Skip to main content

Reset your password

Please enter the e-mail address you used to register to reset your password

Note: The verification e-mail to change your password should arrive immediately. However, in some cases it takes longer. Don't forget to check your spam folder.

If you haven't received the e-mail in 24 hours, please contact customerservices@ioppublishing.org

Registration complete

Thank you for registering with Physics World
If you'd like to change your details at any time, please visit My account

Close
Home » Page 1329

Tiny pressure sensor takes off

Researchers in Japan have built a tiny sensor that can measure the pressure differences on a butterfly’s wing, helping to better understand the dynamics of insect flight. The team hopes to study the different pressures acting on the wing during take-off, something that has never been measured before. The work will help in building robotic insect-sized flyers or to develop artificial wings.

The seemingly impossible manoeuvres that insects can perform during flight – such as hovering and sudden turns that are very difficult for birds – have long interested researchers. Among the many winged insects, butterflies, and more specifically the Papilionidae family of butterflies (commonly known as swallowtail butterflies) possess a unique wing design that allows them to ascend in a zigzagging path, with low flapping frequency. Hidetoshi Takahashi from Tokyo University, who is lead author and part of the team conducting the research, points out that, according to conventional aerodynamics, the estimated force generated by a flapping insect wing should be insufficient to support its body weight. This means that the actual aerodynamic force of an insect wing exceeds that observed under steady aerodynamics, – where there are equally distributed forces acting across a surface – making it more likely that some “unsteady aerodynamic phenomena” come into play. That is why many researchers have been trying to reveal the mechanism behind this unsteady force, explains Takahashi.

Unsteady aerodynamics

To find out more about these unsteady phenomena, the team has tried to measure the differential pressure distribution – responsible for the aerodynamic force – across an insect’s wing. The work had two main aims – first, to develop a microelectromechanical system (MEMS) differential-pressure sensor that is light enough to let the butterfly achieve flight and that also has high sensitivity to detect minute pressure differences. The second was to measure the force on the wing, mainly during take-off, as the actual aerodynamic force generated by real insect wings during free flight has never been measured directly. “Previous research has been limited to large-scale, tethered conditions using robotic flappers. This makes it difficult to duplicate the actual interaction of the aerodynamic forces with the body motion and wing deformation of insects,” explains Takahashi.

Tiny sensor

The researchers built a piezoresistive cantilever, measuring 125 µm × 100 µm × 0.3 µm. The differential pressure between the upper and lower surfaces of the cantilever causes it to bend and this deformation, in turn, registers as a resistance change in the sensor. “The resolution of the differential pressure is 0.02 Pa from –20 Pa to 20 Pa. Also, the structure is very simple so that the sensor chip can be subminiaturized easily” says Takahashi.

The sensor was then attached to a butterfly wing and the output was measured through a copper-polyimide electrode and gold wires. The total weight of the attachment, including the sensor chip, electrode and wires is 35 mg – lighter than the amount of food that the butterfly consumes at a given time, which is about 100 mg.

“We measured the differential-pressure distribution of four points on the wings of eight butterflies during take-off. “Our measurements show that the differential pressure simply rises and falls periodically and symmetrically in accordance with wing motion. The magnitude of the differential pressure increases as the position shifts from the wing root to the tip during take-off,” explains Takahashi. The researchers also found the instantaneous pressure at the forewing tip reaches a maximum of 10 Pa, which is 10 times larger than the wing loading of the butterfly.

The team points out that understanding the varying aerodynamic forces acting on flying insects using this direct measurement method could help in developing artificial insect-sized flyers in the future. Such robotic insects could be built specifically to easily get into restricted or dangerous spaces, such as disaster sites, to help assess the situation. Also, the studies could help in building artificial wings for aerodynamic experiments or real-time flight control.

The work is reported in Bioinspir. Biomim. 7 036020.

Mind your Zs and Ws

By Hamish Johnston

On Wednesday I will be at CERN in Geneva to hear about the latest in the quest for the Higgs boson – and if the rumours are to be believed, I won’t be disappointed.

