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New Sentinel satellite tracks dirty air

A UK-Dutch-built Earth observing spacecraft shows its promise with some stunning images of pollution.

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It’s been working less than a month but already the UK-Dutch-built Sentinel-5P satellite is returning spectacular new views of Earth’s atmosphere.

The spacecraft was designed to make daily global maps of the gases and particles that pollute the air.

The first sample images released by mission scientists show plumes of nitrogen dioxide flowing away from power plants and traffic-choked cities.

S5P has even captured the ash and sulphur emissions from Agung volcano.

The mountain, sited on the Indonesian island of Bali, is in the midst of a big eruption.

Researchers, led from the Netherlands Met Office (KNMI), still have another five months of calibration work ahead to get the satellite’s data ready for public use.

But it is clear, says principal investigator Pepijn Veefkind, that when fully operational, the new Sentinel will be an extremely powerful tool to monitor air quality.

“It’s been amazing to see how quickly we were able to get the satellite working. This is a big improvement on what we’ve been able to do before. In just a week, we’ve got more data out of Sentinel-5P than in several years of operation of a previous mission,” he told BBC News.

Image copyright Copernicus Sentinel data (2017) – ESA/DLR Image caption Mount Agung’s emissions of sulphur dioxide could temporarily cool the global climate ever so slightly

Sentinel-5P is the latest spacecraft in a fleet of Earth observers being commissioned by the European Union and the European Space Agency.

Built by Airbus in Britain, the new spacecraft was launched into an 824km-high orbit by a Russian rocket on 13 October.

It carries a single instrument called Tropomi. This is a spectrometer that observes the reflected sunlight coming up off the Earth, analysing its many different colours.

In so doing, it can detect the presence in the atmosphere of a suite of trace gases such as nitrogen dioxide, ozone, formaldehyde, sulphur dioxide, methane, carbon monoxide and aerosols (small droplets and particles).

All affect the air we breathe and therefore our health, and a number of them also play a role in climate change.

The sample images were released during a briefing event at the German space agency in Oberpfaffenhofen near Munich. It is where Sentinel-5P’s data is processed.

Image copyright ESA Image caption Artwork: S5P is the first Sentinel whose construction has been led from the UK

One of the first images shows nitrogen dioxide over Europe. These emissions come largely from motor vehicles and the combustion of fossil fuels in industrial processes.

High concentrations of the pollutant are evident over parts of the Netherlands, the Ruhr area in western Germany, the Po Valley in Italy and over parts of Spain.

NO2, a yellow-brown gas, will, in the right weather conditions, promote the production of ground-level ozone, which is a severe respiratory irritant.

Image copyright Copernicus Sentinel data (2017) – ESA/KNMI Image caption NO2 emissions coming from power plants in India

Another sample image shows pollution drifting away from power plants in India. The worst of this pollution runs from north of Patna in the state of Bihar to south of Raipur in the state of Chhattisgarh.

Another image is a global map of carbon monoxide.

Image copyright Copernicus Sentinel data (2017) – ESA/SRON Image caption Carbon monoxide: There is a clear difference between the northern and southern hemispheres

Dr Veefkind explained: “You see straight away the difference between the northern and southern hemispheres. But you also see the strong concentrations over Amazonia, central Africa and Madagascar that are the result of biomass burning. We see some fires over Australia, too. Look also at how the pollution from China spreads out over the Pacific.”

Perhaps the most topical image is the one of Mount Agung. S5P sees both the ash and sulphur dioxide coming out of the volcano. If Agung’s activity increases substantially, these emissions have the potential to travel high and wide in the atmosphere, cooling the global climate by shading the planet from incoming solar radiation.

Sentinel 5P is an important British contribution to the EU/Esa Sentinel satellite constellation.

UK industry has provided components for other spacecraft in the series already in orbit, but 5P is the first platform whose construction was led from Britain.

“It’s fantastic to see the power of Europe’s Sentinel-5P, both globally and in close-up on sources of pollution,” said Airbus UK executive Dr Ralph Cordey.

