ISRO Set to Launch All-Weather Surveillance Satellite EOS-09 Aboard PSLV-C61 On May 18

By Surabhi Gupta

New Delhi: In a key move to ramp up India’s Earth observation and strategic surveillance capabilities, the Indian Space Research Organisation (ISRO) will launch the PSLV-C61 mission on 18 May 2025, at 6:59 am IST from the Satish Dhawan Space Centre at Sriharikota. The rocket will be carrying the state-of-the-art radar imaging satellite EOS-09, also referred to as RISAT-1B, into sun-synchronous orbit.

The mission carries substantial weight in both civilian and national security terms, as it is happening while India is rapidly extending its space-based surveillance capacity against threats and disasters.

Strategic Eye in the Sky

The EOS-09 satellite uses an advanced C-band Synthetic Aperture Radar (SAR), which can provide all-weather, day-and-night imaging. This is especially important for monitoring the India-Pakistan and India-China borders in real-time and for coastal surveillance and counter-terrorism.

"This launch is strategically timed," said former ISRO scientist Manish Purohit. "It strengthens monitoring at borders and coasts, particularly with respect to sensitive areas. The satellite can detect ingress or suspicious movement deemed vital in anti-terror operations, especially after the recent Pahalgam terror attack and Operation Sindoor," added Purohit.

Purohit also noted that the satellite would serve as a follow-on to the earlier RISAT-1 mission, which was decommissioned in 2017. While RISAT-2 and EOS-01 used X-band radar for higher resolution, EOS-09’s C-band SAR strikes a balance, offering up to 1-meter resolution while covering wider swaths of territory.

Civilian and Disaster Management Applications

EOS-09 will have general uses next to its military profile. The satellite will be useful for many civilian applications, including, agricultural (crop monitoring, soil moisture), urban monitoring, hydrology, forestry mapping. Additionally, it provides critical disaster management uses by providing real-time map of floods, tracking cyclones, and assessing landslide movement.

"The satellite has five imaging modes that include High-Resolution Spotlight and Medium Resolution ScanSAR and ISRO can switch between ultra-fine-detail monitoring and wide area monitoring," explained Purohit.

"EOS-09 complements existing satellites such as Resourcesat, Cartosat, and RISAT-2B. These satellites collectively provide a powerful Earth observation platform and layer of surveillance," Purohit said.

Expanding the Space Surveillance System

The 1,710-kg EOS-09 satellite is part of India’s complete plan of placing 52 Earth observation satellites in orbit over a five-year period. These will monitor everything from climate change and agriculture to strategic infrastructure and border movements.

ISRO Chairman V. Narayanan has repeatedly stressed the critical role of satellite technology in national security and governance. “With the PSLV-C61/EOS-09 mission, ISRO continues to demonstrate its commitment to both technological excellence and the national interest,” he recently stated.

The Indian National Space Promotion and Authorization Centre (IN-SPACe), which oversees private sector participation in India’s space programme, echoed this sentiment. “We have fairly strong capabilities already. It is just that it needs constant enhancement,” said IN-SPACe Chairman Pawan Kumar Goenka.

A Packed Calendar Ahead

The launch of PSLV-C61 is just the beginning of a busy period for ISRO, with multiple high-profile missions lined up between May and July 2025. These missions reflect a strategic pivot in India’s space ambitions—from exploration to application, from demonstration to deployment.