Sky & Telescope - July 2024 - 8

NEWS NOTES
Ascraeus
Mons
Tharsis
Pavonis
Mons
Arsia
Mons
Volcanic deposits
might conceal
glacier ice
Noctis
Labyrinthus
Noctis Mons
Noctis Mons is in the Tharsis volcanic
province, between the jumbled terrain of Noctis
Labyrinthus and the canyons of Valles Marineris.
Although more eroded and lower than other
nearby volcanoes, it rivals the others in diameter
(black dashed circle).
points reaching 9,000 meters and
sloping away, that's when we thought:
Could this possibly be a volcano? " Lee
says. " Now that we know that is there,
it's very difficult to unsee it. "
The discovery of the volcano ties in
SOLAR SYSTEM
Giant Volcano Discovered on Mars
SCIENTISTS HAVE UNCOVERED the
remains of a giant volcano on Mars.
Orbiters since 1971 had imaged the
formation, provisionally named " Noctis
Mons, " but extensive erosion concealed
its nature until now.
Located near the equator, Noctis
Mons is 250 kilometers (160 miles)
wide and, even eroded as it is, reaches
elevations of more than 9 kilometers
(almost 30,000 feet), announced Pascal
Lee (Mars Institute and SETI Institute)
at the 55th Lunar and Planetary Science
Conference in The Woodlands, Texas.
For decades, heavy deterioration prevented
the volcano's detection, he adds.
A combination of fracturing, thermal
erosion, and glacial erosion has produced
a jumbled landscape, with a few
elevated mesas - sandwiches of lava,
volcanic fragments, and water ice - cut
through by a network of valleys and collapsed
areas.
Still, he and collaborators pieced
together clues to reveal these formations'
volcanic origin. The ridge of
mesas curves around an eroded summit,
which has the remnant of a caldera, a
collapsed volcanic crater, in the middle.
" When we saw that arc of high
Noctis Mons (black dashed circle) is shown
on an elevation map of Mars.
with other findings in the region. Lee
and Sourabh Shubham (University of
Maryland, College Park) previously
spotted hints of a glacier buried nearby,
underneath the volcanic slopes. Those
hints came in the form of a glacier-like
sulfate-salt deposit. Lee and Shubham
proposed at last year's Lunar and Planetary
Science Conference that a layer of
volcanic material had landed on top of
glacier ice, reacting with the acidic water
to form mineral deposits that mimicked
the shape of the glacier underneath it.
Later erosion removed the upper layers
of volcanic material, revealing the salt
layers underneath. " The ice is probably
still there, but it's protected from disappearing
by salt, " Lee says.
Lee and Shubham think that
the giant Noctis Mons volcano was
similarly built like a layer cake, with
alternating deposits of ice and volcanic
material. This is borne out by the slopes
of the mesas, in which salt deposits
alternate with layers of volcanic material.
Taken together, the eroded volcano
and the glacier-like remnant lead Lee
and Shubham to speculate that glacier
ice might still be concealed beneath the
surface near the Martian equator.
Alexis Rodriguez (NASA's MarNoctis
Mons
shall Space Flight Center), who wasn't
involved with the study, says other
mechanisms, such as uplift caused by
magma rising underneath the region,
could have formed the eroded dome
that Lee and colleagues call a volcano.
But he adds that the combination of
glaciers and magmatism is tantalizing
for the prospect of finding biosignatures.
" If it's really true, " he notes, " it
would be a very important discovery. "
¢JAVIER BARBUZANO
8
JULY 2024 * SKY & TELESCOPE
MAP OF GIANT VOLCANO'S LOCATION: BACKGROUND IMAGE: NASA / USGS MARS GLOBE; GEOLOGIC INTERPRETATION AND ANNOTATIONS BY PASCAL LEE
AND SOURABH SHUBHAM 2024; ELEVATION MAP: BACKGROUND IMAGE: NASA MARS GLOBAL SURVEYOR (MGS) MARS ORBITER LASER ALTIMETER (MOLA)
DIGITAL ELEVATION MODEL. GEOLOGIC INTERPRETATION & ANNOTATIONS BY PASCAL LEE AND SOURABH SHUBHAM 2024)
a u qE
Marineris
o t
r
Val les

Sky & Telescope - July 2024

Table of Contents for the Digital Edition of Sky & Telescope - July 2024