shock wave.

ESO/NRAO/NAOJ ALMA

NASA/ESA Hubble

NASA/Chandra

But a supernova with a detector like this, it is something that has never been observed.

The “spillover” from a supernova would depend on how far away it was from Earth. But such an energetic event, close enough to Earth, could potentially send huge numbers of neutrinos streaming our way – to be picked up by detectors. This could potentially shed light on the mechanics of stellar explosions, and how these events evolve over time.

Dune will also look for a hypothetical phenomenon known as proton decay. Protons are very stable sub-atomic particles; they have never been seen to transform into lighter cosmic building blocks.

However, in some theories of particle physics, such as the still-unconfirmed framework known as supersymmetry, this should happen.

“It’s the ultimate rare decay. It’s another way of looking for ‘new physics’, separate from the LHC, where you don’t need to go to high energies,” said Prof Söldner-Rembold.

LHC at CERN

Cern, the organisation that operates the Large Hadron Collider, is one of those that is now involved with Dune. The cost of the entire project is on the order of $1bn, but some international partners pay through in-kind contributions.

The detectors will be filled with liquid argon, with the first of the four 10-kilotonne modules due to be installed in the 2020s. Neutrino collisions create electrons and flashes of light in the liquid argon, which leave observable traces of the neutrinos. The project is set to run for three decades.

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From BBC: “Sergey Ananov: Two days on ice with three polar bears”

BBC

Sergey Ananov

In July Russian adventurer Sergey Ananov was forced to ditch his helicopter in icy waters between Canada and Greenland. Here he describes his two-day battle against high winds and extreme temperatures – and a few unexpected guests.

I always feel very free, relaxed and happy when I’m flying helicopters and that was exactly how I was feeling shortly before 11:30 on 25 July.

I was halfway through a six-hour flight from Iqaluit in Canada to Nuuk in Greenland. I was flying above a thick carpet of fog and underneath a bright canopy of cloud, steering my Robinson R22 through this fluffy grey corridor, quite alone in the world with the engine noise and a feeling of intense happiness. Next to me, in the passenger seat, sat an extra fuel tank that I had nicknamed Wilson, after the volleyball in Castaway. And 1,500ft (460m) below me – though I could not see it because of the fog – lay the ice and cold waters of the Davis Strait.

Suddenly, I felt a jolt in the tail and I lost about half the power to the blades. The engine was running fine so I took it to signal a problem in transmission. The speed was dropping sharply – not good. I didn’t want to risk falling like a pebble out of the sky so I made the adjustments I needed to accelerate, which meant losing altitude. The helicopter was shaking and veering alarmingly to one side and within a few seconds it became clear to me that I would not be able to continue my flight.

Sergey Ananov

It was Day 42 of my solo attempt to become the first person to circumnavigate the world in a helicopter weighing less than one tonne.

A thousand thoughts went through my head, among them this one: “Oh God, I have flown 34,000 miles and it’s only 4,000 more till I get my world record in Moscow.” And: “Why does this have to happen to me here, not above the swamps of Florida or the prairies of Canada or even somewhere in Siberia, where I would just be able to land, get out my phone and call for help?”

I switched the helicopter on to auto-rotation, a safety mode that allows it to glide downwards. Dropping through the layer of fog, which was just 200 feet (60m) above the sea, I saw, out of the corner of my eye, an inviting lump of ice. But I was rapidly losing rotation and it would have been dangerous to try to extend the flight to reach it, so I headed straight for the water.

I don’t agree with the word “crashed” that journalists are so fond of. It was not a crash. It was a forced landing on water, and it was a very controlled and soft one. I was completely unharmed.

The helicopter’s tail sank immediately. I knew there was a danger that my weight would tip the aircraft on to my side – starboard – and trap me in deep water, so I threw my weight to my left to force the helicopter on to port side. It fell on that side and the blades, which were still turning, smashed to pieces on the surface.

