Tech trials to find Antarctica’s ‘missing’ iron meteorites

The project to find Antarctica’s “missing meteorites” is making excellent progress, say scientists.

A group led from Manchester University is developing detection equipment it believes will discover a bounty of iron space objects buried in the polar ice.

This survey gear has just come through a week of successful trials.

Presently, 10 times fewer iron meteorites are found in Antarctica compared with other parts of the globe.

The scientists say this discrepancy has nothing to do with differing fall rates; rather, it can be explained simply by the tendency of metal objects to sit just under the ice surface out of the view of collectors.

The team’s equipment, adapted from mine-detection technology, was dragged behind a snowmobile across a simulation field set up at the Ny-Ålesund research base on Svalbard in the Arctic.

Dummy meteorites were hidden in a glacier at varying depths and then the system driven over them to locate their positions.

“It’s gone really well,” said Dr Geoff Evatt. “We’ve got the mechanics of the detector pretty nailed down in terms of the towing, the data-logging, the GPS coordinates – the way we use the system.

“There’s the inevitable teething problems, of course, in making sure the equipment all works with the environment in the cold, but the only way to sort out those problems is to get out here and start using the detector, he told BBC News”

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    Of the more-than-35,000 meteorites catalogued in collections worldwide, something like two-thirds have been retrieved from Antarctica.

    Not only does the colour contrast make for easier prospecting, but hunters also get a helping hand from the way the ice sheet moves. Meteorites that crash in Antarctica’s high interior are buried and transported towards the coast, ultimately to be dumped in the ocean.

    But if this conveyor happens to run into a barrier on the way – such as a range of mountains – the ice will be forced upwards and scoured by winds to reveal its cargo.

    Meteorite hunters on the continent concentrate their searches in these special “stranding zones”.

    What they have noticed, however, is a bias towards stony-type space rocks.

    The iron ones are underrepresented compared with the global distribution. Modelling work by Dr Evatt and his team suggests the metal meteorites are still there; they just do not come back to the surface in the same way.

    It is thought that as they start to rise through the ice, their iron absorbs energy from the Sun and efficiently warms the meteorites’ undersides, enabling them to sink back down.

    Manchester team-member, Dr Katherine Joy will be heading out to Antarctica later this year on an initial survey to assess the stranding zones.

    Places with the highest density of stony-type meteorites sitting on the surface should also be the locations with the greatest number of iron meteorites hidden in the ice below.

    “A reconnaissance trip will help the team investigate which blue icefields that have not been visited before are productive for meteorite collection,” she said.

    “The outcomes of this initial search will help us to target where to take the full detector setup to test for buried meteorites.”

    This is likely to happen in the austral summer of 2019/2020. But working in these remote locations will be extremely challenging and will require the assistance and expertise of the British Antarctic Survey.

    Equipment failure is an ever-present hazard and the team knows it has to go with a detector that is robust and simple to use.

    “Ny-Ålesund has been reasonably comfortable so if we’ve needed to pop up a lid on the equipment and get our hands dirty with the electronics, we can,” said Dr Evatt.

    “We’ve also been able to come back to the base in the evening and make fine adjustments. However, when we use this system in anger in Antarctica, we won’t have those luxuries. The aim therefore is to develop a system with minimal switches and user interface, and one that is robust not just to the environment but to human error.”

    The hope is that iron meteorites “numbering in the low tens” can be recovered on the 2019/2020 expedition.

    These will be brought back to Manchester to be curated and studied.

    Iron meteorites are interesting because they represent the smashed up innards of bodies that almost became planets at the start of the Solar System.

    They therefore provide clues about events that occurred some 4.6 billion years ago when the Earth was forming.

    Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos

Tiangong-1: Defunct China space lab comes down over South Pacific

China’s defunct Tiangong-1 space lab mostly broke up on re-entering the Earth’s atmosphere above the South Pacific, Chinese and US reports say.

It re-entered the atmosphere around 00:15 GMT on Monday, China’s Manned Space Engineering Office said.

