COMPARATIVE PLANETARY VOLCANISM WITHIN THE SOLAR SYSTEM

By applying what we know of volcanism on Earth, we can better comprehend the volcanic processes and landforms observed remotely on other bodies. The converse is true, too: only by studying other Solar System worlds, we can more fully understand the volcanic phenomena that have shaped Earth.

The terrestrial planetary bodies (Mercury, Venus, Earth, Mars, the Moon, and Io) have been shaped by silicate volcanism. On these worlds, mafic volcanism seems to dominate over other compositions, based on morphological, chemical, and mineralogical data obtained from orbit, and on analyses of samples where available. The Apollo astronauts returned samples of lunar lavas that, based on bulk major-element chemistry, are similar to basalts on Earth. Meteorites that originated on Mars also display mafic or even ultramafic compositions.

In contrast, icy processes dominate over silicate volcanism on the icy moons of the outer Solar System: jets on Enceladus spurt water vapor that condenses to ice and helps to feed Saturn’s E ring; vents on Europa may similarly erupt water vapor into space; and even Pluto and Charon appear to have experienced some volcanic resurfacing.

Humanity will build on this understanding of planetary volcanism in the coming years, with the Europa Clipper mission acquiring multi-spectral images in search for evidence of plumes erupting onto the Europan surface. The Dragonfly mission to Titan will feature a rotorcraft to study that moon’s chemistry, interior, and prospects for cryovolcanism and habitability. In the inner Solar System, the BepiColombo mission will build on what we learned about Mercury’s volcanic properties from the MESSENGER mission. The InSight lander is gathering new data of Mars’ interior, to better understand the evolution and thermal budgets of terrestrial planets. And the Psyche mission promises to return information on the enigmatic phenomenon of “ferrovolcanism” when it visits the metal-rich asteroid 16 Psyche. We have led an effort to synthesize our current understanding of comparative planetary volcanism, and in this presentation will discuss some of the key aspects of volcanism as a fundamental geological process.