As the big day approaches, physicists have moved away from gossiping about whether a discovery will be announced (no, if you consider individual experiments, which are both expected to report evidence at the 4-sigma level…yes if you “unofficially” combine these results to get a statistical significance greater than the magical 5-sigma) and on to the nitty-gritty of what has been seen in the various detection channels.

Once the Higgs is created in the LHC, it can be detected in a number of different ways – or “channels” to use the jargon – several of which are being scrutinized by the LHC’s experiments. Two important channels involve the Higgs decaying to a pair of W bosons (WW) or a pair of Z bosons (ZZ). Conventional theories say that the physics behind these decays is similar, so the assumption is that evidence of both should be seen in the LHC data. However, rumours coming out of CERN suggest that this is not the case – the WW signal doesn’t appear to be there.

However, the Higgs can also decay creating two photons (what’s known as the diphoton channel) and the word on the street is that many more events than expected have been seen in this channel. This also contradicts the absence of WW events because conventional theory predicts that a large diphoton signal should also be accompanied by a large WW signal.

Meanwhile, researchers at Fermilab in the US have been rifling through their data from the now switched-off Tevatron collider and have announced further analysis of their own Higgs search today. The Tevatron results seem to suggest that the LHC should be seeing WW events.

So why isn’t the LHC seeing WW decays? One possibility is that there’s something wrong with how the LHC is looking for these events – a rather boring situation that can be fixed. More tantalizing is that the LHC is right about the WW deficit – which could mean that the particle glimpsed so far is not the “real Higgs”, but rather an “imposter”!

The unexpectedly high diphoton signal is also interesting in itself. It could point to the existence of a new charged particle not described by the Standard Model of particle physics, or it could mean that there are a multitude of Higgs particles – or something completely different.

Indeed, the only certainty is that much more work will be needed before physicists get a handle on the Higgs. So Wednesday will likely be remembered as the beginning of a new era in particle physics – as well as the end of a long search for the Higgs boson.

The July 2012 issue of Physics World is out now

By Matin Durrani

Ernest Rutherford used to enjoy “noisy and appalling” golf at Cambridge with his Trinity College colleagues. Niels Bohr was a keen footballer who played in goal for the top Danish side Akademisk Boldklub in the early 1900s. Arthur Eddington was a passionate cyclist who coined the “Eddington number”, E, which is the number of days on which you have cycled at least E miles. (He reached an incredible 84.) And, of course, CERN physicists are handily placed for a spot of Alpine hiking, climbing and skiing when their hunt for the Higgs has worn them down.

PWJul12cover-200px.jpg

But for some physicists, sport is more than just something they take part in – it is what they study too. This month’s issue of Physics World looks at some of the challenges in the “physics of sport”, including the effects of technology and rule change on sporting performance, the physics of the prosthetic devices that are leading disabled athletes to success, and how gymnasts, divers and long jumpers are all unconscious masters of manipulating the law of conservation of angular momentum.

Members of the Institute of Physics (IOP) can access the entire new issue free online through the digital version of the magazine by following this link or by downloading the Physics World app onto your iPhone or iPad or Android device, available from the App Store and Google Play, respectively.

The digital issue also contains a trio of unmissable videos on the physics of running, cycling and swimming filmed with Steve Haake, director of the Centre for Sports Engineering Research at Sheffield Hallam University.

Here’s a rundown of other highlights of the issue:

• SKA’s double site splits opinion – The decision to build the world’s biggest radio telescope – the Square Kilometre Array – on two separate sites in Africa and Australasia has been praised by many. Jon Cartwright examines if the split site will hamper its science prospects

• Supercharging Japan’s atom smasher – The KEKB collider in Japan is halfway through a major revamp that may help to explain why there is more matter than antimatter in the universe, as Michael Banks reports

• Critical point: Sporting knowledge – When we say that athletes “know” the laws of physics, what we really mean, argues Robert P Crease, is that they know the laws of “physics”

