Planetary geology enriches our knowledge of other planets and moons (natural satellites) in the solar systems, but in doing so it also, in a comparative way, helps us better understand the evolution of Earth. For example, let's look at a story about NASA’s ambitious plans to return to the moon.
Rasoul Sorkhabi
Editor, Core Elements
The U.S. Lunar Landing: Round Two
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Some of us remember watching Neil Armstrong’s moon landing on TV on July 20, 1969. Humans walked on the moon again in December 1972 during the Apollo 17 mission, but there has been no moonwalking since then (except for, of course, on the dance floor).
Now, NASA wants to return to the moon, with much bigger plans. But why now, after more than five decades?
Recent developments: In the past, the United States and the (former) Soviet Union were the only players in the race to outer space. But things have changed:
In 2018, China’s Chang’e 4 mission soft landed on the far side of the moon for the first time, followed by the Yutu-2 rover mission in 2019. China’s Cheng’e 5 brought back moon samples in 2020.
In 2023, India’s Chandrayaan-3 made the first soft landing near the lunar south pole.
In January 2024, Japan’s SLIM landed on the moon.
The Artemis program: NASA’s Artemis (named after the Greek goddess of hunt and wilderness, and twin sister of Apollo) consists of several discrete lunar missions:
Artemis I was launched in November 2022 (after several delays). It successfully tested its Space Launch System (the most powerful yet) and placed Orion spacecraft into a lunar orbit.
Artemis II is planned to lift off in 2025 and will be the first crewed test flight orbiting the moon on the Orion.
Artemis III, planned for 2026, will land American astronauts on the moon’s South Pole.
Two years later, Artemis IV is scheduled to complete a crewed lunar landing and put up the Lunar Gateway station (the only space station outside of Earth’s orbits).
Finally, in 2030, Artemis V will deliver astronauts to the Lunar Gateway station. This will form the base for sending astronauts to Mars.
There are a variety of reasons to go to the Moon:
Political supremacy: The United States may wish to get ahead in the race to the new frontier of outer space.
Scientific reasons: The moon’s rocks hold critical clues to the history of Moon-Earth system.
Mineral resources: The moon’s rocks store precious metals such as rare-earth-elements.
Water and energy: The moon’s polar regions, which do not see sunlight, contain a lot of frozen water, which can be used for drinking, breathable oxygen, and hydrogen fuel.
Lunar economy: Space will increasingly become a new frontier for tourists and ventures led by commercial corporations.
Geoscientists! Stay tuned for many new rock samples from the moon and Mars.
Go deeper: A recent article inScientific American describes NASA’s Artemis program. Also check out YouTube videoclips by NASA and The Smithsonian Institute.
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A recent study published in the PNAS suggests that “Martian Ocean” resides beneath the crust.
Context:
Images of Martian topography have indicated the presence of rivers and seas on Mars during the early history of the planet—more than 3 billion years ago.
Some frozen water is still present in the polar areas of Mars, but overall, Mars is a dry red planet.
Martian water mystery: Where did all the ancient waters on Mars go? Many have speculated that the Martian waters evaporated and were lost to space, and some waters may have been sequestered in deep aquifers. But it is ultimately still a mystery.
Driving the news: A recent study tried to provide more insight into this question.
The new study: Wright and colleagues analyzed and modeled geophysical data collected by NASA’s Mars InSight Lander.
The Mars InSight Lander, equipped with a seismometer, collected data from Mars’s crust from 2018 to 2022. This was the first mission to study the crustal depths of Mars.
In their new paper, Wright and colleagues propose that huge volumes of water exist in fractured igneous rocks within Mars at depths of 12 to 20 kilometers.
The authors used compression (p) and shear (2) seismic wave velocities, as well as bulk porosities from the Mars Insight Lander to model the properties of deep rocks on Mars such as density, porosity, pore aspect ratio (ratio of width to height), liquid water saturation, mineral bulk modulus, and mineral shear modulus.
The presence of water in the rocks best describes the seismic data and rock properties.
Limitations and broader impacts:
The study is limited only to areas up to 4500 km away from the Lander. But if the model results can be valid for other parts of Mars’s crust, it would mean huge volumes of water exist.
All this water, if present, will not be easily accessible because even on Earth we do not drill such deep wells.
The study is yet another example of how geophysical and petrophysical techniques often used for hydrocarbon exploration can be applied to other fields.
Go deeper: Read the full study, published in PNAS here.
Quiz of the Week
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Last week’s quiz question was: What are the three deepest points in the oceans?
Challenger Deep at 10,924 m deep, located at the southern end of the Mariana Trench, western Pacific, offshore the Philippines
Brownson Deep at a depth of 8,378 m, located near the Puerto Rico Trench in the North Atlantic
Meteor Deep at 8265 m in depth, located in the South Sandwich Trench in the South Atlantic
Note that they all are situated at subduction zones.
Here is this week’s quiz question: Of the two seismic waves, P and S, which one is mainly used in seismic survey of petroleum basins. Why? How can we also use the other seismic waves to get extra information?
Please send your response by October 31 to editorial@aapg.org (subject line: Core Elements Quiz)
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