ISRO's next big space launch after Chandrayaan-3 and Aditya L-1 is the X-ray Polarimeter Satellite (XPoSat). The primary objective of this satellite is to “study various dynamics of bright astronomical X-ray sources in extreme conditions.”
XPoSat is anticipated to be launched in a few months using a Polar Satellite Launch Vehicle (PSLV). It is designed to have a mission life of at least five years.
XPoSat is hailed as India's first polarimetry mission and the world's second of its kind after NASA's Imaging X-ray Polarimetry Explorer (IXPE), launched in 2021.
Polarimetry, in simple terms, is a method to study how light waves move. It helps us understand the direction and patterns in which light waves vibrate as they travel.
Understanding X-Rays in Space
X-rays have high energy and short wavelengths, typically ranging from 0.03 to 3 nanometers, according to NASA. Some X-rays are incredibly small, even smaller than a single atom of various elements.
When an object is very hot, it emits radiation with shorter wavelengths, and X-rays are a result of this. Celestial objects that emit X-rays are extremely hot, often reaching temperatures in the millions of degrees Celsius. Pulsars, galactic supernova remnants, and black holes are examples of such scorching celestial bodies.
Why did ISRO create XPoSat?
Understanding the emissions from astronomical sources like black holes and neutron stars is complex. The processes involved are challenging to grasp, and current space observatories can't provide precise information about these emissions. To better comprehend these phenomena, newer and advanced devices and technologies are created that can measure specific properties accurately.
XPoSat Payloads
The XPoSat spacecraft will carry two scientific payloads in low Earth orbit. The main one, POLIX (Polarimeter Instrument in X-rays), will measure the polarization parameters (degree and angle) of X-rays from about 40 bright astronomical sources. This is the first payload of its kind in the medium X-ray energy band dedicated to polarimetry measurements. POLIX is a collaborative effort between the Raman Research Institute (RRI) and ISRO's UR Rao Satellite Centre (URSC) in Bengaluru.
The second payload, XSPECT (X-ray Spectroscopy and Timing), will provide information on how light is absorbed and emitted by celestial objects. It will observe various sources like X-ray pulsars, black hole binaries, and low-magnetic field neutron stars, offering valuable spectroscopic details.