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Archive for the 'UCL Science Picture of the Week' Category

Fossil crab

By Oli Usher, on 17 November 2014

Fossilised crab. Credit: UCL Geology Collections

Fossilised crab. Credit: UCL Geology Collections

This specimen, from UCL’s Geology Collections, shows a well-preserved fossilised crab. Its legs are largely intact and even the texture of its abdomen can be made out. The claws, however, are missing.

Crabs’ claws are one way to tell male and female specimens apart (males’ claws are generally larger). Interestingly, the shape of a crab’s underside also hints at its sex in most species.

(Any amateur or expert determinations of this crab’s sex are most welcome in the comments below.)

Crabs have existed since the Jurassic period, 145-200 million years ago.

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Countdown to touchdown

By Oli Usher, on 10 November 2014

Comet C-G, seen by Rosetta’s NAVCAM on 6 November 2014. Philae’s landing site is towards the top of the image. Credit: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

After a decade of travelling around the Solar System, the Rosetta probe is now at its destination: Comet 67-P/Churyumov-Gerasimenko (or Comet C-G to its friends).

The Rosetta mission is made up of two parts which have spent the last decade bolted together: the orbiter, and the lander, known as Philae.

Just after 9am GMT on Wednesday, Philae will separate from the mother ship and begin its descent to the comet’s surface. Around seven hours later, if all goes well, it will touch down on C-G’s rough surface.

This will be the first ever landing on a comet.

The gravitational force between two objects is directly proportional to their masses and the distance between them. Philae, at around 100kg, weighs much the same as a (large) human being, but the comet has a tiny fraction of the Earth’s mass. The pull between them is therefore minuscule – of the order of the gravitational force experienced by an object weighing just one gram on Earth.

Even though Philae will only be approaching Comet C-G at walking pace, the low gravity means it will need to attach itself to the surface with a harpoon to avoid bouncing back into space.

Because of this, the manoeuvre has been compared to a ‘docking’ rather than a ‘landing’.

UCL’s Prof Andrew Coates is a member of the Rosetta Plasma Consortium, which will be monitoring the plasma environment of the comet during Philae’s descent and landing. (He was also closely involved with the design and construction of Rosetta’s scientific payload.) He will be at mission control in Darmstadt on Wednesday as the lander begins its descent.

“The Rosetta orbiter and lander provide unique perspectives on how comets interact with the solar wind and on charged dust from the surface. The historic landing attempt will be a huge opportunity for coordinated observations,” says Prof Coates.

Comet seen over Rosetta's solar array, 14 October 2014. Credit: ESA/Rosetta/Philae/CIVA

Comet seen over Rosetta’s solar array, 14 October 2014, when the comet was around 16km away. Credit: ESA/Rosetta/Philae/CIVA (All rights reserved)

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The Hubble Space Telescope’s successor: UCL’s contribution

By Oli Usher, on 3 November 2014

JWST NIRSpec calibration assembly. Photo credit: UCL MSSL

JWST NIRSpec calibration assembly. Photo credit: UCL MSSL

The James Webb Space Telescope (JWST), currently under construction by NASA and ESA, will be the successor to the wildly successful Hubble Space Telescope. Unlike Hubble, which specialises primarily in observing the same light our eyes see (with limited ultraviolet and infrared capabilities), JWST is specially designed to observe in the infrared.

These wavelengths are interesting to scientists as they allow them to peer through thick dust clouds which scatter visible light, revealing areas of star birth and planetary systems forming. They also reveal the distant past of the cosmos, which has been redshifted out of the visible spectrum thanks to its extreme distance. Infrared observations are extremely challenging to do from the ground as most wavelengths of infrared are absorbed by the atmosphere.

(Hubble’s capabilities in visible light will be largely replaced by a new generation of ground-based observatories, such as the European Extremely Large Telescope.)

A vast project like JWST involves numerous institutions around the world – and among their number is UCL. UCL’s Mullard Space Science Laboratory is providing part of the NIRSpec (Near Infra-Red Spectrograph) instrument, which in turn is part of the European contribution to the telescope project. JWST will also be launched from a European Ariane rocket in 2018.