• An impaired cosmic vision – The European Space Agency recently picked a probe to Jupiter as its next large-class mission. Paul Nandra, a director of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, says the decision could devastate astronomy

• The fastest man on no legs – Prostheses remained unchanged for thousands of years, but that all changed once amputee athletes got involved in the design process. James Poskett explores the stories behind the elite sports prostheses we see today

• Material advantage – Sprinters are running faster than ever before, but why are javelin throwers not throwing further and swimmers not swimming faster? Steve Haake, director of the Centre for Sports Engineering Research at Sheffield Hallam University in the UK, explains the effects of technology and rule change on sporting performance

• Balance, angular momentum and sport – Roland Ennos from the University of Manchester explains how athletes and the rest of us use simple physics principles to perform amazing balancing acts

• Technology for life – The fight against cancer offers rewarding career opportunities for medical physicists as well as healthcare professionals, as Giulia Thompson, who leads the R&D team at Elekta, describes

• Once a physicist: Crispin Duenas – the University of Toronto physicist who will be representing Canada in archery at this summer’s Olympic Games

• The Great Physics Games – In this month’s Lateral Thoughts column, Kate Oliver takes a wry look at how physicists compete to succeed

If you’re not yet a member, you can join the IOP as an imember for just £15, €20 or $25 a year via this link. Being an imember gives you a full year’s access to Physics World both online and through the apps.

Web behaviour could track corn-planting dates

Farmer
(Courtesy: Dreamstime)

Web searches can peak and trough in line with the prevalence of flu, dengue fever, kidney stones, stroke, deaths by suicide and depression. Now researchers from Austria and Portugal have found that internet data can also indicate corn planting and harvest dates in the US.

“This paper is the first to appear on an environmentally related application of web-search data, which we feel has great potential in other environmental areas,” Marijn van der Velde of the International Institute of Applied Systems Analysis (IIASA) told Physics World. “We believe this is only the first glimpse of a host of options that may become possible once search volumes increase around the world and access to absolute search volumes becomes possible.”

Van der Velde and colleagues from IIASA and Portugal’s University of Aveiro used Google Insights for Search to analyse corn (maize) planting and harvesting data in the US state-by-state and week-by-week.

Crop-calendar dates are invaluable for monitoring and modelling. At the moment, according to van der Velde, they are either derived directly from climate data or are based on old information from the 1990s/2000s, for example the crop-calendar dataset of Sacks et al compiled in 2010.

But climate is not necessarily a good indicator of planting date since social and technological factors may also come into play. Van der Velde said that when Waha et al (2011) simulated global-planting dates based on climate conditions and crop-specific temperatures, the simulated dates were accurate within one month (giving a three-month window) for only 50% of the grid cells.

“The search data effectively encapsulates many of the different factors that affect planting dates such as weather and technology,” he said. “In a practical sense the results of our work are comparable to global datasets on planting dates (Sacks et al 2010) with the advantage that our results are up to date.”

Web searches in the US for corn planting and harvesting peaked at the end of May and the middle of October. Use of Google Correlate indicated a strong link between those searching for corn planting terms and investigating other agricultural issues.

At a state level, search data for corn planting week-by-week generally agreed well with a global crop-calendar dataset. Iowa and Nebraska, which are among the highest corn-producing US states, both showed high search volumes for the term “corn planting”. Data trends for harvest searches were not so clear, perhaps because some people were searching for the term for cultural reasons such as Thanksgiving.

The team’s efforts to look at wheat and soybean in the same way were foiled by inadequate search volumes. At the moment Google Insights for Search only provides data below a national level and week-by-week for relatively popular search terms. It also normalizes searches according to the highest search volume, rather than providing absolute search volumes.

“Once internet use is increasing in data-poor regions it may well be possible to obtain data on, for instance, crop-disease infestations before a capacity to monitor and report these infestations has been established,” said van der Velde.

Monitoring real-time web-search activity also has potential for predicting how farmers are responding to climate change. “Other agronomical uses could include combining real-time weed and pest infestation searches with remotely sensed satellite observations of phenological development,” said van der Velde. “For instance, in 2009, the searches for ‘weeds’ and ‘blight’ – including ‘potato blight’ – both peaked in comparison to other years, which corresponds to online reports of blight impacting both potatoes and tomatoes.”