Then I undid my safety belt and opened the door. Instantly I was up to my neck in icy water. I was wearing a survival suit, but only around my legs and waist – the top part hung loose because I find it quite impossible to fly with one covering my arms and upper body. Such was my adrenaline at that moment that I didn’t feel the cold at all. I swam out of the helicopter and then dived back down to retrieve the life raft, which was stowed under my seat.

Whenever I had mentally rehearsed a landing on water I had programmed my brain to think that the life raft was my first priority. It did save my life, though not in the way I imagined.

It turned out I was just 50m or so from the lump of ice I had spotted before making my landing, and this was better than any inflatable raft. I swam over and climbed on to it. It was about 15-20m in diameter and would be my home for the foreseeable future. By this time, the helicopter had disappeared from view – within 30 seconds or so it had sunk into the dark blue water.

Floating ice in Disko Bay, Greenland, close to the Davis Strait

Then I took off my survival suit. Wearing nothing but my underwear, and shaking violently in the wind, I tipped as much water as I could out of the suit. Then I put it back on, squelchy wet and freezing cold. I did it up, lifting the ridiculous built-in hat over my head.

The wind was absolutely killing me. I got down in a horizontal position and inflated the life raft. It was yellow and square. I tied one end of the raft to my leg and held on to the other with my hand, and hid underneath it, using it as a windbreaker.

That was when I started to beat myself up. I was travelling with two trackers, a distress beacon and a satellite phone, but they had all gone down with the helicopter. “Why didn’t you dive in and get them?” I asked myself. “Sure, it would have been very unpleasant but you should have dived in.”

Still, I felt confident that the alarm would be raised. I had several friends who I knew were monitoring my progress carefully and would see that the tracker on the helicopter had come to a standstill. But I also knew that the tracker’s final position may have been some distance from the place where I landed, and since it was not manually activated my friends had no way of knowing I was still alive.

Data from Ananov’s flight tracker shows his attempt to circumnavigate the world

I had a few packs of water, amounting to perhaps half a litre, and a small pack of protein bars – about 2,000 calories of food. I also had three flares, which had been packed inside the life raft.

I got up and tried moving around a little, to keep my circulation going, but I found myself panting as though I were doing hard physical exercise. Throughout my time on the ice I did not stop shivering at all.

One thing I was not particularly worried about was polar bears. My block of ice was adrift at sea, with just a few more lumps of ice nearby. Mainly it was water – water, water, water. And the wind.

Then, about four hours after my forced landing, I was lying on my stomach in my makeshift tent, trying to retain heat and breathing as shallowly as I could through my nose, when I heard the sound of heavy breathing nearby and crunching snow. Footsteps. I peeked from under the bottom of the life raft and I saw him, a polar bear, sniffing the air and walking in my direction.

Polar bears are amongst the world’s most powerful predators. Getty Images

I had to make an instant decision. And I decided that since he had surprised me I would surprise him. So I jumped up and threw off the life raft. Boo! Then I rushed at him, arms upstretched, roaring.
“Grrrrrrrrrrrrrrrrrrrr!”

I was trying to show anger, and I really was angry – with myself, with the situation I was in and with this bear that had somehow found its way on to my lump of ice. How dare he come here and try to eat me!

It must have looked ridiculous – like when you pretend to be a monster with children. But it worked. The bear turned and ran away. “Ok,” I thought, “he knows that I am the boss – now I have to build on that.” So I chased after him.

Polar bears hunt for seals near the edges of sea ice. Arturo de Frias Marques

We reached the edge of my piece of ice and he jumped nimbly to another. Well, I couldn’t do that, so I stood on the edge, my arms still in the air, my eyes black coals of rage, roaring. And I saw that the sea around me had been quite transformed, everything moved around by the wind. No longer was my ice lump isolated, a little island, but it now butted against others. Evidently, I was not safe from bears.

The bear jogged on another 25m or so. Then he sat down on his backside and turned and looked at me mutely, like a dog. He wanted to know what I would do next – and so did I.

Polar bears are not territorial and will avoid confrontation. Getty Images

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