X Close

Science blog


News, anecdotes and pictures from across science and engineering at UCL


From summer interns to cubesats in space

By Charlotte E Choudhry, on 7 October 2016


Many students send emails requesting summer internships at UCL Physics & Astronomy, but one particularly caught Dr Anasuya Aruliah’s eye. Vishal Ray was a 2nd year Aerospace Engineering undergraduate at the prestigious Indian Institute of Technology Bombay, India (IIT). He belonged to a student team building their own miniature satellite. Vishal was just the student that Dr Aruliah needed for her new direction of research: satellite drag. After a successful application to the International Students Dean’s Summer Student Scholarships, he was awarded a 2 month internship in summer 2015.
Dr Aruliah’s group, the Atmospheric Physics Laboratory (APL), is a subgroup of the Astrophysics Group. It has a long history of researching the upper atmosphere using a global circulation atmospheric model. They also operate a network of Fabry-Perot Interferometers (FPIs) in Arctic Scandinavia to observe the aurora. The Earth’s atmosphere is like an onion skin, with the troposphere (the domain of weather forecasters), stratosphere and mesosphere as layers on top of each other. The thermosphere is the final layer of the Earth’s atmosphere, and is the altitude region between 90-400km. Low Earth Orbit (LEO) satellites occupy the top of the thermosphere, and rely on upper atmospheric models to predict their orbits.

Recently the APL group found a discrepancy between measurements of thermospheric winds calculated from Doppler shifts of airglow photons, and winds determined from atmospheric drag on the Challenging Minisatellite Payload (CHAMP) satellite. This is an important puzzle to solve because satellite drag measurements are put into atmospheric models to bring them as close to reality as possible. If the ground and satellite measurements do not agree, then which is correct?

The IIT miniature satellite, commonly called a cubesat, is composed of a single cube, only 30 cm in length, width and breadth, and weighing only 10 kg, as much as a few bags of sugar. Their cubesat is called Pratham. This fits perfectly with UCL’s involvement in the European Union FP7-funded QB50 project, in which fifty cubesats carrying miniaturised sensors will be launched nearly simultaneously. This is an international collaboration involving many universities, academic institutes and the space industry. It is an unprecedented science operation, with potential for future Space Weather monitoring campaigns. The QB50 cubesats will be carried by rocket into the upper thermosphere, and fall to Earth in decaying orbits while sampling regions of the thermosphere and ionosphere that were previously poorly understood owing to the lack of detailed measurements.

“The simplicity and low cost of cubesats has spurred much excitement and creativity amongst young (and old) engineers and scientists over the last few years. There are new frontiers being opened by this miniaturised space technology,” said Dr Aruliah.

The UCL Mullard Space Science Laboratory (MSSL) designed and built one of the three key sensors: the Ion Neutral Mass Spectrometer, which will be carried on several of the cubesats, as well as their own cubesat called UCLSat. The QB50 cubesats are scheduled for launch in three batches over the winter period of 2016-2017. Two batches from a Ukrainian-Russian Dnepr rocket, and a third from the International Space Station. During Vishal’s internship at UCL he met with the MSSL cubesat and sensor team, led by Mr Dhiren Kataria and Dr Rob Wicks; and with Dr Stuart Grey in the UCL Department of Civil, Environmental & Geomatic Engineering.

Dhiren Kataria holding the UCLSat designed and built at MSSL

Dhiren Kataria holding the UCLSat designed and built at MSSL

Vishal used his experience to write several sophisticated computer programs to calculate drag coefficients from simulations of a cubesat orbiting in our 3-dimensional atmospheric model called CMAT2. This work was subsequently built upon by Dr Aruliah’s 4th year project student, Jennifer Hall. Jennifer wrote her own programs to derive and compare satellite drag coefficients from CMAT2 simulations and EISCAT radar measurements. Jennifer’s project won the UCL Physics & Astronomy Tessela prize for best use of computer technology in a 4th year project.

IIT Pratham group

Pratham team at the Indian Institute of Technology Bombay. Vishal Ray is 2nd from the right in the top row.

One year on, after a busy 3rd year of studies, Vishal has written up his summer project as a journal paper, and “Pratham” was scheduled for launch at 0530 UTC on the 26 September 2016. The IIT Bombay student team installed their cubesat on the launch vehicle PSLV C-35 on the remote island of Sriharikota in South India. Vishal said that he “…had goosebumps when we actually placed the satellite on the launch vehicle module and completed the testing for one last time!”. “Pratham” was successfully launched and will measure the total electron count from 800 km altitude in a Sun Sychronous Orbit. MSSL were the first to receive Pratham’s beacon signal, which the students were incredibly excited to hear. You can hear the cubesat from 4:20 onwards as it passes within range of the detector at MSSL. The signal is decipered as “Pratham IIT Bombay Student Satellite”. The accompanying image is of Theo Brochant De Viliers (MSSL) beside the MSSL receiver.

The prospect of finally being launched is very exciting, with both projects having been nearly 10 years in the making. Once launched, the missions will change from the technical challenges of the innovation of miniature sensor devices to the scientific challenges of collecting, analysing and interpreting the measurements. The rewards will be great: from the new technologies surrounding cubesats; to the training of future space scientists and engineers, and to the Space Weather community.