At the moment search volumes limit widespread use of the method. “Given the exponential increases in search volumes over the last five years and increasing internet penetration in the developing world, the real future benefit will be in deriving crop calendars in those countries where such information is currently sparse or unreliable,” said van der Velde. “Ultimately, we anticipate that a combination of different types of crowd-sourced information such as pictures, data, reports and observations can be analysed in parallel to improve the understanding of our interactions with and in the environment and improve our capacity to respond adequately.”

The team reported the study in Environmental Research Letters (ERL).

Between the lines

Sporting questions answered

Is it easier to score with a penalty shot in football or in handball? How much of an advantage did elite swimmers gain by wearing the (now-banned) one-piece hydrophobic suits in competitions? And how can it be that headwinds are bad news for runners and long-jumpers but good for discus throwers? The answers to these questions and many more can be found in 100 Essential Things You Didn’t Know You Didn’t Know About Sport, a timely if somewhat unoriginal book by the veteran science writer and University of Cambridge mathematician John Barrow. Although the book will induce severe déjà vu among fans of Barrow’s writing – he has recycled its title, its format and at least one of its jokes from his 2008 book 100 Essential Things You Didn’t Know You Didn’t Know – the counter-argument “if it ain’t broke, don’t fix it” is a compelling one. As with its predecessor, each of the 100 “essentials” in Barrow’s latest book is explained in the form of an easily digestible essay on some topic related to physics, mathematics or both. A good example is #98 “Some Like It Hot”, in which Barrow draws on material from a post on the Engineering Sport blog to explain why trackside temperatures in the velodrome at the forthcoming Olympic Games will be kept at a cosy 25 °C. The key consideration, Barrow observes, is air drag. At 25 °C, air has a density of around 1.185 kg m–3, but at 20 °C, the density increases to 1.205 kg m–3. That may not sound like a big difference, and indeed even at a velocity of 20 m s–1 (a typical value for the “sprint finish” in many cycling events) the corresponding change in drag force amounts to around 1% of the total drag each cyclist experiences. But as Barrow repeatedly shows, small differences can have big effects on the record book, and over the 4 km distance of the pursuit event, raising the air temperature by 5 °C should knock about 1.5 s off the racers’ times. With most (though not all) of the essays focused on Olympic events, the book should prove popular among spectators this summer.

  • 2012 Bodley Head £10.00hb 320pp

Some like it cold

If the current burst of media attention on summertime sport leaves you, well, cold, then Gliding for Gold: the Physics of Winter Sports may be the perfect antidote. Written by the science writer and former theoretical physicist Mark Denny, the book begins with a short introduction to the surprisingly complicated physics of ice. At the time of writing, Denny reports that materials scientists had identified at least 15 different forms of the stuff, and although nearly all of the ice on the Earth’s surface is of the relatively simple hexagonal-lattice type, its properties are still not fully understood. Despite our incomplete knowledge, though, it is still possible to make a number of interesting observations about sports played on icy surfaces. In the book’s first section, for example, Denny shows that speed skaters must move their bodies in ways that differ dramatically from those adopted by runners, thanks to the almost uniquely slippery nature of ice and the design of their skates. The pay-off is that the skaters are considerably speedier: the best of them can achieve average speeds of more than 14 m s–1 over a 500 m track – some 38% faster than Usain Bolt over 100 m. As for snow, our understanding of its behaviour is, if anything, even less complete; as Denny puts it, “to a physicist, snow is ice with complications”. For the most part, Denny deals with such complications by first creating “toy” models that ignore them, then introducing sliding friction, air resistance, athlete fatigue et al. to show how they affect the results of calculations. This is a classic physics trick, but Denny is careful not to push it into “assume a spherical cow” territory. Physicist readers will also appreciate the book’s appendices, which include a “technical notes” section containing detailed derivations of results presented earlier in the book.

