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What if a solar super-storm hit?

One September day in 1859, over the course of a few minutes, an event occurred that was to have spectacular consequences here on Earth. A sudden flash of brightness, known as a solar flare, had just erupted on the Sun, releasing about 10²² kJ of energy – equivalent to 10 billion Hiroshima bombs exploding at the same time. A massive coronal mass ejection (CME) hurled out about a trillion (10¹²) kilograms of charged particles at speeds of some 3000 km/s. As the material interacted with the Earth’s magnetosphere – the magnetic shield that usually protects us from high-energy charged particles from space – it triggered the largest ever “solar super-storm” on record.

Known as the Carrington Event – after the English astronomer Richard Carrington who spotted the flare – this super-storm saw the magnetic field around the Earth being stretched and torn apart. Accompanied by numerous sunspots, it led to the northern lights being seen as far south as the equator and created surges of energy that crippled the world’s electronics infrastructure.

Back in the mid-19th century, that infrastructure amounted to no more than about 200,000 km of telegraph lines and so the impact on the human population was relatively benign. But today’s world, which relies hugely on space technology and massively interconnected networks of power lines and fibre-optic cables, would be severely damaged if a Carrington-type event were to repeat itself. The consequences could be catastrophic and long-lasting.

In fact, it has now dawned on us – thanks to data from NASA’s Kepler mission, numerical modelling and the study of historical records – that the mood of our nearest star is far more hostile than we used to think. According to Jim Green, director of NASA’s planetary-science division, the Earth is, on average, in the path of Carrington-level events every 150 years – putting us five years overdue. Moreover, according to estimates made by Pete Riley, a heliophysicist at NASA and the US Department of Defense, the probability of another Carrington Event occurring within the next decade is as high as 12% (Space Weather 10 S02012).

In recent decades, we have already seen glimpses of the dangers that could lie in store. In March 1989, for example, a geomagnetic storm that was about a third of the strength of the Carrington Event caused an electricity grid operated by the Canadian firm Hydro-Québec to fail, triggering a nine-hour blackout for about six million people. Meanwhile, the “Halloween storm” of October 2003 – which was about half as intense as Carrington – disabled a number of satellites, destroyed a dozen transformers in South Africa and crippled a large section of its power systems. These events should have been a wake-up call, but little has been done about the potential threats. As the heliophysicist Pete Worden, director of NASA’s Ames Research Center, candidly puts it: “Space weather destroys stuff.” So what can be done?

SolarMAX is on the case

To help find answers, I was last year invited by the UK and European space agencies to take part in a 40-strong international, multidisciplinary task force of experts, led by Worden and Green. Over a period of six weeks, our group – dubbed SolarMAX – gathered at the International Space University in Strasbourg, France, to work out the risks from a solar super-storm to our modern way of life and to identify the best ways of limiting the potential damage. The result was a 100-page document to be disseminated to governments, space agencies and industry. You can read the full report online, although the human impact of a storm might be more apparent in my fictionalized account of the dramatic aftermath of such an event (see “Solar super-storms: a possible tale”, below).

It would be nice to pretend that everything will be fine in the event of a solar super-storm striking the Earth, but our findings were sobering. Severe disturbances to the Earth’s magnetic field would induce electric currents in the ground and overhead transmission lines – in fact, if the cables are long enough, the currents would be large enough to melt high-voltage AC transformers, which are critical components in all power grids. New transformers typically take up to a year to manufacture and install – and utility companies rarely keep backups as these devices cost at least $10m each. Any Carrington-level event would therefore generate widespread power outages that would last months, if not years, across most of the developed world, in particular North America and Europe. The lower latitudes of India and China, coupled to generally less conductive soil and more robust power infrastructures, means they would not be nearly as badly affected.

Without power, people would struggle to fuel their cars at petrol stations, get money from cash dispensers or pay online. Water and sewage systems would be affected too, meaning that health epidemics in urbanized areas would quickly take a grip, with diseases we thought we had left behind centuries ago soon returning. Worse still, most of the developed world works on a “just-in-time” philosophy, meaning that there is never more than two to three days’ worth of supplies available in urban areas at any given moment, be it food, fuel or medicine.

Nuclear power plants are another concern as they rarely have more than a week’s worth of backup power onsite to run their cooling systems. A switched-off reactor usually takes a month to cool down far enough to avoid a meltdown, which means that firms would find themselves fighting to get their hands on supplies of diesel fuel to operate those backup systems. With more than 300 nuclear power plants across North America and Europe, how many catastrophic meltdowns could be avoided? The relative vulnerability of the power grid across Europe to a solar super-storm coupled to the location of nuclear plants can be seen in figure 1, below.

Map of Europe showing soil conductivity, location of nuclear power stations and high-voltage power lines — **1 Danger points** This map shows the location of European nuclear power plants (red dots) and the known main power-grid transmission lines linking them, with higher voltages indicating a more vulnerable line. Also shown are power-grid transformers (black dots) and ground conductivity, which ranges from pale grey (low) to dark grey (high). The power surge a transformer will receive during a solar super-storm depends on the voltage on the transmission lines and on the geomagnetically induced current in the cable, which itself depends on the intensity of the storm, the geomagnetic latitude and the length of the line. (Data supplied by Ashley Dale)

Major disturbances to the ionosphere, caused by increased X-ray emissions from the Sun, would cause aircraft on the Earth’s dayside to lose their on-board navigation management systems and communications with the ground. Without air-traffic control, pilots would struggle to land their planes safely, while passengers, pilots and crew would receive much higher doses of cosmic radiation, which the Earth’s magnetic field and atmosphere together normally shields us from. Pilots, who are classified as radiation workers, typically fly above about 97% of our atmosphere – exposing them to an order of magnitude more radiation than people on the ground – but the increase in radiation dosage at such altitudes during a Carrington-like event would significantly threaten pilots’ and passengers’ health.

Satellites would be affected too, with the electrostatic discharges generated by geomagnetic storms frying electronics, damaging solar panels and confusing star-tracking orientation systems. The Earth’s atmosphere would also heat up and expand during such an event, increasing the drag on satellites in low Earth orbit and causing them to burn up on re-entry. Many TV broadcasts would cease, radios and mobile phones would not function, weather forecasts would end and defence systems would be made redundant.

