...the earth is flat.
[sorry, just watched the evening news, couldn't help myself.]
Stevenage: for readers outside of the UK it may not ring much of a bell, and indeed, with no disrespect to Stevenagians, for most UK readers it is not one of our most famous and glamorous metropolitan areas. Located around 50 km north of London, Stevenage has Roman and Saxon roots and has been a market town for more than a millennium. Its name may originate from the Old English for ‘place of the strong oak’, but exactly why its coat of arms depicts a sword thrust through the heart of the oak remains something of a mystery to me.
But Stevenage has one claim to fame that originated close to a century ago and continues today: what is sometimes referred to as a military-industrial complex. The English Electric Company established a facility for making aircraft parts and engines there in 1918, and continued to do through the Second World War. Furthermore, according to the Royal Aeronautical Society, “it is also thought that… there was a secret explosive weapons establishment which designed and created sabotage devices.” In the 1950s and 60s Britain’s very own intercontinental ballistic missile, Blue Streak, was assembled at Stevenage and shipped to Australian desert where the requirements for its testing (along with nuclear devices) emptied the land of its native inhabitants and changed the outback forever. The remains of the first missile launched from Woomera on June 5th, 1964, were discovered not far from Giles Meteorological Station in Western Australia in 1980 and are on display there (after a hardly intercontinental journey of perhaps a thousand kilometers):
For more of the story of the British militarisation of the Australian desert, I recommend my next book, but enough advertising and back to Stevenage. The aerospace facilities there continue to thrive and are now the location for Airbus Defence and Space and Paradigm Secure Communications, housing “Airbus Defence and Space’s spacecraft design and build facility and the headquarters of Paradigm Secure Communications.” They are also now the location for the very large sand pit that is affectionately referred to as ‘Mars Yard’. As the European Space Agency reported recently:
A state-of-the-art ‘Mars yard’ is now ready to put the ExoMars rover through its paces before the vehicle is launched to the Red Planet in 2018.
ESA, the UK Space Agency and Airbus Defence and Space opened the renovated test area in Stevenage, UK, today.
ExoMars is a joint endeavour between ESA and Russia’s Roscosmos space agency. Comprising two missions for launch to Mars in 2016 and 2018, ExoMars will address the outstanding scientific question of whether life has ever existed on the planet, by investigating the atmosphere and drilling into the surface to collect and analyse samples.
Extended Mars Yard opening
The programme will also demonstrate key technologies for entry, descent, landing, drilling and roving.
Filled with 300 tonnes of sand, the 30 x 13 m Mars yard at the Stevenage site of Airbus Defence and Space mimics the appearance of the martian [sic] landscape. Its walls, doors and all interior surfaces are painted a reddish-brown colour to ensure the rover’s navigation cameras are confronted by as realistic a scenario as possible. … The yard will also be available after the rover has landed on Mars in 2019, to help overcome any challenging situations that might be encountered on the Red Planet.
The sand pit was honoured by a visit by a leading politician, the Secretary of State for Business – how often does a political photo-op feature suits in the sand?
The ExoMars rover represents the best of British high-value manufacturing… The technologies developed as part of the programme, such as autonomous navigation systems, new welding materials and techniques, will also have real impacts on other sectors, helping them stay on the cutting edge.
Not only is it hugely exciting that Europe’s next mission to Mars will be British-built, but it is incredibly rewarding to see the benefits of our investment in the European Space Agency creating jobs here in the UK.
Bravo for the sand pit!
Being still in the throes of editing and correcting the proofs for the new book (with the exception of compiling the index, the least enjoyable part of the whole process), I am particularly paranoid about fact-checking. I have one important (and, I'm sure, obvious) piece of advice: never believe anything you read or see in the press or on the web, without at least a triple-fact-check.
I intend, in tandem with the new book, to evolve this blog naturally into looking at topics arid as well as arenaceous, and, as I have been doing for the last few years, I keep an eye on the news. I just came across a wonderful illustration of the fact that there remains an awful lot new under the sun still to be discovered – on every scale. As I emphasise in the book, while our awareness of the complexity, diversity and value of the ecosystems of arid lands is a long way behind that of temperate and tropical environments, we are, nevertheless, redressing that imbalance on a daily basis. Take, for example, the just-announced discovery of a new species of desert mammal, the weird and wonderful Macroscelides micus:
Scientists from the California Academy of Sciences have discovered a new species of round-eared sengi, or elephant-shrew, in the remote deserts of southwestern Africa. This is the third new species of sengi to be discovered in the wild in the past decade. It is also the smallest known member of the 19 sengis in the order Macroscelidea. The team’s discovery and description of the Etendeka round-eared sengi (Macroscelides micus) is published this week in the Journal of Mammalogy.
