The primary instrument on the SCISAT‐1 payload is an infrared Fourier Transform Spectrometer (FTS) coupled with an auxiliary 2‐channel visible and near infrared imager called ACE‐FTS. The ACE‐FTS measures solar radiation at high spectral resolution as it passes through different layers of the atmosphere. The atmospheric absorption thus measured provides information on vertical profiles of atmospheric constituents, temperature, and pressure. An imager monitors aerosols based on the extinction of solar radiation using two filtered detectors. A suntracker is also included in the instrument, which provides fine pointing during occultation.
The FTS is a modified version of the classical Michelson interferometer using 2 cube corner retroreflectors on a rotating V‐shaped scan arm as moving mirrors and a folded optical layout including double passing of the beams in each arm of the interferometer. This design results in a high spectral resolution instrument with a compact size. The design also provides self‐compensation for the tilt and shear in the interferometer for both the moving and stationary optics making the alignment invariant to any variation due to thermo‐elastic deformation or other sources of alignment modification. The mechanism is based on a flexure blade pivot designed for indefinite long operating life. The optical path difference that is achieved by the combination of the motion of the scan arm and the optical doubling is ±25 cm plus margin for turn‐around. A signal‐to‐noise ratio better than 300 is achieved.
The raw data (Level 0) is transmitted from the satellite to ground stations. Specific data processing is then performed to obtain spectrally calibrated, geo‐located, transmittances of the atmosphere, called Level 1B.
ACE‐FTS Optical Payload on Canadian Science Satellite SCISAT
After 10 Years On‐orbit
Optical Payloads for Space Missions ; 423-442
2015-12-10
20 pages
Aufsatz/Kapitel (Buch)
Elektronische Ressource
Englisch
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