Saturn’s moon Titan has a methane cycle with clouds, rain, rivers, lakes, and seas; it is the only world known to presently have a volatile cycle akin to Earth’s tropospheric water cycle.
Anomalously specular radar reflections from the southern tropical region of Saturn’s moon Titan were observed with the Arecibo Observatory and Green Bank Telescope (AO/GBT) from 2000-2008 and interpreted as evidence for liquid surfaces. The Cassini Saturn orbiter imaged Titan’s surface at infrared and microwave wavelengths from 2004-2017 and discovered >500 lakes/seas.
It did not, however, observe liquid surfaces in the regions that are anomalously specular to AO/GBT.
A new study by scientists from several institutions in the U.S. and one in France has found evidence that suggests the bright patches spotted on Titan‘s surface 20 years ago are dry lake beds.
For the study, scientists gathered all the available data on the bright spots from several observatories and Cassini. After a long analysis, they found that the bright spots could be one of three things: dry lake beds, settled rainfall, or dunes.
They eliminated rainfall as a possibility by noting rain has only ever been observed falling on the moon twice, making the possibility of giant rain puddles remote. They also excluded the possibility of vast expanses of dunes because the weather on the moon only allows for their formation in other locations. That left dry lake beds as the only logical conclusion.
However, the results of the study now raise the question of what happened to the liquid that once formed the lakes over them.
Scientists think that it is possible that it moved from near the poles to other parts of the moon, but they also suggest that it could have evaporated and was destroyed by sunlight.
They further suggest that future researches looking for habitable planets needs to be cautious when looking for evidence of liquid because it could dry up.
- Jason D. Hofgartner et al. The root of anomalously specular reflections from solid surfaces on Saturn’s moon Titan. Nature Communications. DOI: 10.1038/s41467-020-16663-1