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Friday, 5 December 2014

Collapsing Ice Shelves

In 2002 the Larsen B Ice Shelf on Antarctica collapsed spectacularly. An area of ice twice the size of Greater London was lost in less than a month. This occurred in the northernmost region of Antarctica - the Peninsula - which has warmed-up by more than five times the global average over the last century[1]. A result of this is that, in certain parts of the Peninsula, the surface of the ice is starting to melt. The water from this melting can accumulate to form lakes up to 4km long. Larsen B was covered in these lakes, but just before the ice shelf collapsed these lakes started to drain. First one drained, then those around it, then those around them in a chain reaction that is suggested to have been key to the sudden collapse of the ice shelf[2].

Photograph of Larsen B ice shelf collapse in February 2002 by NASA MODIS
In February 2002, satellite images of the area stunned scientists as they watched 3,250 square kilometers of ice sheet disintegrate within the space of a month. By the end of 2006 the Larsen A and B glaciers were losing 22-40 billion tonnes of ice per year. Image credit: MODIS, NASA's Earth Observatory (CC-BY 2.0)

We don’t know what caused the lakes to drain so suddenly, or exactly how this links to the ice shelf’s collapse. Various hypotheses have been suggested as triggering the collapse; including the forces that the weight of the lakes exert on the ice shelf[2], and the melting of the ice shelf from below by heating from the ocean[3]. However, it is clear from the sudden drainage of the lakes that their role needs investigation, especially as they are beginning to appear further south on the Antarctic Peninsula.

Thursday, 20 November 2014

A Swift glance at red dwarfs

November 20, 2014 is a huge day for NASA’s Swift spacecraft, as it marks the tenth anniversary of its launch. Currently orbiting our planet, Swift is scanning the skies for potential sources of events known as Gamma-ray bursts (GRB’s). Each burst is a huge, but relatively brief, flash of very high energy radiation coming from interstellar space. Astronomers believe they happen fairly frequently (we detect around one per day according to NASA), and last from a few milliseconds up to a few minutes. Swift’s role is to detect these events using the Burst Alert Telescope (BAT), in order to find out what exactly is causing them. This telescope has a very wide angle lens, which can see about a sixth of the sky at any one time – about the same as one of our eyes can see - and scans around 88% of the entire sky each day[1].

Gamma-ray bursts can happen at any moment, so Dr Kim Page and her team at the UK Swift Science data centre (UKSSDC) based in the University of Leicester take turns to be ‘on-call’ for when BAT is triggered. There are two ways BAT can be provoked into action; by a quick rapid spike in high-energy waves or by a cumulative increase in a particular part of the sky over a longer period of time. These two mechanisms are known as the “rate trigger” and “image trigger” respectively, named for the specific way in which they pick up radiation. If the telescope is triggered it sends a message to the various cameras onboard Swift to “switch on”, which then turn and face the area of sky from where the original signal was first detected. At the same time, it sends an automated SMS to the on-call team members at the UKSSDC, whilst also writing each team member an email containing the relevant data about the location, time and intensity of the trigger source. The X-ray, UV and optical cameras on Swift can then investigate the radiation burst further. The Swift team have found this to be extremely effective and usually the phenomenal increase in energy has a Gamma-ray burst at the centre. But, as we will see, this is not always the case.

Artist's impression of the NASA Swift spacecraft
The Swift spacecraft has been orbiting the Earth since 2004, collecting data about the locations of over 800 gamma-ray bursts; extremely high energy events which occur deep in space. From understanding more about the causes and nature of GRB’s, astronomers hope to understand the early universe better. Image credit: NASA E/PO, Sonoma State University/Aurore Simonnet

Occasionally, an event which isn’t a GRB will cause the detectors to swing round and peer into the depths of space. On April 23, 2014, BAT picked up a huge influx of energy coming from a small constellation known as Canes Venatici (part of the Ursa Major group). The image trigger alerted Dr Page with a text message at around 10pm, telling her and her team that there was a potential GRB in this constellation. Within two minutes the Swift cameras had collected as much data about the position of the source as they could. This data was then cross-referenced with catalogues of stars and galaxies, to see if this patch of sky had produced GRB candidates on previous occasions - making it more likely to be a “false positive”. As a matter of fact it had – and the team found that the patch of sky they were looking at contained a binary red dwarf system, about 60 light years away. So, by then we knew what was setting BAT off, says Dr Page, Red dwarf stars are well known for their highly energetic flares. But the fact that this system could be expected to produce powerful flares didn’t prepare Dr Page and her team for the sheer enormity of the flares they were seeing this time.

