The India Space Research Organisation (ISRO) launched its one of the longest missions, PSLV-C54, on November 26, 2022 to inject into multiple orbits nine satellites including an Earth observation satellite (EOS-06), named OceanSat-3 from First Launch Pad, Satish Dhawan Space Centre, Sriharikota at 11.56 a.m. IST. Besides EOS-06, eight nano-satellites include ISRO Nano Satellite-2 for Bhutan (INS-2B), Anand, four Astrocast satellites, and two Thybolt satellites. This is the 56th flight and the last mission of the year for PSLV and the 24th flight of the PSLV-XL version with six PSOM-XLs.
Objectives of the Mission
Objectives of the PSLV-C54 Mission are as follows:
- To ensure the data continuity of ocean colour and wind vector data in order to sustain the operational applications
- To improve the applications by accommodating some additional datasets. For example, sea surface temperature and more bands in the optical region for fluorescence and in the infrared region for atmospheric corrections
- To develop and improve related algorithms and data products to boost the utility of the mission and serve in well-established application areas
About Satellites and their Payloads
PSLV-C54 injected into orbits the following satellites:
- The 1117- kg EOS–06 (OceanSat-3) is the third-generation satellite developed by India in the OceanSat Series. It will provide continuity to the services of the OceanSat-2 spacecraft with enhanced payload capability and application areas. It consists of ocean colour monitor (OCM-3), sea surface temperature monitor (SSTM), Ku-Band scatterometer (SCAT-3), and ARGOS (a joint Indo-French satellite mission for oceanographic studies.) ARGOS will reinforce the existing fleet of Indo-French satellites meant for weather surveillance, according to France. SCAT-3 will check the continuity of wind vector data.
OceanSat Series
The OceanSat Series consists of three missions, devised by ISRO for oceanographic and atmospheric studies. The other two missions are OceanSat-1 and OceanSat-2.
OceanSat-1 was launched on May 26, 1999 by PSLV-C2 from Satish Dhawan Space Centre, Sriharikota, which carried an OCM, designed to monitor the colour of the ocean and a multi-frequency scanning microwave radiometer (MSMR), built to collect data by measuring microwave radiation passing through the atmosphere over the ocean. These instruments recorded the chlorophyll content, yellow substance, and suspended sediments in the ocean waters; sea surface temperature, sea surface winds, water vapour in an atmospheric column, and water content in clouds. The satellite was sent to the sun synchronous orbit at an altitude between 600 km and 800 km. (A sun-synchronous orbit is a polar orbit, in which the satellite passes over any given point of the planet’s surface at the same local mean solar time.)
OceanSat-2 was launched on September 23, 2009 by PSLV-C14 from Satish Dhawan Space Centre, Sriharikota, to provide the continuity of operational services of OceanSat-1, with enhanced application potential. It carried three payloads—OCM-2, OSCAT, and radio occultation sounder for atmosphere (ROSA), developed by the Italian Space Agency. In 2016, SCATSAT-1 was launched after SCAT on OceanSat-2 became dysfunctional. SCATSAT-1 carried an OSCAT similar to the one on OceanSat-2.
- ISRO Nano Satellite-2 for Bhutan (INS-2B), developed by India, is a diplomatic satellite which is configured with INS-2 Bus. It consists of two payloads, namely, NanoMX and APRS-Digipeater, developed jointly by the Department of Information Technology and Telecom (DITT), Bhutan, and U R Rao Satellite Centre (URSC) India, respectively. It weights 18.28 kg.
- Anand nano-satellite, developed by Pixxel, India, is a technology demonstrator to demonstrate the capabilities and commercial applications of miniaturised earth-observation camera for Earth observation using a micro-satellite in the Low Earth Orbit. It is a three-axis stabilised satellite and consists of a satbus (accommodating telemetry, on-board computers, tele-command, electrical power system and attitude determination and control system or ADCS) and a payload unit. It weighs 16.51 kg.
- Astrocast nano-satellite, constructed by the US-based Spaceflight, is a technology demonstrator satellite for the Internet of Things (IoT). Four Astrocast satellites have been sent in this mission, which were kept inside the ISISpace QuadPack dispenser, which presents them from being contaminated. A 3U spacecraft, Astrocast, weighs 17.92 kg.
- Thybolt satellite, developed by Dhruvaspace, India, is a 0.5U spacecraft bus, consisting of a communication payload to enable rapid technology demonstration and development of constellation for multiple users. Two Thybolt satellites have been sent in this mission which demonstrate Store-and-Forward Functionality for authorised users in the amateur frequency band. It weights 1.45 kg.
About PSLV-C54
The rocket PSLV-C54 has a height of 44.4 metre and a lift off mass of 321 tonne. The EOS-06 will be separated in Orbit-1. Thereafter, Orbit change is planned by using two orbit change thrusters (OCTs). The Passenger Payloads (PPLs) will be separated in Orbit-2.
The rocket has four propulsion stages. The first and third stages used hydroxyl-terminated polybutadiene (HTBP) based composite solid propellants, while the second and fourth stages used earth-storable liquid propellant.
The features of the four stages are given below:
Stage 1 comprised a PS1 engine and six PSOM-XL booters. The length of PS1 is 20 metres while that of PSOM-XL is 12 metres. The diameters of PS1 and PSOM-XL are 2.8 metres and 1 metre, respectively. The propellant mass of PS1 is 139 tonnes while that of PSOM-XL is 12 tonnes.
Stage 2 comprised a PS2 engine, which is 12.8 metres in length, 2.8 metres in diameter, and has 41 tonnes of propellant mass.
Stage 3 comprised an HPS3 engine, having a length of 3.6 metres, a diameter of 2 metres, and a propellant mass of 7.65 tonnes.
Stage 4 comprised a PS4 engine, having a length of 3 metres, a diameter of 1.34 metres, and a propellant mass of 2.5 tonnes.
Significance of the Mission
The EOS-06 will observe ocean colour data, sea surface temperature, and wind vector data to use in oceanography, climatic and meteorological applications. The satellite will also support the potential fishing zones using chlorophyll, wind speed, and land-based geophysical parameters.
With this launch, Bengaluru-based space tech start-ups, Dhruva Space and Pixxel, have become other private space-tech start-ups, that launched their private satellites. Earlier, Skyroot Aerospace had launched a private rocket, Vikram-S.
Moreover, this mission also marks the extended cooperation in space between the space scientists of ISRO and Bhutan, under the leadership of Prime Minister Narendra Modi.
Future Goals
ISRO is further planning to launch OceanSat-3A satellite from Satish Dhawan Space Centre, Sriharikota in 2023. OceanSat-3A will carry OCM, SSTM, and Scatterometer for Oceansat-3 which will mainly observe and monitor the ocean.
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