Literature Review: Miniaturized Concepts for Spaceborne Hyperspectral Earth Observation

Objectives

The aim of the study was to review new cost-effective and high-performance hyperspectral observation concepts which could be considered for future implementation in spaceborne Earth Observation missions, particularly within the context of the next generation of EUMETSAT satellites. The study particularly focused on Static Fourier Transform Spectrometer (SFTS) technologies and Partially Scanned Interferogram (PSI) methodologies. Within the scope of available information, these concepts were discussed in terms of their physical background, potential applications, development of concepts and designs, and validation status.

Overview

For at least two decades, observations from hyperspectral spaceborne atmospheric sounding instruments in the optical domain have been widely used operationally in various fields including numerical weather prediction, chemistry transport modelling, air quality control, and climate modelling.

A breakthrough was achieved with the development of spectrometers capable of providing hyperspectral measurements (with a resolution power of approximately 1000) covering the entire globe, along with reasonable spatial sampling rates achieved once or twice per day. This breakthrough was complemented by advancements in data processing capabilities, enabling data centres and users to handle the increased volume of data. The underlying instrument concepts, primarily dynamic Fourier Transform Spectrometers for the terrestrial infrared (TIR) domain and dispersive grating spectrometers for the solar visible (VIS) to shortwave infrared (SWIR) domains, have proven reliable, often exceeding expected lifetimes with good performance.

The term “classical” now refers to these concepts. They could be integrated into a continuous observation system with consistent performance in the future, likely with improvements in cost and size due to lessons learned and technological advancements in optics, detectors and system integration. It is widely acknowledged that achieving higher signal-to-noise ratio (SNR), spectral resolution, or spatial resolution/sampling with classical concepts would likely result in undesirable and disproportionate increases in size, mass and power.

As science and programmatic requirements evolve, next generation missions must incorporate innovative concepts and technologies to achieve significant miniaturization. This approach would also facilitate the implementation of high-performance missions tailored to specific application fields.

This review was initially intended to focus on Static Fourier Transform Spectrometers (SFTS) technologies and Partially Scanned Interferograms (PSI) methodologies. This decision was based on the anticipation that SFTS would emerge as the most promising candidate for miniaturization, especially when considering the flexibility of bandwidth requirements for next-generation missions, with the potential to compete with classical concepts such as the dispersive grating spectrometer. However, during this review process, it became apparent that strict focus solely on SFTS was not ideal. Consequently, the scope of the review was expanded to include various other miniaturization concepts, though it does not claim to cover all new concepts comprehensively.

The full results of the literature review can be found in the Final Report under Study Documents below.