PSLV-C51

PSLV-C51

Subject: Science and Technology

Context: ISRO’s workhorse Polar Synchronous Launch Vehicle delivered its 53rd successful mission on Sunday.

Concept:

• It launched Amazonia-1, a 637-kg commercial remote sensing satellite for the Brazilian space research agency INPE, and 18 co-passenger satellites (five being Indian satellites and 13 from the US) from Satish Dhawan Space Centre at Srihari kota in Andhra Pradesh.
• It was inserted into sun synchronous orbit.
• Amazonia-1 is the first satellite designed, developed and launched by the Brazilian space research agency and is intended to monitor deforestation and agricultural activities in the Amazon region in Brazil.It will monitor the country, the Amazon and bio reserves in the country.
• It is first full-fledged commercial satellite launch (Earlier three launches involving auxiliary small satellites) for New Space India Limited (NSIL).
• NSIL is a commercial arm of ISRO created in 2019 to commercialise ISRO research and capabilities.
• 4 of the co-passenger satellites were signed for launch by IN-SPACe, ISRO’s small satellites facilitation agency, and others by NSIL.
• Among Indian satellites three are UNITYsats built by students from the Jeppiaar Institute of Technology, Sriperumbudur, G.H. Raisoni College of Engineering, Nagpur, and Sri Shakti Institute of Engineering and Technology, Coimbatore, and a fourth one called the Satish Dhawan Sat (SDSAT) was built by the firm Space Kidz India.
• The UNITYsats will provide radio relay services while the SDSAT, a nano satellite, will study radiation, space weather and demonstrate long-range communication tech
• The fifth Indian satellite on the launch was the Sindhu Netra, a commercial payload to demonstrate technology.
• Pixxel India (Start up billed as India’s version of SpaceX) was suppose to send satellite in this launch (first of its satellite ‘Anand’ was to be on this launch to image whole globe) but software issues didn’t make it ready for the launch.

About Sun Synchronous orbit

• Sun-synchronous orbit or a heliosynchronous orbit allows a satellite to pass over a section of the Earth at the same time of day. It lies in a plane that maintains a fixed angle with respect to the Earth-sun direction
• Since there are 365 days in a year and 360 degrees in a circle, it means that the satellite has to shift its orbit by approximately one degree per day.
• These satellites orbit at an altitude between 700 to 800 km. These satellites use the fact since the Earth is not perfectly round (the Earth bulges in the center, the bulge near the equator will cause additional gravitational forces to act on the satellite. This causes the satellite’s orbit to either proceed or recede.
• These orbits are used for satellites that need a constant amount of sunlight. Satellites that take pictures of the Earth would work best with bright sunlight, while satellites that measure longwave radiation would work best in complete darkness.