Aditya-L1 and Proba-3: First Joint Study of Solar CMEs

🗞️ Why in News The Indian Space Research Organisation (ISRO) announced on 15 October 2026 that, for the first time, observations of the same solar eruptions by India’s Aditya-L1 and the European Space Agency’s (ESA) Proba-3 have been jointly analysed and published. Scientists at the Indian Institute of Astrophysics (IIA), Bengaluru, combined data from two coronagraphs, VELC on Aditya-L1 and ASPIICS on Proba-3, to measure the mass, density and energetics of coronal mass ejections (CMEs) in the region very close to the Sun.

The Study at a Glance

The observations are from September 2025. What is new is the joint analysis, which ISRO announced on 15 October 2026.

What a CME Is, and Why the Inner Corona Is Hard to See

ISRO defines CMEs as “large eruptions from the Sun in which huge amounts of magnetized plasma are thrown out into interplanetary space. When such eruptions are directed towards Earth, they can disturb the near-Earth space environment.” ESA’s Proba-3 media kit adds that CMEs or solar storms “can affect the functioning of satellites or communication and power networks down on Earth.”

The corona is the outermost layer of the Sun. ESA counts among its mysteries “the counterintuitive fact that it is more than a million degrees hotter than the surface of the Sun underneath it.”

The difficulty. The Sun is, in ESA’s words, “around a million times brighter than the brightest point within the corona”. A telescope that does not block the Sun’s disc “is blinded by this light and cannot see the corona, like trying to see a firefly right next to a floodlight.” A coronagraph solves this by blocking the disc and creating an artificial eclipse. Natural total eclipses are “rare and very brief, lasting at most a few minutes.”

The gap this study addresses. ISRO notes that “observing CMEs very close to the solar disk is challenging, and earlier space coronagraphs only partially succeeded in observing them and could not track the early evolution of faint CMEs.” As a result, “how CME energy is shared between kinetic, thermal, and magnetic in the inner corona has remained poorly constrained.” ESA describes the region within three solar radii as the place “where the solar wind and coronal mass ejections are born”, and says it “remains largely unexplored”.

The Two Missions

How Proba-3 makes its eclipse. The ASPIICS instrument is split across the pair. A 1.4 m occulting disc sits on the Occulter spacecraft, and the coronagraph optics sit on the Coronagraph spacecraft. When the two line up with the Sun about 150 metres apart, the disc blocks “the blinding body of the Sun”. ESA explains that stray light spilling over an occulter’s edge (diffraction) blurs the inner corona, and that this gets worse when the occulter is close to the coronagraph. For Proba-3, ESA says, the observing distance is “around two orders of magnitude larger than that of any other coronagraph so far.” Holding the pair in place needs formation flying “down to a single millimetre of precision”. ESA’s media kit says Proba-3 creates artificial total eclipses “for six hours at a time in every 19hr 36min orbit.”

“First” claims, attributed. ISRO calls Proba-3 “the world’s first precision formation-flying mission”. ESA’s own wording is that Proba-3 is “the first spacecraft to: perform precise formation flying manoeuvres and study the Sun’s corona this close to the solar rim”, and that it “marks the first time ever that ESA flies two spacecraft in precise formation together”.

How the Two Coronagraphs Worked Together

The two instruments looked at “almost the same part of the solar corona” in two different ways, and “share a common field of view in the low corona”.

• ASPIICS (imaging). Its white-light and green-line images “enable accurate estimates of a CME’s shape, dynamics, and mass.”
• VELC (spectroscopy). Its green-line spectra “provide information on CME gas at about two million degrees”, which gives “independent estimates of the CME’s density and thermal energy.” The paper’s abstract names the line as the Fe XIV 5303 Angstrom line.
• Rare overlap. Only two CMEs, on 14 and 16 September 2025, were caught by both instruments at once between July and December 2025. In both, “VELC caught the eruptions at an early stage.”

Key Findings

• The two instruments agree. “Estimates of mass and thermal energy from ASPIICS and VELC agree well, despite the two instruments using different geometric assumptions, physical considerations, and observation types.”
• Magnetic energy matters. “The estimated magnetic energy is comparable to or greater than the kinetic energy.” It is an estimate built on stated assumptions.
• The method is the message. ISRO’s conclusion: “pairing a coronagraph that images the corona with one that measures its spectrum yields a more complete, cross-checked view of the origin and evolution of CMEs.”

What it does and does not show. The study covers two eruptions and how they behaved close to the Sun. It is about how CMEs start and share their energy, not about their effects at Earth.

Static Background: Aditya-L1 and the L1 Point

The L1 point. “Aditya” means the Sun in Sanskrit, and L1 is Lagrange Point 1 of the Sun-Earth system. ISRO explains L1 as “a location in space where the gravitational forces of two celestial bodies, such as the Sun and Earth, are in equilibrium.” A satellite in a halo orbit around L1 has “the major advantage of continuously viewing the Sun without any occultation/eclipses.” Aditya-L1 does not travel towards the Sun: it “will neither land on the Sun nor approach the Sun any closer.”