Spacecraft that run satellite-navigation systems would either be lost entirely or produce data of limited use – hitting agriculture, surveying, oil drilling and timing. Our transportation-management infrastructure would grind to a halt, from air to sea. With more than 1000 operational satellites in orbit (costing an average of nearly $100m each), our space infrastructure could take a decade or more to recover. In fact, a study carried out in 2008 by the US National Research Council estimated that the satellite blackouts caused by space weather could cost upwards of $2 trillion in the first year alone. Meanwhile a separate 2013 study by insurance broker Lloyd’s of London and Atmospheric and Environmental Research, a climate and weather risk-management agency, estimated that the total collateral damage of a Carrington-level event on the world economy would amount to some $2.6 trillion.

Super-sized solutions

You might think I am scare-mongering, but the plain fact is that our reliance on electricity has made us extremely vulnerable to anything that could cut supplies. So to get a clearer idea of how often Carrington-level events are likely to occur, researchers at NASA are currently mining data from the Kepler space observatory. The mission was designed primarily to discover Earth-like planets orbiting other stars and has so far gathered data on more than 170,000 “main-sequence” stars in our galaxy. But by observing the variation in the luminosity of these stars over time, astronomers can spot and quantify the scale and likelihood of stellar super-storms.

Image showing a close-up of the solar surface — **Red hot** A close-up of the solar surface as seen by the Big Bear Solar Observatory using the Visible Image Spectrometer H-alpha filter (red light produced by energetic hydrogen atoms). (Courtesy: Big Bear Solar Observatory)

Although only about 4% of the Kepler data has been scoured for super-storms, the work has shown that the Carrington event of 1859 really was nothing special. Preliminary estimates reveal that super-flares with an energy of 10²⁴ kJ occur on the surface of stars just like our own once every 350 years, while those with energies of 10²⁵ kJ take place every 800 years, and 10²⁶ kJ flares every 3500 years. In contrast, an asteroid colliding with the Earth and creating as much collateral damage probably takes place only once every few thousand years. Policy-makers and politicians need to realize that super-flares are not just a threat, but inevitable.

Studying the Kepler data also gives us insights into how the properties of a star affect its volatility. For example, its rotation rate does not seem to alter the scale of super-flares produced, but the higher the rate, the more likely a super-flare event is to occur. The good news – if you can call it that – is that our star has a relatively low rotation rate. But we also need to get a better understanding of the Sun’s magnetic field and its weather because its field lines are intricately connected to those of each major body in the solar system. These lines in particular act as “channels” for solar wind to propagate along, triggering the formation of Van Allen belts – layers of plasma extending out to about 60,000 km beyond the Earth – and also “ring currents” carried by ions trapped in the magnetosphere. Both phenomena influence how solar weather generates solar super-storms so knowing more about them is vital (see “The nature of the Sun”, below).

The bottom line is that a deeper understanding of the Sun’s magnetic field and how it interacts with the Earth’s would help us obtain more accurate and longer-term forecasts of solar weather, as would a deeper knowledge of other solar mysteries, such as the origin of the Sun’s 11-year solar cycle, how sunspots form and why the surface of the Sun is so much cooler than the corona above. In fact, a sub-group of scientists in the SolarMAX project concluded that the best solution would be to send an array of 16 lunchbox-sized cube satellites into orbit around the Sun, located at about 45 million km from the Sun at their closest point and about 150 million km at their furthest. Such a mission would give us enough empirical data on the nature of the magnetic field between the Sun and the Earth with a high enough spatial resolution to help develop our understanding and therefore more accurate models for forecasting. The mission would also let us observe the Sun’s entire surface in almost real time, giving scientists the full picture of the surface when forecasting weather. And by splitting the satellite constellation into two elliptical orbits, tilted relatively, it would be possible to get a full 360° view in 3D of the surface features and solar phenomena. Right now we only ever look at the Sun from one side.

Current satellites give us no more than 15–30 minutes’ advance notice of imminent solar events and all have gone beyond their expected mission lives. Our proposed mission would let us make accurate forecasts – for up to a week into the future – of when, where and with what magnitude solar events will take place. Such forecasts would let us save the power grid by pre-emptively switching off vulnerable lines before a solar storm occurs. Planes could be grounded in time, satellites could be reoriented to limit damage, and national recovery programmes could be swung into action. Such warnings could also reduce the chance and expense of false alarms. What is more, we estimate that such a fleet of satellites would cost no more than $500m at today’s price – just 3% of NASA’s annual budget.

Smart ways forward

Another possible way of minimizing the potential disruption from space weather is to exploit the fact that many nations – at least in the developed world – are slowly updating their power transmission lines so that energy use can be measured at different points in the grid in real time via “smart meters”. This technology lets energy companies monitor and adjust performance to deliver power more efficiently in response to local changes in demand, but such information would be invaluable during major solar events. A real-time solar-weather response system would help to reduce the damage to the power grid by isolating vulnerable segments of the network from the rest of it to allow for smaller local failures rather than large inter-connected failures. The US is leading the way on this front – albeit in a small way – with a bill unanimously approved in 2010 to allocate $100m to developing protection for the bulk-power system and electric infrastructure from cybersecurity and solar-weather threats.

An accurate space-weather forecasting system would also help maximize the life expectancy of satellites by giving us time to manoeuvre them to minimize damage to solar panels. But future satellites need to be designed so that instruments vulnerable to sudden increases in radiation are better protected. The SolarMAX consortium examined some quite far-out ways of doing this, although it bugged me that there had to be simpler solutions to the problem. In fact, I quickly realized that engineers designing satellites and spacecraft had not thought much about simply optimizing the internal layouts of a craft so that sensitive, on-board instruments are shielded as well as possible from radiation.

It occurred to me that such equipment (and astronauts too for that matter) could be better protected simply by redistributing the existing internal architecture of a craft so that sensitive payloads are surrounded by non-sensitive bulk material such as polyethylene, aluminium and water. It would be a kind of “free lunch” because we would not need to make the craft heavier and so avoid making the mission more expensive; we would just need to rearrange what needs to be on board anyway. Not only would the craft be more likely to survive a major solar event, but it would also function for longer because prolonged exposure to radiation is essentially what kills off spacecraft in the long term.