Sengis are otherwise known as elephant-shrews because they have a snout that resembles an elephant’s trunk, but they are not shrews – indeed, remarkably, they are more closely related to elephants. But the fact is that they are in a class of their own. Again from the California Academy of Sciences:
Few mammals have had a more colorful history of misunderstood ancestry than the elephant-shrews, or sengis. Most species were first described by Western scientists in the mid to late 19th century, when they were considered closely related to true shrews, hedgehogs, and moles in the order Insectivora. Since then, there has been an increasing realization that they are not closely related to any other group of living mammals, resulting in biologists mistakenly associating them with ungulates, primates, and rabbits. The recent use of molecular techniques to study evolutionary relationships, in addition to the more traditional morphological methods, has confirmed that elephant-shrews represent an ancient monophyletic African radiation. Most biologists currently include the elephant-shrews in a new supercohort, the Afrotheria, which encompasses several other distinctive African groups or clades. These include elephants, sea cows, and hyraxes (the Paenungulata); the aardvark and elephant-shrews, and the golden-moles and tenrecs.
The newly-discovered round-eared sengi is a charming little critter (image by John P. Dumbacher, the lead author of the paper):
Macroscelides micus is a true xerocole, an animal cleverly adapted to living – indeed, thriving – in arid conditions. This sengi lives on and around the Etendeka Plateau, a large area of volcanic rocks formed 130 million years ago as the South Atlantic was beginning to form – they were originally connected to the vast landscapes of the Paraná volcanics of Brazil.
This image from the California Academy of Sciences paper shows this stark and remote terrain (together with an example of the bizarre and unique xerophyte, welwitschia – but that’s another story):
Which brings me back to the beginning of this post and a slight rant about fact-checking. Like, I am sure, most of us, when a topic like this comes up, one of the first questions is where exactly is the Etendeka Plateau? Look at the two maps at the head of this post. On the left is the map reproduced in an article on the discovery in one of our illustrious British newspapers (and yes, given the recent news, I’m being sarcastic). Accompanied by the words “Mapped: Found in a remote area of Namibia, on the inland edge of the Namib Desert (mapped) at the base of the Etendeka Plateau”, it places the poor sengis right in the midst of the dunes of the Namib sand sea. Xerocoles they may be, but that’s pushing things a bit too far. The correct location – some 500 kms north – is shown on the right-hand map and is clearly illustrated in detail in the original paper if anyone had cared to check.
I find this time and time again. Google maps can’t even get my home location in London right, so why believe a map of an obscure and remote location reproduced in a newspaper? The answer is simply for no reason at all. It’s a sobering thought – if, on so many occasions, a simple fact-check on something you are particularly interested in reveals sloppiness and error, what about all the other stuff we don’t bother to fact-check?
More than fifty years ago, my parents particularly enjoyed the production that opened the newly constructed Mermaid Theatre in London (now sadly, and controversially, converted to a ‘Conference and Events Centre’). The play was a musical, based on an 18th century comedy by Henry Fielding, and included the satirical song It must be true. I remember, for years after, my father periodically singing to himself the opening line: “It must be true, for I read it in the papers, didn’t you?”
Wise man, my Dad.
Serendipity is a wonderful thing, and I was surprised and delighted to find, completely by accident while looking for something else, this document, published back in March:
In the acknowledgment section, the following appears:
The idea for this publication came from the film documentary “Le Sable: enquête sur une disparition,” directed by Denis Delestrac and broadcast on Arte channel on May 28, 2013.