The seven payloads. ISRO says all seven were developed indigenously: four view the Sun directly, and three study particles and fields in situ at L1.

The mission’s listed science objectives include the “Development, dynamics and origin of CMEs” and the “Drivers for space weather”. This study is a direct return on that objective.

Significance: The Mains Angle

• New science from Indian hardware. The study gives what ISRO calls “new observational constraints on the early evolution of CMEs”, using a payload built by an Indian institute.
• Space weather. CMEs aimed at Earth “can disturb the near-Earth space environment” (ISRO), and solar storms can affect satellites and communication and power networks (ESA). ISRO notes that measurements near the Sun are “very valuable for understanding the physical processes that shape CME properties and subsequent evolution.”
• Two methods, one answer. Imaging and spectroscopy reached matching estimates of mass and thermal energy by different routes. That cross-check is stronger than either instrument alone.
• Launched by India, studied with Aditya-L1. India launched Proba-3 on a PSLV as a commercial mission. An IIA-led team now pairs its data with Aditya-L1’s, in a study ISRO says shows “the strength of coordinated observations and associated international cooperation”.
• Aditya-L1’s growing return. ISRO presents the work as showing “the growing scientific impact of Aditya-L1”.

Way Forward

• Plan joint observing windows. Only two CMEs were caught by both instruments in six months, so coordinated schedules would add events.
• Build a larger sample. Two CMEs show the method works; firm conclusions about how CMEs share energy need many more.
• Feed the results into space-weather work, so that measurements near the Sun improve how CME behaviour is understood further out.
• Widen Indian use of Aditya-L1 data, so that more institutions turn the observatory’s data into published science.

UPSC Relevance

GS Paper 3: science and technology, developments and their applications; awareness in the field of space; achievements of Indians in science and technology.

Prelims: CMEs, the corona, coronagraphs, the L1 point and halo orbit, Aditya-L1 and its payloads, Proba-3 and formation flying.

Mains: “Explain why observing coronal mass ejections in the inner corona matters, and how the joint Aditya-L1 and Proba-3 study shows the value of international collaboration for India’s space science.” (GS3, 250 words)

📌 Facts Corner, Knowledgepedia

Prelims, statement-ready facts:

• ISRO announced the first joint analysis of the same solar eruptions by Aditya-L1 and Proba-3 on 15 October 2026.
• The study was led by IIA, Bengaluru, with European and American solar physicists; journal: Astronomy & Astrophysics.
• VELC (Aditya-L1) takes spectra, 1.05 to 1.5 solar radii; ASPIICS (Proba-3) takes images, about 1.1 to 3 solar radii.
• Aditya-L1: PSLV-C57, 2 September 2023; halo orbit around Sun-Earth L1 from 6 January 2024; seven payloads.
• Proba-3 (ESA): launched by PSLV-XL from Sriharikota on 5 December 2024; two spacecraft about 150 m apart.
• The two CMEs: 14 September 2025 (about 645 km/s) and 16 September 2025 (145 km/s).

Prelims, the traps:

• The CMEs were observed in September 2025, not October 2026; the news is ISRO’s announcement of 15 October 2026.
• Proba-3 is an ESA mission, not an ISRO one: India’s PSLV launched it, as a dedicated commercial mission of NSIL.
• VELC is the spectroscopic instrument and ASPIICS the imaging one, not the other way round.
• The magnetic energy was estimated on stated assumptions, not measured directly.
• Aditya-L1 sits about 1.5 million km from Earth (about 1% of the Earth-Sun distance); it does not approach the Sun.

Mains, arguments and keywords:

• Keywords: coronal mass ejection; inner corona; energy partitioning; space weather; coronagraph; formation flying; international cooperation.
• Pairing imaging with spectroscopy gives a cross-checked view; joint windows and a larger sample of CMEs are the way forward.

Interview, be ready for:

• “India launched Proba-3 for ESA; now their data pair with Aditya-L1. What does that say about India in space science?” India launched the mission, and an IIA-led team now uses its data alongside Aditya-L1’s.

Revision Flowchart

Sources: ISRO, “First Joint View by Coronagraphs on India’s Aditya-L1 and Europe’s Proba-3 Decodes Solar Eruptions Near Their Birthplace”, 15 October 2026 (release); Agarwal, A., Mishra, W., Ramesh, R., et al., “Coordinated Coronagraphic Observations from Proba-3 and Aditya-L1: Investigating CME Energetics in the Inner Corona”, arXiv:2609.06340, published in Astronomy & Astrophysics, 2026 (DOI 10.1051/0004-6361/202661733); ISRO, Aditya-L1 and Aditya-L1 mission details; ESA, Proba-3 media kit and Proba-3 science payloads; ISRO, PSLV-C59/Proba-3 mission.

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