On May 17, 2025, the Indian Space Research Organisation (ISRO) began a 22-hour countdown for the highly anticipated launch of the EOS-09 earth-imaging satellite aboard the PSLV-C61 rocket, marking the 63rd mission of India's most frequently flown launch vehicle, the Polar Satellite Launch Vehicle (PSLV).

Scheduled for lift-off at 5:59 am IST on May 18 from the Satish Dhawan Space Centre in Sriharikota, this mission also represents the 101st launch from India’s only spaceport.

The EOS-09 satellite, weighing 1,700 kilograms, is designed for a minimum operational life of five years and will be placed in a Sun Synchronous Polar Orbit at an altitude of 529 kilometres, approximately 18 minutes after launch. Notably, EOS-09 is a radar imaging satellite (formerly known as RISAT), capable of day and night imaging through clouds and adverse weather, providing all-weather surveillance capabilities.

A key aspect of this mission is ISRO’s commitment to reducing space debris. After deploying the satellite, the PSLV’s upper stage will use orbit change thrusters to gradually lower its orbit, facilitating its eventual de-orbiting and atmospheric burn-up.

Similarly, EOS-09 carries extra fuel for a controlled de-orbit at the end of its service life, ensuring it does not contribute to the growing problem of space debris.

The launch comes shortly after a ceasefire between India and Pakistan, but ISRO clarified that the timing is coincidental, as satellite and launch preparations began months in advance.

The EOS-09 joins a constellation of Indian satellites serving both strategic and civilian roles, including the CARTOSAT and RISAT series, EMISAT, and communication satellites like GSAT-7 and GSAT-7A, which support India’s armed forces. The RISAT series is unique in its use of radar imaging, which enables round-the-clock, all-weather observation, unlike conventional optical satellites that rely on visible light.

In recent years, ISRO has adopted the ‘EOS’ (Earth Observation Satellite) nomenclature for all earth-imaging satellites, reflecting their dual-use potential for both defence and civilian applications. India currently operates around 55 satellites for various purposes, but ISRO Chief Dr. V. Narayanan has highlighted the need for 100-150 satellites to monitor the country’s extensive land and maritime borders.

However, satellite launches are subject to approvals and budget allocations from the relevant government ministries, such as Defence or Earth Sciences, depending on the satellite’s intended use.

Adding to the significance of this mission, 40 Indian parliamentarians from the Parliamentary Standing Committee of Science and Technology will witness the PSLV-C61 launch at Sriharikota as part of their official visit to government establishments in Tamil Nadu and Andhra Pradesh.

Their presence underscores the importance of India’s space programme and its growing strategic and technological ambitions. The PSLV-C61/EOS-09 mission not only showcases ISRO’s technological prowess but also its responsible approach to space sustainability and national security.

Agencies