MIST

Magnetosphere, Ionosphere and Solar-Terrestrial

Latest news

2019 Rishbeth prize winners announced

We are pleased to announce that the Rishbeth Prizes this year are awarded to Affelia Wibisono and Michaela Mooney , both of the Mullard Space Science Laboratory (UCL).
 
Affelia Wibisono wins the prize for the best MIST student talk, entitled “Jupiter’s X-ray Aurorae as seen by XMM-Newton concurrently with Juno”. Michaela wins the best MIST poster prize, for a poster entitled “Evaluating auroral forecasts against satellite observations”.
 
MIST Council would like to congratulate both Affelia and Michaela. As prize winners, Affelia and Michaela have been invited to write articles for Astronomy & Geophysics, which we look forward to reading.

Call for MIST/GEM Liaisons

There is a potential opening for a member of the MIST community to act as a liaison with the GEM (Geospace Environment Modelling) group. This will be an opportunity to act as a representative of the UK MIST community and inform GEM about relevant activities within the MIST community.

GEM liaisons will typically have the following responsibilities:

  1. Attend​​ a preponderance ​​of ​​GEM Steering ​​Committee ​​meetings​ ​at ​​summer​ ​workshop and​ ​mini-GEM​ ​​(June​ ​and​ ​December)
  2. Provide​​ written​​ annual​​ report​​ to​​ GEM Communications ​​Coordinator​​​ (by ​​April)
  3. Help ​​recruit ​​new​ ​GEM Steering​ ​Committee ​​members ​​​(as ​​needed)
  4. Provide ​​feedback​​ from​​ the​​ MIST community ​​and​​ share​​ with the GEM Chair/Vice​ ​Chair​ ​​(ongoing)

At this stage we would like to welcome any expressions of interest for this role from the community. If you are interested in being a GEM Liaison, then please This email address is being protected from spambots. You need JavaScript enabled to view it. including up to 100 words detailing why you would like to be a liaison and how your experience equips you for this role, and how often you would be able to attend GEM meetings.

If you have any further questions or would like more information about what the role would entail then please get in touch!

ESA Voyager 2050

As was touched upon at the business lunch at NAM, ESA has launched the next in its series of milestones to shape long-term scientific planning, which is called Voyager 2050.
 
The next milestone in this process is a call for white papers, and this is outlined in detail here. In short, 20 page proposals are invited describing clear science questions and explaining how a space mission would address those questions. The deadline is 5 August 2019.
 
MIST Council hopes that members of the MIST community are planning to submit white papers to this call, and we would be very interested to hear from those who are planning to do this, or those who have already applied to be part of the Topical Teams also outlined in the call.

MIST Council election results

Following a call for nominations, Greg Hunt (Imperial College London) and Maria-Theresia Walach (Lancaster University) have been elected unopposed to MIST Council. We congratulate the two new MIST councillors!

We would also like to express our thanks and appreciation to both Ian McCrea and Sarah Badman who are leaving MIST Council, for their invaluable contributions and commitment to the MIST community.

UK Space Agency call for nominations for the position of Chair of the Science Programme Advisory Committee

The UK Space Agency (UKSA) is seeking a new Chair for the Science Programme Advisory Committee (SPAC). The position of Chair of the Science Programme Advisory Committee will become vacant on 1 July 2019.

The UK Space Agency welcomes applications from the UK space science community. The full position and person specifications are on the Government's website.

 

Untangling the periodic ‘flapping’ and ‘breathing’ behaviour of Saturn’s equatorial magnetosphere

By Arianna Sorba, Department of Physics and Astronomy, University College London, UK.

At Saturn, the planet’s rotation axis and the dipole axis are aligned to within 0.01° [Dougherty et al., 2018], and so the magnetosphere’s magnetic field should be extremely azimuthally symmetric. However the Cassini space mission, which orbited Saturn from 2004-2017, observed mysterious periodic variations in the magnetic field at a period close to the planetary rotation rate. These observations suggested that the outer magnetosphere’s equatorial current sheet was `flapping’ above and below the rotational equator once per planetary rotation, to a first approximation acting like a rotating, tilted disc [Arridge et al., 2011].

However this ‘flapping’ picture does not fully explain the observed magnetic field periodicities. More recently, some studies have suggested the magnetosphere may also display ‘breathing’ behaviour; a periodic large-scale compression and expansion of the system, associated with a thickening and thinning of the current sheet [Ramer et al., 2016, Thomsen et al., 2017]. In Sorba et al. [2018], we investigate these two dynamic behaviours in tandem by combining a geometric model of a tilted and rippled current sheet, with a force-balance model of Saturn’s magnetodisc. We vary the magnetodisc model system size with longitude to simulate the breathing behaviour, and find that models that include this behaviour agree better with the observations than the flapping only models. This can be seen in the figure below, which shows that for an example Cassini orbit, both the amplitude and phase of the magnetic field variations are better characterised by the flapping and breathing model, especially for the meridional component (middle panel).

The underlying cause of this periodic dynamical behaviour is still an area of active research, but is thought to be due to two hemispheric magnetic field perturbations rotating at different rates. The study by Sorba et al. [2018] provides a basis for understanding the complex relationship between these perturbations and the observed current sheet dynamics.

For more information, please see the paper below:

Sorba, A.M., N. Achilleos, P. Guio, C.S. Arridge, N. Sergis, and M.K. Dougherty. (2018), The periodic flapping and breathing of Saturn's magnetodisk during equinox, J. Geophys. Res. Space Physics, 123. https://doi.org/10.1029/2018JA025764

Figure: Radial (a), meridional (b), and azimuthal (c) components of the magnetic field measured by Cassini along Rev 120 Inbound. Magnetometer data shown in black, flapping only model shown in red, and flapping and breathing model shown in blue. Annotation labels underneath the time axis give the cylindrical radial distance of Cassini from the planet centre, and Saturn magnetic local time.