EOS-08 is ISRO’s latest Earth Observation Satellite, slated for launch by the Small Satellite Launch Vehicle (SSLV)-D3 which is scheduled for Thursday, August 15, 8:47 PM – 9:47 PM PDT. The primary objectives of the EOS-08 mission include designing and developing a microsatellite, creating payload instruments compatible with the microsatellite bus, and incorporating new technologies required for future operational satellites.
Built on the Microsat/IMS-1 bus, EOS-08 carries three payloads: Electro Optical Infrared Payload (EOIR), Global Navigation Satellite System-Reflectometry payload (GNSS-R), and SiC UV Dosimeter. The EOIR payload is designed to capture images in the Mid-Wave IR (MIR) and Long-Wave IR (LWIR) bands, both during the day and night, for applications such as satellite-based surveillance, disaster monitoring, environmental monitoring, fire detection, volcanic activity observation, and industrial and power plant disaster monitoring. The GNSS-R payload demonstrates the capability of using GNSS-R-based remote sensing for applications such as ocean surface wind analysis, soil moisture assessment, cryosphere studies over the Himalayan region, flood detection, and inland waterbody detection. Meanwhile, the SiC UV Dosimeter monitors UV irradiance at the viewport of the Crew Module in the Gaganyaan Mission and serves as a high-dose alarm sensor for gamma radiation.
The spacecraft mission configuration is set to operate in a Circular Low Earth Orbit (LEO) at an altitude of 475 km with an inclination of 37.4°, and has a mission life of 1 year. The satellite has a mass of approximately 175.5 kg and generates power of around 420 W. It interfaces with the SSLV-D3/IBL-358 launch vehicle.
EOS-08 marks a significant advancement in satellite mainframe systems such as an Integrated Avionics system, known as the Communication, Baseband, Storage, and Positioning (CBSP) Package, which combines multiple functions into a single, efficient unit. This system is designed with cold redundant systems using commercial off-the-shelf (COTS) components and evaluation boards, supporting up to 400 Gb of data storage. Additionally, the satellite includes a structural panel embedded with PCB, an embedded battery, a Micro-DGA (Dual Gimbal Antenna), an M-PAA (Phased Array Antenna), and a flexible solar panel, each serving as key components for onboard technology demonstration.
The satellite employs a miniaturized design in its Antenna Pointing Mechanisms, capable of achieving a rotational speed of 6 degrees per second and maintaining a pointing accuracy of ±1 degree. The miniaturized phased array antenna further enhances communication capabilities, while the flexible solar panel incorporates a foldable solar panel substrate, GFRP tube, and CFRP honeycomb rigid end panel, offering improved power generation and structural integrity. A pyrolytic graphite sheet diffuser plate, known for its high thermal conductivity of 350 W/mK, reduces mass and finds application in various satellite functions. Furthermore, the EOS-08 mission adopts a new method of integrating housekeeping panels using a hinge-based fixture, significantly reducing the duration of the Assembly, Integration, and Testing (AIT) phase.
Incorporating additional novel schemes, the EOS-08 mission improves satellite technology through X-band data transmission, utilizing pulse shaping and Frequency Compensated Modulation (FCM) for X-Band data transmitters. The satellite’s battery management system employs SSTCR-based charging and bus regulation, sequentially including or excluding strings at a frequency of 6 Hz. The TM-TC system supports dual modes, including CDMA and Direct PSK, with miniaturized microstrip filters tailored for data and TM-TC applications. The mission’s indigenization effort is evident in its solar cell fabrication processes and the use of a Nano-Star Sensor for Microsat Applications. Additionally, the inertial system benefits from reaction wheel isolators that attenuate vibrations and a single antenna interface is utilized for TTC and SPS applications. Thermal management is enhanced using materials such as AFE BGA, Kintex FPGA, Germanium Black Kapton, and STAMET (Si-Al Alloy) Black Kapton to handle the thermal properties of COTS components. The mission also incorporates an auto-launch pad initialization feature, further demonstrating its commitment to innovative mission management.