Abstract. A highly miniaturized limb
sounder for the observation of the O2 A-band to derive temperatures
in the mesosphere and lower thermosphere is presented. The instrument
consists of a monolithic spatial heterodyne spectrometer (SHS), which is able
to resolve the rotational structure of the R-branch of that band. The
relative intensities of the emission lines follow a Boltzmann distribution
and the ratio of the lines can be used to derive the kinetic temperature. The
SHS operates at a Littrow wavelength of 761.8 nm and heterodynes a
wavelength regime between 761.9 and 765.3 nm with a resolving power of about
8000 considering apodization effects. The size of the SHS is
38 × 38 × 27 mm3 and its acceptance angle is
±5∘. It has an etendue of 0.01 cm2 sr. Complemented by front
optics with an acceptance angle of ±0.65∘ and detector optics,
the entire optical system fits into a volume of about 1.5 L. This allows us
to fly this instrument on a 3- or 6-unit CubeSat. The vertical field of view
of the instrument is about 60 km at the Earth's limb when operated in a
typical low Earth orbit. Integration times to obtain an entire altitude
profile of nighttime temperatures are on the order of 1 min for a vertical
resolution of 1.5 km and a random noise level of about 1.5 K. Daytime
integration times are 1 order of magnitude shorter. This work presents the
design parameters of the optics and a radiometric assessment of the
instrument. Furthermore, it gives an overview of the required
characterization and calibration steps. This includes the characterization of
image distortions in the different parts of the optics, visibility, and phase
determination as well as flat fielding.
This article presents the characterization and analysis of a commercial off-the-shelf (COTS) CMOS detector utilized in a miniaturized satellite payload for atmospheric temperature measurements. To evaluate the performance of the selected CMOS detector, a series of tests were performed. The temperature dependent dark current, the readout noise and the system gain are determined, which are provided for the subsequent system performance evaluation and data processing. A case study is established to simulate the space radiation effect to determine the needed shielding thickness on the instrument. The effect of radiation damage on the CMOS image sensors is investigated using a Co-60 Gamma radiation source.
Abstract. A highly miniaturized limb sounder for the observation of the O 2 A-Band to derive temperatures in the mesosphere and lower thermosphere is presented. The instrument consists of a monolithic spatial heterodyne spectrometer (SHS), which is able to resolve the rotational structure of the R-branch of that band. The relative intensities of the emission lines follow a Boltzmann distribution and the ratio of the lines can be used to derive the kinetic temperature. The SHS operates at a Littrow wavelength of 761.8 nm and heterodynes a wavelength regime between 761.9 nm and 765.3 nm with a resolving power of
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