The first day of 2024 marked a significant milestone for the Indian Space Research Organisation (ISRO) as it launched the X-ray Polarimeter Satellite (XPoSat), its first mission of the year. This remarkable achievement not only highlighted the mission's success but also signified India's growing expertise in space exploration and research. Notably, XPoSat stands out as a totally women-engineered satellite, a testament to the exceptional talent and dedication of the women at ISRO as stated by the Mission Director M. Jayakumar, who shared his elation at a press conference post the launch.
On its landmark 60th mission, the PSLV-C58 rocket, with XPoSat as its primary payload, ascended from the Satish Dhawan Space Centre in Sriharikota at 9.10 am, accompanied by 10 other satellites destined for low-earth orbits. By approximately 9.32 am, each satellite were precisely positioned in a 650km orbit with a six-degree inclination, showcasing exceptional engineering precision.
A strategic orbital manoeuvre was planned as part of the mission's immediate objectives, aiming to lower XPoSat's altitude to about 350 km. This crucial operation involved reactivating the fourth stage of the PSLV-C58 rocket, enabling the PSLV Orbital Experimental Module-3 (POEM-3) experiment. POEM-3, equipped with 10 sophisticated scientific instruments, marked an innovative use of the rocket's fourth stage.
XPoSat, the mission's core, was outfitted with two primary scientific instruments: POLIX (Polarimeter Instrument in X-rays) and XSPECT (X-ray Spectroscopy and Timing). POLIX's design enables it to measure polarization in medium X-rays within the 8-30 keV range (with keV denoting Kilo electron Volt), while XSPECT excels in detailed spectroscopic analysis in the 0.8-15 keV range.
“The study of polarization in X-rays is crucial for understanding these light waves' properties and behaviors as they travel through space. XSPECT's role in spectroscopic analysis is equally vital, examining the properties of light emitted, absorbed, or scattered by materials to determine their composition, structure, and physical properties. X-rays, electromagnetic waves with wavelengths significantly shorter than visible light, range from about 0.01 to 10 nanometre, compared to the visible light spectrum observable to the human eye, spanning approximately 400 to 700 nanometre,” explained space expert Girish Linganna.
Over its five-year mission, XPoSat aims to analyse the polarisation of X-rays from around 50 potential cosmic sources within the 8-30 keV energy range. Additionally, it is set to conduct extensive spectral and temporal analysis of cosmic X-ray sources within the 0.8-15 keV energy band.
“Studying X-rays from cosmic sources is critical. These rays provide unique insights into the universe's most extreme and high-energy processes, such as those occurring in black holes, neutron stars, and supernova remnants. X-rays can penetrate regions of space inaccessible to visible light, offering unparalleled insights into these high-energy events. Other forms of light, including visible, infrared, and radio waves, also play crucial roles in astronomy, revealing information about cooler, less energetic processes. The earth's atmosphere absorbs X-rays, presenting a significant challenge for studying them from the ground. Therefore, space-based X-ray observatories are essential for directly detecting and studying X-rays emitted by cosmic sources,” remarked Linganna.
The 'Decoding Cosmic X-Ray Mysteries' aspect of XPoSat's mission is integral to advancing our understanding of the universe. The study of these high-energy rays sheds light on fundamental processes essential to understanding celestial evolution and behaviour. This research may lead to groundbreaking discoveries in astrophysics, enhancing our understanding of the universe's origins and dynamics. Additionally, the technologies developed for this mission have potential Earth-based applications, including in materials science, medical imaging, and radiation detection.
Space experts point out that the XPoSat mission, a mission engineered entirely by women, stands as a testament to ISRO's commitment and expertise in unraveling the cosmos's mysteries. The mission is expected to push the boundaries of our cosmic understanding and enriching both our scientific heritage and technological capabilities. The mission is also expected to enhance the insightful study of X-ray astronomy.
