ISRO’s New Year launch: Special space observatory, X-ray telescope

The PSLV-C58 rocket, with primary payload XPoSat and 10 other satellites to be deployed in low-earth orbits, is scheduled to lift off from the Satish Dhawan Space Centre in Sriharikota at 9.10 am on Monday.

ISRO launch: Special space observatory, X-ray telescope

The payload for the X-ray Polarimeter Satellite mission. (PTI)

The Indian Space Research Organisation (ISRO) began the new year with the launch of its first X-ray Polarimeter Satellite (XpoSat), a space-based observatory to study X-ray polarisation and its cosmic sources — celestial bodies including black holes, neutron stars and magnetars.

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.

#WATCH | PSLV-C58 XPoSat Mission launch | ISRO launches X-Ray Polarimeter Satellite (XPoSat) from the first launch-pad, SDSC-SHAR, Sriharikota in Andhra Pradesh.

(Source: ISRO) pic.twitter.com/ua96eSPIcJ

— ANI (@ANI) January 1, 2024

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.

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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.

“This is a great trend, in fact, an overwhelming one. We should have a regular stream of science satellites, preferably one per year,” S Seetha, former ISRO scientist who led the Mangalyaan mission, told The Indian Express.

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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 is primarily due to the difficulty in developing sensitive instrumentation. In this regard, XPoSat is a beginning for India,” said Seetha.

Anjali Marar works at the Raman Research Institute, Bengaluru

Anonna Dutt

Anonna Dutt is a Principal Correspondent who writes primarily on health at the Indian Express. She reports on myriad topics ranging from the growing burden of non-communicable diseases such as diabetes and hypertension to the problems with pervasive infectious conditions. She reported on the government’s management of the Covid-19 pandemic and closely followed the vaccination programme. Her stories have resulted in the city government investing in high-end tests for the poor and acknowledging errors in their official reports. Dutt also takes a keen interest in the country’s space programme and has written on key missions like Chandrayaan 2 and 3, Aditya L1, and Gaganyaan. She was among the first batch of eleven media fellows with RBM Partnership to End Malaria. She was also selected to participate in the short-term programme on early childhood reporting at Columbia University’s Dart Centre. Dutt has a Bachelor’s Degree from the Symbiosis Institute of Media and Communication, Pune and a PG Diploma from the Asian College of Journalism, Chennai. She started her reporting career with the Hindustan Times. When not at work, she tries to appease the Duolingo owl with her French skills and sometimes takes to the dance floor. ... Read More