Almost 30 years since the last UK nuclear test, it remains necessary regularly to underwrite the safety and effectiveness of the National Nuclear Deterrent. To do so has been possible to date because of the development of continually improving science and engineering tools running on ever more powerful high-performance computing platforms, underpinned by cutting-edge experimental facilities. While some of these facilities, such as the Orion laser, are based in the UK, others are accessed by international collaboration. This is most notably with the USA via capabilities such as the National Ignition Facility, but also with France where a joint hydrodynamics facility is nearing completion following establishment of a Treaty in 2010. Despite the remarkable capability of the science and engineering tools, there is an increasing requirement for experiments as materials age and systems inevitably evolve further from what was specifically trialled at underground nuclear tests (UGTs). The data from UGTs will remain the best possible representation of the extreme conditions generated in a nuclear explosion, but it is essential to supplement these data by realizing new capabilities that will bring us closer to achieving laboratory simulations of these conditions. For high-energy-density physics, the most promising technique for generating temperatures and densities of interest is inertial confinement fusion (ICF). Continued research in ICF by the UK will support the certification of the deterrent for decades to come; hence the UK works closely with the international community to develop ICF science. UK Ministry of Defence © Crown Owned Copyright 2020/AWE. This article is part of a discussion meeting issue ‘Prospects for high gain inertial fusion energy (part 1)'.

This paper describes the development of the science orbit for the 2016 ESA/NASA collaborative ExoMars/Trace Gas Orbiter (TGO) mission. The initial requirements for the ExoMars/TGO mission simply described the science orbit as circular with a 400 km altitude and a 74 deg inclination. Over the past year, the JPL mission design team worked with the TGO science teams to refine the science orbit requirements and recommend an orbit that would be operationally feasible, easy to maintain, and most important allow the science teams to best meet their objectives.

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