Tiangong-1 was launched in 2011 to carry out docking and orbit experiments.

It was part of China’s efforts to build a manned space station by 2022, but stopped working in March 2016.

What do we know about where it came down?

The rather vague “above the South Pacific” is the line from space officials.

Experts had struggled to predict exactly where the lab would make its re-entry – and China’s space agency wrongly suggested it would be off Sao Paulo, Brazil, shortly before the moment came.

The European Space Agency said in advance that Tiangong-1 would probably break up over water, which covers much of the Earth’s surface.

It stressed that the chances of anyone being hit by debris from the module were “10 million times smaller than the yearly chance of being hit by lightning”.

It’s not clear how much of the debris reached the Earth’s surface intact.

Why did the space lab fall like this?

Ideally, the 10m (32ft)-long Tiangong module would have been taken out of orbit in a planned manner.

Traditionally, thrusters are fired on large vehicles to drive them towards a remote zone over the Southern Ocean. This option appears not to have been available after the loss of command links.

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    Thirteen space agencies, under the leadership of the European Space Agency, used radar and optical observations to follow Tiangong’s path around the globe.

    Tiangong means ‘Heavenly Palace’

    • The module was launched in 2011 to practise rendezvous and docking
    • Two astronaut crews visited in Shenzhou capsules – in 2012 and 2013
    • They included China’s first female astronauts Liu Yang and Wang Yaping
    • China plans a more permanent space station in the next decade
    • It has developed a heavy-lift rocket, Long March 5, for the purpose

      Is this the biggest space hardware to fall out of the sky?

      Tiangong was certainly on the large size for uncontrolled re-entry objects, but it was far from being the biggest, historically:

      • The US space agency’s Skylab was almost 80 tonnes in mass when it came back partially uncontrolled in 1979. Parts struck Western Australia but no-one on the ground was injured
        • Nasa’s Columbia shuttle would also have to be classed as an uncontrolled re-entry. Its mass was more than 100 tonnes when it made its tragic return from orbit in 2003. Again, no-one on the ground was hit as debris scattered through the US states of Texas and Louisiana

          Astrophysicist Jonathan McDowell believes Tiangong is only the 50th most massive object to come back uncontrolled.

          Skip Twitter post 2 by @planet4589

          By my calculations, Tiangong-1 will be the 50th most massive uncontrolled reentry from Earth orbit in history.

          — Jonathan McDowell (@planet4589) March 25, 2018

          Report

          End of Twitter post 2 by @planet4589

          China has launched a second lab, Tiangong-2, which continues to be operational. It was visited by a re-fuelling freighter, Tianzhou-1, just last year.

          China’s future permanent space station is expected to comprise a large core module and two smaller ancillary modules, and will be in service early in the next decade, the Asian nation says.

          A new rocket, the Long March 5, was recently introduced to perform the heavy lifting that will be required to get the core module in orbit.

Shipping faces demands to cut CO2

A battle is under way to force the global shipping industry to play its part in tackling climate change.

A meeting of the International Maritime Organisation in London next week will face demands for shipping to radically reduce its CO2 emissions.

If shipping doesn’t clean up, it could contribute almost a fifth of the global total of CO2 by 2050.

A group of nations led by Brazil, Saudi Arabia, India, Panama and Argentina is resisting CO2 targets for shipping.

Their submission to the meeting says capping ships’ overall emissions would restrict world trade. It might also force goods on to less efficient forms of transport.

This argument is dismissed by other countries which believe shipping could actually benefit from a shift towards cleaner technology.

The UK’s Shipping Minister Nusrat Ghani told BBC News: “As other sectors take action on climate change, international shipping could be left behind.

“We are urging other members of the International Maritime Organisation (IMO) to help set an ambitious strategy to cut emissions from ships.”

Trade and prosperity

The UK is supported by other European nations in a proposal to shrink shipping emissions by 70%-100% of their 2008 levels by 2050.

Guy Platten from the UK Chamber of Shipping said: “We call on the global shipping industry to get behind these proposals – not just because it is in their interests to do so, but because it is the right thing to do.

