Sriharikota (Andhra Pradesh) | The 22-hour countdown for the launch of an earth imaging satellite on-board a PSLV rocket commenced here on Saturday, ISRO sources said.

The lift-off for the PSLV-C61 is scheduled to take place at 5.59 am from the first launch pad at this space port on May 18, which is also the 101st mission for the Bengaluru-headquartered space agency.

"The countdown started by 7.59 am on Saturday. Total 22 hours countdown," sources told PTI.

The Polar Satellite Launch Vehicle (PSLV) in its 63rd mission, would carry the Earth Observation Satellite (EOS-09) which would be capable of capturing high-resolution images of the Earth's surface under all weather conditions.

The round-the-clock imaging by the satellite is vital for applications like agriculture, forestry monitoring, disaster management, urban planning and national security.

Weighing around 1,696.24 kg, the EOS-09 satellite would join the constellation of Earth Observation satellites, aimed at addressing the need for expanded real-time coverage across the country's vast territory.

The EOS-09 (RISAT-1B) is a follow-on to the RISAT-1 satellite which is equipped with similar configuration. It complements and supplements data from the Resourcesat, Cartosat and RISAT-2B Series satellites.

The Earth Observation Satellite-09 is a repeat satellite of EOS-04 launched in 2022. It has been designed with the mission objective to ensure remote sensing data for the user community engaged in operational applications and to improve the frequency of observation.

The PSLV-C61 rocket, after a 17 minute journey, is expected to place the EOS-09 satellite into the Sun Synchronous Polar Orbit (SSPO). Scientists, after the satellite gets separated in the desired orbit, would use the Orbit Change Thrusters (OCT) on the vehicle to reduce the altitude of the orbit, later.

The mission life of EOS-09 is 5 years, ISRO said.

According to scientists, a sufficient amount of the fuel has been reserved for de-orbiting the satellite after its effective mission life by lowering it to an orbit that ensures its decay within two years, towards ensuring a debris-free mission.