ISRO launches Earth Observation Satellite EOS-08

ISRO’s latest Earth Observation Satellite ‘EOS-08’ launched by the Small Satellite Launch Vehicle (SSLV)-D3 from Satish Dhawan Space Centre, Shriharikota.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.

Image Credit: ISRO

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 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 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.

Indian Earth Observation Satellite-6 (EOS-6) was launched

The third generation Indian satellite for monitoring the oceans, formally named Earth Observation Satellite-6 (EOS-6) was launched by the Indian Space Research Organization (ISRO) in partnership with the Ministry of Earth Sciences (MoES) among others, from its First Launch Pad (FLP) at Satish Dhawan Space Centre (SDSC), Sriharikota. The ocean observing mission is a follow-up to OceanSat-1 or IRS-P4 and OceanSat-2 launched in 1999 and 2009, respectively. The satellite was launched aboard the proven launch vehicle PSLV (Polar Satellite Launch Vehicle) on its 56th flight (24th flight of the PSLV-XL version).

The Oceansat-3 was placed in the polar orbit at a height of about 740 kilometers above sea level. While at 1100 kilograms, it is only slightly heavier than Oceansat-1, for the first time in this series it houses three ocean observing sensors viz Ocean Color Monitor (OCM-3), Sea Surface Temperature Monitor (SSTM), and Ku-Band scatterometer (SCAT-3). There is also an ARGOS payload. All these sensors have their own importance for India’s blue economy aspirations.

The advance 13-channel OCM with 360 m spatial resolution and 1400 km swath will observe the day side of the earth every day and will provide crucial data on the distribution of ocean algae which is the base of the food chain within the marine ecosystem. The OCM-3 with a high signal-to-noise ratio is expected to provide improved accuracy in daily monitoring of phytoplankton having a wide range of operational and research applications including fishery resource management, ocean carbon uptake, harmful algal bloom alerts, and climate studies.