  • 2011 Johns Hopkins University Press £15.50/$30.00pb 200pp

Super-tornadoes spotted in the Sun

Giant tornado-like structures with diameters exceeding the width of the United States have been identified in the Sun’s outer atmosphere, the corona. The discoverers say the twisters might provide a mechanism for the transfer of energy within the Sun, which could help to explain a longstanding mystery of why the Sun’s corona is drastically hotter than its surface.

The corona is a region of ionized gas that extends millions of kilometres from the surface of the Sun into space. Physicists have known for more than half a century that it has a temperature of several million kelvin, while the solar surface is a relatively mild 6000 K. This surprising feature of the Sun has challenged astrophysicists, who are yet to directly observe the mechanism by which the corona is heated.

But new opportunities to observe the Sun – and the processes involved in the transfer of energy between solar layers – are being provided by NASA’s Solar Dynamics Observatory (SDO), launched in 2007. Data from one of SDO’s scientific instruments called the Atmospheric Imaging Assembly (AIA), has been analysed in this latest work by a group of researchers at the University of Oslo in Norway, led by the astrophysicist Sven Wedemeyer-Böhm.

Speedy twister

Wedemeyer-Böhm’s group has found within the AIA data evidence of swirls of gas in the corona that resemble tornadoes. The twisters have diameters between 1500 and 5500 km, and some are ring-like while others have spiral arms. Each tornado event identified lasted for a few minutes as coronal gases with temperatures of around one million kelvin were rotated at speeds in excess of 10,000 km/h.

Earlier studies have revealed that the Sun’s surface is also covered with vortex flows of gas due to thermal instabilities in the underlying layers. Wedemeyer-Böhm’s team believes that the solar tornadoes are connected to these surface vortices by the Sun’s magnetic field. The team’s idea is that magnetic flux emerging from the Sun’s interior is forced to twist as it passes through the solar surface, leading to the generation of tornadoes in the overlying layers.

In a paper in Nature this week (486 505), the researchers describe how they have identified 14 super-tornadoes and they estimate that more than 10,000 of them exist at any one time in the sections of the Sun that are magnetically quiet. The upper boundaries of individual tornadoes have been spotted at varying elevations in the corona, but the length of each tornado must be at least 2000 km – the typical distance between the corona and the solar surface.

Fuelling the corona

By combining their observations with numerical simulations of the Sun’s outer layers, the researchers propose that these magnetic tornadoes can provide a mechanism for transferring heat to the corona. “The tornado as we see it extends from the surface through the chromosphere into the corona. It is really strongest in the chromosphere but releases the energy in the corona above,” Wedemeyer-Böhm told physicsworld.com. He acknowledges, however, that the tornadoes probably do not account for all of the energy transfer. “It may most likely not account for all of the required energy in quiet regions but probably for a good portion of it.”

Indeed, a separate group published a paper last year based on data from NASA’s AIA instrument, which also presented a potential mechanism for the transfer of heat to the corona. This group led by Scott McIntosh of the National Center for Atmospheric Research in Boulder, Colorado, identified in the corona an abundance of a phenomenon called Alfvénic waves. These waves – predicted by the Swedish Nobel laureate Hannes Alfvén – were detected in short-lived jets of gas in the corona known as spicules, which are significantly thinner than the tornadoes identified in this latest work.

McIntosh believes that the newly identified tornadoes could represent a large-scale manifestation of Alfvénic waves. “Almost any form of pulling, pushing, tweaking, twisting or pinging will drive wave energy upward into the atmosphere and they are all flavours of Alfvénic motion,” he says. “What is reported in this article is a form of that motion, but on a larger coherent length scale.”

In search of more twisters

Looking to the future, Wedemeyer-Böhm says his group will try to work out the amount of coronal heating accounted for by these tornadoes. It will do so by analysing more data from the AIA instrument and developing its numerical models.

Peter Cargill, a space and atmospheric physics researcher at Imperial College, London, is impressed by the scope of the research. “The main thing I come away with is the impression of how much information comes from an analysis of the solar atmosphere using data from as many different layers as are available and how numerical models can help interpret the data.”