After outlining my thinking to the group, I was allowed to pick a team of seven people – including Chunhui Wang, an “astronaut ergonomist” at the Astronaut Center of China – who together spent a few weeks exploring the potential advantages of my approach. We developed a case study based around a potential Mars mission that is currently being developed by the US-based Inspiration Mars Foundation, which wants to send a two-person manned probe on a Mars fly-by mission, reaching within 150 km of the red planet some time in the next decade. We worked with the foundation on its latest plans for the craft’s internal architecture and – by characterizing the radiation profile associated with its particular trajectory – were able to estimate the dose that astronauts flying to Mars might expect to receive. By redistributing the existing internal architecture of the spacecraft, we were able to cut the expected radiation dosage of the two-person crew by 15–20%. Though the radiation problem associated with space activities currently has no single solution, I saw this as a big win.

My proposal is just one of many practical – and feasible – solutions to the potential dangers of space weather. The risks are real. Solar super-storms are inevitable. Whether one affects civilization here on Earth is not a question of “if”, but “when”. However, damage can be averted with the technology we have today. The primary obstacle and danger lies not within the Sun, but with the ignorance of decision-makers concerning space weather: governments, industry and the public. As a species, we have never been more vulnerable to the volatile mood of our nearest star, but it is well within our ability, skill and expertise as humans to protect ourselves.

The nature of the Sun

Artistic impression of the Sun, the solar wind, and the Earth and its magnetic field — (Courtesy: NASA)

What is the Sun made of?

All matter in the Sun is plasma: hot, ionized gas. Consisting mostly of protons, electrons and helium ions along with some oxygen and iron, this plasma moves across the surface like a deep and frothy ocean, circling the equator once every 25 days (at about 2 km/s) and once every 35 days near the poles. This rotation acts like a dynamo, producing the magnetic fields of the Sun. Over time, these field lines form vast channels, or “flux tubes”, on which the ionized gas is lifted up out of that fiery ocean in massive waves, leaving the Sun in a stream known as the solar wind.

What are sunspots?

The turbulence in the Sun’s superheated ocean, which is instigated by the differences in lateral rotation speed, makes the flux tubes gradually twist, break and reconnect with other lines beside them. These twisted and entangled magnetic field lines eventually inhibit the convection and effectively cut off the plasma flow in those channels, leading to a small but powerful local magnetic pole. Isolated from the circulatory system of the Sun, this pole gradually cools and forms a sunspot that can last for several days or weeks.

What about solar flares?

Magnetic field lines in the Sun’s corona – the aura of plasma encircling the Sun – contain lots of energy, which means that when the lines reconnect, lots of energy is released to create a huge explosion that we call a solar flare. Consisting of gamma rays, X-rays, protons and electrons, these flares are typically equivalent to 100 million Hiroshima bombs in terms of released energy.

How are coronal mass ejections created?

Occasionally, huge bubbles of plasma and magnetic field lines are ejected from the Sun over several hours in an event that is more energetic than any other in our solar system. Known as a coronal mass ejection (CME), such an event typically occurs after a solar flare, which means they are most common during a solar maximum (when the Sun is most active during its 11-year cycle). However the Carrington Event (see main text) occurred during a solar minimum, while not all solar flares cause CMEs and not all CMEs accompany solar flares.

How do CMEs affect us?

The Earth lies in the path of about 10% of all CMEs, with us typically getting hit eight minutes after a solar flare and anywhere between eight hours and three days after a CME, depending on their magnitude and trajectory. Like the Sun, the Earth also has a magnetic field originating from its molten core and how the two fields interact with the trajectory of a CME through the vacuum of space makes its path not at all simple.

What about Van Allen belts?

These are vast shells of plasma surrounding the Earth held in place by our own magnetic field. Disruptions to the Earth’s magnetic field through solar events affect the location of these shells, which can go some way to damaging the spacecraft they envelop. This plasma is delivered from the Sun via solar wind and any plasma lost from the Van Allen belts through disruption is quickly replenished.

And the ring current?

This is a doughnut-shaped region of mainly hydrogen, helium and oxygen ions surrounding the Earth’s equatorial plane. It shields the planet’s lower latitudes from electric fields induced in the magnetosphere. The waxing and waning of the ring current is a crucial element of our space weather as the process occasionally transfers charge from the surface of the Earth to satellites, potentially damaging them. Astronomers are not sure if these charged particles come from solar wind or our ionosphere – but better models of how particles are transported and accelerated between the Sun and the Earth would improve our understanding of the ring current.

Solar super-storms: a possible tale

Photos of helicopters in emergency action — (Courtesy: iStock/Destonian)

Day 1 Andrew has just returned from work and is settling down for the evening in his London flat. Susan should be home late, flying back from a business trip to Quebec. Suddenly the TV and lights go off. Eggs sizzling in the frying pan gently fall silent. A power cut. Andrew fumbles for his phone and uses the torch app. He opens the curtains to find the street lights are out too; it’s dark as far as he can see. His neighbours are out on the street chuckling to each other, lit only by their phones. He goes to make a Facebook status update – no 4G. No signal? An early night then, after some eggs that are luckily just about cooked.

Day 2 Andrew wakes up at 5 a.m. to a siren wailing outside. He stumbles around for a glass of water. The taps aren’t working. There is only some barely cool white wine in the fridge. Susan still isn’t home. Opening his curtains again, he sees what looks like rush hour traffic despite the early hour. He spots at least a dozen helicopters over the city. This must be serious. Looks like a day off work! Andrew dresses and steps outside to buy food and drink from the local shop. The ATM machines are not working. He hardly has any cash. The shops are empty. The shopkeeper says something about space weather causing this. Space weather?

Day 3 Susan still isn’t home. Andrew hasn’t been able to find out if her flight landed. They have no way of contacting each other. The battery on his mobile phone has died, anyway. There are looters in the streets. He has limited food and his only water is in the toilet cistern. He leaves a note for Susan and drives out to his parents in the countryside. But the GPS is not working and he’s not sure of the way. It’s a two-hour drive in normal traffic and he only has half a tank of fuel. He knows the fuel pumps are not working. There may be road-blocks.