“It shows the close link between skilled engineering and the understanding and monitoring of our planet’s atmosphere. Here in the UK, industry has led the satellite and built important parts of the Tropomi instrument – we should be very proud of that.”

The EU/Esa Sentinel series of satellites

The “P” in the spacecraft’s name stands for “Precursor”.

This references the fact that the Tropomi instrument onboard comes before a near-identical sensor that will eventually fly on Europe’s next-generation weather satellites from 2021.

Putting up 5P now also ensures there is no data gap in observations should an ageing, previous-generation instrument suddenly fail.

That sensor, called Omi, flies on the US space agency’s Aura satellite.

Although still in good health, it is operating far beyond its design lifetime.

Tropomi is more than a mere gap-filler, however. It has 10 times better resolution, seeing features in the atmosphere as small as 7km by 3.5km. And while this cannot distinguish particular point sources of pollution, this vision is sufficiently sharp to distinguish what is happening over sub-city scales.

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

Science & Environment

RemoveDebris: Space junk mission prepares for launch

A spacecraft that will test the best methods to clean up space debris is nearing completion.

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A mission that will test different methods to clean up space junk is getting ready for launch.

The RemoveDebris spacecraft will attempt to snare a small satellite with a net and test whether a harpoon is an effective garbage grabber.

The probe has been assembled in Surrey and will soon be packed up ready for blast off early next year.

Scientists warn that the growing problem of space debris is putting spacecraft and astronauts at risk.

It is estimated that there are about half a million pieces of man-made rubbish orbiting the Earth, ranging from huge defunct satellites, to spent rocket boosters and nuts and bolts.

Any collisions can cause a great deal of damage, and generate even more pieces of debris.

The RemoveDebris mission is led by the Surrey Space Centre at the University of Surrey.

The assembly of the spacecraft, which is about the size of a washing machine, has taken place at Surrey Satellite Technology Ltd (SSTL) and is almost complete.

Dr Jason Forshaw, project manager on the RemoveDebris team, said: “RemoveDebris will be one of the world’s first missions in this area…. We have technologies on here that have never been demonstrated in space before.”

Image copyright Max Alexander Image caption The spacecraft has been assembled in the UK and will soon be packed up for launch

The spacecraft will first head for the International Space Station on a resupply rocket.

It will then be unpacked by astronauts before being launched from the orbiter to begin its experiments.

RemoveDebris has its own space junk on board – small satellites. It will release one of these into space and then will use a net to recapture it.

It will also fire a small harpoon at a target plate to see if the technology can accurately work in the weightless environment.

It will finally test future de-orbiting technology. As the orbiter descends to Earth it will deploy a 10sq m sail, which will change the spacecraft’s speed and ensure it burns up as it enters the atmosphere.

“It will prevent the spacecraft from becoming space junk itself,” explained Dr Forshaw.

The hope is that the technology-testing mission, which has cost £15m, will lead to larger clean-up efforts.

“People are starting to realise the significance of space junk and the problem it presents,” Dr Forshaw said.

Image copyright RemoveDebris Mission Image caption The spacecraft will establish whether a net could ensnare a small satellite

Scientists estimate that there are about 7,500 tonnes of rubbish in space and we are reaching a critical point. .

Dr Hugh Lewis, senior lecturer in aerospace engineering at the University of Southampton, said: “For some people, space debris is one of these things that is out of sight, out of mind.

“But from my perspective it is one of the worst environmental catastrophes that we have encountered.”

Even very small pieces of junk can do a great deal of damage.

Last year a loose fleck of paint is thought to have caused a crack in a window on the International Space Station.

Image copyright ESA Image caption Last year a small piece of debris chipped a window on the International Space Station

The largest pieces, though, present a pressing problem.

In 2012, a European satellite called Envisat, the size of a double decker bus, suddenly stopped working.

Since then it’s been circling the Earth, threatening other key satellites in its path.

