X-ray Polarimeter Satellite


X-ray Polarimeter Satellite
X-ray Polarimeter satellite (XPoSat) in deployed configuration.jpg
X-ray Polarimeter satellite in deployed configuration
Mission typeSpace observatory
OperatorIndian Space Research Organisation (ISRO)
Mission durationPlanned: 5 years[1]
Spacecraft properties
BusIMS-2 [1]
ManufacturerRaman Research Institute, ISRO
Payload mass125 kg (276 lb) [2]
Start of mission
Launch dateNovember 2021[3]
RocketPSLV [4]
Orbital parameters
Altitudecircular 500 to 700 km[5]
Inclination≤30° [2]
Main detector
Collecting area640 cm2 [2]
Resolution5-30 keV [1][6][2]
Polarimeter Instrument in X-rays (POLIX)
X-ray Spectroscopy and Timing (XSPECT)

The X-ray Polarimeter Satellite (XPoSat) is a planned space observatory to study polarisation of cosmic X-rays. It is planned to be launched in 2021, and to provide a service time of at least five years.[2]

The telescope is being developed by the Indian Space Research Organisation (ISRO) and the Raman Research Institute.


Studying how radiation is polarised gives away the nature of its source, including the strength and distribution of its magnetic fields and the nature of other radiation around it. XPoSat will study the 50 brightest known sources in the universe, including pulsars, black hole X-ray binaries, active galactic nuclei, and non-thermal supernova remnants.[2][4] The observatory will be placed in a circular low Earth orbit of 500 to 700 km.[2][5]


Project began in September 2017 with ISRO grant of ₹95,000,000. Preliminary Design Review (PDR) of the XPoSat including the POLIX payload was completed in September 2018, followed by preparation of POLIX Qualification Model and beginning of some of its Flight Model components fabrication.[7]


Two payloads of XPoSat are hosted on IMS-2 platform.[2] Primary scientific payload is Polarimeter Instrument in X-rays (POLIX), which will study the degree and angle of polarisation of bright astronomical X-ray sources in the energy range 8-30 keV.[1][6] POLIX, a 125 kg (276 lb) instrument,[2] is being developed by the Raman Research Institute.[4][5][6][8] Its science objectives are to measure:[8]

  • the strength and the distribution of magnetic field in the sources
  • geometric anisotropies in the sources
  • their alignment with respect to the line of sight
  • the nature of the accelerator responsible for energising the electrons taking part in radiation and scattering

Secondary payload is XSPECT (X-ray Spectroscopy and Timing), which will give spectroscopic information of soft X-rays in the energy range of 0.8-15 keV.[9]

See also


  1. ^ a b c d ISRO announces Seven Mega Missions. GK Today. 20 May 2019.
  2. ^ a b c d e f g h i j Future Exploration Missions of ISRO. Indian Space Research Organisation (ISRO). Dr. M. Annadurai, Director, ISAC, ISRO. UNCOPUOS 60th Session, Vienna. 2019.
  3. ^ S. Somanath (3 August 2020). An Evening with Dr. S. Somanath, Director, VSSC, Trivandrum (video). Event occurs at 45:09–46:04. Retrieved 14 August 2020 – via YouTube. Presentation slides available here via Imgur.
  4. ^ a b c 5 Unique Space Science Missions That ISRO Will Be Flying in the Near Future. Jatan Mehta, The Wire. 27 June 2019.
  5. ^ a b c ISRO announces Seven Mega Missions. GK Today. 20 May 2019.
  6. ^ a b c "Chandrayaan 2 launched: Here are future ISRO missions to space". The Indian Express. 2019-07-22. Retrieved 2019-07-23.
  7. ^ "Raman Research Institute, Annual Report 2018-19" (PDF). Archived (PDF) from the original on 9 August 2020.
  8. ^ a b X-ray Polarimeter Experiment (POLIX). Raman Research Institute. Accessed on 2 August 2019.
  9. ^ "Government of India, Department of Space, Annual Report 2020" (PDF). Archived (PDF) from the original on 14 February 2020.