Scientists have discovered that the small icy worlds on the edge of the Solar System, particularly dwarf planets Eris and Makemake, could be more suitable for hosting life. These two dwarf planets may have sufficient geothermal activity to support liquid water oceans, as suggested by modeling based on new observations from the James Webb Space Telescope (JWST).
The research, titled "Moderate D/H ratios in methane ice on Eris and Makemake as evidence of hydrothermal or metamorphic processes in their interiors: Geochemical analysis" published in the journal Icarus, points to potential geothermal processes beneath the surfaces of the two dwarf planets situated in the Kuiper Belt beyond Neptune's orbit.
This artist’s impression shows the surface of the distant dwarf planet Makemake.
Geothermal Activity Detected on Icy Dwarf Planets Eris and Makemake
The identification of recent methane isotopologues on Eris and Makemake's surfaces suggests geothermal processes, marking the first such discovery beyond Neptune. This implies these dwarf planets might be warmer than initially believed, potentially favoring conditions for life.
Eris, Pluto, Haumea, and Makemake are dwarf planets in the Solar System, defined by self-gravity and a spherical shape but distinguishable from full planets by their inability to clear orbital debris.
Eris, larger than Pluto, orbits about 6,289,000,000 miles from the sun, with a 1,444-mile diameter. It takes 557 years to complete one orbit and was named after the Greek goddess of discord. Makemake, the third-largest dwarf planet, has an 888-mile diameter, orbits every 309 years, and was named after the god of fertility by the Rapa Nui people of Easter Island.
Recent findings, published in the journal Icarus, reveal traces of new methane on Eris and Makemake's surfaces, potentially indicative of geothermal activity, hinting at cryovolcanism or a hot rocky core.
Co-author Noemí Pinilla-Alonso emphasizes the unexpected internal dynamism of Eris and Makemake, challenging conventional wisdom on the composition of large trans-Neptunian objects. This discovery, facilitated by the JWST, measured the methane composition on their surfaces, focusing on the deuterium-to-hydrogen (D/H) ratio to reveal chemical origin and history.
Christopher Glein, co-author and planetary scientist, notes the moderate D/H ratio contradicts primordial methane, suggesting a geochemical origin in the deep interior, reshaping our understanding of these icy worlds, and emphasizing endogenic forces in shaping the outer solar system.
Implications for Titan's Habitability
The recent discovery of methane isotopes on Eris and Makemake indicates ongoing outgassing, supported by another isotope ratio involving carbon-12 and carbon-13.
Will Grundy, leading the JWST observations, suggests the possibility of warm or hot geochemistry in the rocky cores of these dwarf planets. This could result in cryovolcanic processes delivering methane to the surfaces, potentially in geologically recent periods, evident from a carbon isotope ratio pointing to resurfacing.
Remarkably, the models explaining methane formation on Eris and Makemake might apply to Saturn's moon Titan. Recent research suggested that carbon-based molecules, including methane, might not reach Titan's subsurface ocean after lingering on the surface.
If geothermal processes within Titan's rocky core produce methane, akin to Eris and Makemake, it challenges assumptions about Titan's habitability, as its ocean could receive carbon chemistry internally rather than from the surface.
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