Hidden in the archives: Finding the first-ever evidence of exoplanetary system

By Oli Usher, on 13 April 2016

You never know what hidden treasures can be uncovered in the archives.

And this was certainly the case at Carnegie Observatories’ collection when research for an article led to the unexpected discovery of a 1917 glass plate showing the first-ever evidence of a planetary system beyond our own Sun.

It all started last year when UCL astrophysicist Dr Jay Farihi contacted Carnegie Observatories’ Director, John Mulchaey, whilst researching an article on planetary systems surrounding white dwarf stars. Farihi was searching for a glass plate that contained a stellar spectrum of van Maanen’s star – a white dwarf discovered by Dutch-American astronomer Adriaan van Maanen.

The 1917 photographic plate spectrum of van Maanen's star from the Carnegie Observatories’ archive.

The 1917 photographic plate spectrum of van Maanen’s star from the Carnegie Observatories’ archive.


Mauna Kea diary

By ucapowe, on 7 January 2015

Amidst the indescribable stress that is writing up my PhD, there is a massive silver lining. I’m currently writing this from 2,800m (that’s about 9,200 feet), half way up the Mauna Kea volcano in Hawaii. I say volcano, it’s not actually erupted for several thousand years and (the reason that I’m here) it has billions of pounds worth of massive telescopes on top of it.

The peak of Mauna Kea, with Subaru, Keck 1, Keck 2 and NASA IRTF telescopes. Photo: Alan L (CC BY)

During the second year of my PhD, my supervisors and I, whilst looking at some data everyone had assumed was assumed was empty, discovered the first molecule containing a noble gas in it in space. Those of you who know anything about Chemistry will know this is really weird. Noble gasses are so named because they’re noble: they don’t mix with the other elements.

However, in the remnants of a star that exploded around 1000 years ago, the conditions for it to actually do so happened. This is a massive deal and needs following up quickly – which as well as taking over a substantial chunk of my time over the past year has now brought me to Hawaii.

The Crab Nebula - where UCL researchers discovered argon hydride molecules. Photo credit: NASA/ESA/Hester/Loll/Barlow

The Crab Nebula – where UCL researchers discovered argon hydride molecules. Photo credit: NASA/ESA/Hester/Loll/Barlow

Last night was my first trip up to the summit, where I spend several hours at NASA’s Infrared Telescope Facility. It’s an odd experience being that high up. Everything needs to be a little bit slower. There are perpetual reminders that you are somewhere not normal. From the warning signs to the bottles of oxygen placed liberally around the control room.

People don’t function so well that high up.

Our trip was mostly to acclimatise to the 4,200m altitude and get used to the instruments we will be using. This is a good thing, because while Mauna Kea has 350 clear nights a year, last night was not one of them.

Last night there was a storm. The drive up to the summit was a pretty hairy experience with squalls of wind  and rain. Thankfully it wasn’t me doing the driving.

The only work that needed doing last night was calibration set up, for which we didn’t need to be able to actually see stars. Just as well, as there’s no way that we could have.

This weather system should have passed by tomorrow so we’ll be free to do science.

NASA Infrared Telescope Facility. Photo: Afshin Darian (CC BY)

* * *

Night 2

Tonight’s drive up was much clearer. As well as stars we could see the top of a thunder storm out over the pacific and the orange glow from a neighbouring volcano (a nice reminder that although it hasn’t erupted for several thousand years, Mauna Kea is not actually extinct).

Clearer… until we got to the summit.

Inside the NASA Infrared Telescope Facility. Photo: Patrick Owen

Inside the NASA Infrared Telescope Facility. Photo: Patrick Owen

Having prepared and calibrated everything and chosen our first standard star to use as a check for everything, the Telescope Operator said “no”.

Apparently it’s 100% humidity outside and it is lovely and misty.

We had a slight tease at about midnight: we got as far as opening the telescope dome and finding our standard star. Alas, just as we started taking actual measurements the humidity shot back up and we had to close the dome.

Night 3

There’s a massive difference when we get up to the summit tonight! Stars! I can see stars, not particularly brightly, which is mostly to do with the lack of oxygen at this altitude meaning my eyes aren’t working as well as they should, but stars!

NASA Infrared Telescope Facility at night. Photo: NASA

If I can see stars, the telescope can see stars. After some changing of instruments and refilling of coolants (no mean feat at that altitude) we were finally ready to get started.  We found and observed out standard star without much of an issue.

Then we started looking for the little “knots” of gas we are observing in the Crab Nebula.  This took us a while longer than planned, but we got there and all lined up on the instrument so we could get the data we need. Nothing. Tried again. Nothing. By this time it was also about 3am, the combination of the time and the lack of oxygen made this all rather difficult to cope with.

The Crab Nebula is full of knots and filaments of gas. Photo: NASA/ESA/Hester/Loll/Barlow

We set the telescope to run for a two hour run to see if we could get anything at all.  Other than some cosmic rays (really not what we’re looking for at all) we got… nothing.  Frustration and worry about our calculations and whether what we were doing was right ensued.  I paced. Lots.  As the sun came up I went outside to get some fresh air (and see the telescopes, I’d only been up here in the dark until now), before heading down to the base camp for some fried food and sleep.