Cargill feels, however, that there are still many unanswered questions concerning the transfer of energy between the corona and the solar surface. “You might ask whether these tornadoes exist over multiple scales, what is the distribution of injected energy in them, and similar questions for waves, braiding, spicules and so on”.

Will CERN scientists announce the discovery of the Higgs boson on 4 July?

By James Dacey

Since my blog on the topic last week, speculation has intensified even further over whether CERN scientists are on the cusp of announcing the official discovery of the Higgs boson. The reason being that officials have announced an extraordinary scientific seminar to be held at CERN on 4 July, the eve of this year’s major particle-physics conference, ICHEP, in Melbourne. Journalists have been invited and promised updates from the LHC’s two main experiments looking for the Higgs – ATLAS and CMS.

hands smll.jpg

The seminar, announced last Friday, appears to be CERN’s response to avoid facing a potentially difficult quandary. In brief, the issue is as follows. Everybody knows that both CMS and ATLAS researchers have spent the first half of 2012 ploughing through new data. These LHC scientists are looking to either confirm, or to destroy, the bumps that appeared in their respective datasets last December, corresponding to a possible Higgs particle with an energy of roughly 125 GeV/c2.

If indeed they have both confirmed the particle to the gold-standard statistical level of “5-sigma significance” then they would surely have to reveal this to the physics community at the ICHEP conference. But from a political point of view, it would seem a bit odd to make the long-awaited Higgs discovery announcement in Australia, a country that is halfway across the world from the LHC and not a CERN member. Indeed, CERN’s PR guru James Gillies was quoted a couple of weeks ago as saying that the Higgs announcement will be made in Geneva. So the decision to hold this seminar next week is surely CERN’s way of making the announcement in Switzerland, while avoiding the need to withhold new science in Australia.

That said, perhaps it is not as clear-cut as the situation suggests. A source at CERN close to Physics World says that LHC scientists will not be declaring an official “discovery” unless both ATLAS and CMS have 5-sigma results that don’t disagree with each other. According to our source, for researchers to reach this point by 4 July “might be a tall order”. I reckon that if the scientists do not quite have the statistics for an official discovery – or indeed one or both of the two bumps have vanished – it could still make for an interesting seminar. But it will certainly leave the scientific leaders at CERN with a tough gig next Wednesday when sharing this news with the assembled journalists who have flown into Switzerland from around the world at fairly short notice.

So the question in this week’s poll is:

Will CERN scientists announce the discovery of the Higgs boson on 4 July?
Yes
No

Let us know by visiting our Facebook page. As always, please feel free to explain your choice by posting a comment on the poll.

As excitement builds towards the seminar, you may want to hear Peter Higgs talk about his life in science and the search for the eponymous boson in a special audio interview with Physics World.

In last week’s poll we asked you whether CERN scientists should be encouraged to discuss ongoing LHC analyses with the outside world. It was fascinating to see that opinion was divided on this issue. 55% of respondents opted for “Yes, they should discuss the scientific process in the open”, while the other 45% went for “No, they should wait until conclusions are firmly established”.

The question was asked because amid all the recent speculation over the Higgs, there has been little on the blogs from the LHC researchers themselves over these latest developments in the Higgs hunt. You could argue of course that there are very good reasons for this, not least because this is an incredibly important and busy time in their scientific careers that requires complete focus. But on the other hand, if LHC scientists were to share their current thoughts with the outside world (outside the walls of the LHC experimental control centres) then it could provide a fantastic insight into how science really works.

The poll also attracted some interesting comments including this one from Larry E Jaynes who wrote: “By all means be as transparent as possible. It serves no purpose to talk about sigma confidence of findings when the public doesn’t have a clue as to what that represents. I say if it’s not ‘local confidence’ don’t improvise to fool the public.”

Thank you to everyone who participated and we look forward to your responses in this week’s poll.

