# The Liquidus Temperature for Methanol-Water Mixtures at High Pressure and Low Temperature, with Application to Titan

## TL;DR

This study measures the liquidus temperature of methanol-water mixtures at high pressures to understand their antifreeze properties, revealing methanol's significant role in maintaining Titan's subsurface ocean.

## Contribution

It provides new experimental data on methanol-water freezing behavior at high pressures relevant to Titan's environment, highlighting methanol's effectiveness as an antifreeze.

## Key findings

- Methanol lowers the freezing point of water at high pressures.
- Metastable states are observed in the Ice-III regime.
- Methanol is more effective as an antifreeze than previously thought.

## Abstract

Methanol is a potentially important impurity in subsurface oceans on Titan and Enceladus. We report measurements of the freezing of methanol-water samples at pressures up to 350~MPa using a volumetric cell with sapphire windows. For low concentrations of methanol, the liquidus temperature is typically a few degrees below the corresponding ice freezing point, while at high concentrations it follows the pure methanol trend. In the Ice-III regime, we observe several long-lived metastable states. The results suggest that methanol is a more effective antifreeze than previously estimated, and might have played an important role in the development of Titan's subsurface ocean.