NIRSpec will break down the light into its component wavelengths, allowing for precise measurements of the motion and chemical makeup of stars and galaxies.

The Calibration Assembly, pictured here, built by UCL, ensures accurate observations by periodically testing the accuracy of the instrument’s colour measurements.

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Simplifying complex data

By Oli Usher, on 27 October 2014

One challenge in science is how to represent vast datasets in a way that the human eye and brain can understand. UCL statisticians Sofia Olhede and Patrick Wolfe have worked on methods of simplifying data on relationships between things in a way which captures all the important features, but is not so unwieldy that the patterns are lost.

blogs contour

The top pair of images on this page show data on how frequently blogs supporting different parties link to each other – showing frequent linking between fellow US Republican Party blogs and US Democratic Party blogs (top and bottom quadrants of the picture) but very little crossing the political divide (left and right quadrants). Peaks (in red and yellow) show groups of blogs that link to each other frequently, blue areas show combinations of blogs that rarely never link to each other. The lower image is a 2D map of exactly the same data.

The next image shows a mathematical approximation of the shape of the distribution of linking in that data – showing how the underlying pattern of blogs linking to each other is actually rather simple.

blogs idealized

 

A detailed article on the science behind these images – and what they tell us – will be published here on the UCL Science blog on Wednesday.

Picture credits: Patrick Wolfe, Sofia Olhede (UCL Statistical Science).

Data from Adamic and Glance

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Marvellous maps

By Oli Usher, on 20 October 2014

Part of George Greenough’s 1819 geological map of England & Wales, showing modern-day Cumbria (then Cumberland and Westmoreland)

Part of George Greenough’s 1819 geological map of England & Wales, showing modern-day Cumbria (then Cumberland and Westmoreland)

This picture shows part of George Bellas Greenough’s 1819 geological map of England and Wales – the first to comprehensively map what lies beneath England’s countryside. This page shows the counties of Cumberland and Westmoreland (modern Cumbria).

Greenough was a pioneering geologist of the 19th century who left his collections to UCL when he died in 1855. (His name is commemorated in UCL’s Earth Sciences student society, the Greenough Society.)

Some of Greenough’s maps, along with other historic items from UCL’s Geology Collections, were publicly displayed on Friday as part of Earth Sciences week.

 

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Space Shuttle commander visits UCL Academy

By Oli Usher, on 13 October 2014

NASA Administrator Charlie Bolden (right) with UCL Academy principal Geraldine Davies (left)

NASA Administrator Charlie Bolden (right) with UCL Academy principal Geraldine Davies (left)

Last week saw Charlie Bolden – a former Space Shuttle pilot who now heads up NASA – visit UCL Academy. In this week’s Picture of the Week, he can be seen visiting the school’s facilities with the principal, Geraldine Davies.

UCL Academy is a non-denominational state school in Swiss Cottage, around two miles north of UCL’s central London campus. The school, which is sponsored by UCL, educates local children and charges no fees, and has extensive input into its teaching from UCL academics and students. It opened in 2012, and recently sent its first student to UCL – to study chemistry.

Bolden gave an inspirational talk to students, and was mobbed by students as he toured the school afterwards.

UCL space scientist Lucie Green, who arranged the visit (and is one of the school’s governors), said: “UCL has a long history of working with NASA that began shortly after its formation in 1958. Today, we have an extended family that includes the UCL Academy and it’s wonderful to see the Academy being the focus for an inspirational visit by Charles Bolden. This is a very positive example of the value-added that comes from having such a broad community where we can work together for the benefit of the students.”

The event is covered in a post on the UCL Events blog, which begins:

Charlie Bolden was born in the deep south of the US, during the days of segregation and institutionalised racism. Despite this inauspicious start in life, he went on to a high-flying military career, commanded the Space Shuttle, spent 28 days in orbit and, in 2009, was made head of NASA by President Obama. He is the first African American to hold the position…

Read the full post here.

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UCL’s first Nobel Prize

By Oli Usher, on 7 October 2014

William Ramsay's Nobel Prize

William Ramsay’s Nobel Prize certificate. Photo: public domain

This week is Nobel Prize week. Prof John O’Keefe (UCL Cell & Developmental Biology) has just been announced as the winner of the 2014 Physiology or Medicine Nobel Prize for his work on positioning systems in the brain.