A week later Andrew reaches his parents on foot after his car was hijacked. They have a large water tank and a good supply of food, but looters abound. A solar super-storm has crippled the power and space infrastructure. Most of Europe and North America is floundering. Several nuclear power plants have suffered catastrophic meltdowns around the country. Diseases are spreading in the cities. China and India have not been too badly affected and are sending in troops and aid to help recovery.

A month later Things seem to be on the road to recovery. The water is running again but power is temperamental. Susan’s flight was diverted to Lyon, France, where she has been stranded since. The Chinese have been distributing food, water, medical and sanitation supplies. The government has begun to regain some level of order.

A year later Susan and Andrew have been back at work for a few months, though things have been slow to restart and the future of their jobs is now uncertain. Their insurance firm refuses to pay up for the damage looters did to their flat. Oil and gas prices have spiralled out of control, and there are going to be severe food shortages for some time. It will take years before certain conveniences return to normal. The geopolitical map has drastically changed. Many of their friends are looking to leave the UK and start new lives in the East.

Rosetta rendezvous with comet at long last

The European Space Agency’s Rosetta mission made history today, as it became the first spacecraft to rendezvous with a comet. After spending a decade in pursuit of the celestial body, Rosetta is now a mere 100 km from the comet’s surface, and will edge closer to it over the coming months as it studies the comet. The ultimate aim of the mission is to place its “Philae” landing module onto the comet’s surface in November.

Rosetta’s target, Comet 67P/Churyumov–Gerasimenko, is currently about 405 million km from Earth (about halfway between the orbits of Jupiter and Mars) and is hurtling towards the inner solar system at nearly 55,000 km/h. The comet’s 6.5-year elliptical orbit around the Sun takes it from beyond Jupiter to between the orbits of Mars and Earth. The spacecraft will accompany it for more than a year of its journey, as the duo swing around the Sun and back out towards Jupiter.

‘We are here’

“After 10 years, five months and four days travelling towards our destination, looping around the Sun five times and clocking up 6.4 billion kilometres, we are delighted to announce finally ‘we are here’,” says Jean-Jacques Dordain, director-general of ESA.

Rosetta’s journey to the comet saw it make three gravity-assisted flybys of Earth and one of Mars, to keep it on course since its 2004 launch. On its way, the spacecraft also passed by two asteroids – Šteins and Lutetia – and managed to gain excellent views and detailed measurements of the objects, revealing previously unknown information such as their core structures. Rosetta spent nearly 31 months in hibernation since it entered deep space in 2011, before the researchers sent a signal waking it up in January this year. The last of a series of 10 essential “rendezvous manoeuvres”, which began in May, to adjust Rosetta’s speed and trajectory to gradually match those of the comet were carried out today.

Rubber-ducky personality

According to the mission scientists, Comet 67P had already begun to “reveal its personality” while Rosetta was on its approach this year. Images taken by its OSIRIS camera between late April and early June showed that its activity was variable, with the comet’s gas and dust “coma” brightening up and dying down over six weeks. Other measurements made by the spacecraft showed that the comet was emitting water vapour into space at about 300 millilitres per second, and that its average temperature is about –70 °, indicating that the surface is predominantly dark and dusty rather than clean and icy. Last month, images taken from a distance of about 12,000 km began to reveal that the comet’s nucleus comprises two distinct segments joined by a “neck”, giving it a “rubber-ducky”-like appearance.

Comets are the primitive remainders of the clouds of dust and gas that served as the building blocks of our star system. In many ways, they are thought to have remained much the same during billions of years and should contain pure material from the early days of the solar system. There is also the possibility that comets could have brought with them the carbon-based organic molecules needed to start life on our planet and so comets are of great interest to researchers.

Close-up of the comet by Rosetta, taken August 2014 — Celestial paparazzi: stunning close-up detail focusing on a smooth region on the “base” of the “body” section of comet 67P/Churyumov-Gerasimenko. The image was taken by Rosetta’s OSIRIS narrow-angle camera and downloaded today, 6 August 2014. The image clearly shows a range of features, including boulders, craters and steep cliffs. The image was taken from a distance of 130 km and the image resolution is 2.4 metres per pixel. (Courtesy: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA)

Over the coming six weeks, Rosetta will describe two triangular-shaped trajectories in front of the comet, first at a distance of 100 km and then at 50 km, before eventually edging as near as 30 km to attempt a close, near-circular orbit. While doing so, the suite of instruments on board will conduct a detailed scientific study of the comet, scrutinizing the surface for a target site for its Philae lander.

Possible landing sites

The mission hopes to identify as many as five possible landing sites by late August, before the primary site is chosen in mid-September. The final timeline for the sequence of events for deploying Philae – currently expected for 11 November – will be confirmed by the middle of October.

“Over the next few months, in addition to characterizing the comet nucleus and setting the bar for the rest of the mission, we will begin final preparations for another space-history first: landing on a comet,” says Matt Taylor, ESA’s Rosetta project scientist. “After landing, Rosetta will continue to accompany the comet until its closest approach to the Sun in August 2015 and beyond, watching its behaviour from close quarters to give us a unique insight and real-time experience of how a comet works as it hurtles around the Sun.”

Standards lab overlooked spy agency’s cryptography ‘back door’, say scientists

The National Institute of Standards and Technology (NIST) lacks independence and uncritically adhered to the wishes of US electronic eavesdroppers in releasing a weakened random-number generator in 2006. So says a group of mathematicians and computer scientists in a new report commissioned by the lab following the leaking of documents last year by the former National Security Agency (NSA) contractor Edward Snowden. According to those documents, the NSA designed an encryption algorithm to include a “back door” so that it could copy encryption keys from internet users without their knowledge. The algorithm was approved by NIST, which itself develops cryptography technology and advises US companies and government agencies on electronic security issues.

Random-number generators are at the heart of encryption on the Internet. In particular, they provide the 1s and 0s that make up many of the keys that are used to encipher and decipher communications – in e-mail exchange, banking and medicine, for example. While sequences of truly random numbers are notoriously difficult to generate, online randomization relies more on data-based “pseudo-random” processes. These usually involve taking a more-or-less random “seed” – such as the data associated with timings of key strokes or hard-drive access – and then stretching that seed into a sequence using a specially designed algorithm.

