MIRI

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MIRI ( Mid Infrared Instrument ) is an astronomical instrument for observation in the mid- infrared light spectrum between 5 and 28 µm wavelength.

The first deployment is planned for the James Webb Space Telescope . It is being developed and built by NASA and a European consortium with the help of ESA in a joint project. While the US supplies the detectors and associated electronics, the EU provides the optical and mechanical components. The Jet Propulsion Laboratory  (JPL), the Goddard Space Flight Center and a European consortium from 26 nations led by the Astronomy Technology Center in Edinburgh are involved in the project.

Unlike the Hubble Space Telescope and the other instruments of the James Webb Space Telescope, the MIRI can explore the young universe at a high redshift in the medium-wave infrared and thus help to research the earliest phase of star formation.

technology

MIRI was designed so that it can be used both as a camera and as a spectrograph . For both different tasks, different system properties were determined accordingly. It consists of a camera with three identical 1024 × 1024 detector arrays and a spectrograph. The angular resolution for the spectrograph is approx. 0.19 ″.

The MIRI project currently specifies the following requirements:

  • Highest failure safety in the vacuum of space at 7 Kelvin
  • Low heat dissipation and conduction to save cooling energy
  • Highest optical accuracy, also in terms of positioning and repeatability
  • Resistance to the vibrations at startup
  • Very long service life of at least 5 years (expected 10 years)
  • Compact and lightweight design

The MIRI also includes four mechanical components that must meet the high accuracy and environmental requirements. These are the two electrically driven grid wheels, the filter wheel and the protective flap (Contamination Control Cover). The wheels have different positions on their circumference, which can be maintained very precisely via a notch. Filters and grids are placed on the various positions to change the optical properties of the light beam for special examinations.

Active cooling

Since the radiation that MIRI is supposed to observe is comparatively long-wave , the instrument must be actively cooled to below 15  Kelvin (detectors ≈ 7  K ) so that it can work. Otherwise, the own heat radiation would disturb the sensitive detectors and the thermal noise itself would be too great to get good results. This requires increased insulation and active cooling, which is achieved using a heat pump ( cryocooler ) that has never been used on this scale . The initial cooling phase at commissioning is set for ≈ 300 days. A time in which the optics remain closed with a protective flap to prevent contamination with condensing gases from other areas that are not so cold.

Cooperation partner of the European consortium

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