India Opens the Sun to the World: Aditya-L1 Ushers in a New Era of Global Solar Science.

India has entered a historic phase in solar science with the Aditya-L1 mission, the country’s first dedicated space observatory for studying the Sun. The Indian Space Research Organisation (ISRO) has now opened the mission to the global scientific community through its first Announcement of Opportunity (AO) cycle, inviting researchers to submit observation proposals.

This move marks a transition from the mission’s deployment phase to full-scale collaborative scientific research, placing India among the world’s leading nations conducting advanced solar studies. Scientists from India and across the globe will now have the opportunity to request dedicated observation time using some of the mission’s most powerful instruments.

The decision reflects a major step in India’s growing role in international space science and demonstrates ISRO’s commitment to open scientific collaboration and global knowledge sharing.

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The Strategic Importance of the Sun–Earth L1 Orbit

The Sun–Earth Lagrange Point L1 is one of the most valuable observation points in space science. Located about 1.5 million kilometers from Earth, this gravitationally stable point allows spacecraft to maintain a continuous view of the Sun.

Unlike Earth-orbiting satellites that frequently pass through Earth’s shadow, a spacecraft at L1 can observe the Sun without interruptions from eclipses or occultation. This uninterrupted monitoring capability is essential for studying dynamic solar phenomena such as:

• Solar flares

• Coronal mass ejections (CMEs)

• Solar wind acceleration

• Magnetic field variations

• Coronal heating processes

Aditya-L1 reached its operational halo orbit around L1 on January 6, 2024, after launching from the Satish Dhawan Space Centre on September 2, 2023. Since then, the spacecraft has been steadily sending back valuable data about solar behavior.

This orbit makes Aditya-L1 comparable to global solar observatories such as NASA and ESA’s missions that monitor the Sun continuously to predict space weather events.

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Opening the Observatory to Global Researchers

ISRO’s Announcement of Opportunity represents a major milestone in the mission’s lifecycle. Researchers can now submit scientific proposals to utilize the spacecraft’s observational capabilities.

Approved proposals will receive access to observation time during a three-month window from April to June 2026.

Two key instruments will be available for this cycle:

1. Visible Emission Line Coronagraph (VELC)

The VELC instrument is designed to observe the Sun’s outer atmosphere, or corona, which is millions of degrees hotter than the solar surface. The instrument acts like an artificial eclipse, blocking the Sun’s bright disk and allowing scientists to study faint coronal structures.

VELC will help scientists understand:

• The origin of coronal mass ejections

• Solar magnetic field dynamics

• The mechanism behind coronal heating

• The acceleration of solar winds

2. Solar Ultraviolet Imaging Telescope (SUIT)

The SUIT instrument studies the Sun in ultraviolet wavelengths. These wavelengths are crucial for understanding the solar photosphere and chromosphere, the layers responsible for driving solar variability.

SUIT provides high-resolution images that help scientists analyze:

• Solar irradiance changes

• Sunspot formation

• Magnetic field interactions

• Energy transport mechanisms

Research proposals must be submitted through the Aditya-L1 Proposal Processing System, where they will be evaluated by ISRO’s Time Allocation Committee based on scientific merit and technical feasibility.

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Seven Scientific Instruments Studying the Sun

Aditya-L1 carries seven sophisticated scientific payloads, each designed to observe different aspects of the Sun.

Remote Sensing Instruments

These instruments observe the Sun directly.

• VELC (Visible Emission Line Coronagraph) – Studies the solar corona

• SUIT (Solar Ultraviolet Imaging Telescope) – Captures ultraviolet images

• SoLEXS (Solar Low Energy X-ray Spectrometer) – Observes solar flares

• HEL1OS (High Energy L1 Orbiting X-ray Spectrometer) – Studies high-energy X-ray emissions

In-Situ Instruments

These measure solar particles and fields in space around the spacecraft.

• ASPEX (Aditya Solar Wind Particle Experiment) – Studies solar wind particles

• PAPA (Plasma Analyser Package for Aditya) – Measures plasma composition

• MAG (Magnetometer) – Monitors magnetic fields

Together, these instruments allow scientists to analyze solar activity from multiple perspectives, providing a comprehensive picture of solar dynamics.

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Understanding Space Weather

One of the primary objectives of Aditya-L1 is to improve our understanding of space weather.

Space weather refers to disturbances caused by solar activity that can affect Earth’s technological systems. These include:

• Satellite disruptions

• GPS signal disturbances

• Power grid failures

• Radiation exposure risks for astronauts

• Communication interruptions

For example, powerful coronal mass ejections can send billions of tons of charged particles toward Earth. When these particles interact with Earth’s magnetic field, they can create geomagnetic storms.

Accurate forecasting of such events is becoming increasingly important as modern society becomes more dependent on satellite infrastructure and global communication systems.

Aditya-L1’s continuous monitoring capability allows scientists to detect early signs of these events and improve predictive models.

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The Significance of Solar Maximum in 2026

The timing of the Announcement of Opportunity is particularly important because 2026 coincides with the solar maximum, the most active phase of the Sun’s roughly 11-year solar cycle.

During solar maximum:

• Sunspot numbers increase dramatically

• Solar flares become more frequent

• Coronal mass ejections intensify

• Solar radiation variations become stronger

These events provide scientists with a rare opportunity to observe solar processes at their peak intensity.

Aditya-L1’s coronagraph will play a critical role during this phase by enabling continuous observation of coronal activity, helping scientists capture real-time data on solar eruptions.

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A Major Step Toward Open Science

One of the most notable aspects of this initiative is ISRO’s commitment to open data policies.

In an unusual move that strongly promotes collaborative science, the agency has announced no proprietary period for the mission’s data during the first observation cycle.

This means:

• Data will be released immediately after collection

• Scientists worldwide will have equal access

• Collaborative research will be encouraged

• Global solar research will accelerate

All mission data will be available through the Indian Space Science Data Centre (ISSDC).

As of now, more than 23 terabytes of mission data have already been released, and several scientific papers based on this data have appeared in international peer-reviewed journals.

This open approach mirrors the practices of major space agencies such as NASA and the European Space Agency, ensuring that Aditya-L1 contributes significantly to global solar research.