“The public expects us all to take action, they understand that international trade brings prosperity, but they rightly demand it is conducted in a sustainable and environmentally friendly way. We must listen to those demands, and the time for action is now.”

The problem has developed over many years. As the shipping industry is international, it evades the carbon-cutting influence of the annual UN talks on climate change, which are conducted on a national basis.

Instead the decisions have been left to the IMO, a body recently criticised for its lack of accountability and transparency.

The IMO did agree a design standard in 2011 ensuring that new ships should be 30% more efficient by 2025. But there is no rule to reduce emissions from the existing fleet.

The Clean Shipping Coalition, a green group focusing on ships, said shipping should conform to agreement made in Paris to stabilise the global temperature increase as close as possible to 1.5C.

Tangible goals

A spokesman said: “The Paris temperature goals are absolute objectives. They are not conditional on whether the global economy thinks they are achievable or not.”

So the pressure is on the IMO to produce an ambitious policy. The EU has threatened that if the IMO doesn’t move far enough, the EU will take over regulating European shipping. That would see the IMO stripped of some of its authority.

A spokesman for the Panamanian government told BBC News his nation supports the Paris Agreement.

“But”, he said, “Panama, as a developing country that depends on the maritime sector for its progress, and aware that the welfare of its population relies on shipping, believes in the necessity of a well though-out and studied strategy that allows sustainable and efficient reduction of emissions.

“To haste into an uncalculated strategy that aims to reduce emissions to zero by the year 2050 does not take into account the current state of technology.”

A recent report from the International Transport Forum at the rich nations’ think tank the OECD said maximum deployment of currently known technologies could achieve almost complete decarbonisation of maritime shipping by 2035.

A spokesperson for another of the nations resisting targets told BBC News: “My country pushed very hard to get the deal in Paris. But you will notice that many of the countries opposing the restrictions on CO2 are developing countries that are distant from some of their markets.”

Campaigners say huge improvements in CO2 emissions from existing ships can be easily be made by obliging them to travel more slowly. They say a carbon pricing system is needed.

International shipping produces about 1,000 million tonnes of CO2 annually – that’s more than the entire German economy.

The meeting runs from Tuesday.

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‘Send in the drones’ to protect soil

Squadrons of drones should be deployed to locate and penalise farmers who let soil run off their fields, a report will say.

A coalition of campaigners complains that the Environment Agency can only check soil on 0.5% of farms each year.

Their report says drones can help to spot bad farming, which is said to cost more than £1.2bn a year by clogging rivers and contributing to floods.

The government said it was considering the ideas for combating soil run-off

The proposals come from the Angling Trust, WWF and the Rivers Trust – with support from the RSPB. Their preliminary briefing has been seen by the Environment Secretary Michael Gove.

The groups say poor farming is the chief cause of the UK’s decline in the health of rivers, and a major contributor to flooding.

They calculate that investment in stopping soil loss would pay back many times over.

But, they say, Environment Agency enforcement of soil protection is under-funded, and careless farming in remote fields is often hard to spot.

The challenge is particularly acute in the West Country where many farmers grow maize on steep slopes. The plants are widely spaced and soil left uncovered between them is liable to be flushed away in heavy rains.

Over-stocking livestock is another problem, as hooves compact fields and create a crust which blocks water from seeping into the sub-soil.

In Herefordshire, a trial drone surveillance scheme is said by the report to have worked well to prevent soil loss.

It focuses on maize – and also on potatoes, which exhaust soil and make it more likely to be washed away.

National effort

Under the trial, the Environment Agency shifted its local budget towards drones. Guided by a contour map, it identified the areas of fields most susceptible to losing soil in heavy rain.

The Agency offset the cost of drones by handing their farm advisory role locally to the Wye and Usk Foundation.

Simon Evans, a spokesman for the foundation, told BBC News: “When we started to tackle this problem in 2000 we had lost spawning salmon along the whole length of the English Wye.

