- 4257 - MERCURY - closest planet to the Sun. Scientists have since discovered that salt glaciers may exist on Mercury even though it is the closest planet to the sun and our solar system's smallest world. The discovery could show that even the most volatile conditions in the inner solar system may occasionally have conditions found on Earth.
------------------ 4257 - MERCURY - closest planet to the Sun
- Of the four
terrestrial planets Mercury is the one closest to the Sun. We have a spacecraft that has visited this
small planet. MESSENGER was the first
spacecraft that did a flyby of Mercury.
-
- There new findings
that complement recent discoveries that revealed Pluto has nitrogen glaciers.
As Pluto exists on the far side of the solar system, the two discoveries imply
that the glaciation extends from the hottest regions of the solar system, close
to the sun, out to its frigid outer limits.
-
- Scientists from the
Planetary Science Institute (PSI) believe that these salt glaciers might create
the right conditions for life, similar to some of the extreme environments on
Earth where microbial life flourishes.
Specific salt compounds on Earth create habitable niches even in some of
the harshest environments where they occur, such as the arid Atacama Desert in
Chile. This makes us ponder the
possibility of subsurface areas on Mercury that might be more hospitable than
its harsh surface.
-
- Locations like
those highlighted are of pivotal importance because they identify volatile-rich
exposures throughout the vastness of multiple planetary landscapes. They also
suggest that the solar system could contain so-called "depth-dependent
Goldilocks zones," regions on planets and other bodies where life might be
able to survive not on the surface, but at specific depths that posses just the
right conditions.
-
- This challenges the
idea that Mercury is devoid of volatiles, chemical elements and compounds that
can be readily vaporized and were vital to the emergence of life on Earth. It indicates volatiles may be buried below
the surface of the tiny planet in Volatile Rich Layers (VRLs).
-
- These Mercurian
glaciers, distinct from Earth's, originate from deeply buried VRLs exposed by
asteroid impacts. Salt flow likely
produced these glaciers and that after their emplacement, they retained
volatiles for over 1 billion years."
-
- The glaciers of
Mercury are arranged in a complex configuration with hollows that form young
"sublimation pits" with sublimation being the process by which a
solid is instantly transformed into a gas skipping a liquid phase.
-
- These hollows
exhibit depths that account for a significant portion of the overall glacier
thickness, indicating their bulk retention of a volatile-rich composition. These hollows are absent from surrounding
crater floors and walls.
-
- This suggests that
clusters of hollows within impact craters may originate from zones of VRL
exposure caused by space rock impacts; as the impacts expose the volatiles,
they sublimate into gases, leaving the hollows behind.
-
- This area is
located in Mercury's north polar region and is marked by intricate
disintegration patterns that seem significantly large enough to have wiped
clear entire populations of craters, some dating as far back as 4 billion
years. Beneath this collapsed layer at the Borealis Chaos is an even more
ancient, cratered surface that has been previously identified through gravity
studies.
-
- The juxtaposition
of the fragmented upper crust, now forming chaotic terrain, over this
gravity-revealed ancient surface suggests that the VRLs were emplaced atop an
already solidified landscape.
-
- These findings
challenge prevailing theories of VRL formation that traditionally centered on
mantle differentiation processes, where minerals separate into different layers
within the planet's interior. Instead, the evidence suggests a grand-scale
structure, possibly stemming from the collapse of a fleeting, hot primordial
atmosphere early in Mercury's history.
-
- This atmospheric
collapse might have mainly occurred during the extended nighttime periods on
Mercury when the planet's surface was not exposed to the sun's intense heat,
leading temperatures to drop from around 800 degrees Fahrenheit, hot enough to melt lead to minus 290 degrees
Fahrenheit .
-
-
- Salt-dominated VRLs
on Mercury may have also grown extensively due to underwater depositions, an
idea that also represents a significant departure from prior theories about the
early geology of the closest planet to the sun.
-
- Water released
through volcanic degassing may have temporarily created pools or shallow seas
of liquid or supercritical water like a dense, highly salty steam, allowing
salt deposits to settle. Subsequent
rapid loss of water into space and trapping of water in hydrated minerals in
the crust would have left behind a salt- and clay mineral-dominated layer,
which progressively built up into thick deposits.
-
- Mercury was
shrinking for at least 3 billion years and it still might be today. What more can we learn from this planet
closest to the Sun. In a few billion
years the Sun will expand and Earth may experience some of the same
environments?
-
-
December 6, 2023
MERCURY - closest planet to the Sun 4257
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