Privately funded spacecraft will look for dangerous asteroids

Today an American non-profit organization announced a space mission to map the inner solar system for evidence of asteroids that could strike the Earth. The five-and-a-half-year voyage, which the organization describes as the first privately funded deep-space mission, is due for launch in 2016 or 2017.

The ambitious plan is organized by the B612 Foundation. Named after the asteroid home of Antoine de Saint-Exupéry’s “Little Prince”, it aims to “open up the frontier to space exploration and protecting humanity on Earth”. That protection focuses on mapping the orbits of the tens of thousands of near-Earth asteroids with diameters of at least 140 m that could strike the Earth with an explosive force of at least 100 megatonnes of TNT. That is 3.5 times the diameter of the object that struck Tunguska, Siberia, in 1908, uprooting up to 80 million trees and shattering windows hundreds of kilometres away.

According to B612, more than 98% of such asteroids remain totally unknown to astronomers. The mission aims to find and track more than 90% of them. “Our goals are primarily philanthropic, in doing our part to save the planet, or somewhere on the planet, from an unlikely but potentially enormous disaster,” says Clark Chapman, a planetary astronomer at the Southwest Research Institute in Boulder, Colorado, who is the foundation’s secretary.

More than saving the Earth

Chapman adds that the foundation foresees other benefits from the mission. “Of course, we also have subsidiary scientific goals. And our mapping of these asteroids is a necessary precursor to identifying objects that could be mined for space resources in the future – or visited by astronauts as tests of systems that could eventually send people to Mars,” he says.

The spacecraft, called Sentinel, will take off from NASA’s Kennedy Space Center in Florida aboard a Falcon 9 rocket. A gravitational slingshot manoeuvre off Venus will put the craft into an orbit around the Sun close to that of Venus.

The craft will carry an infrared telescope to map the locations and trajectories of Earth-crossing asteroids. “These are very dark objects,” explains Scott Hubbard, professor of aeronautics and astronautics at Stanford University and the programme architect for B612. “You have to look in the thermal infrared to detect them.”

Ball Aerospace of Colorado – which developed the Spitzer and Kepler space telescopes – has designed the Sentinel telescope and will build it under a fixed-price contract. The instrument will feature a 50 cm aluminium mirror to collect infrared signals in a large field of view. Images will be recorded by an array of 24 million pixels cooled to –133 °C.

Working with NASA

The craft will transmit the data that it gathers via NASA’s deep-space network, which Sentinel will also use for tracking and navigating, to the Sentinel Operations Center in Boulder. That centre will then use NASA’s Minor Planet Center in Cambridge, Massachusetts, to forward the data to educational and research institutions, and to governments. NASA’s Jet Propulsion Laboratory in Pasadena, California, will carry out a comprehensive hazard analysis on the information, determining the orbits of individual asteroids and assessing their threats to the Earth.

The telescope will scan the entire night half of the sky every 26 days to identify every moving object. Repeated observations of individual asteroids will permit astronomers to calculate their orbits and predict their positions accurately for a century or more in the future.

The nature of the mission has changed since it was conceived about 10 years ago. “The original genesis was planetary stewardship – an interest in mitigating a threat,” Hubbard explains. “But we realized that you can’t mitigate something you can’t find.”

The total cost of the mission remains to be calculated but Chapman expects to announce a “fairly firm cost” later this year. Meanwhile, Hubbard says that foundation is seeking funds for the venture. “We’ve had a few angels who have provided seed funding to look at the feasibility and the technical size [of the project],” he says. “We’re somewhere between angel investment and round one of venture capital.”

Peter Higgs in the spotlight

My life as a boson
My life as a boson

Peter Higgs is not someone who craves the limelight. He lives a quiet life in a flat in Edinburgh, the city where he spent the bulk of his academic career as a particle theorist, and rarely ventures into TV or radio studios to pontificate on the frantic hunt at CERN and Fermilab for the boson that bears his name. If anything, the 83-year-old Higgs is acutely embarrassed by the term “the Higgs boson”, which – he feels – singles him out at the expense of other theorists who were also involved in conceiving the core ideas that led to its prediction.

