Principal Investigator: Hartmut H. Aumann, NASA Jet Propulsion Laboratory
Proposal Title: The Spaceborne Infrared Atmospheric Sounder SIRAS for EOS Follow-on Missions
(a) Objectives and justification for work; (b) Accomplishments of prior years work; (c) Outline of proposed work and methodology; (d) One or two relevant recent publications authored by the PI or Co-I.
The Atmospheric Infrared Sounder (AIRS) instrument currently under development for EOS-PM1 will demonstrate the importance of high resolution atmospheric infrared data to the science and operational communities. The benefits demonstrated by the AIRS must be carried over to science and operational observing systems which can provide the long term data base of continuous observations required for climate studies and continued ability to improve weather forecasting. New technology and design techniques are now available that allow the Spaceborne Infrared Atmospheric Sounder (SIRAS) to meet the requirements of AIRS in a smaller, lighter and less costly system. The objectives of this IIP are to demonstrate that the anticipated size, mass, and cost of the SIRAS can be realized while meeting the science requirements and use this information in response to a future Announcement of Opportunity. This effort is well suited to the IIP since a system level approach is proposed while only validating unproven technologies to minimize costs. The following area of the Mission to Planet Earth Science Research Plan is addressed by the SIRAS: Seasonal-to-Interannual Climate Variability and Prediction.
The SIRAS instrument employs a radically different optical system that incorporates new technology "diffractive" optics. The optical design has a greater field of view in the spectrometer thereby allowing 4x smaller elements while preserving radiant throughput (or A¸). Additionally, an image field scrambler is used to mitigate the problems associated with imaging the scene onto the grating. In the proposed 1 year laboratory demonstration, a prototype SIRAS spectrometer will be developed. The prototype will include the entire optical chain for one leg of the system including the scan mirror (stationary), telescope, image field scrambler and the longest wavelength spectrometer. All optical elements will be built to their flight design, and mounted and aligned in a flight-like housing. The focal plane will be a portion of the longest wavelength focal plane required for the flight system and consist of an "M10" array borrowed from the AIRS program to minimize IIP costs. The system will be tested for radiometric, spatial and spectral performance. Also as part of this proposal, a SIRAS flight conceptual design will be developed. At the end of the first year, a proposal will be submitted for a 2nd and 3rd year effort leading to the development of a full scale Engineering Model.