Indian Space Research Organisation (ISRO) kicked off the new year by launching its inaugural X-Ray Polarimeter Satellite (XPoSat), providing valuable insights into celestial entities such as black holes. The satellite was aboard a Polar Satellite Launch Vehicle rocket.
The PSLV-C58 rocket, with primary payload XPoSat and 10 other satellites to be deployed in low-earth orbits, lift off from the Satish Dhawan Space Centre in Sriharikota at 9.10 am on Monday.
XpoSat is only the world’s second such mission. In 2021, NASA had launched Imaging X-ray Polarimetry Explorer (IXPE) to operate and perform X-ray polarisation measurements within the soft X-ray band, whereas XPoSat will operate within the medium X-ray band.
It will carry two payloads — POLIX (Polarimeter Instrument in X-rays) and XSPECT (X-ray Spectroscopy and Timing). According to ISRO, POLIX is expected to observe about 40 bright astronomical sources of different categories; XSPECT will study the electromagnetic spectrum generated by different matter.
X-ray polarisation serves as a crucial diagnostic tool for examining the radiation mechanism and geometry of celestial sources. The insights derived from X-ray polarisation measurements on celestial objects like black holes, neutron stars and active galactic nuclei, hold the potential to significantly improve the understanding of their physics.
Built entirely by two Bengaluru-based institutes — ISRO’s UR Rao Satellite Centre and Raman Research Institute — XPoSat was conceptualised in 2008 and the formal agreement with the space agency was inked in 2015.
XPoSat will become the country’s third space-based observatory after the recently launched solar mission Aditya-L1, and AstroSat launched in 2015.
Across the world, there have been only a handful of experiments on X-ray polarisation measurements. Some of these have been balloon-based and short-duration experiments by NASA and collaborators. Indian astronomers, using AstroSat, have undertaken timing and broadband spectroscopy of X-ray sources but no polarisation studies were performed.
XPoSat is, therefore, expected to be a gamechanger in the field, as there have been only timing, spectroscopy and imaging-based studies done in this X-ray frequency band, globally.
This launch follows the accomplishment of the Gaganyaan Test Vehicle D1 mission in October. The 25-hour countdown commenced on Sunday for the lift-off conducted at 9.10 am from the Satish Dhawan Space Centre in Sriharikota, Andhra Pradesh.
The PSLV-C58 rocket, in its 60th mission, carried primary payload XPoSat and 10 other satellites to be deployed in low earth orbits. According to ISRO, it is the first dedicated scientific satellite from ISRO to carry out research in space-based polarisation measurements of X-ray emission from celestial sources.