“Working with the Agency hasn’t only improved soil – it’s also benefited fish, because we’ve now got 65 miles of the Wye with salmon spawning successfully.”

The report will urge ministers to replicate this scheme on a national level.

One of its authors, Mark Lloyd from the Angling Trust, told BBC News: “The rules on protecting soil aren’t being enforced. We need a baseline of regulation to stop bad farmers doing the wrong thing and to stop good farmers looking over the fence and seeing someone else get away with it.

“The trouble is that the Environment Agency can only respond to major incidents. But soil run-off is diffuse pollution – it comes in hundreds of thousands of trickles, not normally one big incident.”

“What we really need is Treasury support, because for an investment of tens of millions of pounds you get hundreds or billions of pounds in benefit to local councils, water companies, and society as a whole.”

The report will call for a strategic approach to land use management in the UK, to be overseen by the new body proposed by Mr Gove to ensure environmental standards post-Brexit.

This would allow different farming practices in different areas. It would lead to farmers in parts of the West Country being incentivised to revert cropland to pasture or woodland to capture rainfall and bind vulnerable soils together.

The groups say farmers who allow soil to run off fields should first be given advice. But if they transgress again they should be prosecuted and lose farm grants.

Farmers who help prevent flooding and increase the carbon content of their soils should be rewarded through the grant system.

Investing in soil

One potato farmer, Sam Bright from Woodmanton, told BBC News he had worked with the Wye and Usk Foundation to improve soil conservation through a range of measures, including planting buffer strips of grass round field edges; increasing pastureland; and using minimum tillage, which avoids the traditional method of overturning soil with a plough.

In earlier years, he used to sell off his wheat straw to livestock farmers after harvest – now he chops it and leaves it on the soil surface. “The worms are pulling the straw residue right down into the soil for us. So we’ve got good organic levels right through the soil profile. It’s improving our drainage, our soil structure and our soil health,” he told me.

Kate Adams from the Wye and Usk Foundation has been advising local farmers. “The biggest step by far is for a farmer to take the first step in acknowledging that there’s something on the farm that needs to be addressed,” she told BBC News.

“I don’t tell farmers what to do. There’s no point me selling them a conservation message if that’s not what they are interested in. Whatever advice I give has to go with the grain of what they want to do. And most of them want to improve how their farm works.”

The NFU’s Diane Mitchell told me: “The awareness amongst farmers about the importance of investing in our soil health is at an all-time high, with increasing uptake in techniques such as cover cropping and minimum tillage.

“The NFU sees good soil health as a key element of any new domestic agricultural policy in the future, helping deliver dual benefits for our productivity and for public goods, such as carbon and soil biodiversity.”

A government spokesman told BBC News: “Our farmers work hard to keep our soils rich, our rivers clean and to help in the fight against environmental degradation. We are considering the proposals put forward (in the report) to improve these efforts further.


Soil benefits

The report says protecting soil has multiple benefits. It:

  • improves the ability of future farmers to grow crops,
  • save on fertilisers and pesticides;
  • reduces the need for dredging;
  • is good for anglers and tourism;
  • reduces flooding;
  • protects against drought by recharging aquifers;
  • uses less diesel by minimising ploughing;
  • saves costs for water firms, so cuts bills;
  • locks up carbon to tackle climate change;
  • increases wildlife.

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Antarctica ‘gives ground to the ocean’

Scientists now have their best view yet of where Antarctica is giving up ground to the ocean as some of its biggest glaciers are eaten away from below by warm water.

Researchers using Europe’s Cryosat radar spacecraft have traced the movement of grounding lines around the continent.

These are the places where the fronts of glaciers that flow from the land into the ocean start to lift and float.

The new study reveals an area of seafloor the size of Greater London that was previously in contact with ice is now free of it.

The report, which covers the period from 2010 to 2016, is published in the journal Nature Geoscience.

“What we’re able to do now with Cryosat is put the behaviour of retreating glaciers in a much wider context,” said Dr Hannes Konrad from the University of Leeds, UK.