But while Higgs does not like to crow too much about himself, he is by no means some sort of recluse. Indeed, Higgs was delighted to give this special audio interview to Physics World while visiting Bristol last month as part of a series of other speaking engagements in the city. In the interview, he emphasizes that at least five other theorists – Robert Brout, Francois Englert, Gerald Guralnik, Carl Hagen and Tom Kibble – deserve credit for predicting the Higgs boson, adding that “the person who is still slightly aggrieved is Phil Anderson, the condensed-matter theorist, who said he knew it all already”.

Higgs also talks about how the Higgs boson came to be so named, what his current research interests are, why he holds no particular religious views – and what he thinks is the best analogy anyone has ever made for the Higgs boson. “The one I object to least is the one used by David Miller,” says Higgs, referring to the University College London physicist who wrote one of the winning entries in a 1993 competition set by then UK science minister William Waldegrave, after the latter asked physicists to explain – on one sheet of A4 paper – what the Higgs boson is and why it needed to be found.

Miller famously likened the boson to former British prime minister Margaret Thatcher moving through a crowded room, gaining mass as other people congregate around her. “I do object when people draw an analogy with dragging something through treacle,” Higgs points out. “That’s [a] dissipative [process] and this isn’t.” If CERN announces next week that a Higgs boson has been officially “discovered”, you can be sure that Higgs will have to put up not just with woolly analogies, but also with the world’s spotlight being on him once again.

Bringing alien atmospheres into focus

Tau Bootis system

An artist's impression of the Tau Boötis system. (Courtesy: ESO/L Calçada)

By Tushna Commissariat

It seems as if no sooner have I finished writing about exoplanets, then there is some more interesting news from the field and I am back at it.

Following last week's story on the cosiest exoplanet system, today an international team of astronomers has used the European Southern Observatory's Very Large Telescope (VLT) to carry out a detailed study of the atmosphere of a large "hot Jupiter" exoplanet. Specifically, it is a non-transiting exoplanet – one that does not pass across the face of its parent star.

Transiting is one of the methods researchers use to look for exoplanets – by searching for small dips in a star's light-curve that occur when a planet crosses its face during a "transit". But using this method means we can only find planets that transit their stars from the point of view of Earth. Another method, the radial-velocity method, looks for changes in the radial velocity of the star – tiny shifts that occur because of the gravitational pull of a planet orbiting it. But this method does not give us any information about the planet's atmosphere, as no spectrum is seen. Hot Jupiters are a class of exoplanets with masses that are close to or more that the mass of Jupiter. They tend to orbit close to their parent stars and are easily detected.

Now, astronomers have managed to directly capture the faint glow from one of the first detected exoplanets, Tau Boötis b, and have both studied its atmosphere and measured its orbit and mass precisely for the first time – in the process solving a 15-year-old problem. Surprisingly, the team also finds that the planet's atmosphere seems to be cooler higher up, the opposite of what was expected. Tau Boötis b is one of the closest known exoplanets and was previously only detected using radial-velocity measurements of the system, so the atmosphere was unknown.

The team used the CRIRES instrument on the VLT and high-resolution spectroscopy results, combined with specialized algorithms that ignore the host star's much stronger signal, to tease out the weak signal of the planet.

The team also probed the planet's atmosphere and measured the amount of carbon monoxide present, as well as the temperature at different altitudes by means of a comparison between the observations and theoretical models. Surprisingly, the researchers found that the planet has an atmosphere with a temperature that decreases higher up, contrary to other hot Jupiters, which show "temperature inversion" – an increase in temperature with height.

The results prove that high-resolution spectroscopy from ground-based telescopes can be very useful for the detailed analysis of the atmospheres of non-transiting exoplanets. In the future, the detection of different molecules will allow astronomers to learn more about the planet's atmospheric conditions. By making measurements along the planet's orbit, astronomers may even be able to track atmospheric changes between the planet's morning and evening.

The paper on the new work will be published in Nature.

Copyright © 2026 by IOP Publishing Ltd and individual contributors