2017.B.1.3. The Compact Infrared Imager and Radiometer (CIIR)

Author(s)

Rory Evans (1)
Simon Calcutt (1)
Neil Bowles (1)

University of Oxford, United Kingdom

Session

B.1

Keywords

Microbolometer, Thermal Infrared, CubeSat, Radiometer, Blackbody

Abstract

The Compact Infrared Imager and Radiometer (CIIR) is a novel concept design for a 6U CubeSat spacecraft, suitable to achieve various science goals through infrared remote sensing. The initial concept was developed from design heritage of the Compact Modular Sounder (CMS), currently orbiting on TechDemoSat-1. CMS is the most recent in a long history of thermal infrared instruments developed in Oxford, the heritage of which continues through to CIIR.

CIIR develops the CMS design into a CubeSat with the required spacecraft subsystems, and uses an improved detector array to extend the operations to medium resolution (150 m at 800 km altitude) mapping of thermally derived surface properties (e.g. composition and thermal inertia), and atmospheric sounding. Miniaturisation of the imaging radiometer is possible due to the performance of uncooled microbolometer arrays which reduce system complexity and power requirements, but still maintain a wide spectral range.

Whilst meeting CubeSat specifications CIIR has two important features to ensure that the data returned is comparable to typical instruments. First, a cavity blackbody is included as a traceable radiometric calibration target ensuring < 0.5 K accuracy. Second, the optical design of the instrument includes an intermediate focal plane between the input telescope, and the detector focal plane. The intermediate focal plane holds the filter array, and allows many discrete narrow or broad spectral channels (>10) to be used.

By covering a spectral range from 5 to 20 μm the microbolometer array is suited to a range of differently customised filters, meaning that the potential targets are vast. For example, following the Diviner Lunar Radiometer a trio of filters around 8 μm would allow the characterisation of lunar silicate mineralogy, similar filters could be used when mapping the mineralogy of an asteroid. Alternatively, a set of filters similar to the High Resolution Dynamics Limb Sounder (HIRDLS) may be used in a limb viewing mode to observe atmospheric species such as ozone and water, or without filters as a broadband mapper.

The future aims of the work on CIIR are to; demonstrate through modelling and testing the performance of remote sensing measurements; define and document the interfaces of subsystems critical to different science objectives; build and test a calibrated flight ready system. This presentation will include details of the design of CIIR and applications of the spacecraft, along with the current and future steps to develop CIIR into a flight ready CubeSat.