“Our method for monitoring grounding lines requires a lot of data but it means you could now basically build a permanent service to monitor the state of the edges of the continent,” he told BBC News.

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    Although the end product is quite simple, the process of getting to it is quite a complex one.

    Viewed from above, the position of grounding lines is not always obvious.

    The glaciers themselves are hundreds of metres thick, and where they begin to float as they come off the continent can be hard to discern in simple satellite images.

    But there are radar techniques that can find their location by spotting the up and down tidal movement of a glacier’s floating ice. This, however, is just a snapshot in time.

    What Dr Konrad and colleagues have done is use these known positions and then combine the data with knowledge about the shape of the underlying rock bed and changes in the height of the glaciers’ surface to track the evolving status of the grounding lines through time.

    The new study triples the coverage of previous surveys.

    On the face of it, the results are pretty much as expected.

    Of the 1,463km² of grounded ice that has been given up, most of it is in well documented areas of West Antarctica where warm ocean water is known to be infiltrating the undersides of glaciers to melt them.

    Dr Konrad explained: “If you take 25m per year as a threshold, which is sort of the average since the end of the last ice age, and you say anything below this threshold is normal behaviour and anything above it is faster than normal – then in West Antarctica, almost 22% of grounding lines are retreating more rapidly than 25m/yr.

    “That’s a statement we can only make now because we have this wider context.”

    The new data-set confirms other observations that show the mighty Pine Island Glacier, one of the biggest and fast-flowing glaciers on Earth, and whose grounding line had been in major retreat since the 1940s, appears now to have stabilised somewhat.

    The line is currently going backwards by only 40m/yr compared with the roughly 1,000m/yr seen in previous studies. This could suggest that ocean melting at the PIG’s base is pausing.

    Its next-door neighbour, Thwaites Glacier, on the other hand, is seeing an acceleration in the reversal of its grounding line – from 340m/yr to 420m/yr.

    Thwaites is now the glacier of concern because of its potential large contribution to global sea-level rise. And the UK and American authorities will shortly announce a major joint campaign to go and study this ice stream in detail.

    Elsewhere on the continent, 10% of marine-terminating glaciers around the Antarctic Peninsula are above the 25m/yr threshold; whereas in East Antarctic, only 3% are.

    The significant stand-out in the East is Totten Glacier, whose grounding line is retreating at a rate of 154m/yr.

    Overall, for the entire continent, 10.7% of the grounding line retreated faster than 25m/yr, while 1.9% advanced faster than the threshold.

    One fascinating number to come out of the study is that grounding lines in general are seen to retreat 110m for every metre of thinning on the fastest flowing glaciers. This relationship will constrain computer models that try to simulate future change on the continent.

    Leeds co-author Dr Anna Hogg said: “The big improvement here is Cryosat, which gives us continuous, continent-wide coverage, which we simply didn’t have with previous radar missions.

    “Its capabilities have allowed us to build up a picture of retreat rates, especially at the steeply sloping margins of the continent, which is where these changes are taking place. We have eight years of coverage now and it’s guaranteed in the future for as long as Cryosat keeps working,” she told BBC News.

    Since conducting the study at Leeds, Dr Konrad has now moved to the Alfred Wegener Institute in Bremerhaven, Germany.

    Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos

Space junk demo mission launches

A UK-led experiment to tackle space junk has been sent into orbit.

It takes the form of a small satellite that will practise techniques for tracking debris and capturing it.

The RemoveDebris system is heading to the International Space Station where astronauts are expected to set the experiment running in late May.

Space junk is an ever-growing problem with more than 7,500 tonnes of redundant hardware now thought to be circling the Earth.

Ranging from old rocket bodies and defunct spacecraft through to screws and even flecks of paint – this material poses a collision hazard to operational missions.

RemoveDebris will showcase technologies that could be used to clean up some of this techno-garbage.

The 100kg demonstrator left Earth on Monday onboard a SpaceX Falcon 9 rocket. It should arrive at the ISS on Wednesday.

