DESIS – DLR Earth Sensing Imaging Spectrometer

Can Earth’s problems be solved by looking at it from above? By capturing detailed spectral data of its surface, DESIS aimed to answer this question positively. 

Mission Objective

DESIS is an imaging Spectrometer which was installed on the ISS which aims to depict the land surface, oceans, and atmosphere.

Mission Significance

• New information about the surface.
• Monitoring environmental problems.
• Evaluate and improve the dynamic correlations among geophysical factors across continents.

Source: DLR

Engineering Challenges

DESIS faced various challenges as a hyperspectral instrument operating externally on the ISS, among them:

• The system is highly sensitive to calibration drift because of its wide spectral range.
• DESIS must maintain precise optical alignment while handling rapid temperature changes from the ISS’s transitions between sunlight and shadow, due to the micro-vibrations.
• Stray light is a major concern as well, since reflections from ISS structures, Earthshine, and scattered sunlight can easily contaminate faint spectral signatures.

All these requirements must be met with a compact, lightweight design that can generate high-quality hyperspectral data in a dynamic, non-specialized imaging setting.

Methodology Overview

DESIS instrument was constructed by DLR. The hyperspectral instrument can be seen as a push-broom imaging spectrometer, and it has several components that allow its function and special abilities. However, DESIS characteristics are useless without the operating platform – MUSES.

MUSES is a Multi-User System for Earth Sensing. It serves as a platform for hosting Earth-observing instruments. These instruments encompass a range of capabilities, including high-resolution digital cameras and hyperspectral imagers, such as DESIS. MUSES is equipped to accommodate up to four such instruments concurrently, with the added flexibility to swap, enhance, and provide robotic servicing for these payloads.

Source: DLR

Acktar’s Solution

Acktar provided Fractal Black coating to DESIS’s optical system to prevent internal reflections and minimize stray light. The coating’s high spectral uniformity and near blackbody absorption are exactly what is needed to support DESIS optical and thermal requirements.

Impact

• Agricultural and forest ecosystem management.
• Monitoring vegetation health and stress parameters of the surface
• Assessment of soil degradation.
• Urban development tracking.
• Inland water monitoring, including content and pollution levels.
• Evaluating natural and environmental disasters and coordinating humanitarian responses.
• Developing and enhancing hyperspectral imaging methods and processing techniques.

Source: IOF

Since its launch in 2018, DESIS has received vast data from around the globe. The data is not publicly available but can be used for specific scientific purposes through direct request. The raw data from the DESIS mission serves scientists and researchers across various fields, enabling them to make critical decisions that impact life on Earth.

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