Tuesday, 11 November 2014

Comet Chemistry

Dirty snowballs, snowy dirtballs and the leftovers of solar system formation. These names are commonly used to describe the often visually stunning ice extravaganzas that streak across our skies from time to time - comets. These somewhat simplistic names mask the importance of comets as repositories for material from which the planets formed. Comets contain volatile chemicals - materials that vapourize at relatively low temperatures, such as water, carbon dioxide, ammonia, and methane. This means comets have very limited lifetimes - they get vapourized and lose a lot of their mass each time they pass close to the Sun - so we know that each one we see is relatively new to the inner solar system, giving astronomers a window through which to observe the elemental and isotopic evolution of the early solar system.

The Sun emits light across much of the spectrum, from the blues, greens and reds we can see down into the infrared and up into the ultraviolet. When that light reaches an object, like a comet, some wavelengths of light get absorbed while others are reflected, depending on which materials are present. Similarly, certain molecular interactions also emit light but only at certain wavelengths. This leads to the creation of “spectral lines”. However, even the Sun’s spectrum contains thousands of absorption lines, known as the Frauenhofer lines.

Comparison of images for the continuous electromagnetic spectrum, emission and absorption spectral lines, and the solar spectrum.
Different elements and chemicals absorb and emit light at different wavelengths, so by analysing these spectral lines we can determine which materials are present. (Public domain image)

Current methods for determining the composition of a comet from the relative comfort of the Earth rely on the analysis of these spectral lines, but this approach is hampered in a number of ways. Firstly, there is the problem of the sheer number of spectral lines detected, and the superposition of these lines in relation to one another. Identifying the distribution of one molecule amongst the thousands of lines that can be detected in one observation is a complex and difficult process. This can also limit the detection of rarer chemicals as they can be masked by more prevalent compounds. Interference from the Earth's atmosphere is also an issue when ground based telescopes are used. The atmosphere can absorb photons at a number of different wavelengths, so some lines of certain species (molecular oxygen and water for example) are not detected at all.

On top of all this, as a fast moving object hurtling towards the Sun, the only volatiles available to study are those located in the comet's coma - the cloud of gas surrounding the solid ‘nucleus’ of a comet. The composition of the coma is assumed to be different from that of the nucleus because the volatile elements vapourize more quickly, so the coma is expected to have more of them and may not reveal some non-volatile elements present in the nucleus. As the relationship between the chemicals observed in the coma and those contained in the nucleus is unknown, abundances in the protoplanetary disk that seeded our solar system cannot be accurately inferred either.

Annotated photograph of comet 103P Hartley 2. Copyright Nick Howes.
Annotated photograph of Comet Hartley 2, showing the solid nucleus in the centre, the gaseous coma surrounding it, and a faint tail. Comet 103P Hartley was once described as a weird little comet by NASA, due to its high levels of activity.
Photograph ©Nick Howes, used with permission. All rights reserved.

At present, knowledge of a comet's interior is limited mostly to theoretical models. Models suggest that comets are composed of a non-volatile component, usually referred to as dust, and a volatile one consisting of ice[1]. To date, only two comets have been comparatively well studied; Halley's comet from its 1986 sojourn around the solar system and comet Tempel 1. Comet Tempel-1 was the main focus of the successful NASA Deep Impact mission which provided the first opportunity to look inside a comet.

Friday, 24 October 2014

Can we make room temperature superconductors?

What do high speed levitating trains, MRI machines and particle accelerators have in common? They all use superconductors. Superconductors are materials that can carry electrical current for long distances without losing energy, and can even produce their own magnetic fields.

Why are superconductors important?


These materials have a vast and diverse range of uses, mainly because they allow for the production of extremely efficient wires. The relationship between electric current in wires and magnetic fields is an intimate one - a magnetic field is created every time an electric charge moves, and every time a magnetic field is changed an electric field is created. This means superconducting materials play an important role in creating efficient and powerful electromagnets. These can be used to construct MagLev trains that float above the tracks, eliminating friction and allowing them to travel at incredibly high speeds, in MRI scanners, and even in particle accelerators such as the Large Hadron Collider where the Higgs Boson was discovered! This is an incredibly exciting prospect - not losing power to electrical resistance could have a profound effect on saving energy resources.

The Shanghai Transrapid maglev train has a top speed of 431 km/h (268 mph), racing the 30km from Pudong International Airport to downtown Shanghai in just 7 minutes and 20 seconds. Image credit: Lars Plougmann

Monday, 13 October 2014

India's MOM seeks answers

In 2010 the Indian Space Research Organisation (ISRO) began a mission to send a spacecraft to orbit Mars – the Mars Orbiter Mission (MOM). Three years later they launched the craft and finally, on 24th September 2014 it reached its destination. The spacecraft’s primary objective is to test and develop the necessary technologies needed for interplanetary space travel - a technology which will allow India to plan future missions through the solar system and beyond. Its secondary objective, though, is scientific research. As the craft orbits the planet it will be collecting data about the planet’s atmosphere and surface.

