Free Astronomy Magazine January-February 2021

39 JANUARY-FEBRUARY 2021 ASTRO PUBLISHING Sinlap. Menrva, is the largest crater on Titan at around 425 kilometres across, which means it intersects both the dunes and the plains. Sinlap is thought to be the youngest crater and while it is located in the dune region, it has signs of water ice and doesn’t display the same char- acteristics of a dune crater and couldn’t be classified into either of the two groups. It is possible that the dune craters originally had exposed water ice which was then covered with or- ganic material, and Sinlap’s younger age means that this process is still occurring. Erosion is thought to occur quite quickly with even the younger craters covered by a thin layer of organic material. “Titan seems to have a composi- tional latitudinal dependence that is also reflected in the impact craters as well,” says Anezina. “This latitu- dinal dependence seems to unveil many of Titan’s secrets, showing us that the surface is actively con- nected with atmospheric processes and possibly with internal ones.” Further investigation of Titan’s craters will be possible in the future when NASA’s Dragonfly lander mis- sion visits Selk, one of the dune craters. The mission is due to launch in 2027 and arrive at Titan in 2034 to study several sites on the moon. ! L ’atterrisseur Dragonfly de la NASA au-dessus de la surface de Titan, la lune principale de Saturne. Profitant de l’atmosphère dense de ce satellite, Dragonfly sera équipé de moteurs à hélices qui lui permettront de se déplacer dans les airs, à la recherche de sites potentiellement intéressants. L’un de ceux-ci sera le cratère Selk. Décollage de la mission prévu en 2027, arrivée sur Titan en 2034. [Johns Hopkins APL] been altered compositionally show- ing two different evolution routes. The VIMS data show a difference in abundances between the crater floors and ejecta blankets for the dune craters, which is in contrast to the RADAR data. This suggests that there is a difference in the surface layer between the floor and ejecta that doesn’t affect the subsurface composition. It is possible that this is due to the dune craters becoming infilled with a fine layer of sand sed- iment. The composition of craters and ejecta is generally the same for the plain craters, which the authors say suggests that the plain craters are being “cleaned” of sediment. This could be caused by fluvial erosion, and agrees with previous assump- tions that more rain falls in the higher latitudes of Titan. There are two craters which are ex- ceptions to the rule: Menrva and