In the decades since the first grainy images beamed back to Earth to reveal our first close looks at Saturn and its moons, Titan has remained veiled in mystery.
The landing of the Huygens probe in 2005 brought us closer than ever before to a distant moon, showing the surface of Titan to be an ‘alien Earth,’ with methane rains and rivers, towering sand dunes, and a subsurface water ocean.
But, the probe died just 72 minutes after touching down, leaving the Cassini spacecraft to carry on its observations alone, from orbit.
Save for some mosaics mapping the surface, which suffered ‘seams’ from variations in resolution and lighting, the common image of Titan is of a cue ball moon blanketed completely in a thick haze.
Now, using 13 years of data from Cassini’s Visual and Infrared Mapping Spectrometer (VIMS) instrument, NASA has stitched together the most detailed global view yet, showing what Titan might look like if one could see right through its dense atmosphere.
‘With the seams now gone, this new collection of images is by far the best representation of how the globe of Titan might appear to the casual observer if it weren’t for the moon’s hazy atmosphere, and it will likely not be superseded for some time to come,’ NASA says.
The alien moon’s notoriously thick atmosphere makes studying Titan’s surface a challenging task, as the aerosols scatter visible light.
To work around this, the space agency focused on infrared wavelengths, where the effects of scattering and absorption are weaker, allowing for a much clearer picture.
Even so, obtaining a global, mosaic view is no easy task.
‘Making mosaics of VIMS images of Titan has always been a challenge because the data were obtained over many different flybys with different observing geometries and atmospheric conditions,’ NASA says.
‘One result is that very prominent seams appear in the mosaics that are quite difficult for imaging scientists to remove,’ NASA explains.
‘But, through laborious and detailed analyses of the data, along with time consuming hand processing of the mosaics, the seams have been mostly removed.’
For the full color view, the space agency combines images captured in three different color channels – red, green, and blue.
The researchers also rely on a technique known as the band-ratio technique to smooth out the ‘seams,’ and make subtle variations more apparent, revealing some of the surface materials in better detail.
This, NASA says, was all made possible with Cassini’s VIMS instrument.
‘It is quite clear from this unique set of images that Titan has a complex surface, sporting myriad geologic features and compositional units,’ NASA says.
‘The VIMS instrument has paved the way for future infrared instruments that could image Titan at much higher resolution, revealing features that were not detectable by any of Cassini’s instruments.’