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Instrument demonstration effort for the CLARREO mission
Author(s): Frédéric Grandmont; Louis Moreau; Hugo Bourque; Joe Taylor; Frédéric Girard; Martin Larouche; James Veilleux

Paper Abstract

NASA and other national agencies ask the National Research Council (NRC) once every decade to look out ten or more years into the future and prioritize research areas, observations, and notional missions to make those observations. The latest such scientific community consultation referred to as the Decadal Survey (DS), was completed in 2007 [1]. DS thematic panels developed 35 missions from more than 100 missions proposed, from which the DS Executive Committee synthesized 17 missions, with suggested order presented in three time-phased blocks. The first block with aim for near term launch (2010-2013) included four missions. The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission is one of them.

The CLARREO mission was classified as a Small Mission to be contained in a 300 M US$ budgetary envelope. CLARREO will provide a benchmark climate record that is global, accurate in perpetuity, tested against independent strategies that reveal systematic errors, and pinned to international standards. The long term objective thus suggests that NOAA or NASA will fly the CLARREO instrument suite on an operational basis following the first scientific experiment

The CLARREO missions will conduct the following observations:

1. Absolute spectrally-resolved measurements of terrestrial thermal emission with an absolute accuracy of 0.1 K in brightness temperature (3σ or 99% confidence limits.) The measurements should cover most of the thermal spectrum.

2. Absolute spectrally-resolved measurements of the solar radiation reflected from Earth. The measurements should cover the part of the solar spectrum most important to climate, including the near-ultraviolet, visible, and near-infrared.

3. Independent measurements of atmospheric temperature, pressure, and humidity using Global Positioning System (GPS) occultation measurements of atmospheric refraction.

4. Serve as a high accuracy calibration standard for use by the broadband CERES instruments on-orbit.

Following the DS conclusion, and considering the early development stage of the mission, NASA funded three Instrument Incubator Programs (IIP) to push instrument concepts to a higher level of maturity. A joint proposal between University of Wisconsin (UW) and Harvard University was selected to address the first above objective and part of the fourth one in the corresponding spectral region. In order to achieve this goal, four complementary technologies are to be developed [2]:

(1) On-orbit Absolute Radiance Standard (OARS), a high emissivity blackbody source that uses multiple miniature phase-change cells to provide a revolutionary on-orbit standard with absolute temperature accuracy proven over a wide range of temperatures.

(2) On-orbit Cavity Emissivity Modules (OCEMs), providing a source (quantum cascade laser, QCL, or “Heated Halo”) to measure any change in the cavity emissivity of the OARS.

(3) On-orbit Spectral Response Module (OSRM), a source for spectral response measurements using a nearly monochromatic QCL source configured to uniformly fill the sensor field-of-view.

(4) Dual Absolute Radiance Interferometers (DARI), providing spectral coverage from 3.3 to 50 μm that can be inter-compared to dissect any unexpected systematic errors in overlapping spectral regions.

ABB's GFI (Generic Flight Interferometer) has been selected as the favoured architecture for the DARI, mainly due to the maturity of the design and its space heritage. A GFI with commercial grade components was optimised for the selected spectral range. The architecture of the GFI will ensure a high response stability between calibrations.

Paper Details

Date Published: 20 November 2017
PDF: 5 pages
Proc. SPIE 10565, International Conference on Space Optics — ICSO 2010, 1056512 (20 November 2017); doi: 10.1117/12.2309125
Show Author Affiliations
Frédéric Grandmont, ABB Bomem Inc. (Canada)
Louis Moreau, ABB Bomem Inc. (Canada)
Hugo Bourque, ABB Bomem Inc. (Canada)
Joe Taylor, Univ. of Wisconsin (United States)
Frédéric Girard, ABB Bomem Inc. (Canada)
Martin Larouche, ABB Bomem Inc. (Canada)
James Veilleux, ABB Bomem Inc. (Canada)

Published in SPIE Proceedings Vol. 10565:
International Conference on Space Optics — ICSO 2010
Errico Armandillo; Bruno Cugny; Nikos Karafolas, Editor(s)

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