Mid-Wave Long-Wave Infrared Spectrometer Bi-Faceted Grating
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Solution Overview
Problem
Current small spacecraft missions face challenges in accurately assessing the composition and volatile content of small bodies like asteroids and planetary surfaces due to the lack of compact, high-resolution spectrometers that can provide simultaneous wavelength range coverage, making it difficult to determine water quantity, phase, and presence of organics or other volatiles.
Innovation Solution
A mid-wave and long-wave infrared point spectrometer (MLPS) with a bi-faceted grating and dual detector system, capable of splitting light into two spectral ranges (2-4 μm and 5.5-12 μm) to discriminate water forms and quantify volatile content, while also measuring temperature and surface composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate instruments are used to assess reflected and emitted light ranges, then measurement coverage is comprehensive, but instrument size and complexity increase
Solution Approach 1:
The patent combines mid-wave infrared (2-4 μm) and long-wave infrared (5.5-12 μm) spectrometers into a single integrated instrument. The optical assembly uses a beam splitter to divide incoming light into two spectral ranges, which are then focused onto separate detector arrays. This merging approach provides comprehensive wavelength coverage while maintaining a compact design suitable for small spacecraft, eliminating the need for separate instruments.
Solution Approach 2:
The spectrometer is designed to perform multiple functions simultaneously: measuring both reflected sunlight (mid-wave) and thermal emission (long-wave) from planetary surfaces. The dual-detector system enables the instrument to assess water quantity, phase, and composition across the entire 2-12 μm spectral range in a single observation, making it universally applicable to diverse planetary exploration scenarios.
2Measurement precision
If high resolution spectrometry is implemented, then measurement precision improves, but instrument size and power consumption increase
Solution Approach 1:
The patent replaces traditional mechanical scanning spectrometers with a fixed optical assembly that uses diffraction gratings and mirror arrays to achieve high spectral resolution. The mid-wave detector array and long-wave detector array are positioned to receive dispersed light directly, eliminating moving parts while maintaining resolution capabilities. This substitution reduces instrument mass and complexity while preserving measurement precision.
3Adaptability or versatility
If integrated wavelength range coverage is achieved, then scientific capability improves, but device complexity increases
Solution Approach 1:
The optical assembly is segmented into distinct functional sections: a beam splitter that separates mid-wave and long-wave light, separate focusing optics for each spectral range, and dedicated detector arrays. This segmentation allows each component to be optimized for its specific function while maintaining overall integration. The modular design achieves comprehensive wavelength coverage without excessive complexity, as each segment handles a specific portion of the spectral range.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables precise determination of water abundance, phase, and presence of volatiles, as well as surface composition and thermal properties, facilitating detailed planetary exploration and resource assessment for small spacecraft missions.
Implementation Method 1
A small neutron spectrometer (e.g., Mini-NS in LunaH-Map [4], developed for the Moon) can quantify H abundance coarsely for a slow asteroid flyby
Implementation Method 2
The mentioned dual wavelength range may also be used to measure volatile content and temperature simultaneously for surfaces providing both accurate quantification by correction of thermal emission addition to the 3 μm feature
Implementation Method 3
with sufficient integration time on a sunlit surface, the disclosed MLPS may also be used to sense the H2O bend at, for example, ̃6 μm in its 5.5-12 μm channel
Data Source
AI summary
Methods and devices to implement mid-wave and long-wave infrared point spectrometers are disclosed. The described methods and devices involve bi-faceted gratings, high-operating-temperature barrier infrared and thermal detectors. The disclosed concept can be used to design flight spectrometers that cover broad solar reflectance plus thermal emission spectral ranges with a compact and low-cost instrument suitable for small spacecraft reconnaissance of asteroids, the Moon, and planetary satellites as well as mass-constrained landed missions.