Research and analysis

Mission Review: Solar Orbiter

Published 14 August 2025

1. Executive Summary

Solar Orbiter is a Sun-observing probe developed by the European Space Agency (ESA) with contributions from the US National Aeronautics and Space Administration (NASA).

The UK Space Agency commissioned RAND Europe and Ipsos to produce a monitoring and evaluation (M&E) framework for future evaluations of the National Space Science Programme (NSSP) and the Science and Exploration Bilateral Programme (SEBP). As part of this, RAND Europe has conducted two mission reviews, into Solar Orbiter and the James Webb Space Telescope, to test this framework, but they do not constitute full evaluations.

Through the NSSP, the UK contributed £33m to the development of Solar Orbiter spacecraft and its instrumentation. The UK contributed to the development of four of the ten instruments hosted on Solar Orbiter, leveraging significant heritage in solar physics instrument development.

The UK played an important role in mission formulation, with the UK solar physics community involved since the early stages of the mission. Early engagement and enthusiasm from UK solar physics researchers, coupled with early UK financial support, led to successful UK proposals for leading roles in two instruments and contributions to two more. While internal funding decisions initially limited the UK to just two leadership roles, following funding shortfalls by international partners the UK stepped in to assume leadership roles on another instrument.

All four instruments which the UK led or contributed to were delivered on time and to specification, being delivered to Airbus UK in 2017 for integration into the payload ahead of launch in 2020. Stakeholders stated that the technological advancements made, as well as the reliability of delivery, have positioned the UK as a ‘partner of choice’ in space science and has led to future mission opportunities within ESA and with other bilateral partners. Examples include ESA’s upcoming space weather monitoring mission, Vigil, and NASA’s HelioSwarm and IMAP missions.

Solar Orbiter has supported high-skilled jobs and advanced the UK’s technological capabilities in space instrumentation, plasma physics and thermal engineering. All stakeholders involved in instrument development highlighted that involvement in Solar Orbiter was critical to the retention of employees, expertise and institutional knowledge developed through previous missions. Solar Orbiter grants supported 7.6 full-time equivalent (FTE) employees in the 2024–25 financial year, with more likely supported during the earlier development and build phases.

The downstream exploitation of data provided by Solar Orbiter has led to significant scientific and technical advancements. Improvements in solar modelling and ‘connection science’ aiming to increase understanding of the relationship between the solar surface and the solar wind feed directly into improved space weather modelling and forecasting capabilities. On one occasion a custom data-processing pipeline was implemented to provide science-ready data just 12 minutes after it was captured, as opposed to the standard three-month timeframe, showcasing the value of in situ space weather monitoring instrumentation. The risks of severe space weather events are outlined in key documents such as the UK government’s National Risk Register and the Severe Space Weather Preparedness Strategy. Potential impacts include disruption to power grids and transportation infrastructure as well as ground- and space-based instrumentation and digital infrastructure, presenting a key risk to the UK economy and population. Improved forecasting capabilities allow the UK to mitigate these risks.

The UK played a key role in the coordination of early Solar Orbiter Observing Plans (SOOPs), combining instrument knowledge, scientific expertise and operational experience. This role provided UK researchers with significant influence over the early scientific output of Solar Orbiter’s diverse instrument suite. This operational role would have been difficult to achieve without UK researchers’ familiarity with Solar Orbiter’s instrument suite gained through the development process.

Solar Orbiter plays a major role in outreach and engagement activities for participating organisations, both as instrument developers and downstream data users. Across development and post-launch, 200 public engagement efforts were reported by instrument development teams, with a majority involving direct engagement with the public. According to stakeholders, involvement in space science missions is a point of pride for the institutions involved, bringing significant reputational benefits. One stakeholder highlighted that involvement in world-leading space science missions like Solar Orbiter has been mentioned by prospective employees in job interviews, highlighting the inspirational impact of space science missions like Solar Orbiter.

Broadly, the NSSP enables UK leadership in international space science missions with a relatively small level of funding, as demonstrated in the UK’s leading role in the development of Solar Orbiter’s instrumentation suite and early operational role despite making only a relatively small contribution through the NSSP compared to the overall mission cost of approximately €1.35bn at launch. Despite these positive impacts, the UK Space Agency could take a more pro-active approach to identifying areas of existing expertise and strategic priority, using the NSSP as a lever through which to influence international space spending.

Overall, this mission review finds that the UK’s investments into Solar Orbiter have and continue to deliver significant value to the UK scientific community and industrial participants, showcasing the UK’s cutting-edge instrument development capabilities on the world stage. Given the expected operational longevity of Solar Orbiter and the recent launch date, the scientific benefits to the UK will likely continue to develop over the course of the mission’s lifetime. Further M&E efforts should be undertaken to assess the impacts of the UK’s investment into these instruments as Solar Orbiter’s operational life progresses.