The NSA algorithm – Dual Elliptic Curve Deterministic Random Bit Generation (Dual_EC_DRBG) – relies on the fact that elliptic curves can be used to construct “one-way functions”. This means that while it is straightforward to multiply a pair of x, y co-ordinates on such a curve to generate a second set of co-ordinates, it is very hard to reverse the operation to arrive back at the original values of x and y. DUAL_EC uses elliptic curves with two publicly declared co-ordinates – P and Q. The algorithm multiplies Q by a factor that is initially dependent on a pseudo-random seed and then removes some of the bits from the resulting x co-ordinate. The programme then re-sets the factor by multiplying it by P, and the new factor is subsequently multiplied by Q to produce the next output sequence. Repeating this cycle many times, Dual_EC should produce a long string of pseudo-random bits.

Trivial for an attacker

However, there is a snag. It turns out that all future (and past) outputs can be predicted if an attacker is able to work out just one set of output co-ordinates from the truncated x value associated with them – a relatively trivial task given the fact that Dual_EC, unlike other similar algorithms, cuts off very few of the 1s and 0s describing the x co-ordinate (just two out of 32 bytes) – and, crucially, if that attacker knows the mathematical relationship between P and Q.

If P and Q were themselves selected purely at random then this kind of attack, cryptographers say, would be practically impossible. In contrast, however, the algorithm is vulnerable if the person setting it up chooses the values non-randomly – in other words, they set up a back door. Many cryptographers believe that the NSA probably knows the relationship between P and Q, and therefore has a back door allowing them to decipher encoded communications.

Being more open

When the story about DUAL_EC and its alleged back door broke last September, NIST responded to the “community concern” by putting the standard containing the algorithm – SP 800-90 (which contains three other random-number generators not under suspicion) open for “public comment”. NIST then announced in April that it had decided to remove the offending program from the standard. In the meantime, NIST also asked its Visiting Committee on Advanced Technology to investigate how the organization could improve its standards work in the future. The committee then entrusted that task to a specially appointed panel of seven experts.

The panel commended NIST for being “forthcoming, open and transparent” in responding to its enquiries, but concluded that these were qualities sometimes lacking when it is developing cryptographic standards. In individually submitted assessments of what had gone wrong, many of the panel members also said that NIST had made a mistake in approving the algorithm in the first place, arguing that it had done so because it had been overly trusting of the NSA.

NIST failed to exercise independent judgment but instead deferred extensively to the NSA
Edward Felten, Princeton University

Panellist Edward Felten, a computer scientist at Princeton University, argues that NIST should not have allowed the NSA to provide the values of P and Q, or, as a minimum, should have asked the agency to provide evidence of the variables’ randomness. “NIST failed to exercise independent judgment but instead deferred extensively to the NSA,” he wrote.

Fellow panellist Bart Preneel of KU Leuven University in Belgium believes that NIST has “lost its credibility” and estimates that it will need “several years” to regain the trust of providers and users of Internet services. “It is clear that this could only happen because in some sense NIST was misled by the NSA,” he says

Asking the wrong question

Chief cyber-security adviser at NIST, Donna Dodson, says that NIST “did not know that there was a back door” in DUAL_EC before September 2013, and that even today it “still doesn’t know” whether the deliberate weakness exists. She adds that “in hindsight” the organization probably would not have issued the algorithm, admitting that although it offered companies the possibility of generating their own values of P and Q, NIST “didn’t make it easy” for people to do this. “We focused on the question ‘did the algorithm have a back door?’, rather than the question we should have asked: ‘could the algorithm have had a backdoor?'”

However, mathematician Richard George, who worked for the NSA as a cryptographer for 41 years before retiring in 2011, says “The NSA has never attempted to put a backdoor in a NIST algorithm.” Indeed, he insists that the values of P and Q were randomly generated. “There is a relationship between those two values but we don’t know what it is,” he says. “We provide crypto-variables for the US government, and the same system that was used to generate those random values I was told was used to generate these.”

The NIST report is called “NIST Cryptographic Standards and Guidelines Development Process” (PDF).

Silicon nanorods bend light in new directions

Ultrathin coatings that arbitrarily manipulate the phase and polarization of electromagnetic waves have been created by researchers in the US. The coatings are made from silicon nanorods using a technique that is compatible with industrial processes such as photolithography. The researchers say that the coatings could be used in new types of optical components that are much less bulky than traditional lenses. The technique could even be used to bend light in ways not possible with conventional lenses.

Fermat’s principle – the rule that light travels along the path of least time – says that electromagnetic waves travel along the path on which they accumulate the least phase. In a medium of higher refractive index, the wavelength shortens and so a wave accumulates more phase across the same distance. A wave therefore bends towards the normal to reduce the distance travelled in the medium and the phase accumulated.

Manipulative metasurface

In a conventional optical component such as a lens, phase accumulates continuously as the wave propagates and this determines the nature of the wave that emerges from the lens. However, if the phase of a wave could be changed discontinuously at a surface (called a metasurface), then the wave could, in principle, be manipulated in ways not possible with conventional optics.

While this is straightforward in theory, the challenge facing physicists is how to create such a phase discontinuity using real materials. In 2011 researchers at Harvard University led by Federico Capasso and Zeno Gaburro covered a surface with V-shaped gold antennas so that the surface could be used to introduce any desired phase shift to optical waves passing through it. While this allows the arbitrary redirection of visible light, there are two major problems with this approach. First, the metallic nature of the surface means that most of the visible light is lost as it travels through the surface. Second, thin layers of metal are very difficult to work with and incompatible with the complementary metal-oxide semiconductor (CMOS) process used to make modern electronic devices.

In the new research, Mark Brongersma and colleagues at Stanford University in California use lossless silicon optical antennas. When illuminated by a particular frequency of light (which can be selected by varying its diameter), the antenna will resonate strongly. This causes the light wave to pick up a phase shift that depends on the relative orientations of its polarization axes to the antenna. By appropriately tailoring the orientations and distances between the antennas, the surface can impart any desired phase shift to the light. This allowed the researchers to reproduce the functions of a bulk lens with a single layer of nanorods just 100 nm thick.

Axicons and Bessel beams

The team was able to create various types of “lenses” using this technique. These include traditional focusing lenses and an axicon. The latter is a specialized type of conical lens that transforms an ordinary laser beam into a Bessel beam – a ring-shaped beam used in optical tweezers and eye surgery.

