In general, a spectrum can tell us about the composition of the source of the radiation, or of any substance between the source and the detector. Each material has its own fingerprint and spectroscopy allows us to decompose this in constituent parts.

Shorter wavelengths will likely saturate NIRSpec, especially at lower resolutions

Without having studied the details, that may make sense for a detector array. The figure shows that Titans clouds are a factor 50 brighter at 1 µm than at 4 µm. The red lines show the level at which the detectors saturate. At a lower resolution, each pixel obtains photons from a larger solid angle, so it reaches its maximum number of photons per unit time (maximum brightness = saturation) at a lower intensity, compared to a higher resolution with more individual detectors. Wherever the thin lines in the figure are larger than the thick lines, the detector would be saturated and the magnitude of the peaks of the thin lines would not be detectable.

In general, a spectrum can tell us about the composition of the source of the radiation, or of any substance between the source and the detector. Each material has its own fingerprint and spectroscopy allows us to decompose this in constituent parts.

Shorter wavelengths will likely saturate NIRSpec, especially at lower resolutions

Without having studied the details, that may make sense for a detector array. The figure shows that Titans clouds are a factor 500 brighter at 1 µm than at 4 µm. The red lines show the level at which the detectors saturate. At a lower resolution, each pixel obtains photons from a larger solid angle, so it reaches its maximum number of photons per unit time (maximum brightness = saturation) at a lower intensity, compared to a higher resolution with more individual detectors. Wherever the thin lines in the figure are larger than the thick lines, the detector would be saturated and the magnitude of the peaks of the thin lines would not be detectable.