Outbursts Upon Cooling of Low‐Temperature Binary Mixtures: Experiments and Their Planetary Implications
Year: 2024
Type: article
Abstract: For many binary mixtures, the three‐phase solid‐liquid‐vapor equilibrium curve has intermediate pressures that are higher than the pressure at the two pure triple points. This curve shape results in a negative slope in the high‐temperature region near the triple point of the less volatile component. When freezing mixtures in the negative slope regime, fluid trapped below confined ice has latent heat released with more vapor upon cooling, and thus increases in pressure. If the rising pressure of the confined fluid overcomes the strength of the confining solid, which may be its own ice, it can produce an abrupt outburst of material and an increase in the system's overall pressure. Here, we report experimental results of freezing‐induced outbursts occurring in the N 2 /CH 4 , CO/CH 4 , and N 2 /C 2 H 6 systems, and provide insight into the phenomenon through a thermodynamics perspective. We also propose other binary systems that may experience outbursts and explore the geological implications for icy worlds such as Titan, Triton, Pluto and Eris as well as rocky bodies, specifically Earth and Mars.
DOI: 10.1029/2024je008457
Language: English
Topic: Astro and Planetary Science
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G1380325028, G2268656542, PREVIOUS STUDIES HAVE SHOWN THAT THE LAKES OF TITAN ARE COMPOSED OF METHANE AND/OR ETHANE BUT THE RELATIVE PROPORTIONS ARE MOSTLY UNCLEAR. UNDERSTANDING THE PAST AND CURRENT STABILITY OF THESE LAKES REQUIRES CHARACTERIZING THE INTERACTIONS OF LIQUID METHANE AND ETHANE ALONG WITH NITROGEN. PRIOR INVESTIGATIONS FOUND THAT THE FREEZING POINT OF METHANE IS DEPRESSED WHEN MIXED WITH NITROGEN. RECENT WORK SHOWS THAT ALTHOUGH METHANE AND ETHANE HAVE SIMILAR FREEZING POINTS WHEN MIXED THEY CAN REMAIN LIQUID DOWN TO 72 K. CONCURRENTLY WITH THE FREEZING POINT MEASUREMENTS WE ACQUIRE TRANSMISSION SPECTRA OF THESE MIXTURES TO UNDERSTAND HOW THE SPECTRAL FEATURES CHANGE WITH CONCENTRATION AND TEMPERATURE. ANY MIXING OF THESE TWO SPECIES TOGETHER WILL DEPRESS THE FREEZING POINT OF THE LAKE BELOW TITAN S SURFACE TEMPERATURE PREVENTING THEM FROM FREEZING. THE NEXT STEP IS TO DETERMINE HOW THE METHANE-ETHANE SYSTEM BEHAVES IN THE PRESENCE OF A NITROGEN ATMOSPHERE. PRELIMINARY RESULTS INDICATE THAT AT HIGH PRESSURE THE TERNARY SYSTEM CREATES TWO SEPARATE LIQUID PHASES. THROUGH SPECTROSCOPY WE DETERMINED THE BOTTOM LAYER TO BE NITROGEN RICH AND THE TOP LAYER TO BE ETHANE RICH. UNDERSTANDING THE FREEZING POINTS OF COMBINATIONS OF THESE SPECIES HAS IMPLICATIONS FOR NOT ONLY THE LAKES ON THE SURFACE OF TITAN BUT ALSO FOR THE EVAPORATION/CONDENSATION/CLOUD CYCLE IN THE ATMOSPHERE AS WELL AS THE STABILITY OF THESE SPECIES ON OTHER OUTER SOLAR SYSTEM BODIES. THESE RESULTS WILL GUIDE CURRENT THEORETICAL MODELS AND INTERPRETATION OF FUTURE OBSERVATIONAL DATA. WE WILL USE THE CRYOGENIC ASTROPHYSICAL ICE LAB AT NORTHERN ARIZONA UNIVERSITY TO MEASURE THE COMPOSITION AND STABILITY OF LIQUIDS AND ICES UNDER VARIOUS TEMPERATURES AND PRESSURES. OUR CRYOGENIC LABORATORY SETUP ALLOWS US TO EXPLORE ICES DOWN TO 30 K THROUGH IMAGING AND TRANSMISSION SPECTROSCOPY. SAMPLES WILL INCLUDE MIXTURES OF METHANE ETHANE AND NITROGEN. WE WILL ALSO PERFORM MODELING TO UNDERSTAND THE CHEMISTRY INTERACTIONS CAUSING THESE PHENOMENA. THE PROPOSED WORK WILL BE DIRECTLY APPLICABLE TO NASA S SOLAR SYSTEM WORKINGS OBJECTIVES OF CHARACTERIZING AND UNDERSTANDING THE CHEMICAL MINERALOGICAL AND PHYSICAL FEATURES OF PLANETARY SURFACES AND FLUID INVENTORIES THAT INTERACT WITH THE SURFACE. WE WILL ALSO DEVELOP THEORETICAL AND EXPERIMENTAL BASES FOR UNDERSTANDING THESE FEATURES IN THE CONTEXT OF THE VARYING CONDITIONS THROUGH TIME AFTER FORMATION., G549985663
OpenAlex ID: W4403155430