Optics expert John Pendry of Imperial College London is impressed. “If anyone in the electronics or photonics game wanted to use a material, it would have to be silicon,” he explains. “You can lay down silicon extremely flat and shape it very precisely. Metals are nowhere near silicon in terms of the precision and the control you can exert over them; so, if you can translate a technology like metasurfaces into a silicon environment, you’re on to a real winner because you can hook on to this bandwagon that’s been rolling for half a century now.”

I think that Intel or other companies based on CMOS technology can implement such a metasurface now
Erez Hasman, Technion-Israel

In the experiment, the metasurfaces were fabricated by electron-beam lithography, but team member Erez Hasman, now at the Technion-Israel Institute of Technology in Haifa, says that commercial companies could produce large quantities using industrial processes such as photolithography. “I think that Intel or other companies based on CMOS technology can implement such a metasurface now,” he says.

“The theoretical concept is not surprising at this point, but the fact that they built it and it works is interesting,” agrees Andrea Alù, an expert on metasurfaces at the University of Texas at Austin. He looks forward to the development of optical components that are not possible with normal lenses. Hasman suggests that one of the first such uses might be to interface waveguides with free space. “In general, the modes of a laser resonator or a waveguide are very complex and different from the modes of free space,” he says. Coupling the two together to allow signals to pass between them, he explains, is very difficult using a lens or a prism but should be no problem using the 2D metasurface.

The research is published in Science.

Ice cream that changes colour, tag-team parenting and the ITER director-general hits back

A very pink ice cream in a waffle cone — Shades of pink: the Xamaleón ice cream in action. (Courtesy: IceXperience)

It has been a cracker of a summer here in south-west England, with lots of sunshine and temperatures in the mid-twenties just about every day. Not surprisingly, I have been eating my fair share of ice cream, but unlike this concoction whipped up by a physicist-turned-chef in Spain, the stuff you get in Bristol does not change colour when you lick it!

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Magnetic erosion could explain heavyweight Mercury’s density

Mercury’s high density and large iron content could have been caused by magnetically excited collisions within part of the Sun’s protoplanetary disc, suggests new research from scientists at the American Museum of Natural History. These collisions could have knocked off the rocky, non-magnetic parts of the dust grains, leaving behind iron-enriched material from which Mercury could have formed.

Compared with the other rocky planets in the solar system, Mercury is unusually dense. The planet is estimated to contain about 70% iron by mass, compared with the near-30% values attributed to Earth and Venus. First acknowledged almost half a century ago, this peculiarity is an enduring puzzle. Explanations for the anomalously high iron content are varied, with popular theories including the removal of silicates from the surface of the young Mercury by a giant impact, or evaporation within a hot solar nebula.

Puzzling potassium

Recent measurements taken by NASA’s MESSENGER spacecraft, however, appear to have ruled out many of these models, including the evaporation hypothesis. Any such evaporation of silicates would require high enough temperatures to also remove potassium – a result that contrasts with the terrestrial potassium/thorium ratios MESSENGER has measured. While the giant-impact hypothesis remains viable – provided that the displaced material did not amass again onto the planet’s surface – some newer theories propose instead that Mercury’s iron enrichment might have occurred very early in its history, when tiny dust grains in the protoplanetary disc initially combined to form larger boulders and planetesimals.

In the new work, astrophysicist Alexander Hubbard proposes one such model. “In the solar nebula, at the position that Mercury now occupies, the ambient magnetic field was surprisingly strong,” he says. A narrow window exists in which the temperature is hot enough to support an amplified magnetic field – brought about by the differential rotation of the inner and outer parts of the protoplanetary disc – and yet cool enough to lie below iron’s Curie temperature. Here, the field would have been sufficient to magnetically saturate the iron-rich grains, causing them to violently smash together. “These collisions could have knocked off the rocky bits of the dust grains, in a process we name ‘magnetic erosion’,” says Hubbard. “The surviving iron-rich dust would have gone on to form Mercury.”

Lost silicates

In contrast – along with being stripped from the growing iron grains – the silicate-rich particles would be prevented from combining because of the negative charge they accumulate, he proposes, which would cause them to repel each other. Iron-rich particles – which can rearrange their charges – do not experience this limitation. Unable to accumulate at the same rate as the iron, the silicates would eventually be lost to the host star. According to Hubbard, the very limited area in which magnetic erosion could occur explains why similar levels of iron enrichment are not seen in our solar system’s other rocky planets.

Magnetic erosion is “certainly an interesting idea”, says Hannah Jang-Condell, an astronomer from the University of Wyoming who was not involved in this study. Jang-Condell expresses concern, however, about the temperatures required for the erosion to take place – at around 1000 K, this would be “fairly close to the sublimation temperature for silicate grains (∼1500 K)…[giving] a very narrow range of radii in which this effect could take place”. In addition, she notes, typical models of protoplanetary discs around Sun-like stars only produce temperatures as high as 1000 K at Mercury’s orbital radius in young, rapidly accreting systems – leaving questions as to whether the discs’ cooling would leave enough time for magnetic erosion to occur.

Steven Desch, a theoretical astrophysicist at Arizona State University who was also not involved in the study, also has reservations. “[The paper] assumes dust grains have high electric charges that prevented them from approaching each other, but in reality dust in the solar nebula was probably electrically neutral,” he says, explaining that, if that were the case, grains would stick together regardless of their magnetism. “Collisional stripping of Mercury’s silicate mantle remains a viable, and the most probable, mechanism for explaining its high core mass,” he says.

The research is described in the journal Icarus.

Why we’re five years overdue for a damaging solar super-storm

The cover feature of the August issue of Physics World, which is now out in print and digital formats, looks at the Sun – and in particular, at the consequences here on Earth of a “solar super-storm”. As I point out in the video above, these violent events can disturb the Earth’s magnetic field – potentially inducing damaging electrical currents in power lines, knocking out satellites and disrupting telecommunications.

One particularly strong solar super-storm occurred back in 1859 in what is known as the “Carrington event”, so named after the English astronomer who spotted a solar flare that accompanied it. The world in the mid-19th century was technologically a relatively unsophisticated place and the consequences were pretty benign. But should a storm of similar strength occur today, the impact could be devastating to our way of life.

