India inches space program forward with launch of X-ray polarimetry satellite

Meanwhile, ISRO chief sets sights on next crewed mission

India kicked off the new year with the launch of an X-ray polarimetry space observatory to research cosmic radiation.

The Indian Space Research Organisation's (ISRO) XPoSat launched aboard its Polar Satellite Launch Vehicle, this time known as PSLV-C58, on New Year's Day. Its lifespan is slated for a minimum of five years.

"On January 1, 2024, yet another successful mission of the PSLV has been accomplished. The PSLV-C58 has placed the primary satellite XPoSat in the desired orbit of 650km with six-degree inclination," announced ISRO chairman S Somanath.

XPoSat is the world's second X-ray polarimetry space observatory and the first from India. It follows NASA's Imaging X-ray Polarimetry Explorer (IXPE) launched in 2021. These spacecraft are intended to study sources of cosmic radiation such as black holes, pulsars, and neutron stars.

The observatory is equipped with two payloads: POLIX (Polarimeter Instrument in X-rays) and XSPECT (X-ray Spectroscopy and Timing) to measure the angle and degree of polarization – both elements that should provide further insight into existing data.

The POLIX payload will measure the polarization of X-rays in the 8-30 keV energy band from 50 potential cosmic sources, while the XSPECT conducts studies of cosmic X-ray sources in the 0.8-15 keV band.

It's a task that can't be done from Earth because the atmosphere absorbs X-rays.

After depositing XPoSat, the launch vehicle took ten payloads residing on the PSLV Orbital Experiment Module 3 (POEM-3) to a 350km orbit at 9.6 degree inclination.

POEM is based on the spent fourth stage of the PSLV. Usually, this element is discarded after deploying a satellite, but its clever recycling as a low-cost micro-gravity test bed gives it a second life for startups, academia, and other budget users. The mission with XPoSat was the third iteration of POEM.

Among the items on fourth stage were a radiation shielding experimental module, an experiment to count interplanetary dust, and a fuel cell demonstration.

Chatter has commenced that the latest mission ups the ante for India's space program, bringing it into line with other leaders in the industry.

"A great start to 2024 thanks to our scientists! This launch is wonderful news for the space sector and will enhance India's prowess in this field," exclaimed prime minister Narendra Modi.

Meanwhile, Somanath reminded observers that there's yet more to come for India's space program. After all, "2024 is going to be the year of Mission Gaganyaan."

The homegrown human space mission is slated for launch in 2025. ®

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