With new eyes, EnMAP, a hyperspectral satellite launched on April 1, 2022, has successfully transmitted its first image to Earth. It depicts the Bosporus in high resolution and three different wavelengths of light: visible, short and long wave near infrared. This allows us to see things that are normally unseen, such as the state of the vegetation or the composition of the soil.
Our eyes can only see a very limited part of the light spectrum. However, it is precisely the wavelength ranges of radiation beyond that that can provide valuable information about the nature and condition of materials, rocks or even living systems such as vegetation. For this reason, research uses hyperspectral cameras: instruments that capture radiation beyond our borders and break it down into individual wavelength ranges using spectrometers.
A German environmental satellite was launched on April 1, 2022, bringing such a hyperspectral instrument into orbit for the first time. The EnMAP satellite scans the earth’s surface using two high-resolution spectrometers and captures the radiation reflected from the subsoil in the visible and infrared wave range between 420 and 2,450 nanometers.
The Bosphorus with different eyes
The EnMAP satellite took its first picture during a flight over the Bosporus – the strait near Istanbul that separates Europe from Asia. The image covers a strip of this region about 30 kilometers wide and 180 kilometers long. Here you can see three sections from the 54-kilometer-long central area of this test image. The image on the left shows a true-color representation that roughly corresponds to human color perception.
The center image is a false-color image from the VNIR camera, recording wavelengths from 420 to 1,000 nanometers. In this near-infrared range, for example, the radiation from vegetation can be captured and allows conclusions to be drawn about biomass and photosynthetic activity. It is colored red here.
The right section is from the satellite’s SWIR camera, which detects slightly longer wavelength infrared between 900 and 2,450 nanometers. From this radiation, conclusions can be drawn, among other things, about the geological composition of the subsoil. For example, you can see clayey soils or limestone, but also, like here, the buildings in the city of Istanbul.
High quality already
“Even the first data from EnMAP show what the German environmental satellite can do,” says Sebastian Fischer, EnMAP overall project manager at the German Space Agency at DLR. Because the calibration of the instruments is not yet complete. “But these first images give us a very good foretaste of what scientists around the world can expect.”
The EnMAP team is very satisfied with the first images of the new hyperspectral satellite: “The high quality of the data in all channels is clearly visible on the one hand in typical spectra such as for vegetation and on the other hand in low noise and disturbing image stripes with the extensive dynamic range, which especially in dark areas like water becomes clear,” explains Fischer.
Before the scientific operation of the satellite begins, there will now be a six-month calibration phase, which will optimize the instruments in orbit and further improve data quality.
Image Credit: Getty