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New holographic waveguide augments reality

A new optical gadget that uses holographic technology looks set to transform wearable, augmented-reality displays. That is the claim of engineers in the UK, who have developed a device that could be incorporated into a variety of existing technologies and allows users to overlay full-colour, 3D, high-definition images onto their normal line of sight, so that it interacts with their surroundings. This, the researchers say, sets it apart from similar augmented-reality (AR) technologies such as Google Glass and virtual-reality devices such as Oculus Rift.

Immersive information

In recent years, immersive augmented-reality or virtual-reality mobile or computer displays have become more commonplace. From greeting cards that play videos when scanned by a mobile phone to futuristic windshield displays in luxury cars, the line between digital and analogue visual information is being blurred by new technologies. But developing AR displays that seamlessly integrate digital information into the everyday environment can be a challenge. Particularly difficult is overlaying high-quality colour images that are still transparent enough not to obscure the field of vision.

Now, developers at a UK-based company, TruLife Optics, together with researchers from the adaptive-optics group at the National Physical Laboratory (NPL) near London, have overcome this overlay problem. They have created an optical component that consists of a waveguide (a rectangle of high-quality glass or plastic that acts as the lens) that contains two postage-stamp-sized holograms overlaid onto it. TruLife Optics is a spin-off from Colour Holographic – a company with expertise in producing holograms.

Earlier this month, TruLife Optics launched its glass waveguide/hologram systems, which can be bought by AR device developers for about £360. The devices are not standalone products and must be incorporated into an eyewear frame, along with a microdisplay, which provides the input image.

Reflecting waveguides

The waveguide itself is about 10 cm long, 3 cm wide and 2.8 mm thick, including the two holograms. The holograms provide a convenient way of routing light in a controllable manner. In the team’s device, incoming images from a microdisplay are routed into the first hologram, where the light is turned 90° through the length of the waveguide, via total internal reflection. Then the light hits the second hologram, where it is turned a further 90° so it is projected into the human eye. This means that the overlaid transparent images are projected from the centre of the device into the eye and are perfectly focused.

Using holograms also means a component can be created that is, at most, 2.8 mm thick, making it easy to incorporate into any eyewear. The researchers claim that the image projected “does not lose any fidelity or resolution and is focused to accommodate the eye, thus avoiding the need to squint or move your eye to see the information”. TruLife Optics also plans on making bespoke components that match the requirements of individual developers. The team has a “developer zone” to help buyers and a hackspace, where it encourages customers using its product to discuss possible improvements to the device and contribute towards its evolution.

Simon Hall, a senior researcher at NPL who was key in the development of the component, told physicsworld.com that in the years ahead, the team hopes to produce workable demonstrators for curved waveguides (curved lenses for glasses) and be able to carry out aberration correction to allow the use of prescription lenses. “Adaptive systems allow the image focal plane to follow the accommodation state of eyes. We hope that in five years’ time a number of AR systems available in the market would incorporate our technology,” says Hall. “There are multiple specialist applications of this technology…medical and industrial applications could also be produced.”

Real-time applications

Indeed, there could be a range of applications for the device, including entertainment and educational technologies plus displays built into car windscreens and shop windows. Hall also describes more specific applications such as an infrared version that could be developed for firefighters or eyewear worn by doctors during surgery. With the latter, Hall describes a scenario where a colleague in a distant city or country could view and advise on a surgical procedure in real time. The team also envisions that its technology could be useful for experimental scientists and engineers who could overlay a schematic plan on equipment they are working on.

A SKA for astronomy

The Square Kilometre Array (SKA) promises to usher in a new era in radio astronomy. Astronomers will use the telescope to probe the early universe by looking as far back in time as the first 100 million years after the Big Bang. It will also be employed to search for life and planets, as well as to study the nature of dark energy. This video takes you on a tour of the sites in Australia and southern Africa that will host the SKA, featuring artists’ impressions of the impressive telescope equipment. The film will also transport you to the headquarters of the SKA Organisation in the UK, where scientists and engineers describe the challenges and opportunities that lie ahead.

When completed, the SKA will be the world’s largest radio telescope, with a total collecting area of one million square metres. Construction of the first phase is scheduled to begin in 2018. This will see an array of 254 dishes being built in South Africa’s Karoo region covering the bulk of the high and mid-frequencies of the radio spectrum. Meanwhile, the Murchison region in Western Australia will host the low-frequency section of the array with 96 dishes accompanied by approximately 250,000 individual dipole antennas.

Engineers involved in the SKA project are full of impressive facts about the scale of the technology infrastructure. For instance, they say that the number of data being collected by the array will be equivalent to 10 times the global Internet traffic. And given its processing capabilities, the array will be able to survey the sky 10,000 times faster than any existing radio telescope and at a sensitivity that is 50 times greater. To put the latter figure in perspective, it means that the SKA would be able to detect an airport radar signal on a planet tens of light-years away.

“I think it’s fair to say that the SKA really represents the next step in the evolution of low-frequency radio astronomy,” says Jeff Wagg, a SKA project scientist featured in the film. “Observing the universe at low radio frequency not only tells us about the evolution of gas in our own galaxy and other galaxies, but also tells us about the evolution of star formation in the universe.”

In addition, the film takes a look at some of the precursor telescope arrays that are being developed in both host nations as a means of testing some of the SKA technologies. South Africa has the MeerKAT array, which is currently under construction in the Karoo and had the first of its 64 antenna inaugurated in March. Meanwhile, Australia has the Murchison Widefield Array (MWA), which is already up and running. It also has the Australian Square Kilometre Array Pathfinder (ASKAP), which astronomers are currently commissioning and testing.

“There are some really exciting images coming out of those instruments right now,” says SKA engineer Roshene McCool, referring to developments at ASKAP and MeerKAT. McCool says that as well as being important scientific instruments in their own right, the SKA precursor projects will also return a lot of practical information about building telescope arrays in these environments. “The design and the construction of those telescopes has built both infrastructure and also human capital in those areas so that we have skilled people who understand what is actually quite a specialized area,” she says.

The July issue of Physics World features an update on the SKA project, including the surprise news that Germany has announced its intention to withdraw from the project. Members of the Institute of Physics (IOP) can read the article in the magazine. Being an IOPimember gives you a full year’s access to Physics World both online and through the app.