The journey to Mars, though relatively short compared to a journey to other planets, is a complicated one; out of the 23 missions which have been launched to orbit Mars, only 10 have been fully successful. For India, this maiden voyage means the chance to explore the red planet whilst also developing their technological know-how. The whole mission has cost ISRO about $70 million - making it the cheapest vessel to enter Mars’ orbit since exploration of the planet began! For comparison, NASA had to pay a similar amount per seat to fly their own astronauts to the International Space Station in a Russian spacecraft. This is an incredible feat for technology and may lead to reduced costs for future missions to Mars.

Mars Orbiter Mission - India - ArtistsConcept
An artist's impression of the Mars Orbiter Mission spacecraft orbiting Mars. The basic structure was based closely on ISRO’s first mission - Chandrayaan-1. Image credit: Nesnad, via Wikimedia Commons. (CC-BY-SA-3.0)

Mars is the outermost of the four rocky planets in our Solar System, and is also Earth’s neighbour. Despite having similar rocky compositions these two planets couldn’t be more different. The oceans, flora and fauna which are so prevalent on Earth are completely absent on Mars, and yet the two planets’ orbits are separated by a mere 54.6 million kilometres – a galactic stone’s throw away. Astronomers and planetary scientists have been studying the planet for a while now, and yet there is still so much we cannot decipher about the planet and its history.

Tuesday, 7 October 2014

Cosmic Inflation, BICEP2 and Planck

Cosmic inflation is the exponential expansion of space in the early universe. In other words, how did the universe go from being so small at the time of the big bang to the size it is today?

But why do we even think this occurred? In the 1920's, astronomer Edwin Hubble noticed when looking at galaxies through a telescope, that the galaxies were actually moving away from one another. The further apart they were, the faster they moved.

The only logical explanation for this was that the universe was in fact expanding. If everything seemed to be moving away from each other in all sorts of directions, then surely at some point in the past, it must have been very small, hot and dense. This led to what we now know as the Big Bang Theory, so called because of the implication that the universe began a single point and exploded outwards.

time line of the universe, from big bang to today. Public domain image courtesy NASA.
The Big Bang is believed to have occurred 13.7 billion years ago, after which the universe rapidly expanded in a period of time we call Inflation. Scientists are still searching for conclusive evidence of this, and seek to test the two fundamental assumptions upon which it is based; that the same physical laws apply everywhere in the universe, and that on large scales on large scales the universe is homogeneous and isotropicImage credit: NASA (public domain)

Everywhere we look in the universe, we see billions of galaxies evenly spread. Up until 1979, nobody could explain why this was. That was until a young cosmologist by the name of Alan Guth put forward a possible solution to the problem; he called it inflation.

Monday, 6 October 2014

Science Writing Workshop

One of our recent pledges was to run a series of "how to write about science" workshops, designed to help kick-start careers in science journalism; and we're already working on our first such workshop.

UKSEDS TWDK science communication workshop banner


TWDK have teamed up with the UK's largest student space society, UKSEDS, to offer a science writing workshop aimed at university students. In a hands-on session lasting from 10am til 4pm, we will cover all the basics you need to get you started in science journalism including:

  • Language use – technical science writing is very different from popular science writing. This activity covers how to get your tone right, tailor your writing style to different audiences and age groups.
  • Picking a story – regular writing needs inspiration, but how do you find suitable topics? This activity covers how to find and read press releases, and practice choosing which ones are suitable for you to build upon.
  • “Good” vs “bad” science writing – what makes a piece of science writing good, or bad? We look at some common mistakes and pitfalls, and discuss how to identify and avoid them.
  • Writing from a science paper – published science papers are a common starting point for science journalists, but understanding them can be tricky if you’re not a specialist in that area. Learn some tips on how to read papers to extract the key points you need, and practice writing summaries of a number of real papers in a variety of topics.
  • Editing articles – no first draft will be perfect, and articles always need to be edited. Often this will be done by somebody else, and editing other people’s work can help you understand both the process and alternative styles that may strengthen your own writing.
  • Starting a blog - how to get started in the world of science blogging; setting up your own blog or joining a network both have their own advantages. We look at guest blogging, common sites, what you need to set up your own blog and some useful tools.

Tuesday, 30 September 2014

TWDK makes two "Your Life" pledges

Your life STEM campaign logo
Helping young people to discover a passion for science that takes them to university and beyond is an important part of our mission here at TWDK.

So I'm very happy to announce that Things We Don't Know is one of 200 British businesses that are pledging their support for the Your Life campaign, with the purpose of inspiring young people to study maths and physics as a gateway to exciting and wide-ranging careers.

Specifically, TWDK is making the following two pledges: