Jupiter's moon Europa may have had a slow evolution

Date:
June 17, 2023
Source:
Arizona State University
Summary:
Europa may have a metamorphic origin for the ocean. While some
scientists speculated this, a research team shows that if Europa
indeed formed from hydrated rocks (i.e., rocks have hydrogen and
oxygen), then enough of Europa's interior should get hot enough to
release water directly from the hydrated rocks to form the ocean
and ice shell.


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==========================================================================
FULL STORY ========================================================================== Jupiter's moon, Europa, is slightly smaller than Earth's Moon and is
one of the most promising places to search for alien life.

Amid the Jovian system, Europa is of particular interest to scientists
because of the strong evidence for nutrients, water and energy to
potentially provide a habitable environment for some form of life beyond
Earth. In addition, Europa is believed to be made up into four layers
(from surface to center): an ice shell, salt water ocean, rocky mantle,
and metallic core.

Like Earth, Europa's ocean touches the rocky seafloor, which may allow
for rock-water chemistry favorable for life. Some scientists also believe
that the seafloor may host volcanoes, which can provide more energy and nutrients for a potential biosphere.

ASU scientists Kevin Trinh, Carver Bierson and Joe O'Rourke of the School
of Earth and Space Exploration investigated the consequences of Europa
forming with low initial temperatures, using computer code that Trinh
wrote. Their findings have been recently published in Science Advances.

Hydrated rocks may be a key ingredient Europa may have a metamorphic
origin for the ocean. While some scientists speculated this, Trinh and
his team show that if Europa indeed formed from hydrated rocks (i.e.,
rocks have hydrogen and oxygen), then enough of Europa's interior should
get hot enough to release water directly from the hydrated rocks to form
the ocean and ice shell.

"The origin of Europa's ocean is important because the moon's potential to support life ultimately depends on the chemical ingredients and physical conditions during the ocean formation process," said Kevin Trinh,
graduate associate at ASU's School Of Earth and Space Exploration.

Metallic core formation requires high temperatures Many scientists
studying this icy moon assumed that Europa formed with a metallic core
during or shortly after accretion. This ASU study contradicts that
prediction, instead arguing that Europa may not have started forming its metallic core until billions of years after accretion (if it happened
at all).

"For most worlds in the solar system we tend to think of their internal structure as being set shortly after they finish forming. This work
is very exciting because it reframes Europa as a world whose interior
has been slowly evolving over its whole lifetime. This opens doors for
future research to understand how these changes might be observed in
the Europa we see today," said Carver Bierson, postdoctoral research
scholar at ASU's School Of Earth and Space Exploration.

The existence of a metallic core is deeply tied to Europa's internal heat, which may also be used to drive seafloor volcanism and contribute to a habitable seafloor environment. However, it is unclear whether Europa
generated enough heat to form such a core. Trinh's code calculates how
heat is generated and distributed throughout a moon, which uses the same governing equations that many geodynamicists used for decades. The team's
novel result, however, comes from challenging the assumptions common to
Europa modeling: A small moon like Europa could form as a cold mixture
of ice, rock, and metal.

However, all of these processes require a hot interior. A small moon
like Europa (~1% of Earth's mass) may not have enough energy to trigger
or sustain Earth-like processes -- metallic core formation, seafloor
volcanism, and ongoing rock-water geochemistry -- which implies that
Europa's habitable potential is uncertain. The exact time at which Europa formed determines how much heat is available from the radioactive decay
of a short-lived isotope of aluminum. Tidal heating (from gravitational interactions with Jupiter and other moons) also governs how quickly
Europa's interior separates into distinct layers.

Europa's seafloor may be cool, hydrated, and experience limited (if
any) seafloor volcanism This study implies that there may be limited hydrothermal activity and seafloor volcanism at Europa, which may hinder habitability. However, confident predictions require more data.

"Europa is not just a wet, baby Earth. It is its own special world,
full of mysteries to unravel," said Joseph O'Rourke, Assistant Professor
at ASU's School of Earth and Space Exploration. In October 2024, NASA
plans to launch a spacecraft called Europa Clipper, which should arrive
at Europa in April 2030.

With the recent work by Trinh, Bierson and O'Rourke, scientists will
be better equipped to interpret incoming data from Europa Clipper,
whose main objective is to evaluate Jupiter's icy moon Europa for the
potential conditions to host life.

* RELATED_TOPICS
o Space_&_Time
# Jupiter # Moon # Solar_System # Astronomy #
Space_Exploration # Asteroids,_Comets_and_Meteors #
NASA # Pluto
* RELATED_TERMS
o Mars_Exploration_Rover o Gas_giant o
Planetary_nebula o Nuclear_fusion o Hydrogen o
Cosmic_microwave_background_radiation o Phoenix_(spacecraft)
o Planetary_habitability

========================================================================== Story Source: Materials provided by Arizona_State_University. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Kevin T. Trinh, Carver J. Bierson, Joseph G. O'Rourke. Slow
evolution of
Europa's interior: metamorphic ocean origin, delayed metallic core
formation, and limited seafloor volcanism. Science Advances, 2023;
9 (24) DOI: 10.1126/sciadv.adf3955 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/06/230617004432.htm

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