Wow! Perhaps, just perhaps, the documentary is raising awareness, might just, somehow, somewhere, be making a bit of a difference…
The complete document is available on the UNEP website. It’s an excellent resource, with a number of very useful references - well-worth a read. I will simply reproduce the conclusions here:
Sand and gravel represent the highest volume of raw material used on earth after water. Their use greatly exceeds natural renewal rates. Moreover, the amount being mined is increasing exponentially, mainly as a result of rapid economic growth in Asia (UNEP and CSIRO, 2011). Negative effects on the environment are unequivocal and are occurring around the world. The problem is now so serious that the existence of river ecosystems is threatened in a number of locations. Damage is more severe in small river catchments. The same applies to threats to benthic ecosystems from marine extraction. A large discrepancy exists between the magnitude of the problem and public awareness of it. The absence of global monitoring of aggregates extraction undoubtedly contributes to the gap in knowledge, which translates into a lack of action. As this issue is truly a major emerging one, there is a need for in-depth research. The implementation of a monitoring mechanism regarding global aggregate extractions and trade would shed light on the magnitude of this issue and bridge the current data and knowledge gap. This would also raise this issue on the political agenda and perhaps lead to an international framework to improve extraction governance, as the current level of political concern clearly does not match the urgency of the situation.
Illustrations thanks to Sumaira Abdulali and the Awaaz Foundation:
Three years ago we embarked in Bali and headed eastward, across the Wallace Line, and island-hopped for a while around the archipelago of Nusa Tenggara. We sailed past the great volcanic edifice of Tambora, originator of the greatest eruption of modern times and the cause of ‘the year without a summer.’ All was peaceful, although the lines of raised beaches along the shore spoke of volcanic and seismic upheaval. The day before we arrived at Komodo – where there indeed be dragons, not to mention spectacular sands – we sailed past the eastern shores of Sumbawa and I photographed the volcano island of Sangeang Api, benignly dormant in the evening light (above left). Today, the tropical languor has been shattered by several major eruptions of Sangean Api over the last 24 hours (above right).
It’s estimated that the ash cloud has reached more than 15 kilometres into the atmosphere, rapidly spreading southward across northern Australia and currently headed for Alice Springs. This dramatic aerial image by Sofyan Efendi (Barcroft Media/Splash News and news.com.au) demonstrates the scale of the eruption.
Not surprisingly, aviation between much of Australia and Indonesia and Singapore is in chaos. Flights have been cancelled and the airport at Darwin closed.
As a geologist, I couldn’t help wishing for the volcanically energetic islands of Nusa Tenggara to demonstrate their prowess as we cruised by, but they remained bashful. What I hadn’t thought of – and I should have, after being stranded in the US by the eruption of the Icelandic volcano with the unpronounceable name a couple of years earlier – was that, as I booked my travel to Alice Springs via Singapore and Darwin for my great outback adventure in 2012, the itinerary came with some risk. Had Sangeang Api decided to put on this kind of show at the beginning of February that year, I would likely never have made it on the expedition – and much of my new book (The Desert: Lands of Lost Borders) would have been very different. Life is uncertain, and I’m grateful to Sangeang Api for waiting a while.
We all know that walking along the beach on wet sand is easier than dragging our feet through the dry stuff. We all know that wet sand is a very different material from dry – the strange inter-granular capillary physics of wet sand allows us to build sandcastles and, it seems, made it a little easier to drag ridiculously heavy objects around the desert for the ancient Egyptians intent on claiming their places in posterity.
Around 4,000 years ago in ancient Egypt lived a typically self-aggrandising nomarch (no, not typo, but the term for a semi-feudal governor), Djehutihotep. His tomb is famous for its paintings, a drawing of one of which is shown above. Hundreds of slaves are dragging a sledge bearing a gigantic statue of Djehutihotep, undoubtedly looking on his works and despairing. Look closely, and you will see a man pouring water, not on the perspiring workers, but on the sand, and research just published has indicated that the Egyptians knew exactly what they were doing in terms of the behaviours of granular materials. As reported on Sci-News.com:
A multinational group of physicists led by Prof Daniel Bonn from the University of Amsterdam has hypothesized that Egyptians probably made the desert sand in front of the sledge wet … In the presence of the correct quantity of water, wet desert sand is about twice as stiff as dry sand. A sledge glides far more easily over firm desert sand simply because the sand does not pile up in front of the sledge as it does in the case of dry sand.