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    The satellite will be stored at the station for a number of weeks, before being released by the orbiting platform’s robotic arm to begin a series of manoeuvres.

    RemoveDebris carries its own “junk” – two small cubesats that it will eject and then track.

    For one of these, the “mother” satellite will demonstrate the laser ranging (Lidar) and camera technology needed to monitor and characterise debris in orbit; for the the other cubesat, it will actually try to snare the object with a net.

    There will also be a demonstration of a small harpoon.

    The RemoveDebris satellite will extend a boom with a target on the end.

    The sharp projectile will be fired at this to learn more about how such devices move and impact a surface in micro-gravity.

    At the end of its mission, RemoveDebris will deploy a large membrane.

    This “sail” will increase the drag from air molecules high in the atmosphere and act to pull the satellite down to Earth much faster than would otherwise be the case.

    The project, which draws on expertise from across Europe, is led from the University of Surrey’s Space Centre.

    Its principal investigator is Prof Guglielmo Aglietti. He said the jury was still out on the best way to capture and remove space junk.

    “As you know, there are other people who are going with the idea of a robotic arm. All these different technologies have their advantages and disadvantages,” he told BBC News.

    “For example, the ones we are testing – the net and the harpoon – are simple and low cost, but could be considered more risky in certain circumstances than a robotic arm.

    “On the other hand, if your piece of debris is spinning very fast, it becomes very difficult to capture it with a robotic arm and an approach with a net could work better.”

    He added: “The reason we are doing this mission this way is because it is low cost. In my opinion, whether or not there are going to be real missions to remove debris will depend on cost. And I worry that if they are extremely expensive, people will think about other priorities.”

    The entire RemoveDebris project is costing €15m (£13m). Half of this is coming from the European Commission; the other half is coming from the 10 partners involved.

    These include Airbus, which supplied the harpoon technology, and Surrey Satellite Technology Limited, which assembled the spacecraft.

    The mission has been organised through NanoRacks, a Houston, US, company that specialises in deploying small satellites from the space station.

    Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos

Conservationists use astronomy software to save species

Researchers are using astronomical techniques used to study distant stars to survey endangered species.

The team of scientists is developing a system to automatically identify animals using a camera that has been mounted on a drone.

It is able to identify them from the heat they give off, even when vegetation is in the way.

Details of the system were presented at the annual meeting of the European Astronomical Society in Liverpool, UK.

The idea was developed by Serge Wich, a conservationist at Liverpool John Moores University, and Dr Steve Longmore, an astrophysicist at the same university. He says that the system has the potential to greatly improve the accuracy of monitoring endangered species and so help save endangered species.

“Conservation is not only about the numbers of animals but also about political will and local community supporting conservation. But better data always helps to move good arguments forward. Solid data on what is happening to animal populations is the foundation of all conservation efforts”.

Currently, conservationists estimate numbers of endangered species by physically counting them or the signs they leave.

This is an inexact science, as the animals can be in areas inaccessible to observers. Further problems can arise if species have migrated to another area since the previous census. Signs of their presence, such as abandoned nests, rely on assumptions such as the number of animals that share the nest and the frequency with which the species build and abandon their nests.

The process is time consuming, expensive and inaccurate. So Dr Wich developed a system to monitor them using infrared cameras mounted on drones.

Trials at Chester Zoo and Knowsley Safari Park showed that the system could pick up animals on the ground from the heat they gave off, even through tree cover.

But the problem was that they couldn’t always identify the species – especially when they were far away. Dr Wich needed a system that could identify different species from their heat signatures.

He explained his problem to his neighbour, Dr Steve Longmore, while chatting over the fence. The neighbour was an astronomer and he explained that he knew someone who identified the size and age of far away stars from their heat signatures.

“I collaborated with quite a few people during my career but astrophysicists were not on my list of potential collaborators,” Dr Wich told BBC News.

“But here we are. It shows how the serendipity of how science works.”

