When a solar storm strikes Earth, it can disrupt technologies vital to daily life. These storms occur when bursts of electrically charged particles and magnetic fields from the Sun collide with Earth’s magnetic field, producing what is known as space weather.
The Earth is currently experiencing one of the most intense solar storms of the past two decades, highlighting the need to better understand these events. An international team of researchers is working on a spacecraft mission designed to study the solar conditions that generate such storms, with the aim of improving space-weather forecasting.
The proposed mission, known as Mesom (Moon-enabled Sun Occultation Mission), would create total solar eclipses in space. By doing so, it would allow scientists to observe the Sun’s outer atmosphere — the solar corona — in unprecedented detail.
Past disruptions show why this matters. In 1989, a coronal mass ejection (CME) triggered a nine-hour power blackout in Quebec, affecting Canada and the US and costing tens of millions of dollars in lost productivity and damaged equipment. More recently, in May 2024, a series of weaker solar eruptions caused thousands of satellites in low-Earth orbit to lose altitude. GPS outages alone cost US farmers an estimated $500 million.
These events pale in comparison with the 1859 Carrington Event, the most powerful solar storm on record. Electrical currents surged through telegraph wires across North America and Europe, shocking operators and even starting fires. A storm of similar magnitude today would have catastrophic consequences for our technology-dependent world, a risk recognised by successive UK governments.
Yet our view of the solar corona — where CMEs originate — remains obscured by the Sun’s own intense brightness. During total solar eclipses, the Moon blocks the Sun’s visible surface, revealing the faint glow of the corona. Studying this region is crucial for understanding how solar storms form and for improving forecasts that could protect Earth’s infrastructure.
Unfortunately, total eclipses are rare and brief, lasting only a few minutes and occurring roughly once every 18 months. Ground-based observations are further limited by weather and atmospheric distortion. Artificial alternatives, known as coronagraphs, use disks and optical filters to block sunlight and have provided valuable data, including from the Soho spacecraft since 1995. However, even the most advanced coronagraphs struggle to observe the deepest layers of the Sun’s atmosphere.
Mesom proposes a different approach: using a natural celestial body as the occulting disk. The Moon, with its near-perfect spherical shape and lack of atmosphere, is an ideal candidate. By flying a mini-satellite into the Moon’s shadow, Mesom would recreate eclipse conditions without Earth’s atmospheric interference.
Developed by engineers and scientists at the Surrey Space Centre and partner institutions, Mesom would exploit the dynamics of the Sun-Earth-Moon system to observe the inner solar corona once a month for up to 48 minutes at a time — far longer than eclipses seen from Earth.
Funded by the UK Space Agency, the project has grown into an international consortium led by UCL’s Mullard Space Science Laboratory. Recently submitted to the European Space Agency for consideration, the mission could launch in the 2030s. Over two years, Mesom would return at least 400 minutes of high-resolution coronal observations — data that would otherwise take more than 80 years to collect from Earth.
The Conversation