The university news release describes the experiments and the results as follows:
Ancient Egyptians transported pyramid stones over wet sand
29 April 2014
Physicists from the University of Amsterdam have discovered that the ancient Egyptians used a clever trick to make it easier to transport heavy pyramid stones by sledge, allowing them to halve the number of workers needed. The researchers published this discovery in the prestigious journal Physical Review Letters.
For the construction of the pyramids, the ancient Egyptians had to transport heavy blocks of stone and large statues across the desert. The Egyptians therefore placed the heavy objects on a sledge that workers pulled over the sand. Research from the University Amsterdam has now revealed that the Egyptians probably made the desert sand in front of the sledge wet. Experiments have demonstrated that the correct amount of dampness in the sand halves the pulling force required.
The physicists placed a laboratory version of the Egyptian sledge in a tray of sand. They determined both the required pulling force and the stiffness of the sand as a function of the quantity of water in the sand. To determine the stiffness they used a rheometer, which shows how much force is needed to deform a certain volume of sand.
Experiments revealed that the required pulling force decreased proportional to the stiffness of the sand. Capillary bridges arise when water is added to the sand. These are small water droplets that bind the sand grains together. In the presence of the correct quantity of water, wet desert sand is about twice as stiff as dry sand. A sledge glides far more easily over firm desert sand simply because the sand does not pile up in front of the sledge as it does in the case of dry sand.
The Egyptians were probably aware of this handy trick. A wall painting in the tomb of Djehutihotep clearly shows a person standing on the front of the pulled sledge and pouring water over the sand just in front of it.
Besides revealing something about the Egyptians, the results are also interesting for modern-day applications. We still do not fully understand the behaviour of granular material like sand. Granular materials are, however, very common. Other examples are asphalt, concrete and coal. The research results could therefore be useful for examining how to optimise the transport and processing of granular material, which at present accounts for about ten percent of the worldwide energy consumption.
The research was supervised by group leader professor Daniel Bonn and is part of the FOM programme 'Fundamental aspects of friction
It’s interesting to note the comment “in the presence of the correct quantity of water” – this graphic from the paper in Physical Review Letters demonstrates the subtlety and fickleness of granular behaviour:
The images show the experimental sledge being pulled through the experimental sand, dry on the left, correctly wetted on the right. The graph shows the force required to move the sledge with across the dry sand (the red line) and with different proportions of water. The green line (1.5% water) reduces the force required a little, but the purple line demonstrates how adding 5% water eases task very significantly – fewer slaves required, although undoubtedly they were given other things to do. However, add a little more water – the black line represents 7.4% – and pulling the sledge becomes harder than in dry sand, the water between the grains turning the material into something more like mud.
So it would seem that the ancient Egyptians’ understanding of the physics of granular materials helped achieve their megalomaniacal ambitions. And the research has provided Egyptologists with an explanation of what that person was doing on the front of Djehutihotep’s sledge - as reported in an article in The Washington Post:
“This was the question,” Bonn wrote in an e-mail to The Post. “In fact, Egyptologists had been interpreting the water as part of a purification ritual, and had never sought a scientific explanation. And friction is a terribly complicated problem; even if you realize that wet sand is harder – as in a sandcastle, you cannot build on dry sand — the consequences of that for friction are hard to predict.”
In the lively discussion period following the US premier screening of Sand Wars in Washington DC a couple of weeks ago, and following the showing at the Zurich environmental film festival, there was one outstanding theme – surprise. Which is exactly what I had always hoped for with the book and then with Denis Delestrac's documentary. The fact that sand plays a heroic role in our daily lives and the workings of our planet sets the scene for the – often surprising – fact that sand is not just sand. Anyone who has occasionally looked at this blog and, in particular, the displays of arenaceous diversity in the Sunday Sand posts will appreciate that the stuff comes in a dazzling variety of shapes, sizes and compositions – no two sands are the same. And this means that if you want to make something with sand, whether it’s glass, filters, concrete, golf course bunkers, foundry castings, silicon electronic components, or a host of other things, any old sand just will not do: it has to be the right kind of sand. Concrete, of course, is the most obvious example, given how much of the stuff each of us uses (or has used on our behalf). The fact that the rapid development of Dubai has only been possible through sand imports when the desert dunes are right there, is a surprise. But the fact is that desert sand just will not do for making good concrete.