Dr Lewis explained: “The biggest pieces of space debris have huge amounts of mass in them. If they were to be hit by something, they would release all that mass in the form of thousands and thousands of more fragments.”

More debris, could lead to more collisions – a cascade effect known as the Kessler syndrome. The fear is that space could eventually become inoperable.

“The environment provides us with really important services – like navigation, timing, communications, weather forecasting and so on,” Dr Lewis added.

“The worst case scenario is probably the loss of some vital satellites… it would mean stepping back probably decades in terms of our technology we take for granted on Earth.”

Image copyright Hugh Lewis Image caption It is estimated that there are about half a million pieces of space junk the size of a marble or larger

The European Space Agency is now looking at how larger satellites like Envisat can be destroyed – but cleaning up space piece by piece will be difficult and extremely expensive.

International space guidelines suggest that satellites should de-orbit themselves after 25 years – but it is difficult to ensure everyone plays by the rules.

Some experts are also concerned that the new push to launch small satellites (known as cubesats) in increasingly large numbers could add to the problem.

Martin Pointer from SSTL said: ” Space junk is definitely a concern for us. As more and more satellites are put up – especially some of the constellations of small satellites – the likelihood of collisions is much greater.

“I think it’s our responsibility to ensure we don’t cause more junk in space and find ways of either removing those at the end of life or for mitigating against problems.”

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River departed ‘before Indus civilisation emergence’

One of the world’s earliest urban civilisations thrived in the absence of a big Himalayan river, a new study finds.

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Further light has been shed on the emergence and demise of one of the earliest urban civilisations.

The Indus society came to prominence in what is now northwest India and Pakistan some 5,300 years ago thanks in large part to the sustenance of a long-lost Himalayan river.

Or so it was thought.

New evidence now indicates this great water course had actually changed its path and disappeared before the Indus people had even settled in the region.

That they lacked the resource offered by a big, actively flowing river will come as a surprise to many; the other early urban societies of the time, in Egypt and Mesopotamia, certainly benefitted in this way.

The new research was led from the Indian Institute of Technology Kanpur and from Imperial College London.

Image copyright NASA/USGS Image caption Infrared satellite imagery picks out the distinctive sediments of the ancient channel Image copyright S.Gupta Image caption Remnant of a street in the urban centre of Kalibangan

The group’s scientists do not disagree that the Bronze Age settlements would have needed a good water supply, but argue that this requirement could have been met instead by seasonal monsoon rains that still collected and ran through the valley abandoned by the old river.

“Our paper clearly demolishes the age-old river-culture hypothesis that assumed that the disappearance of the river triggered the demise of the Harappan civilisation,” said IITK’s Prof Rajiv Sinha.

“We have argued that while large rivers have important connections with ancient societies, it is their departure that controls their stabilisation rather than their arrival.

“This has clearly been demonstrated by the large difference in age data between the demise of the river (8,000-12,000 years ago) and the peak of mature civilisation (3,000-4,000 years ago),” he told BBC News.

Prof Sinha and colleagues report their findings in this week’s Nature Communications journal.

Image copyright A.Carter/Birkbeck, University of London Image caption A collection of mineral grains that helped trace the origin of the palaeo-river

They have examined afresh the course of what is referred to as the Ghaggar-Hakra palaeo-channel, from satellite data and from field investigations.

Much of the archaeology of Indus cities, such as Kalibangan and Banawali, is scattered along this old river course.

The team shows the relict valley to be the former trace of today’s big Sutlej River, which must have abruptly changed course – as many Himalayan rivers are prone to do.

“They tend to switch on 100-year timescales,” explained Prof Sanjeev Gupta from Imperial College.

“But because the Sutlej became incised in its new course, it never switched back and that left the paleo-channel protected. That allowed, I believe, the Indus communities to flourish because they were saved from devastating floods.

“Some of their sites were actually built in the palaeo-channel itself and that makes no sense if there was a big raging Himalayan river there at the time because these people would have been wiped out.”

