Space Mission Mimics Eclipses, Reveals Sun’s Secrets

A novel UK-led space mission intends to recreate artificial solar eclipses, potentially revolutionizing how quickly astronomers understand the Sun’s inner workings. The mission offers closer views of the solar atmosphere than ever before.

Moon’s Shadow to Offer Unprecedented Solar Views

The Moon-Enabled Sun Occultation Mission (MESOM) is proposing a unique method of studying the inner solar corona. The inner solar corona, the Sun’s innermost atmospheric layer, is typically observable only during total solar eclipses on Earth.

Researchers from the Mullard Space Science Laboratory at **University College London (UCL)**, **Aberystwyth University**, and the **Surrey Space Centre**, which is part of the **University of Surrey**, are presenting MESOM.

If approved, MESOM could function for two years and record data equivalent to 80 Earth-based eclipses. This would give solar science an unparalleled opportunity, potentially yielding crucial information regarding the origins of space weather.

How MESOM Will Work

MESOM would position a small satellite in a specific orbit. This orbit allows alignment with the Moon’s shadow approximately every 29.6 days, which is the length of a synodic (lunar) month.

These alignments would replicate total eclipse effects, but in space, reaching a maximum of 48 minutes—ten times longer than typical terrestrial eclipses. Unlike observations from Earth, the satellite will capture data free from atmospheric interference.

Co-investigator **Dr. Nicola Baresi**, from the **Surrey Space Centre**, said: “MESOM capitalises on the chaotic dynamics of the Sun-Earth-Moon system to reproduce total solar eclipse conditions in space while using the Moon as a natural occulter (something which blocks light from a celestial object).”

MESOM seeks to probe the corona’s innermost region, offering key insights into solar storms, space weather, and coronal heating. Currently, this region is poorly understood because it is only accessible during eclipses.

Via its orbital configuration, MESOM would experience a total solar eclipse each synodic month when passing through the darkest part of the Moon’s shadow. This would allow closer solar observations than previously possible.

For comparison, the **European Space Agency’s (ESA)** existing Proba-3 mission observes the corona from approximately 1.1 solar radii (765,000 km), whereas MESOM would reach below 1.02 solar radii (710,000 km), or 56,000 km closer to the Sun.

Mission Instruments

MESOM would utilize several instruments, including a high-resolution coronal imager (led by the **US Naval Research Laboratory**), a corona mass spectrometer (**Aberystwyth University** and **Mullard Space Science Laboratory UCL**), and a spectropolarimeter (**Spanish Space Solar Physics Consortium, S3PC, Spain**).

**Dr. Baresi** stated: “When the Sun is near the orbital plane of the Moon, we can experience total eclipses as long as 48 minutes, which would enable unprecedented and prolonged measurements of physical processes from which adverse space weather events, namely solar flares and coronal mass ejections, may originate.”

While predicting space weather remains a challenge, understanding coronal mass ejections is crucial. In February 2022, a geomagnetic storm caused by a coronal mass ejection resulted in the loss of approximately 40 Starlink satellites (Space.com).

Next Steps for MESOM

The team submitted MESOM to **ESA’s** F-class mission call in May 2025 and anticipates a response later this year. If selected, launch could occur between 2026 and 2028.

F-class missions are designed to be more streamlined and cost-effective than **ESA’s** larger “M-class” missions, featuring a budget ceiling of €205 million (£175 million) and a development timeline of fewer than eight years from selection to launch.