A decade of discovery: AstroSat’s mission and purpose
India’s first multi-wavelength astronomy satellite, AstroSat, has completed 10 years of science observations, ISRO announced. Launched on 28 September 2015, AstroSat was designed to observe the universe across a broad swath of the electromagnetic spectrum—from ultraviolet to hard X-rays—unparalleled in a single mission. With a lift-off mass of about 1515 kg, the observatory has enabled simultaneous investigations of cosmic objects that emit across different wavelengths, a capability that helps astronomers assemble a more complete picture of astrophysical processes.
Payloads and capabilities: watching the sky in multiple colors
AstroSat carries five complementary instruments that work in concert to study a wide range of astronomical phenomena. The Ultraviolet Imaging Telescope (UVIT) captures high-resolution images in the ultraviolet, revealing hot, young stars and distant galaxies. The Soft X-ray Telescope (SXT) analyzes softer X-ray emissions from accreting black holes, neutron stars, and hot gas in galaxy clusters. The Large Area X-ray Proportional Counter (LAXPC) provides timing and spectral information at higher X-ray energies, crucial for tracking rapid variability in compact objects. The Cadmium—Zinc—Telluride Imager (CZTI) extends observations into hard X-rays, contributing to the study of energetic phenomena and the extinction of X-ray photons by interstellar matter. Completing the suite is the Scanning Sky Monitor (SSM), which keeps an eye on the X-ray sky for transient events and outbursts.
In combination, these instruments enable truly multi-wavelength astronomy: astronomers can observe a single source across UV to X-ray bands in a way that’s not possible with a single-telescope mission. This synergy has helped scientists disentangle complex physical processes—such as accretion onto compact objects, stellar evolution in extreme environments, and the energetic feedback that shapes galaxies—while also enabling rapid follow-up on transient events.
Launch, orbit, and a growing scientific legacy
AstroSat was launched aboard the PSLV-C30 rocket from the Satish Dhawan Space Centre in Sriharikota, India. Since entering service, the observatory has operated in a near-Earth orbit optimized for long, stable observations, enabling sustained studies of diverse cosmic sources. Over its first decade, AstroSat has contributed to a growing body of scientific literature, with numerous papers across major astronomy journals that explore black holes, neutron stars, X-ray binaries, active galactic nuclei, and the interstellar medium. The mission’s data have also supported cross-missive collaborations with international partners, expanding India’s role in global space science.
Impact and the road ahead
As India celebrates this 10-year milestone, the AstroSat program stands as a testament to the country’s ambition in space science and its ability to execute complex, capability-building missions. The multi-wavelength approach pioneered by AstroSat has influenced the design of subsequent Indian astronomy projects and has provided invaluable training grounds for a generation of scientists, engineers, and data analysts. While the operational life of AstroSat will be governed by vehicle health and onboard consumables, the mission’s legacy lies in its rich archive of multi-wavelength data, which will continue to fuel discoveries for years to come.
Looking to the future
ISRO has highlighted the importance of sustaining and expanding India’s scientific capabilities in space. As the astronomical community reflects on a decade of AstroSat science, efforts to leverage existing data, combine AstroSat results with future missions, and train the next generation of space scientists remain a priority. The decade-long milestone is not just a celebration of past achievements; it is a signal of ongoing commitment to world-class astronomy from a rising space nation.
