Explained | What ISRO's XPoSat mission is all about

This mission makes India the second nation in the world to launch an advanced astronomy observatory specifically geared to study black holes and neutron stars.

ISRO's PSLV-C58 carrying XPoSat and 10 other satelites lifts off from the spaceposrt of Sriharikota, Monday, Jan 1 2024.

Credit: PTI Photo

The Indian Space Research Organisation (ISRO) welcomed the new year with the launch of its X-ray Polarimeter Satellite (XPoSat), making India the second nation in the world to launch an advanced astronomy observatory specifically geared to study black holes and neutron stars.

The XPoSat mission lifted off from the Satish Dhawan Space Centre in Sriharikota, Andhra Pradesh at 9:10 am IST.

Breaking new ground

XPoSat is 'India's first dedicated polarimetry mission to study various dynamics of bright astronomical X-ray sources in extreme conditions', according to ISRO's official website.

The polarimetry mission will help scientists study how the X-rays from celestial sources are polarised, which can reveal details about the structure and conditions of the objects emitting those X-rays. ISRO is the second space agency after NASA to dedicate a spacecraft to study this feature of black holes.

What are black holes?

When the biggest stars run out of fuel and die, they leave behind black holes or neutron stars, by collapsing under their own gravity—a phenomenon that has intrigued scientists for decades. Black holes have the highest gravitational force in the universe and neutron stars have the highest densities.

XPoSat payloads

According to ISRO, thehe spacecraft carries two payloads, the primary one being POLIX and the secondary one being XSPECT.

Measurement of the polarimetry parameters in the medium X-ray energy range, meaning the degree and angle of polarisation, will be provided by the POLIX (Polarimeter Instrument in X-rays) payload and spectroscopic information will be provided by the XSPECT (X-ray Spectroscopy and Timing) payload.

Commenting on the mission, an IIT-Bombay astrophysicist, Varun Bhalerao told NDTV, "This is only the second mission of its sophisticated class after NASA's 2021 mission named Imaging X-ray Polarimetry Explorer or IXPE. The mission will try to decipher the stellar remnants or corpses of dead stars."

The Polar Satellite Launch Vehicle (PSLV) , which carried the XPoSat, also launched 10 payloads developed by start-ups, educational institutions, and ISRO centres.

These payloads include: Radiation Shielding Experimental Module (RSEM) by TakeMe2Space, Women Engineered Satellite (WESAT) by LBS Institute of Technology for Women, BeliefSa-t0 Amateur radio satellite by K.J. Somaiya Institute of Technology, Green Impulse TrAnsmitter (GITA) by Inspecity Space Labs Private Limited, Launching Expeditions for Aspiring Technologies -Technology Demonstrator (LEAP-TD) by Dhruva Space Private Limited, RUDRA 0.3 HPGP by Bellatrix Aerospace Private Limited, ARKA-200 by Bellatrix Aerospace Private Limited, Dust Experiment (DEX) by PRL, ISRO Fuel cell Power System (FCPS) by VSSC, ISRO and Si-based High Energy cell by VSSC, ISRO.

PSLV's POEM

The PSLV's fourth stage, the PSLV Orbital Experimental Module (POEM) will also see 10 different experiments carried out, which have been developed by several private companies, including Dhruva Space, Bellatrix, K J Somaiya Institute of Technology, K J Somaiya Institute of Technology for Women, India Today reported.

Starting the new year with a successful launch, ISRO has several other big projects—including the Gaganyaan mission and the joint mission with NASA dubbed Nisar—lined up for the year ahead.