Aerial remote sensing supplements earth observation from space and contributes to the development of new satellite instruments and analytic methodologies. The cameras in use so far at EOC are now being replaced by new, improved instruments. They are available to all DLR scientists and their cooperating partners via the EOC user-service Optical Airborne Remote Sensing (OpAiRS).
D-CFFU research aircraft with HySpex (foreground) and HALO (background) before taking off on a joint mission
The instruments supplied in January 2020 replace the system in use since 2012. They are two imaging spectrometers that together cover a wide spectral range from visible light to shortwave infrared. While ordinary digital cameras distinguish only three colours (red, green, blue), the new sensors break down incoming light into almost 1000 different "colours", so-called spectral bands (HySpex VNIR-3000N: 400-1000 nm, 700 bands; SWIR-384: 930-2500 nm, 288 bands). This means the instruments sense details that make it possible to identify, for example, different types of plants and soil, to evaluate the physical condition of trees and agricultural crops, and to draw conclusions about water constituents such as algae or substances that are hazardous to health.
The flights are also used to simulate results from planned satellite missions like EnMAP or CHIME before launch, in order to optimize the design of the instruments and prepare for the subsequent data processing. When the first data arrive from the missions, the OpAiRS sensors assist in the validation of the measurement data from Earth orbit. In this way, aircraft measurements assure, for example, that DLR's DESIS spectrometer operating on the International Space Station supplies reliable data throughout its lifetime. This is anything but self-evident after an often rough rocket launch and many years under sometimes harsh environmental conditions in space.
Regular calibration of the OpAiRS sensors in an in-house calibration lab (CHB) guarantees that the measuring precision always meets the highest requirements. The potential of the new HySpex sensors can thus be fully exploited.
EOC has over 20 years of experience in aerial remote sensing and has carried out hundreds of measurement flights. The new system will further increase the already high measurement accuracy and should open up new fields of application. For example, DLR researchers are working on ways to detect and measure from aircraft sources of the greenhouse gases methane and CO2 in order to investigate at high-resolution important issues relating to climate change and its consequences also at local scales.
Staff of the OpAiRS user service in front of DLR's D-FDLR research aircraft
