On the first day of the year 2024, the Indian Space Research Organisation (ISRO) successfully launched the X-ray Polarimeter Satellite (XPoSat). The satellite took off at 9:10 am from the Satish Dhawan Space Centre in Sriharikota, Andhra Pradesh.
Following the Chandrayaan-3 and Aditya L1 missions, this will be the next historic step towards space exploration by the country.
The satellite, riding a Polar Satellite Launch Vehicle rocket, will study bright astronomical X-ray sources, focusing on extreme conditions. Costing approximately ₹250 crore ($30 million), XPoSat aims to explore celestial objects like black holes and neutron stars.
India will be the world's second nation to launch such an advanced astronomy observatory after NASA's IXPE mission. XPoSat is expected to operate for over five years, exceeding IXPE's two-year lifespan.
ISRO celebrates success
Following the successful launch of the PSLV-C58 rocket carrying the XPoSat satellite, ISRO Chief S Somanath said, “So 1, January 2024, yet another successful mission of PSLV has been accomplished". He further informed that Aditya-L1 is going to reach Lagrange Point on January 6 at 4 pm.
ISRO's Mission Director, Dr Jayakumar, expressed delight, stating, "We are extremely happy to see the grand success of the launch of the PSLV. XPoSat is a space observatory." He also explained how the mission is a testament to women's empowerment in the field of science and technology.
Objectives of the mission
The primary goal of the X-ray Polarimeter Satellite (XPoSat) is to explore the polarisation of intense X-ray sources in space. As the first dedicated scientific satellite from ISRO for this purpose, XPoSat aims to conduct space-based polarimetry measurements of X-ray emissions from celestial sources.
According to the ISRO website, the mission objectives include:
1. Measurement of X-ray polarisation in the energy band of 8-30 keV emanated from X-ray sources.
2. 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 ~ 5 years. The XPoSat payloads will observe the X-ray sources during its transit through the Earth’s shadow, i.e., during the eclipse period.
About XPoSat
The XPoSat spacecraft features two scientific payloads placed in a low Earth orbit:
- POLIX (Polarimeter Instrument in X-rays): The primary payload will measure polarimetry parameters (degree and angle of polarization) in a medium X-ray energy range of 8-30 keV photons of astronomical origin.
- XSPECT (X-ray Spectroscopy and Timing): This payload will provide spectroscopic information in the energy range of 0.8-15 keV.
The 469kg spacecraft will be placed in a 650 km orbit above Earth's surface at the conclusion of the 22-minute mission.
The final stage of the PSLV rocket (PS4) will then descend to a lower orbit of 350 km through two engine restarts.
Following the descent, passivisation of fuels and hazardous chemicals in the upper stage tanks will occur to prevent potential explosions or break-ups.
Post-passivisation, the PS4 stage will be repurposed as a stabilised orbiting platform named PSLV Orbital Experimental Module (POEM), hosting experiments from ISRO Centres, academia, and startups, offering a cost-effective alternative to such satellite launches.
You can find more information about XPoSat on the ISRO website here.
