Atmospheric control of the cooling rate of impact melts and cryolavas on Titan’s surface |
| |
Authors: | Ashley Gerard Davies Christophe Sotin Dennis L Matson Julie Castillo-Rogez Torrence V Johnson Mathieu Choukroun Kevin H Baines |
| |
Institution: | Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109, United States |
| |
Abstract: | As on Earth, Titan’s atmosphere plays a major role in the cooling of heated surfaces. We have assessed the mechanisms by which Titan’s atmosphere, dominantly N2 at a surface pressure of 1.5 × 105 Pa, cools a warm or heated surface. These heated areas can be caused by impacts generating melt sheets and (possibly) by endogenic processes emplacing cryolavas (a low-temperature liquid that freezes on the surface). We find that for a cooling cryolava flow, lava lake, or impact melt body, heat loss is mainly driven by atmospheric convection. Radiative heat loss, a dominant heat loss mechanism with terrestrial silicate lava flows, plays only a minor role on Titan. Long-term cooling and solidification are dependent on melt sheet or flow thickness, and also local climate, because persistent winds will speed cooling. Relatively rapid cooling caused by winds reduces the detectability of these thermal events by instruments measuring surface thermal emission. Because surface temperature drops by ≈50% within ≈1 day of emplacement, fresh flows or impact melt may be difficult to detect via thermal emission unless an active eruption is directly observed. Cooling of flow or impact melt surfaces are orders of magnitude faster on Titan than on airless moons (e.g., Enceladus or Europa).Although upper surfaces cool fast, the internal cooling and solidification process is relatively slow. Cryolava flow lengths are, therefore, more likely to be volume (effusion) limited, rather than cooling-limited. More detailed modeling awaits constraints on the thermophysical properties of the likely cryomagmas and surface materials. |
| |
Keywords: | Titan Enceladus Volcanism Saturn satellites Impact processes |
本文献已被 ScienceDirect 等数据库收录! |
|