Physics on babies’ bottoms

About 10 years after I left university, I went to a reunion of my former classmates. When we talked about our jobs, they were stunned when I told them I was still doing physics pretty much every day. “But I thought you worked on baby nappies!” I confirmed this was accurate, but added that I had just hired a theoretical physicist to help me develop the differential equations for urine transport through nappies.

My classmates thought I was being funny, but I was just telling the truth. I work in the research and development (R&D) division at Procter & Gamble (P&G) and we joke that what we do is not rocket science – it’s harder. The fact is that many commercially available software codes for simulating fluid flow and mechanics do not readily work for nappies. As a result, we continuously face situations where either the theory that describes relevant phenomena does not exist or the simulations are numerically unstable owing to challenges that are specific to our systems.

For example, unlike in geological materials, where the pore structure is typically relatively stable during fluid flow, the materials used for consumer products such as nappies are soft and can deform because of wet collapse or external conditions. In addition, the swelling of super-absorbent materials produces large changes in the dimensions of the pore structure. This poses a range of challenges when developing methods of physically characterizing the materials and theories of how they behave. In short, the stereotypical view that “consumer products are simple to use – therefore they are simple to understand” is almost completely wrong. After 23 years “in baby diapers” (as the Americans would phrase it), I still find myself using physics every day and having a lot of fun too.

An accidental entry

Joining P&G was one of the best decisions of my life, but it happened more or less by chance. I studied physics at the University of Leipzig in what was then East Germany and my diploma thesis focused on developing simulations to compute the molecular orientation of nematic liquid crystals in electrical fields. For my PhD, I extended these simulations to include birefringent optics, making it possible to predict the behaviour of liquid-crystal displays based on the display’s design and material properties.

When I graduated in 1991, I was only 26 years old, but I had met my wife at university and (as was common in East Germany at the time) we decided to have children early. Our daughter was born before I earned my diploma and our son a few years later. My original plan was to stay at university as an assistant after my PhD, working my way towards a tenured professorship. However, while I was working on my thesis the Berlin wall came down and after Germany reunited the university system changed almost overnight. Permanent assistant positions like the one I had hoped for were no longer available; instead, it became common to accept temporary assistant or postdoc positions, with the hope of eventually becoming a professor.

I decided that this new path would be irresponsible for our family and that working in industry would provide a safer and more stable environment. Then I spotted an advertisement in a newspaper; a company called Procter & Gamble was soliciting applications from graduate students to attend a seminar for “technical management”. I thought P&G must be a consulting company (it was unknown in East Germany and this was before the Internet became popular) and I had no idea what technical management was, but I was curious, so I sent in my application.

A couple of weeks later I received an invitation to an interview. When I arrived, the recruiter informed me that P&G was a consumer-goods company and that I would be interviewed for an actual job, since I was already too advanced for the seminar. I didn’t know any more about consumer goods than I did about technical management, but again, I was willing to find out and later that day I was offered a starting position in material development for Pampers, P&G’s brand of nappies.

A physicist among chemists

My first assignment at P&G’s centre in Schwalbach, Germany, was to develop an upgrade for the absorbent gelling material (AGM) in nappies that absorbs and “locks in” urine to keep the baby’s skin dry. AGMs are hydrogels that are made of partially neutralized polyacrylate polymer networks and they were originally invented for agriculture as a means of improving the water-holding capacity of soil. P&G had introduced AGMs into Pampers in the mid-1980s and now my boss was convinced that they could be improved.

AGM development was seen as the domain of chemists, and as the only physicist working on it within P&G and our material suppliers, I was really pushed out of my comfort zone. I had to learn a lot more about polymer chemistry and materials science. But I was also able to ask physics questions such as “How does liquid transport happen in nappies?” and “How can we understand how the swelling of the AGM changes this?” A few of these things were known qualitatively, but to my surprise there was no detailed understanding and no predictive model to guide me. I had to develop models and characterization-test methods on my own and the breadth of the task – which also included working with material suppliers and even supervising some consumer testing – was very new to me. However, I found it exciting and within a few years I led the first AGM upgrade in P&G’s European Pampers plants.

This success encouraged me to push my role as a physicist further. In addition to AGM development, I started programmes aimed at improving absorbent-core technology, and our modelling and simulation programmes. In a way, I think that being a physicist among non-physicists was one of the reasons for my success because my different point of view helped spur us along.

Becoming an ‘expert generalist’

P&G has a dual career system, with management and technologist tracks. I went for the latter, progressing from principal scientist in 1995 to research fellow in 1999. In 2006 I was inducted into the company’s Victor Mills Society, which is the top rung of the technical career track. In fact, it is a bit like being a professor because I get to lead major R&D programmes and help develop new ways of educating and nurturing young innovators. I also collaborate with a range of companies, universities and institutions, and frequently present at conferences.

The term “expert” is usually associated with deep knowledge in one particular field. However, I find it more useful to view myself as an “expert generalist” or “master integrator” – someone with deeper-than-average knowledge and experience of multiple fields. My physics education taught me that “if it is the same equation, then it is the same problem”, and I think this has helped me to think and act like a master integrator because I can find connections between areas that appear unrelated on the surface. This is especially useful at the fuzzy front end of innovation, when the uncertainties surrounding what is needed and what is possible are both very high.

One thing that my physics education did not teach me, however, was the role of emotions and perceptions in the decision-making process. When I started working at P&G, one of the first things I learned was that “perception is reality” for consumers; a product may work fine, but if it does not look that way, consumers will not accept it. It took me much longer to learn that “perception is reality” also applies much more generally in decision making. For example, I sometimes give a talk called “Can I trust your model?” that highlights the challenges of status-quo bias and human behaviour as it applies to innovation. Learning more about how to influence people has become a hobby for me, so I read a lot of books about behavioural science in addition to keeping up with new topics in physics, chemistry, materials science and engineering.

Overall, I have found that working as a technical expert at P&G has given me plenty of new insights, as well as tremendous opportunities for learning. I enjoy tasks that take me outside my comfort zone and being “in nappies” means there is also the sense of excitement that comes with getting new technologies into consumers’ hands – and onto the bottoms of their babies.