BENGALURU: In a first-of-its-kind scientific collaboration, researchers from Bengaluru and their international partners have jointly analysed observations of the same solar eruptions captured by two different space missions, India's Aditya-L1 and the European Space Agency's Proba-3, unlocking fresh insights into how violent solar storms evolve close to the Sun.
The study, published in the journal Astronomy & Astrophysics, was announced in a statement issued by the Indian Space Research Organisation (ISRO) on October 16, 2026. Scientists at the Indian Institute of Astrophysics (IIA) in Bengaluru combined data from the Visible Emission Line Coronagraph (VELC) aboard Aditya-L1 with the ASPIICS coronagraph aboard Proba-3 to measure the mass, density and energetics of coronal mass ejections, or CMEs, the giant eruptions of plasma that the Sun periodically hurls into space.
What makes the work remarkable is that the two instruments looked at almost the same region of the solar corona in two fundamentally different ways. VELC performed spectroscopy, splitting the light from the hot CME gas into its component wavelengths, while ASPIICS captured sharp images of the eruptions. ISRO said the joint observations provide deeper insights into CME evolution than any single-spacecraft observation could deliver on its own.
To understand why this matters, it helps to start with the Sun itself. Our star is a roiling ball of hot, electrically charged gas threaded through with powerful magnetic fields. Every so often, twisted magnetic structures in the solar atmosphere snap and reconfigure, releasing enormous amounts of energy and expelling billions of tonnes of magnetised plasma into interplanetary space. These are coronal mass ejections.
When a CME strikes Earth, it interacts with our planet's magnetic field and can disturb the near-Earth space environment. The consequences range from spectacular auroras to serious disruption: satellites can be damaged or knocked off course, navigation signals can degrade, astronauts in orbit face increased radiation exposure, and in extreme cases power grids on the ground can suffer damage. Predicting when a CME will erupt and how powerful it will be is therefore one of the central goals of space weather science.
Yet observing CMEs very close to the Sun, where they are born and gain their early momentum, has been one of the hardest problems in solar physics. The solar corona, the Sun's faint outer atmosphere, is a million times dimmer than the solar disc itself. A coronagraph blocks the blinding light of the Sun's surface, creating an artificial eclipse that reveals the corona's delicate structures. Even so, the earliest stages of a CME's life unfold in the low corona, a region just above the Sun's surface that earlier instruments could not track with sufficient clarity. As a result, a basic question remained poorly answered: how does a CME's energy divide itself among motion, heat and magnetism as the eruption unfolds?
The new study tackles that question head-on by exploiting the complementary strengths of the two missions. ASPIICS, which stands for Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun, observes the corona in white light and in the green coronal emission line. Its crisp images allow scientists to estimate a CME's shape, its speed and direction of motion, and its total mass with high accuracy. VELC, meanwhile, is a spectroscopic coronagraph. It analyses the light emitted by CME gas heated to about two million degrees, which yields independent estimates of the plasma's density and thermal energy, quantities that images alone cannot pin down. Because the two instruments share a common field of view in the low corona, their data could be fused to build a fuller picture of each eruption.
Such a joint analysis was possible only because the two missions happened to catch the same eruptions at the same time. Aditya-L1, India's first dedicated solar mission, was launched aboard a PSLV rocket on September 2, 2023, and reached its halo orbit around the Sun-Earth L1 Lagrangian point on January 6, 2024. From that vantage point, roughly one and a half million kilometres from Earth on the Sun-facing side, it enjoys an uninterrupted view of the Sun. VELC, the spacecraft's primary payload, was developed by the Indian Institute of Astrophysics in collaboration with ISRO, and it observes the solar corona between 1.05 and 1.5 solar radii in the green coronal emission line at 5303 Angstroms.
Proba-3 is a far newer arrival. Launched by an ESA mission on an Indian PSLV-XL rocket from Sriharikota on December 5, 2024, it is the world's first precision formation-flying mission. Its two spacecraft fly in tandem about 150 metres apart, with one spacecraft positioning itself precisely between the other and the Sun. This arrangement casts a controlled shadow across the second spacecraft, creating a sustained artificial solar eclipse in space. The technique lets ASPIICS image the inner corona continuously, from about 1.1 to 3 solar radii, in white light and in the same 5303 Angstrom green line that VELC watches.
Between July and December 2025, a window during which both coronagraphs were collecting data, the researchers found that only two CMEs were recorded simultaneously by both instruments. Those two events, on September 14 and September 16, 2025, became the basis for the study. In both cases, VELC captured the eruptions at an early stage of their evolution, confirming the instrument's ability to pick out faint eruptions in the low corona. The two events could hardly have been more different: the September 14 CME was a fast eruption racing outward at about 645 kilometres per second, while the September 16 CME was a slow, sluggish event creeping along at just 145 kilometres per second. Together they offered a contrasting pair on which to test the joint analysis method.
By combining ASPIICS imaging with VELC spectroscopy, the team derived estimates of the mass, density and energetics of both CMEs that are more robust than either dataset could provide alone. Imaging gives the geometry and the bulk motion; spectroscopy gives the temperature and the density. Put together, they constrain the thermal energy budget of the eruption, feeding directly into the question of how a CME's energy is partitioned as it grows and accelerates.
The collaboration also marks a notable moment in India-Europe space cooperation. Aditya-L1 and Proba-3 are missions of different agencies, built for different purposes, yet their data turned out to be deeply complementary. The Proba-3 mission itself has a strong Indian connection, having been lofted into orbit by an Indian launcher from Sriharikota. The joint study shows how international coordination, even between missions not originally designed as a pair, can multiply the scientific return of both.
The work is a significant scientific milestone for Aditya-L1, whose payloads are now producing peer-reviewed results from the L1 vantage point. VELC, in particular, has a demanding job: observing the faint corona from space at a spectral resolution high enough to reveal the motions and temperatures of erupting plasma.
More broadly, the result points to a future in which solar physics is done by teams of spacecraft rather than lone sentinels. The Sun does not respect mission boundaries, and neither do its eruptions. By watching the same eruption through different eyes, scientists can separate what is real from what is merely an artefact of one viewing geometry, and can measure quantities that no single instrument can capture. As solar activity continues through the current cycle, both missions will have more chances to catch eruptions in the act, and the catalogue of jointly observed events will grow.
For space weather forecasting, the stakes are practical. The earlier a CME's mass, speed and energy can be measured accurately, the earlier forecasters can estimate when it will reach Earth and how strong its effects might be. Measurements made close to the Sun, in the first stages of an eruption's life, are the most valuable of all, because they feed directly into models that predict the storm's journey across interplanetary space. The Aditya-L1 and Proba-3 results show a path to those early, accurate measurements.
The study's authors note that the two CMEs analysed so far are only the beginning. The overlapping observations offer a template for studying future eruptions with the same combined technique. Each new joint event will refine the method further, adding to the statistics needed to answer the deeper question of how solar eruptions channel their energy. For now, the work stands as a proof that two spacecraft, two agencies and two ways of seeing the Sun can together reveal more than the sum of their parts.
(Reporting based on ISRO, The Hindu and The Times of India.)