National Aeronautics and Space Administration

IXPE

The Imaging X-ray Polarimetry Explorer (IXPE) mission was launched on December 9, 2021 on a SpaceX Falcon 9 rocket from NASA's Kennedy Space Center in Florida into an equatorial orbit of 600 km altitude. The payload consists of three identical grazing incidence telescopes, each comprised of a mirror module assembly, developed at NASA/MSFC, with an X-ray-polarization-sensitive detector, provided by the Italian Space Agency (Agenzia Spaziale Italiana; ASI), at its focus. The payload sits atop a spacecraft bus provided by Ball Aerospace.

The observatory operates in pointing mode observing known targets for multiple (but not necessarily consecutive) orbits. Data are sent to a ground station in Malindi, Kenya, approximately 8 times per day and then are transmitted, via gateways in Italy and the US, to the mission operations center in Boulder, Colorado. From there, science data flows to the science operation center in Huntsville Alabama.

Mission Characteristics

Lifetime

Energy Range

Angular resolution:

Special Features

Payload

• The Mirror Module Assemblies (MMA) consist of three grazing-incidence mirror modules of Wolter-I type each with 24 concentrically-nested mirror shells with diameters ranging from 162 to 272 mm. The MMAs are mounted on an extendable boom which deployed on orbit to give the appropriate 4 m focal length. A tip/tilt/rotate mechanism provides alignment adjustment.
  Field-of-View (FoV) of 12.9 arcmin² square (detector limited);
  Angular resolution (HEW) ~ 20-25 arcsec (MMA only);
  Effective area per module at 167 cm² at 2.3 keV and 197 cm² at 4.5 keV.
• The Detector Units (DUs) are three Gas Pixel Detectors (GPDs) each located at the focus of an x-ray mirror module. Each GPD provides the position, energy, time and polarization information for every absorbed event. The GPD images the photoelectron tracks produced by the x-rays absorbed in a special fill gas and from its initial emission direction the polarization of the source is determined. The initial interaction point and the total charge in the track provide the location and energy of the absorbed x-ray, respectively.
  Detector sensitive area 15 mm x 15 mm
  Spatial resolution (FWHM) ≤ 123 µm (6.4 arcsec) @ 2 keV
  Energy resolution (FWHM) 0.57 keV @ 2 keV (∝ √E)
  

Science Goals

• Enhance our understanding of the physical processes that produce X-rays from and near compact objects such as neutron stars and black holes.
• Explore the physics of gravity, energy, and electric and magnetic fields.

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