Space Weather and Satellite Navigation Systems, by Professor Cathryn Mitchell

As the old saying goes, “All good things must come to an end.” This session marks the last in our Main Lectures for this season and what a fantastic talk to bring the curtains down.

The proceedings began with our host, Adrian Challinor commenting about how he missed the opportunity of seeing the Aurora in London last month but enjoyed seeing all the photographs which were submitted by members for the Astrophotography video.

Adrian introduced Mike Meynell to give us an insight into the night sky. Mike started his talk with an advice to look out for Noctilucent clouds over the late summer evenings after sunset but before darkness sets in. Mike explained that these are collections of ice crystals in the atmosphere and showed some images. Next, he spoke about the Perseid meteor showers and then opened up the talk about the Sun and what led to the fantastic Aurora activity which was seen across the UK in the previous month. We were taken through Mike’s journey of making his first sighting across his street, then over his house and then on Blackheath Park.

The talk ended with a description of the Summer Solstice and the visible planets over the summer period. Mike set out an astrophotography challenge for members to try and capture images of Noctilucent clouds, the Meteor shower or Solar activity.

Adrian then introduced our main speaker, Prof Cathryn Mitchell to talk about Space Weather and Satellite Navigation Systems. Cathryn began by giving us an insight into her early career while studying at University. She was unsure about what type of research to do and her professor bumped off another student and gave her the topic relating to Tomography and imaging systems for medical purposes. This defined her career and led to her completing a PhD on imaging systems on satellites.

On the 1st September 1859, British astronomer, Richard Carrington saw a flash of light while viewing the Sun and this turned out to be the first recorded observation of a Solar Flare. The associated Geomagnetic Storm was then classified as the Great Solar Storm of 1859 and resulted in Aurora sightings all over the Northern Hemisphere in the subsequent days. Telegraph lines of the day were adversely impacted and electrical currents were recorded on these lines although they were not connected to their power batteries.

We were then shown graphs of Solar activity across decades of data which were captured on sunspots. The solar activity which creates these sunspots defines the 11-year solar cycles. It turns out that the peak of the last Solar Cycle in 2012 had a lower number of sunspots compared to prior cycles, as such, there are irregularities from cycle to cycle.

The big question to be asked about solar storms are, “What is the problem?” It turns out, that these storms can have a negative impact on our daily lives including radio interference, GPS navigation, communications, power grids, rail networks, aircraft operations and also manned space flights. Cathryn pointed out that all the Apollo missions to the Moon were very lucky not to have encountered and form of solar storms.

Given the wide areas of possible impact, we need to understand what is being done to mitigate associated risks. It turns out that in 2015, Space Weather has been included in the National Risk Register of Civil Emergencies for the UK, and this was given a rating of medium impact. We also have this DSCOVER Satellite (Deep Space Climate Observatory) which trails Earth along its L1 orbital position and provides advance warnings of impending solar storms directed towards earth. The upcoming ESA Vigil Mission is a ‘sun surveyor’ which will also provide an advance warning system for solar storms which may have an impact on earth.

The talk ended with Cathryn’s personal experiences in seeing the Aurora in the UK last month and concluded that while we all got fantastic views of the Aurora, we should also be very grateful that there was no significant damage caused as a result of the associated Solar storm. It was a very enjoyable and informative talk and we all thanked Cathryn for her excellent presentation.

Q&A segment of the talk

Given that this was the last Main Lecture for this Season, Bobby took the opportunity to thank the team who was responsible for putting together the schedule of talks which began in September 2023. Mike Meynell drew up the list of speakers and this was gradually handed over to Paul May who took over as coordinator of Main Lectures.

Bobby bringing the Main Lectures to a close

Thanks and appreciation were also extended to the team members looking after refreshments, the control room, our colleagues at the Maritime Museum and all the members who have contributed towards organizing and running all the main lecture sessions.