Indian Space Research Organisation (ISRO) has announced that India is set to launch its first X-Ray Polarimeter Satellite (XPoSat), aiming to investigate the polarisation of intense X-Ray sources.

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According to ISRO, while space-based X-Ray astronomy has been established in India, focusing predominantly on imaging, time-domain studies, and spectroscopy, the upcoming XPoSat mission marks a major value addition. This research, supplementing traditional time and frequency domain studies, introduces a novel dimension to X-Ray astronomy, generating anticipation and excitement within the scientific community.

The XPoSat spacecraft is designated for observation from Low Earth Orbit (non-sun synchronous orbit of ~650 km altitude, low inclination of approximately six degree), carrying two scientific payloads. With these two payloads, the XPoSat mission is capable of simultaneous studies of temporal, spectral, and polarization features of the bright X-Ray sources.

The mission objectives include measurement of X-Ray polarization in the energy band of 8-30 keV emanated from X-Ray sources, long-term spectral and temporal studies of cosmic X-Ray sources in the energy band of 0.8-15 keV.

The mission life is expected to be approximately five years. The payloads onboard XPoSat will observe the X-Ray sources during the spacecraft’s transit through the Earth’s shadow, i.e., during the eclipse period.

The primary payload of XPoSat, POLIX (Polarimeter Instrument in X-rays), is designed to measure polarimetry parameters —specifically the degree and angle of polarization — in the medium X-ray energy range of 8-30 keV photons originating from astronomical sources. The POLIX payload was developed by the Raman Research Institute (RRI), Bengaluru, with support from various ISRO centres.

The secondary payload is the XSPECT (X-ray Spectroscopy and Timing) payload, which will provide spectroscopic information within the energy range of 0.8-15 keV. The XSPECT payload was developed by the U.R. Rao Satellite Centre (URSC), ISRO.

The XPoSat will be launched by the Polar Satellite Launch Vehicle (PSLV), from the Satish Dhawan Space Center in Sriharikota.