The range of needs for special sands presents two challenges: how to get the right kind of sand from the place where it naturally occurs to where it is needed and how to ensure that the resources of that right kind of sand are not only sustainable but exploitable without destroying the environment, ecosystems and livelihoods. Meeting these challenges is manifestly failing in many parts of the world, as the documentary describes, and, while it’s easy to see this as a problem of the so-called developing world and that we in the west are far too thoughtful in our approach to environmental and resource management for such issues to arise at home, this is, sadly, not always the case. A notable example is the supply of the specialty sand required – in vast quantities – for the fracking (or fraccing) of oil and gas wells. This is an emotional topic on both sides of the Atlantic and the subject of heated media and social ‘debate’. This is not what my primary focus here is, but I should probably declare my general position: fracking is proven and reliable technology that presents problems only when regulations are loose, regulatory enforcement is deficient, and ‘cowboy’ operators are allowed to flagrantly disregard good engineering practice. The fact that these issues can be, unfortunately, quite often the reality is a justifiable cause for concern – it’s not rocket science to fix but the media frenzy is arguably misdirected. Anyone who would like to discuss this further is more than welcome and I would recommend having a look at the objective report put out last year by The Royal Society and The Royal Academy of Engineering. My point here, however, is specifically about sand.
The technology of hydraulic fracturing involves accessing the oil or gas trapped in essentially impermeable rocks from which they cannot naturally escape. Permeability is induced artificially by water (and yes, also often unknown chemical additives) under extremely high pressures, creating a network of cracks, fractures, through which the hydrocarbons can be persuaded to flow. But creating those fractures is only the start: natural underground pressure would rapidly close them up again – something has to be put into them that keeps them open, and that something is sand. But not just any old sand. It has to be tough and uncrushable pure quartz sand, the grains have to be all of the right size and they have to be smooth and rounded so that they don’t clog up up the fluids or the fractures as they are forced into them. Here is a view of a typical construction sand on the left next to a good frac sand:
The challenge lies in the fact that huge quantities of sand are required for every fracturing operation – often thousands of tons per well. The whole process is shown clearly in this graphic from the Wisconsin Academy:
This demand, along with the enormous volume of water required, not does not frequently feature as an issue in the ‘debate’. With the boom in fracking in the US, demand for the right kind of sand has more than trebled in the last four years – the US Geological Survey estimates that 30 million tons of frac sand was produced in the US in 2013. Where from? Mostly Wisconsin and neighbouring Midwestern states. The seas that covered much of the US more than 450 million years ago deposited, and time and chemistry purified, sands ideal for hydraulic fracturing purposes. Although today these are sandstones, the cement holding the grains together is weak and they can be easily mined and disintegrated back into sand. The scale of the sand-mining industry in Wisconsin and neighbouring parts of Minnesota has escalated dramatically in the last few years to the point where it has clearly become an environmental, social and health issue (the last particularly as a result of the generation of silica dust). At the same time, the industry is a welcome source of employment and state income, but fluctuations in the level of industry fracking activity hardly make for a stable economic benefit. The image at the head of this post is from a recent article by Minnesota Public Radio and shows two views of downtown Winona today and a year ago when the stockpile of sand that became known as ‘Mt. Frac’ filled a vacant lot. It has disappeared not because of the concerns rightly expressed by the local citizens but because of the fall in demand.
As usual, these are issues that are not clearly one that is black-and-white, but they could benefit from a little more awareness and careful discussion – and not only in Wisconsin and Minnesota.
The US Premiere of the documentary Sand Wars, to which your humble correspondent contributed, will be shown as part of the Environmental Film Festival in Washington on the 20th March. The Director, Denis Delestrac, and I will be there, and I understand that there is a discussion program in which we will participate.
So, if you're in the DC area and are at a loss for entertainment that evening, come along! Join the 1.9 million people in France and Germany who watched it when it was aired on ARTE TV last year! See the website for details (as above).
Periodically, I become absorbed in the wonders of the images on the Mars High Resolution Imaging Science Experiment site. I recently became exhausted by the process of obtaining permissions for illustrations in the new book and escaped by browsing the catalog for a couple of hours - it becomes compulsive. So, while I return to the permissions, here a selection of the stunning dunes of Mars that I found particularly wondrous.