He joins a long list of Nobel laureates affiliated to UCL.

The very first of these was Sir William Ramsay, who won the 1904 Nobel Prize in Chemistry. Ramsay is seen as one of the fathers of chemistry at UCL, and he is responsible for the discovery of the noble gases. He also supervised two students who also went on to win Nobel Prizes themselves: Jaroslav Heyrovský and Otto Hahn.

Ramsay’s Nobel Prize certificate, pictured above, is held in UCL’s collections, along with his medal and some of the apparatus he used to carry out his research.

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Mapping the Apollo landing sites

By Oli Usher, on 29 September 2014

Lunar Orbiter Photographic DataApollo 11, which touched down in the Sea of Tranquility on 20 July 1969 was the first manned landing on the Moon. But prior to the human spaceflight project, NASA explored the Moon with robotic probes. One key element of this endeavour was the Lunar Orbiter programme, which included five spacecraft that mapped almost the entire lunar surface in 1966 and 1967. This was in part in order to identify landing sites for Apollo, but the missions also had broader scientific goals.

Shortly before the first manned landing, NASA published a catalogue of all their data from the Lunar Orbiter programme, entitled Lunar Orbiter Photographic Data. This features maps of the entire Moon, with the locations, sizes and shapes of all Lunar Orbiter photos marked on them, along with extensive technical information.

Today, missions like this work entirely online, but in those pre-internet days, the data had to exist in hard copy.

A copy of this book exists in UCL’s planetary science archives, the NASA Regional Planetary Imaging Facility. Among its pages is the mapping of the area Apollo 11 landed in, the Sea of Tranquility (Mare Tranquilitas here). This is located towards the right of this sheet, where the imaging (marked in red) is densest.

Lunar Orbiter V - Sea of Tranquility

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The LHCb experiment

By Oli Usher, on 22 September 2014

The LHCb experiment. Credit: CERN (licence)

The LHCb experiment. Credit: CERN (licence)

This week’s Picture of the Week is the LHCb (Large Hadron Collider beauty) experiment at CERN. Located in a cavern on the the French side of the Circle Line-sized cross-border particle accelerator, LHCb is as big as a house. The detector investigates why our universe is dominated by matter, rather than antimatter.

Prof Nick Brook, the newly appointed Dean of Mathematical & Physical Sciences at UCL, was the computing project leader on the LHCb experiment during the vital period leading up to first data taking. He joins joins a wide range of other CERN researchers based here.

Jon Butterworth, UCL’s head of physics, will give a public talk about his role at CERN and the discovery of the Higgs Boson on 15 October. Click here for more information.

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This picture may be reproduced providing you follow the conditions of the CERN licence.

 

Rosetta landing site chosen

By Oli Usher, on 15 September 2014

Rosetta landing site

The landing site for Philae, the lander component of the Rosetta mission, has been chosen and is marked here with a white cross. Photo credit: ESA

The Rosetta mission, which for the past decade has been on a long and convoluted journey to Comet C-G, has recently reached its destination. It is the only artificial object ever to enter orbit around a comet, and is currently circling around it at an altitude of around 30km. (The cometary nucleus itself is around 4km across.)

Part of Rosetta’s mission is to measure the properties of the plasma (electrically charged gas) that surrounds the comet. To this end, the spacecraft features a suite of five sensors built by the Rosetta Plasma Consortium, a scientific collaboration that includes UCL’s Prof Andrew Coates.

But as well as measuring the plasma around the comet, Rosetta will attempt something never achieved before: it will release a lander that, later this year, will touch down on the comet’s surface. The European Space Agency has today announced the site that the lander, known as Philae, will aim for: a spot known as Site J, pinpointed in the photo above with a white cross. The landing site was chosen as the best compromise between safety (the surface of the comet is uneven in places and could damage the probe) and scientific interest (some parts are more active than others).

Copyright: ESA images are free to use providing they are credited, do not imply endorsement by ESA, do not feature identifiable individuals, and are not used in advertising or promotional materials.

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