The telescope at dawn, with crescent moon. Photo: Patrick Owen

The telescope at dawn, with crescent moon. Photo: Patrick Owen

Night 4

I woke up this “morning” to an email telling me that there had been something wrong with the instrument. Good news as it means we’re probably going to get some good data this evening. Bad news because it was a really simple fix that had we known about it would have allowed us to get some good data last night too.

Ah well, onwards and upwards.  After another slog to get set up and find a new brighter standard star and things, we got observing.

Final night lucky, at about half past three, we finally realised we’d found what we were looking for! Massive amounts of relief all round, we still had to finish the run and get as much data as we could before the sun came up, but we got some.

It’ll take several weeks of processing the data followed by several more weeks of analysis before we know exactly what we have.

That can wait until after I’ve finished writing my thesis.

Sunset from base camp. Photo: Patrick Owen

Sunset from base camp. Photo: Patrick Owen

Patrick Owen is a PhD student in UCL Physics & Astronomy, and has recently returned from observing in Hawaii

UCL stars on ‘The Sky at Night’

By Oli Usher, on 15 December 2014


December’s Sky at Night was practically a UCL full house.

As well as Maggie Aderin-Pocock (UCL Physics & Astronomy) presenting, the programme featured UCL astronomers Serena Viti and Steve Fossey, UCL chemists Andrea Sella and Stephen Price, and was filmed at UCL’s observatory.

Well worth a watch – viewers in the UK can watch the programme again on BBC iPlayer until 14 January 2015 by clicking above.

The show will also be repeated on BBC Four at the following times: 7.30pm on 18 December, and 2am on 19 December.

Rosetta: The best ever opportunity to study a comet

By Oli Usher, on 7 July 2014

The European Space Agency’s Rosetta mission, coming to its climax only now, a decade after launch, will have a number of scientific firsts: the first probe to follow a comet around the Sun while it orbits, the first to orbit a cometary nucleus, and the first to deploy a lander on the comet’s surface.

UCL has made a major contribution to the scientific programme the spacecraft, thanks to its long-standing expertise in plasma physics. Much of this expertise was gained in a previous space mission.

Artist's concept of the Giotto spacecraft approaching Comet Halley. Credit: Andrzej Mirecki (CC-BY-SA 3.0)

Artist’s concept of the Giotto spacecraft approaching Comet Halley. Credit: Andrzej Mirecki (CC-BY-SA 3.0)

In 1986, the Giotto probe flew by Comet Halley, giving the first ever close-up view of a comet’s nucleus. UCL built the probe’s Fast Ion Sensor and led the Johnstone Plasma Analyser team. Thanks to this detector, scientists were able to study the interaction between the comet and the solar wind as the comet ploughed through it, including the enormous bow-shock in front of the comet that extended for around a million kilometres, and the processes by which cometary ions are ‘picked up’ by the solar wind.

Rosetta should give us a lot more than this. Two decades of technological progress mean sharper photos and more sensitive instruments. But the major improvement is in how long the probe will be able to study the comet for, as well as its close-up study of the comet’s ionosphere. Giotto made only a relatively short flyby of Halley, in large part because the comet’s orbit is highly inclined and moves in the opposite direction to Earth’s, and it only passes through the plane of the Solar System on two brief occasions every 76 years. Comet Churyumov-Gerasimenko, Rosetta’s target, is in an orbit that is easier to rendezvous with, which means – with some admittedly difficult and time-consuming orbital mechanics – Rosetta can be brought into orbit around it.

This, in turn, means the changes in the comet, including the growth of its coma, and plasma (gas) and dust tails, can be charted in detail as it proceeds around the Sun.

Computer rendering of the Rosetta spacecraft. Credit: public domain (Celestia)

Computer rendering of the Rosetta spacecraft. Credit: public domain (Celestia)

UCL scientists at the Mullard Space Science Laboratory are particularly closely involved in the Rosetta Plasma Collaboration, a scientific group which will study the electrical properties of the comet as it interacts with the Solar wind. This is a direct continuation of the work done with Giotto nearly three decades ago.

The wait won’t be long now – Rosetta is less than 30,000km from its goal (less than the distance between Earth and geostationary communications satellites), and will begin manoeuvring into orbit in early August. Early data will come sooner, with the first detection of the comet’s plasma expected perhaps as early as this week.

Rosetta is one of a number of missions being discussed at the Alfvén Conference this week at UCL. Named after Hannes Alfvén, a Swedish plasma physicist and Nobel laureate, the conference is bringing together experts from around the world in the field of Solar System plasma interactions, such as those Rosetta will study.

As part of the conference, Matt Taylor, the scientific leader of the Rosetta project will be giving a public lecture tomorrow (Tuesday 8 July) at 6pm. He will outline the probe’s amazing ten year journey, outline Rosetta’s scientific goals and explain why comets are such an important window into the distant past of our Solar System. The lecture is free and open to all, but please reserve your seat as spaces are limited.