Interviewing a MAARBLE Scientist – April 2014

Who is Who

meredithDr Nigel Meredith is a research scientist at the British Antarctic Survey in Cambridge, UK. He has over 15 years of experience analysing radiation belt data to determine the sources of radiation belt variability. He specialises in the role of wave-particle interactions in the acceleration and loss of relativistic electrons in the Earth’s radiation belt and in the production of the diffuse aurora.
Dr Meredith received a BA in Physics from the University of Oxford in 1984 and a PhD in Astronomy from the University of London in 1990. He was the Work Package Manager for the VLF wave database in the EU FP7 project SPACECAST and is currently the Work Package Manager for the statistical analysis of extreme events in the EU FP7 project SPACESTORM. He has published 93 papers in peer-reviewed journals covering a wide range of topics in space plasma physics including 3 in Nature.

Exploring the Wonders of Sky from my Back Yard
“I have been interested in astronomy and space since a very early age”, remembers Dr. Meredith. “As a two year old I was fascinated by the moon and, later, as a boy, I was inspired by the Apollo missions. As a teenager, I spent many happy, if cold, hours outside exploring the wonders of the night sky with my small telescope. I thought it was fantastic to see the moons of Jupiter and the rings of Saturn from my own back yard.”

Dr. Meredith recalls his active involvement in the first ever encounter of a spacecraft with a comet: “For my PhD I studied comets, particularly comets Giacobini-Zinner and Halley around the time of the spacecraft encounters”, he says. “This was an exciting time to study comets and I fondly remember collecting data from a remote mountain top in California and sending it back to Darmstadt to help scientists with the Giotto mission”.
The International Cometary Explorer (ICE) flew through the tail of comet Giacobini-Zinner in September 1985, passing the nucleus at a distance of approximately 7800 km. Later on, in March 1986, ICE transited between the Sun and Comet Halley, whereas the European robotic spacecraft Giotto approached Halley's nucleus at a distance of 596 kilometers, becoming the first spacecraft to make close up observations of a comet.

“We take such transfer of data for granted today – but back in the mid 1980s it was quite novel and we even wrote a paper in EOS about it! I subsequently observed several more comets over the coming years, enabling me to examine the solar cycle dependence of cometary comae”, adds Dr. Meredith. 

giotoThe Giotto space probe, launched in 1985 on an Ariane 1 V14 launcher, brushed past the hidden nucleus of Halley's comet in 1986 (Credit: European Space Agency).

Dr. Meredith explains his involvement with instrumentation in particular the Fabry-Perot interferometer, a sensitive high resolution spectrometer for measuring the Doppler shift and Doppler broadening of spectral lines: “After completing my PhD, I changed fields and began working with the ground-based network of Fabry-Perot Interferometers deployed by University College London (UCL) to study winds and temperatures in the Earth’s mesosphere and thermosphere”, he says. “During this period I developed a new technique to extract temperatures from the Fabry-Perot data. Following on from this work, I managed the design, development, and deployment of a double etalon Fabry-Perot Interferometer, a sub-system of the Rayleigh-Mie-Raman lidar, at the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) in Andoya, Norway”, he concludes. It is important to mention that ALOMAR is part of the Andøya Rocket Range, the world´s northernmost launch site for sounding rockets, and hosts instruments from eight countries.


A view of the Alomar Observatory during lidar measurements (Credit: Trond Abrahamsen)

“In 1996 I moved to the Mullard Space Science Laboratory and began to study wave particle interactions in the Earth’s radiation belts using data from the Combined Release and Radiation Effects Satellite (CRRES). Here I studied processes affecting the acceleration and loss of relativistic electrons in the Earth’s radiation belts and developed global statistical models of the relevant plasma waves using the CRRES data. In 2004 I moved to the British Antarctic Survey to work on radiation belt dynamics with a particular emphasis on the further development of global statistical models of the waves and particles in space as input for radiation belt codes. Most recently, I led a work package to develop a new database of VLF waves using data from seven satellites improving both the global coverage and the statistics of the earlier models derived from CRRES.”

Protecting Satellites and Humans in Space

Solar storms can trigger bursts of fast moving particles and high energy radiation through interplanetary space and accompanying geomagnetic storms can increase the number of energetic particles trapped inside the Earth’s radiation belts. “Radiation belt physics is an exciting field that has scientific as well as societal value. The energetic electrons that inhabit the radiation belts can damage satellites and also pose a risk to humans in space”, warns Dr. Meredith. “Knowledge of the conditions in space is therefore important for satellite operators”, he adds.

Unfortunately, space weather is extremely unpredictable due to uncertainties over the basic physical processes and the need to access reliable data in real time. SPACECAST is a Collaborative Project funded by the European Union FP7 programme to help protect satellites on orbit by modelling and forecasting particle radiation. Dr. Meredith explains how this works: “Today we use our knowledge of the processes affecting the acceleration and loss of energetic electrons to construct models of the outer radiation belt, such as the BAS Radiation Belt Model. We also use these models to forecast the flux of energetic electrons in the outer radiation belt up to 3 hours ahead using a 3 hour forecast of the Kp index and provide these, together with associated risk indices, online []”. 

An important question today in space weather research is what is an extreme event? “This is interesting not only from a scientific but also a practical point of view since satellite operators need to know the largest electron fluxes that may be encountered during a satellite mission”.
To help answer this question, Dr. Meredith is actively involved in the EU FP7 project SPACESTORM: “I will be leading a work package that involves the use of long-term satellite electron data sets and model results to determine the largest fluxes that are likely to be encountered by a particular satellite over a 10, a 50 and a 100 year period”, he explains.


Image of the joint NASA/DOD Combined Release and Radiation Effects Satellite (CRRES). This satellite studied the Earth’s Radiation Belt environment for a 15 month period, from August 1990 to October 1991.(Credit: NASA)

Making a Contribution to Mankind
Dr. Meredith has certainly followed an impressive career path that will inspire young people who wish to get involved with science. However, how easy is it for young talented students to develop a successful career in space science? Science today is increasingly a team effort – so being part of a good team is critical”, says Dr. Meredith. “Since funding priorities change over time and, certainly, during the course of a scientific career, ability to adapt and take on new challenges is also important”, he adds.

But this is not all: “After many years as a research scientist the main lesson that I have learned is that, as in many walks of life, you need to be focussed and work hard to achieve success. It therefore helps if you are passionate about your work”. Certainly, like many professions, science faces several challenges and uncertainties today. “If you accept these uncertainties and embark on a career in science you will get the opportunity to work on interesting and challenging questions, travel and meet fellow scientists all over the world, and ultimately, make your own small contribution to the overall knowledge of mankind”, says Dr. Meredith.

How do you combine your passion about space science with personal life? “I spend my spare time with my lovely wife and young son, Arthur, who will be four this year. I still have that small telescope that I had as a boy in the garage and I look forward to showing him the wonders of the night sky and, hopefully, inspiring him to take an interest in astronomy and, more broadly, the marvels of the natural world”.

The MAARBLE project aims to advance scientific research on radiation belt dynamics and has a particular emphasis on data exploitation. My work within the MAARBLE consortium involves the analysis of 15 months of CRRES satellite measurements of electromagnetic ion cyclotron waves, a type of ultra-low frequency wave that could play an important role in the loss of radiation belt electrons. For SPACECAST and MAARBLE I used the satellite measurements to determine the average spectral properties of the waves and their distribution as a function of position and magnetic activity. The results of this study are being used by my colleagues at BAS as input to diffusion and radiation belt codes to help establish the role of these waves in radiation belt dynamics.

Eleni Chatzichristou

MAARBLE Outreach Team

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