Jump to content

XPoSat

From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by N Jeevan (talk | contribs) at 15:00, 6 December 2023 (→‎top). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Not to be confused with Imaging X-ray Polarimetry Explorer.

X-ray Polarimeter Satellite
X-ray Polarimeter satellite (XPoSat) in deployed configuration
NamesXPoSat
Mission typeSpace observatory
OperatorISRO
COSPAR ID2024-001A Edit this at Wikidata
SATCAT no.58694Edit this on Wikidata
Mission duration5 years (planned)[1]
Spacecraft properties
SpacecraftX-ray Polarimeter Satellite
BusModified IMS-2[1]
ManufacturerRaman Research Institute (RRI)
Launch mass480 kg (1,060 lb)[2]
Payload mass144 kg (317 lb)[2]
Dimensions65 × 65 × 60 cm (26 × 26 × 24 in)
Power1260 watts[2]
Start of mission
Launch date28 December 2023 (planned)
RocketPSLV[2]
Launch siteSatish Dhawan Space Centre First Launch Pad
ContractorIndian Space Research Organisation (ISRO)
Orbital parameters
Reference systemGeocentric orbit
RegimeLow Earth orbit
Altitude650 km (400 mi)[1]
Inclination6°[2]
Period90.0 minutes
Instruments
Polarimeter Instrument in X-rays (POLIX)
X-ray Spectroscopy and Timing (XSPECT)
 

The X-ray Polarimeter Satellite (XPoSat) is an Indian Space Research Organisation (ISRO) planned space observatory to study polarisation of cosmic X-rays. It is planned to be launched on 28 December 2023 or later on a Polar Satellite Launch Vehicle (PSLV),[3][4] with mission life of at least five years.[5][6]

The telescope is being developed by ISRO and the Raman Research Institute (RRI).

Overview

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.[5][7] The observatory will be placed in a circular low Earth orbit of 500–700 km (310–430 mi).[5][1]

History

The XPoSat project began in September 2017 with Indian Space Research Organisation (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.[8]

Payloads

Two payloads of XPoSat are hosted on a modified IMS-2 satellite bus.[5] 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][9] POLIX, a 125 kg (276 lb) instrument,[5] is being developed by the Raman Research Institute.[7][1][9][10]

Polarimeter Instrument in X-rays (POLIX)

POLIX is the primary scientific payload aboard XPoSat. It is a Thomson X-ray polarimeter, which measures the degree and angle of polarization (polarimetry parameters) of astronomical sources in the medium X-ray range (8-30 keV).[11] It has been developed by Raman Research Institute.

Its science objectives are to measure:[10]

  • 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.

The experiment configuration consists of a collimator, central low Z (Lithium, Lithium Hydride or Beryllium) scatterer surrounded by xenon filled X-ray proportional counters as X-ray detectors which collects the scattered X-ray photons. The instrument is rotated along the viewing axis leading to the measurement of the azimuthal distribution of the scattered X-ray photons which gives information on polarisation. Polarised X-rays will produce an azimuthal modulation in the count rate as opposed to uniform azimuthal distribution of count rate for unpolarised X-rays. POLIX has four independent detectors, each with its own front end and processing electronics. Localization of the X-ray photon in the detectors is carried out by the method of charge division in a set of resistive anode wires connected in series.

The prime objects for observation with this instrument are the X-ray bright accretion powered neutron stars, accreting black holes in different spectral states, rotation powered pulsars, magnetars, and active galactic nuclei. This instrument bridges an energy gap in detection capability, between the soft X-ray polarimeters utilising Bragg reflection (OSO-8) or Photoelectron tracks (IXPE), and hard X-ray polarimeters using Compton scattering such as the Cadmium Zinc Telluride Imager (CZTI) on Astrosat.

X-ray Spectroscopy and Timing (XSPECT)

XSPECT is the secondary payload on XPoSat. It measures spectroscopic information and timing of soft X-rays.[12] XSPECT is designed to pursue timing studies of soft X-rays (0.8-15 keV),[11] complementary to what the Large Area X-ray Proportional Counter (LAXPC) does at high energies on AstroSat, while simultaneously providing adequate spectral resolution in the 1-20 keV band. It has an energy resolution of <200 eV at 5.9 keV (-20 °C) and a timing resolution of ~2 msec. It has been developed by the Space Astronomy Group, URSC.

The detector achieves modest effective area without the use of focusing optics using the large area Swept Charge Devices (SCD), a variant of X-ray CCDs. SCDs permit fast readouts (10–100 kHz) and moderately good spectral resolution at the cost of a position sensitivity. These devices are unique in requiring very benign cooling requirement (requiring only passive cooling) unlike traditional X-ray CCDs.

Key science objectives of XSPECT include understanding long-term behavior of X-ray sources through correlation of timing characteristics with spectral state changes and emission line variations.

See also

References

  1. ^ a b c d e f "ISRO announces Seven Mega Missions". GK Today. 20 May 2019. Retrieved 10 December 2021.
  2. ^ a b c d e XPoSat User Meet. 25 May 2023. Event occurs at 1 hour 5 minutes 34 seconds.
  3. ^ "Polarimetry mission set for December launch: Isro chief". Hindustan Times. 27 September 2023. Retrieved 27 September 2023.
  4. ^ "India's first polarimetry mission may be launched this month: Isro". Hindustan Times. 4 December 2023. Retrieved 4 December 2023.
  5. ^ a b c d e "Future Exploration Missions of ISRO" (PDF). Dr. M. Annadurai, Director, ISAC, ISRO. UNCOPUOS 60th Session, Vienna, 2019. ISRO. Retrieved 10 December 2021.
  6. ^ "Loksabha Q&A" (PDF). DEPARTMENT OF SPACE. 5 April 2023.
  7. ^ a b 5 Unique Space Science Missions That ISRO Will Be Flying in the Near Future Jatan Mehta The Wire 27 June 2019
  8. ^ "Raman Research Institute, Annual Report 2018-19" (PDF). Archived (PDF) from the original on 9 August 2020.
  9. ^ a b "Chandrayaan 2 launched: Here are future ISRO missions to space". The Indian Express. 22 July 2019. Retrieved 23 July 2019.
  10. ^ a b X-ray Polarimeter Experiment (POLIX) Raman Research Institute Accessed on 2 August 2019
  11. ^ a b Ghosh, Sahana (11 September 2023). "India to launch world's second X-ray polarimetry space observatory". Nature India. doi:10.1038/d44151-023-00132-x.
  12. ^ "Government of India, Department of Space, Annual Report 2020" (PDF). Archived (PDF) from the original on 14 February 2020.
Retrieved from "https://en.wikipedia.org/w/index.php?title=XPoSat&oldid=1188612245"