Dr Wich worked with astrophysicist Dr Claire Burke, also at Liverpool John Moores University. She told BBC News that her work in identifying the most massive galaxies in the Universe from the light they emit helped her devise software that could identify different types of animal from the pattern of the heat they give off.

Each species, she said, has distinct warmer and colder areas that are unique.

“When we look at animals in the thermal infrared, we’re looking at their body heat and they glow in the footage. That glow is very similar to the way that stars and galaxies in space glow,” Dr Burke explained.

“So we can apply techniques and software used in astronomy for decades to automatically detect and measure this glow”.

The system can also give information about the health of animals. If an animal is injured then that part of the animal’s body will be glowing brighter than the rest. Similarly, diseased animals also have a different heat profile, according to Dr Burke.

“The real advantage this gives you is that if you know how many animals you have and where they are and what kind of health they are in, then you can you can formulate a good conservation strategy for looking after them,” she said.

“And if you can track them as well, then you can tell what they need to survive and thrive and this helps us. If, for example, we needed to relocate animal because its habitat was being destroyed then you would know better what it needed to be relocated to.”

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Plastic bag litter falls in UK seas

A study of litter in UK seas shows the number of plastic bags has fallen, amid a rise in other types of plastic rubbish.

The authors say this could be due to several things – the introduction of charges for plastic bags across Europe, manufacturing changes and shifts in ocean dynamics.

The research found a rise in the proportion of fishing debris.

Some of the plastic debris is likely to be coming from outside the UK.

The reduced proportion of plastic bags in marine litter was found from 2010 onwards. There was a drop of around 30% from the pre-2010 period compared with afterwards.

If charging is a potential contributor, the downward trend could suggest that policies can affect the amount and distribution of certain marine litter items on short timescales. But in their scientific paper, the researchers add that this point is controversial.

A change in the composition of plastic bags, which may speed up the rate at which they decompose, could also be another factor.

Co-author Thomas Maes, who is a marine litter scientist at the government’s Centre for Environment, Fisheries and Aquaculture Science (Cefas), said: “It is encouraging to see that efforts by all of society, whether the public, industry, NGOs or government to reduce plastic bags are having an effect.

“We observed sharp declines in the percentage of plastic bags as captured by fishing nets trawling the seafloor around the UK compared to 2010 and this research suggests that by working together we can reduce, reuse and recycle to tackle the marine litter problem.”

A UK levy of 5p per bag was introduced in 2015.

The study, published in the journal Science of the Total Environment, looked at plastic debris on the seabed off UK coasts over a 25-year period. It compiles the results of 39 separate boat surveys that trawled for plastic between 1992 and 2017.

Bags, bottles and fishing related debris were commonly observed across all areas.

There was no significant trend over time in the percentage of seafloor trawls that contained any plastic litter or in the total plastic litter items found across the long-term datasets.

However, statistically significant trends were found for fishing debris such as nets and lines. The researchers suggest that better training and action by the industry could help reduce the amount of fishing-related items found on the sea bottom.

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The whales who love to sing in the dark

Beneath the Arctic sea ice, in the blanket of January’s polar night, bowhead whales most prefer to sing.

While the songs of humpback whales have long received the most attention, it turns out that their baleen cousins could have a far greater repertoire.

A study of a bowhead population near Svalbard has shown that their musical calls may be as varied as those of songbirds.

This would make them unique among whale populations, and possibly even mammals.

Whalesong mixtape

Over the course of three years, the whales of the Spitsbergen population produced 184 unique song types. The vocalisations were detected 24 hours a day throughout most of the winter each year.

“The alphabet for the bowhead has got thousands of letters as far as we can tell,” Prof Kate Stafford, lead author of the study published in the Proceedings of the Royal Society, told BBC News.

“I really think of humpback whale songs as being like classical music. Very ordered. They might last 20 – 30 minutes. An individual [bowhead] song might only be 45 seconds to 2 minutes long, but they’ll repeat that song over and over again,” the University of Washington researcher added.

Humpback whales are known to sing similar songs across a single season, but for bowheads, song types only lasted a few hours or days before changing.

