These six infrared images of Saturn's moon Titan represent some of the clearest and most seamless global views of the surface of the icy moon, the previously produced. The views were taken using 1
3 years of data acquired with the VIMS instrument (Visual and Infrared Mapping Spectrometer) on NASA's Cassini spacecraft. The images are the result of a concentrated effort to seamlessly combine data from the multitude of different observations that VIMS made during a variety of lighting and viewing conditions during Cassini's mission.
Previous VIMS maps of Titan (for example, PIA02145) show large differences in image resolution and lighting conditions, resulting in significant seams between different areas of the surface. With the seams, this new collection of images is by far the best representation of how the Titan's globe might appear to the casual observer, if not for the hazy atmosphere of the moon, and it probably will not be replaced for some time
Observing the surface of titanium in the visible region of the spectrum is difficult because of the veil around the globe around the globe. This is mainly because small particles, called aerosols in the upper atmosphere of titanium, strongly scatter visible light. But the titanium surface can be more easily imaged in a few infrared windows – infrared wavelengths, where the scattering and absorption of light is much weaker. Here the VIMS instrument shone and separated the haze to get clear images of the titanium surface. (For comparison, Figure B shows titanium as it appears in visible light, as does PIA11603.)
Figure B. Credit: NASA / JPL-Caltech / Stéphane Le Mouélic, University of Nantes, Virginia Pasek, University of Arizona
Producing mosaics from Titan's VIMS images has always been a challenge, as the data has been obtained through many different fly-bys with different observation geometries and atmospheric conditions. One result is that very prominent seams appear in the mosaics, which are quite difficult for imaging scientists to remove. However, through elaborate and detailed analysis of the data, along with time-consuming manual processing of the mosaics, the seams were largely removed. This is an update of the work previously discussed in PIA20022.
Each full-color image consists of three color channels: red, green, and blue. Each of the three color channels combined to produce these views was generated using a ratio of the brightness of the titanium surface at two different wavelengths (1.59 / 1.27 microns [red] 2.03 / 1.27 microns [green] and 1.27 / 1.08 microns [blue]). This technique (called "band-ratio" technique) reduces the stress on seams and emphasizes subtle spectral variations in the materials on the titanium surface. For example, the equatorial dune fields of the moon appear uniformly brown here. There are also bluish and purple areas that may have different compositions than the other bright areas and may be enriched with water ice.
A map of titan with latitude and longitude and labeled surface features can be found in PIA20713
It From this unique series of images, it becomes clear that titanium has a complex surface with innumerable geological features and compositional units. The VIMS instrument has paved the way for future infrared instruments that could image titanium at a much higher resolution, revealing features unremarkable by any of Cassini's instruments.