Sky & Telescope - July 2022 - 9

suggesting that the planet might have
hidden its oxygen among the basalts of
volcanic ash and lava flows. Their model
of Venus's atmospheric history opens up
the possibility that surface water once
existed there.
Another study, however, suggests
that Venus never had much water at
all. Cedric Gillman (Rice University)
and colleagues built a simulation to
trace when and how much water was
delivered to the surface and where it
all went. They consider several paths
for water's arrival on the planet, such
as volcanic outgassing and delivery via
comets, as well as multiple ways for
water to escape the atmosphere. Their
calculations suggest that Venus hosted
at most only a tenth the amount of
water in Earth's oceans today.
Another focus of renewed interest
is a type of Venusian terrain known
as tesserae. Some have suggested that
these regions of deformed, folded rock
represent the oldest preserved crust on
Venus. As such, they might shed light
on whatever global catastrophe(s) Venus
endured in its past.
But a new study, led by Paul Byrne
(Washington University in St. Louis),
describes evidence that some tesserae
formed geologically recently ― and
their formation could even be ongoing.
The studies presented at the LPSC
pThe desolate surface of Venus, as radarmapped
by NASA's Magellan and Pioneer
Venus orbiters
measure the speed of sound on Mars:
240 meters per second (540 mph),
which is slower than on Earth (where
it's 342 m/s). Sounds with frequencies
higher than 240 Hz travel faster, which
means high-pitched sounds arrive
slightly earlier than bass.
Meanwhile the Ingenuity helicopter,
the Little Technology Demonstration
That Could, continues to accompany
Perseverance and scout out its drives.
Even after nearly a year and a regional
dust storm, Ingenuity shows no signs
of wear, said Matthew Golombek (JPL),
and NASA has extended flight operations
through September.
Elsewhere on Mars, the Zhurong
rover that arrived as part of China's
Tianwen 1 mission has been driving
since May 2021 in Utopia Planitia, a
large, flat plain in the planet's northern
hemisphere. Using the rover's six scientific
payloads, the team is investigating
wind-shaped ridges, pitted cones, giant
make clear that even the most basic
questions about Venus's history remain
wide open. Future missions to our sister
planet (S&T: May 2022, p. 12) will help
provide answers.
¢ARWEN RIMMER
troughs, and craters along the way.
The Insight lander's Seismic Experiment
for Interior Structure (SEIS) continues
to collect seismic data, having
logged 1,300 marsquakes and counting.
Four recent ones were strong enough,
with magnitudes greater than 4, to
inform models of the Martian core.
Finally, the United Arab Emirates'
Hope Probe, on a wide orbit around
Mars, is providing continuous global
analysis of the Martian atmosphere,
including the most complete images
yet of the planet's unique aurorae. It
has detected a type of aurora known
as discrete in two-thirds of its observations.
Hope also monitors daily surface
changes and seasonal variability.
Meanwhile, the European Space
Agency has canceled this year's launch
of its ExoMars mission because of the
Russia-Ukraine war.
¢CAMILLE M. CARLISLE, MONICA YOUNG
& DAVID DICKINSON
Eugene Parker in 1977
OBITUARY
Eugene Parker
(1927-2022)
Scientific pioneer and namesake of
NASA's Parker Solar Probe Eugene
Parker has passed away, having forever
altered the way we view the Sun and its
interaction with the solar system.
Born in Houghton, Michigan, Parker
completed his undergraduate degree in
physics from Michigan State University
in 1948 and his PhD from Caltech
in 1951. He taught at the University
of Utah and married his wife, Niesje,
before accepting a position in 1955 at
the University of Chicago. He remained
there for the rest of his career and continued
to publish long after he retired
in 1995.
In 1957, at 30 years old, Parker
proposed the concept of the solar
wind, the charged particles that stream
outward from the Sun. He realized that
if the plasma in the solar corona was so
hot, it wouldn't stay tied down by gravity
but would rather flow outward along
open magnetic field lines.
Though two reviewers rejected his
conclusion, Parker's colleague and editor
of the journal in question, Subrahmanyan
Chandrasekhar, overruled them
and allowed the paper to be published.
Spacecraft observations provided
definitive evidence of the solar wind just
a few years later. The swirling magnetic
field flowing out with these particles
was later named the Parker Spiral, and
his name now graces several other
astrophysical phenomena.
" It is only fitting, " says Angela Olinto
(University of Chicago), " that Gene's
name is quite literally written in our
star, the Sun, and in the physics that
describes stars. "
¢THE EDITORS OF S&T
sk yand tele scope .o r g * JULY 2022
9
VENUS: NASA / JPL-CALTECH; PARKER: UNIVERSITY OF CHICAGO
http://www.skyandtelescope.com
Sky & Telescope - July 2022

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