X-Ray Polarimeter Satellite (XPoSat)

Context- Indian Space Research Organisation (ISRO) has announced that India is set to launch its first X-Ray Polarimeter Satellite (XPoSat).

About

• XPoSat will be launched from the Polar Satellite Launch Vehicle (PSLV) from the Satish Dhawan Space Center in Sriharikota. 
• Its purpose is to study the polarization of powerful X-ray sources. 

What is polarization of X-ray sources? 

• Polarization is considered one of the inherent properties of light. 
• Polarization information provides a deeper understanding of processes and local anisotropies of fields (electric/magnetic/gravity). 
• X-ray polarization is the main diagnostic tool in the study of the radiation mechanism and geometry of celestial sources. 

X-Ray Polarimeter Satellite (XPoSat) mission 

• XPoSat (X-ray Polarimeter Satellite) is India’s first polarimetric mission. 
• The XPoSat spacecraft is designed to observe from low Earth orbit (non-solar synchronous orbit, altitude ~650 km, low inclination  approximately six degrees), carrying two scientific payloads. 
  • POLX: POLX (polarimetric Instrument in X-rays) is designed to measure polarimetric parameters 
    • especially polarization degree and angle
    • in the medium X-ray energy range of 8-30 keV photons.  
  • XSPECT: The secondary payload is the XSPECT (X-ray Spectroscopy and Timing) payload, which enables spectroscopy in the 0.8-15 keV energy range. 
    • The payloads observe the X-ray sources during the time when the spacecraft passes through the Earth’s shadow, i.e. during the eclipse period. 
    • The duration of the assignment is estimated to be five years. 

Importance 

• The analysis of X-ray polarization signatures allows to measure the mass and spin of accreting black holes, to understand the  geometric arrangement and local properties of the source. 
• The emission mechanisms of various astronomical sources such as black holes, neutron stars, active galactic nuclei, etc. originate from complex physical processes and are difficult to understand. 
• Polarimetric measurements add two  dimensions to our understanding, the degree of polarization and the angle of polarization, and are thus an excellent diagnostic tool for understanding the emission processes of astronomical sources. 

Launch Vehicles

• Launchers or Launch Vehicles are used to carry spacecraft into space. 
• India has three active launch vehicles: Polar Satellite Launch Vehicle (PSLV), Geosynchronous Satellite Launch Vehicle (GSLV), Geosynchronous Satellite Launch Vehicle Mk-III (LVM3). 
• PSLV: PSLV was a versatile launch vehicle that was used to launch all  three types of payloads. Earth observation, geostation and navigation. It reached the highest level of success and is considered the workhorse of ISRO.
• GSLV and indigenous cryogenic upper stage made it possible to launch communication satellites up to 2-ton class. 
• LVM3 is a next-generation launch vehicle capable of launching 4-ton-class communications satellites and 10-ton LEO-class payloads into orbit. 
  • The vehicle was developed using completely original technologies, including the C25 cryostage. 
  • The launch vehicle holds the record for all successful launches since the first development flight. 
  • LVM3, classified by humans, has been identified as the launch vehicle for the Gaganyaan mission, called the HRLV. 
  • The Small Satellite Launch Vehicle (SSLV) is  developed with complete indigenous technologies to serve the on-demand small satellite launch market. 

Future Missions of ISRO 

• Gaganyaan: Project Gaganyaan plans to demonstrate human spaceflight capability by taking a crew from a 3 to 400 km orbit for a 3-day mission and returning them  safely to Earth by landing in Indian waters. 
• NASA-ISRO SAR (NISAR): It  is a Low Earth Orbit (LEO) observatory  jointly developed by NASA and ISRO.  NISAR maps the entire globe in 12 days and provides spatially and temporally coherent information to understand changes in Earth’s ecosystems.  
• SPADEX: SPADEX or Space Docking Experiment is a two-spacecraft mission  developed by ISRO to develop technologies related to orbital rendezvous, docking, formation flying for use in human spaceflight, maintenance of space satellites and other close operations.

Source: The Hindu

Download as PDF