YSM Issue 96.3

FOCUS
Astronomy
findings to the relatively well-known
composition of Earth, it is plausible to
conclude that Earth, unlike Venus, did
not experience late accretion events that
affected its core temperature to such a
great extent.
While Earth’s large volume of
surface water broke down the crust
and uppermost mantle of the planet to
form tectonic plates, Venus is closer to
the Sun than the Earth, causing Venus
to rapidly lose surface water through
evaporation. This geophysical difference
is significant, as plate tectonics reduce
internal heat. In addition, the researchers
ran a simulation and found that the mean
impact velocities of late accretions on
Venus were larger than those of Earth.
In other words, small celestial bodies
called planetesimals hit Venus harder
and faster. The lower-velocity impacts
on Earth would lead to less core heating
and an inability to sustain the long-lived
volcanic activity seen on Venus. These
key differences are what lends the ‘planet
of beauty’ its distinct, youthful surface.
Future Directions
Marchi and Korenaga hope to use their
model to make predictions and further
explain the mystery of Venus. “This
difference in late accretion by itself may
not explain all the differences [between
Earth and Venus], but it may help to
push it towards the right direction,”
Korenaga said. The collaboration with
Korenaga, who has studied the origin
of life on terrestrial planets for over a
decade, highlights a key link between
late accretion and the early history of
planets. As it did for Venus, late accretion
played a significant role in Earth's early
history and has a lasting impact on its
present surface features, contributing
substantially to the geological record
of the planet. Thus, understanding
late accretions has other far-reaching
implications for related projects.
According to Marchi, these energetic
events could drastically alter the
chemistry of the atmosphere. For
example, large-scale impacts can lead
to the heating of the crust, generating
a hydrothermal system that could serve
as a possible reservoir for microbes to
ABOUT THE
AUTHORS
PHOTOGRAPHY BY MIRANDA SELIN
The members of Jun Korenaga’s lab: from left to right, (top row) Brianna Fernandez, Darius Modirrousta-
Galian, Amy Ferrick, Jun Korrenaga; (bottom row) Steph Larson, Meng Guo, Coral Chen
thrive. “We strive to understand whether
or not these early impacts could have
had anything to do with the origin of life
on Earth,” Marchi said.
Much of Korenaga’s work in the
past has focused on early Earth and
investigating the geophysical catalysts
for life. “The role of late accretion is
important to discuss generally, for
how you can build a habitable planet,”
Korenaga said. He argues that late-stage
cosmic collisions have a large impact on
whether or not a planet can produce life.
In particular, this research helps us better
understand the geological makeup and
formation of planets, a key ingredient for
a given planet's potential to sustain life.
As a planetary scientist, Marchi is
also involved in space missions and is
currently one of the leaders of the Lucy
Mission, a NASA space probe with
the goal of reaching Trojan asteroids
near Jupiter. Recently, there has been
a revival of interest in Venus in space
exploration. NASA selected two future
space missions to explore Venus in the
coming decade, and the European Space
Union has proposed its own mission.
For next steps, the authors hope to
build off of this work and potentially
explore the geophysics of Earth and
Mars, which could hold more mysteries
of their own. “The work for Venus is
definitely not done,” Marchi said. “But
we'll try to push the new idea forward
to make predictions and try to test that
as much as possible—with new missions
as well.” ■
CINDY MEI
DAVID GAETANO
CINDY MEI is a junior in Grace Hopper studying neuroscience. In addition to writing for YSM, she serves
as vice president on the Junior Class Council and Yale Math Competitions. She also conducts epilepsy
and Tourette’s syndrome research at the Yale School of Medicine..
DAVID GAETANO is a sophomore in Ezra Stiles studying Mechanical Engineering. In addition to writing
for YSM, he is involved in the Yale Undergraduate Aerospace Association.
THE AUTHORS WOULD LIKE TO THANK Simone Marchi and Jun Korenaga for their time and
enthusiasm about their research.
FURTHER READING:
Marchi, S., Walker, R.J., & Canup, R.M. (2020). A compositionally heterogeneous martian mantle due to
late accretion. Science Advances, 6 (7), doi: 10.1126/sciadv.aay2338
24 Yale Scientific Magazine September 2023 www.yalescientific.org