These complex songs are unusual, as most mammals have distinct, repetitive calls which do not vary.

Although less is known about bowhead populations, the authors think it likely that males do the singing during the breeding season.

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    With the ability to break through up to half a metre of ice, and a potential lifespan of 200 years, bowheads can seem quite formidable.

    Yet their blubber, the thickest of any whale species, led to the Spitsbergen population being commercially hunted as early as the 1600s.

    This reduction in their numbers, and the harsh environment of their natural habitat under the ice, has meant that they are poorly studied and remain somewhat mysterious.

    Other bowhead groups, such as the Western Arctic population, are better understood thanks to the knowledge of native Alaskans, Prof Stafford explains.

    Yet she says that overall we know “relatively little” about the species.

    Soloists

    It is not yet known whether individual bowheads sing the same song for a lifetime, or if they change from season to season.

    The reason for the diversity of calls in this one population hasn’t been determined either.

    It wasn’t possible to count the Spitsbergen group using the hydrophone recordings, but previous work in the region had put the population at a minimum of 343 whales.

    What remains, says Prof Stafford, is to acoustically track individuals and learn more about who is vocalising, and why.

    “It’s a mystery that’s going to be really hard to solve,” she said.

    But being able to eavesdrop under the ice in this remote place… It’s pretty remarkable.”

Hawking: Black holes store information

Black holes preserve information about the stuff that falls into them, according to Prof Stephen Hawking.

Physicists have long argued about what happens to information about the physical state of things that are swallowed up by black holes.

This information was thought to be destroyed, but it turned out that this violated laws of quantum physics.

Prof Hawking now says the information may not make it into the black hole at all, but is held on its boundary.

In broad terms, black holes are regions in space where the gravity is so strong that nothing that gets pulled in – even light – can escape.

At the same time, the laws of quantum mechanics dictate that everything in our world can be broken down into information, for example, a string of 1s and 0s. And according to those laws, this information should never disappear, not even if it gets sucked into a black hole.

But according to Einstein’s theory of general relativity, the information must be destroyed. This quandary is known as the information paradox.

Prof Hawking believes the information doesn’t make it inside the black hole at all.

“The information is not stored in the interior of the black hole as one might expect, but in its boundary – the event horizon,” he told a conference at the KTH Royal Institute of Technology in Stockholm, Sweden.

The event horizon is a boundary, or point of no return, where escape from the gravitational pull of the black hole becomes impossible.

Hawking has been working with Cambridge colleague Prof Malcolm Perry and Harvard professor Andrew Strominger on the problem. They believe that information at the event horizon is transformed into a 2D hologram – a phenomenon known as a super translation.

“The idea is the super translations are a hologram of the ingoing particles,” Hawking explained.

“Thus, they contain all the information that would otherwise be lost.”

Prof Marika Taylor, a theoretical physicist at the University of Southampton, told BBC News: “Einstein’s theory says that matter gets sucked into the black hole, falling behind its event horizon.

“Holography seems to suggest that Einstein’s picture of black holes isn’t right. In particular, it’s not clear that there is actually an ‘inside’ to black holes at all – matter which gets sucked in might get stuck at the event horizon and hang around as a hologram there.”

But she added that there was no consensus on this.

On the question of matter getting stuck at the event horizon, she said: “Nobody really understands the details of how this happens – this is what Hawking is trying to work out and what other related ideas ‘fuzzball’ and ‘firewall’ explore too.”

There’s currently little additional detail on the maths behind Prof Hawking’s talk, but he and his collaborators plan to publish a scientific paper in coming weeks.

Light particles – or photons – can be emitted from black holes due to quantum fluctuations, a concept known as Hawking radiation. Information from the black hole might be able to escape via this route.

But, Prof Hawking says it would be in “chaotic, useless form,” adding: “For all practical purposes the information is lost.”

If the information was not in this chaotic form, an observer might be able to reconstruct everything that had fallen into the black hole if they were able to wait for a vast amount of time.

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