b'Geophysics in the surveysNewsTable 6.Passive seismic surveys Location Client State SurveyTotal number ofSpacing Technique Commentsname stations deployedAustralia GA Various AusArray About 180~200 kmBroad-bandThe survey will cover all of Australia to establish temporal seismicspacing~18 months ofcontinental-scale model of lithospheric structure and stations observationsserve as a background framework for more dense (~50km) movable seismic arrays. Deployment of this national array commenced with an initial 11 seismic stations deployed in the NT and will progress to other States and Territories depending on the pace of land clearance process and the status of COVID-19 travel restrictions.NorthernGAQld/NTAusArrayAbout 265 broad- 50 kmBroad-band 1The survey covers the area between Tanami, Tennant Australia band seismicyear observationsCreek, Uluru and the Western Australia border.The first stations public data release of the transportable array was in 2020, with further data and model releases expected by Dec 2022.See: http://www.ga.gov.au/eftf/minerals/nawa/ausarray Various applications of AusArray data are described in the following Exploring for the Future extended abstracts:AusArray overview: http://pid.geoscience.gov.au/ dataset/ga/135284Body wave tomography: http://pid.geoscience.gov. au/dataset/ga/134501Ambient noise tomography (including an updated,higher resolution model for the Tennant Creek to Mount Isa region): http://pid.geoscience.gov.au/dataset/ga/135130Northern Australia Moho: http://pid.geoscience.gov. au/dataset/ga/135179Australia GA Various AusArray,12 high-sensitivity~1000 km Broad-bandSemi-permanent seismic stations provide a back-semi- broad-band4 yearsbone for movable deployments and complement the permanent seismic stations observations Australian National Seismological Network (ANSN) operated by GA, ensuring continuity of seismic data for lithospheric imaging and quality control. Associated data can be accessed through http://www.iris.eduHenderson byte: The latest on Mercurys magnetic fieldOn 1 October 2021, the first of many planned fly bys of Mercury by a new spacecraft was successfully completed. Its purpose, among other things, was to learn more about the nature of Mercurys magnetic field.Before 1 October, two spacecraft had orbited Mercury. The first, Mariner 10, flew by three times during 1974 and 1975 and covered about half of the planets surface. In April 1974 a magnetic field was detected, albeit a weak one, only 1.1% of the strength of Earths magnetic field. Its detection was taken by some scientists as an indication that Mercurys outer core was still liquid, or at least partially liquid with iron and possibly other metals. In which case, a global field could be generated by the dynamo mechanism.The second mission to Mercury, Messenger, was in orbit from 17 March 2011, for four years. By careful analysis of the behaviour of the orbits under gravity, it was confirmed that the planet has a liquid outer core and a solid inner core.To date we know that the field is approximately a dipole of global extent. Like Earths magnetic field, the field is tilted but more asymmetric being stronger at its south pole. The magnetic field is strong enough near the bow shock facing the Sun to slow the solar wind, and produce a magnetosphere.To learn even more about the origin of the magnetic field, BepiColombo, a joint mission of the European Space Agency and the Japan Aerospace Exploration Agency was launched on 20 October 2018. Its arrival in orbit at Mercury is planned for 5 December 2025, after six fly bys. The mission will perform a comprehensive study of Mercury, including characterisation of its magnetic field, the solid and liquid cores in more detail and the magnetosphere. It will also conduct some gravity mapping.BepiColombo comprises two satellites launched together: the Mercury Planetary Orbiter (MPO) and Mercury Magnetospheric Orbiter (MMO). The MPOs scientific payload has eleven instruments including a magnetometer. The MMOs five groups of instruments also include a magnetometer. On arriving in orbit on 5 December 2025, the MMO and MPO satellites will separate and observe Mercury in collaboration for one year or more. Note the date in your calendar!Roger Henderson rogah@tpg.com.auFEBRUARY 2022 PREVIEW 16'