Image copyright S.Gupta Image caption Broken pieces of Indus pottery exposed at the surface at Kalibangan

Dating of the sediments in the palaeo-channel was done using a technique known as optically stimulated luminescence.

It reveals that the initial abandonment of the valley by the Sutlej River commenced after about 15,000 years ago, with complete “avulsion” to its present course shortly after 8,000 years ago.

Prof Gupta said the Indus people were competent engineers and so would have been able to manage their water needs, potentially even accessing underground supplies. But precisely how they operated in these circumstances of reduced water possibilities was now really a question for the archaeologists to answer, he added.

“What is clear though is that this culture had a diverse landscape and they were able to adapt to it,” he told BBC News.

Prof Rita Wright is an anthropologist at New York University and unconnected to the new research.

She said it represented a “major building block” in our understanding but stressed also that it concerned just a part of the region occupied by Harappan society.

“It is focused primarily on a single area in northwest India, [but] enormously important.

“In contrast to the Indus Valley, it presents (and provides evidence for) a very different water ecology. No denying that water was one of the major resources in the Indus, so here we have evidence for significant differences between the Indus valley alluvial plain and the Ghaggar monsoon-driven water system.”

Image copyright NASA/USGS Image caption Indus civilisation urban settlements were spread across what is now NW India and Pakistan Image copyright Spl Image caption The Harappan site at Mohenjo-daro, Pakistan. It was built on the banks of the Indus River

Prof Gupta has written a longer account of the research which can be read here.

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

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Trophy hunting removes ‘good genes’ and raises extinction risk

Hunting animals with the biggest horns, tusks or manes could lead to extinction, according to a study.

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Hunting animals that stand out from the crowd because of their impressive horns or lustrous manes could lead to extinction, according to a study.

Research predicts that removing even 5% of high-quality males risks wiping out the entire population, for species under stress in a changing world.

Animals prized by trophy hunters for their horns, antlers or tusks usually have the best genes, say UK scientists.

Removing these could push a species over the edge, they warn.

There is intense global debate over trophy hunting. Some argue that it should be banned or restricted, while others say it can provide valuable revenue for conservation.

Dr Rob Knell of Queen Mary, University of London, who led the research, said the assumption that so-called selective harvesting is not especially threatening to a population of animals does not take into account recent work.

”Because these high-quality males with large secondary sexual traits tend to father a high proportion of the offspring, their ‘good genes’ can spread rapidly, so populations of strongly sexually selected animals can adapt quickly to new environments,” he said.

”Removing these males reverses this effect and could have serious and unintended consequences.”

Human hunting is different from natural predation in that big-game trophy hunters target large animals, usually males.

They may be awarded prizes for killing animals with exceptionally large antlers, horns or manes.

And illegal poaching of animals such as elephants for the ivory trade also targets animals with the biggest tusks.

Using a computer simulation model, the scientists were able to predict the impact of selectively targeting males on the basis of their secondary sexual traits.

”If the population is having to adapt to a new environment and you remove even a small proportion of these high quality males, you could drive it to extinction,” said Dr Knell.

”You’re removing the genes from the population that would otherwise allow the population to adapt.”

In the past, human hunting has led to the extinction of many animals, from the zebra-like Quagga, which was once common in Southern Africa, to the Tasmanian tiger of mainland Australia and Tasmania.

Hunting is still legal in many countries; trophy hunting takes place over a larger area in Sub-Saharan Africa than is conserved in national parks.

In the US and Canada, there is also a lucrative trophy hunting industry, for the likes of deer and big-horn sheep.

Some argue that revenue from trophy hunting can support conservation efforts and local livelihoods.

The scientists said age restrictions that allow males to breed before being removed could reduce the impact of trophy hunting.

This is already recommended with some species, such as lions.

“When properly regulated trophy hunting can be a powerful force for conservation which is why we’re suggesting a different management approach as opposed to calling for a ban,” said Dr Knell.

The study is published in Proceedings of the Royal Society B: Biological Sciences.

Follow Helen on Twitter.

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