Table of Contents
The Visible Emission Line Coronagraph (VELC) instrument aboard India's Aditya-L1 solar mission is set to transmit around 1440 images of the Sun every day after entering orbit. The high-cadence solar imaging will enormously benefit studies of the enigmatic corona and transform our understanding of the Sun.
Scheduled for launch on September 2, 2023, at 11:50 AM Aditya-L1 carries a total of seven payloads to examine various layers of the Sun and the solar wind. The observatory will be inserted into a halo orbit around the Sun-Earth Lagrange point L1 - a gravitationally stable locationIdeal for uninterrupted solar observations.
After a complex journey of over 100 days from lift-off, Aditya-L1 will reach the L1 point in early 2024. Once commissioned, the pioneering Visible Emission Line Coronagraph (VELC) instrument will commence round-the-clock corona imaging.
Developed by the Indian Institute of Astrophysics (IIA) in Bengaluru, VELC is designed to study the outer layers of the Sun through specialized narrow-band filters. It will observe the corona in visible light starting from extremely close to the solar surface out to several solar radii.
VELC's unmatched imaging cadence of 24 hours a day will produce around 1440 images daily, enabling an unprecedented view of coronal dynamics. Monitoring the highly complex and structured corona is vital to comprehending its role in driving space weather impacts detected across the solar system.
Unraveling Mysteries of the Solar Corona
The corona is the tenuous outer atmosphere of the Sun that is visible during total solar eclipses. With temperatures exceeding 1 million degrees Celsius, the corona is much hotter than the solar surface which is only about 6000 degrees.
Scientists have long pondered over the physical mechanisms that heat the corona to such extreme temperatures and accelerate the supersonic solar wind streaming out through the heliosphere. Observations by the VELC instrument will provide new insights into these enduring mysteries.
VELC utilizes an internally occulting circular disk to block out the Sun's bright photosphere. This artificial eclipse allows detailed imaging and spectroscopy of the fainter corona extending beyond the occultor.
The novel coronagraph can detect the corona starting from just 1.05 solar radii above the surface, closer than any previous solar telescope. Closely monitoring the acceleration region of coronal mass ejections and the initiation of solar eruptions is crucial to predict their space weather impacts.
Halo Orbit Enables Continuous 24-hour Imaging
VELC owes its remarkable imaging capabilities to Aditya-L1's halo orbit around the L1 Lagrangian point. L1 is a gravitationally stable location approximately 1.5 million km from Earth in the Sun-Earth system.
A satellite positioned at L1 enjoys a continuous, unobstructed view of the Sun year-round. In contrast, a satellite in low Earth orbit experiences regular solar eclipses every 90 minutes as it passes into the shadow of the Earth.
The unique vantage point of L1 allows the VELC instrument to image the Sun without any breaks. VELC leverages this 24x7 visibility to capture 24 complete images of the corona every hour. This will generate around 1440 images daily for analyzing short-term changes in coronal structures.
The expansive VELC dataset will enable tracking solar storm evolution and constructing detailed 3D models of the corona. Aditya-L1's real-time storm monitoring and imaging capabilities will significantly advance space weather prediction efforts.
Enabling Cutting-Edge Coronal Research
The flood of VELC images represents an unprecedented boon for solar physicists seeking to unravel long-standing mysteries about the corona's perplexing properties.
Some key science goals aided by VELC include:
- Understanding coronal heating mechanisms
- Studying initiation and acceleration dynamics of coronal mass ejections
- Characterizing the magnetic architecture of the corona
- Investigating propagation of energetic particles through coronal structures
- Exploring the role of coronal transients in driving space weather
VELC images will be processed by the Indian Deep Space Network and forwarded to the Payload Operations Centre at IIA. Researchers will analyze this expansive dataset using advanced image processing algorithms, modeling, and data mining tools.
The insights gleaned will find applications across solar and plasma astrophysics. Aditya-L1 heralds a new era in Sun-Earth studies and cement's India's leadership in space sciences.
The ambitious Aditya-L1 solar mission signifies a major leap forward for Indian solar physics. The novel visible light coronagraph designed by IIA will provide an unprecedented view of the Sun's mysterious outer corona.
Generating around 1440 images daily, VELC will enable cutting-edge research into fundamental questions about coronal heating, solar eruptions, and space weather drivers. Aditya-L1 will cement India's position at the forefront of solar studies and space science.
Summarised from the origianl article by Hemant C.S. for TheHindu.com
Join the newsletter to receive the latest updates in your inbox.