Explained: What Makes ISRO’s Third Developmental Flight, SSLV-D3, Stand Out?

The Indian Space Research Organisation (ISRO) is preparing to launch the Earth Observation Satellite-08 (EOS-08) at 9:17 a.m. on Friday, using the third developmental flight of the Small Satellite Launch Vehicle (SSLV-D3). The launch will take place at the Satish Dhawan Space Centre in Sriharikota, Andhra Pradesh.

This will be ISRO’s third developmental flight in the SSLV program. The first flight, SSLV-D1, launched on August 7, 2022, carrying the Microsat 2A and AzaadiSAT satellites. However, it failed to place the satellites in their intended orbit due to a sensor malfunction that went undetected by the ground teams. The second flight, SSLV-D2, successfully launched on February 10, 2023, deploying the EOS-07, Janus-1, and AzaadiSAT-2 satellites into a 450-kilometer orbit.

What Makes SSLV-D3 Special?

Space experts note that the SSLV is a three-stage rocket powered by solid propellants. Its terminal stage, known as the Velocity Trimming Module (VTM), uses liquid propulsion to fine-tune the rocket’s velocity and ensure the payload reaches its designated orbit. The VTM controls thrust by releasing small amounts of liquid fuel, allowing precise adjustments to the rocket’s speed.

The SSLV stands at 34 meters tall, with a width of 2.1 meters and a liftoff mass of about 120 tonnes. Its design supports a wide range of payloads, including nanosatellites (1-10 kg), microsatellites (10-100 kg), and mini-satellites (100-500 kg). This flexibility, coupled with a rapid launch turnaround time, allows ISRO to meet the growing demand for small satellite launch services.

According to space expert Girish Linganna, the SSLV can launch payloads of up to 500 kilograms into low-Earth orbit (LEO) or up to 300 kilograms into sun-synchronous orbit (SSO). A key advantage of the SSLV is its capability to carry multiple satellites on a single mission, making it a cost-effective and adaptable solution for space launches. With minimal infrastructure requirements and the ability to be launched within 24 hours of setup, the SSLV offers significant operational efficiency.

The EOS-08 satellite is designed for environmental monitoring, disaster management, and will support India’s Gaganyaan mission. This flight marks the completion of the SSLV development program, transitioning SSLV operations to the private sector through partnerships with Indian companies and NewSpace India Limited (NSIL), further strengthening India’s space industry.

EOS-08 Satellite Payloads

EOS-08 will carry three main payloads:

Electro-Optical Infrared Payload (EOIR): This device captures images using infrared light in the Mid-Wave and Long-Wave Infrared ranges, making it valuable for surveillance, disaster monitoring, and environmental research.
Global Navigation Satellite System-Reflectometry (GNSS-R): This payload utilizes satellite signals to study environmental parameters such as ocean winds, soil moisture, and flood detection.
SiC UV Dosimeter: A sensor designed to detect ultraviolet radiation and monitor dangerous levels of gamma radiation, contributing to astronaut safety.

EOS-08 operates in a circular low-Earth orbit at an altitude of 475 kilometers, with an inclination of 37.4 degrees. Weighing around 175.5 kilograms, the satellite generates approximately 420 watts of power and is expected to operate for a year.

According to Linganna, EOS-08 also features advanced satellite technology, including an integrated avionics system, known as the Communication, Baseband, Storage, and Positioning (CBSP) Package, which streamlines communication, data processing, and positioning into one system, enhancing the satellite’s performance and reliability.

This launch not only reinforces ISRO’s advancements in satellite technology but also highlights India’s growing leadership in the global space market, particularly in the small satellite sector.