The Aditya-L1 mission has recently reported its first science result, which involves the precise estimation of the onset time of a solar coronal mass ejection (CME). This achievement was made possible through data collected from the Visible Emission Line Coronagraph (VELC) payload onboard the spacecraft.

The Visible Emission Line Coronagraph (VELC) is a critical instrument aboard India's Aditya-L1 spacecraft, designed to study the Sun's corona. Launched on September 2, 2023, VELC is the primary payload of this mission, which aims to enhance our understanding of solar dynamics and their impact on space weather.

Launched on September 2, 2023, by the Indian Space Research Organisation (ISRO), Aditya-L1 is India's first dedicated mission to study the Sun and is positioned at the Lagrange point 1 (L1), approximately 1.5 million kilometers from Earth. This location allows for continuous observation of solar phenomena without interruptions caused by the Earth's shadow.

The VELC payload is designed to capture 1,440 images of the Sun daily, providing high-resolution data crucial for understanding solar dynamics. It employs advanced imaging techniques, including spectroscopy and Spectro-polarimetry, to analyse various aspects of the solar corona, chromosphere, and solar flares. This capability enables scientists to monitor coronal mass ejections (CMEs) and other solar activities in real-time.

VELC is positioned at the Lagrange Point 1 (L1), approximately 1.5 million kilometers from Earth, allowing it to continuously observe the Sun without interruptions from eclipses or occultations. This unique vantage point enables VELC to create a "total solar eclipse" effect, essential for studying the solar corona in detail.

The coronagraph captures images with a spatial resolution ranging from 1.25 to 2.5 arcseconds, making it capable of observing the corona closer to the Sun than any previous missions. VELC is designed to send back 1,440 images daily, providing real-time data for scientific analysis.

In addition to imaging, VELC incorporates spectroscopy and Spectro-Polarimetry capabilities. This allows scientists to analyse various spectral lines, crucial for understanding coronal heating processes and the dynamics of coronal mass ejections (CMEs).

The primary scientific goals of VELC includes, understanding Coronal Heating: Investigating why the solar corona reaches temperatures exceeding one million degrees Celsius while the Sun's surface remains around 6,000 degrees Celsius.
  
VELC will monitor Coronal Mass Ejections (CME)—massive bursts of solar wind and magnetic fields rising above the solar corona or being released into space. The instrument employs an automated algorithm developed by the Indian Institute of Astrophysics (IIA) and Aryabhata Research Institute of Observational Sciences (ARIES) to detect these events in real time.

By continuously observing solar activities, VELC will provide vital data on space weather phenomena that can affect satellites and communication systems on Earth.

Development And Collaboration

The development of VELC was led by the Indian Institute of Astrophysics (IIA) in collaboration with ISRO (Indian Space Research Organisation). The instrument was assembled and tested at IIA's facilities before being integrated into the Aditya-L1 spacecraft. The payload's design includes advanced optical components crafted to minimize light scatter, enhancing image clarity and data quality.