InSight: Mars’ crust is thin, and its interior is many layered with a molten core
Scientists yesterday released results from the seismometer on the Mars InSight lander that suggest that the crust of the red planet is thin and that its interior is many layered with a molten core.
[T]wo moderate quakes, at magnitude 3.7 and 3.3, have been treasure troves for the mission. Traced to Cerberus Fossae, deep fissures in the crust 1600 kilometers east of the landing site that were suspected of being seismically active, the quakes sent a one-two punch of compressive pressure (P) waves, followed by sidewinding shear (S) waves, barreling toward the lander. Some of the waves were confined to the crust; others reflected off the top of the mantle. Offsets in the travel times of the P and S waves hint at the thickness of the crust and suggest distinct layers within it, Brigitte Knapmeyer-Endrun, a seismologist at the University of Cologne, said in an AGU presentation. The top layer may reflect material ground up in the planet’s first billion years, a period of intense asteroid bombardment, says Steven Hauck, a planetary scientist at Case Western Reserve University.
At 20 or 37 kilometers thick, depending on whether the reflections accurately trace the top of the mantle, the martian crust appears to be thinner than Earth’s continental crust—a surprise. Researchers had thought that Mars, a smaller planet with less internal heat, would have built up a thicker crust, with heat escaping through limited conduction and bouts of volcanism. (Though Mars is volcanically dead today, giant volcanoes dot its surface.) A thin crust, however, might mean Mars was losing heat efficiently, recycling its early crust, rather than just building it up, perhaps through a rudimentary form of plate tectonics, Mojzsis says.
The thin crust provides a solid basis for explaining the large volcanoes and vast lava plains on the planet. Combined with the light gravity, magma would have found an easier path to the surface. Handed this knowledge, planetary geologists can now make a first stab at outlining more precisely the planet’s early volcanic history.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon. Or you can buy it directly from the author and get an autographed copy.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Scientists yesterday released results from the seismometer on the Mars InSight lander that suggest that the crust of the red planet is thin and that its interior is many layered with a molten core.
[T]wo moderate quakes, at magnitude 3.7 and 3.3, have been treasure troves for the mission. Traced to Cerberus Fossae, deep fissures in the crust 1600 kilometers east of the landing site that were suspected of being seismically active, the quakes sent a one-two punch of compressive pressure (P) waves, followed by sidewinding shear (S) waves, barreling toward the lander. Some of the waves were confined to the crust; others reflected off the top of the mantle. Offsets in the travel times of the P and S waves hint at the thickness of the crust and suggest distinct layers within it, Brigitte Knapmeyer-Endrun, a seismologist at the University of Cologne, said in an AGU presentation. The top layer may reflect material ground up in the planet’s first billion years, a period of intense asteroid bombardment, says Steven Hauck, a planetary scientist at Case Western Reserve University.
At 20 or 37 kilometers thick, depending on whether the reflections accurately trace the top of the mantle, the martian crust appears to be thinner than Earth’s continental crust—a surprise. Researchers had thought that Mars, a smaller planet with less internal heat, would have built up a thicker crust, with heat escaping through limited conduction and bouts of volcanism. (Though Mars is volcanically dead today, giant volcanoes dot its surface.) A thin crust, however, might mean Mars was losing heat efficiently, recycling its early crust, rather than just building it up, perhaps through a rudimentary form of plate tectonics, Mojzsis says.
The thin crust provides a solid basis for explaining the large volcanoes and vast lava plains on the planet. Combined with the light gravity, magma would have found an easier path to the surface. Handed this knowledge, planetary geologists can now make a first stab at outlining more precisely the planet’s early volcanic history.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon. Or you can buy it directly from the author and get an autographed copy.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
So with a thin crust I would expect the seismometer could pick up the impact of a booster or other item IFF it hit in a relatively close but known location.
A thin Martian crust would be somewhat surprising. I’d thought it would be thick for the reasons cited. If Mars is ‘”. . . losing heat efficiently . . “, how, exactly, is that accomplished?
So Mars is a New York pizza and not a Chicago pizza.
I am with Blair Ivey on this one, the Martian moons are not much more than captured astroids, the tidal pull would be insufficient to keep a large hot molten core for this reason, unlike earth. Let’s explore other factors.
A meteor impact to create a hole in the Martian surface as big as the Helena’s basin “without a thick crust” would’ve broken the planet, or had been filled with molten core lava. (note that Mars does not have rings, or a moon formed from the debris)
The observed evidence suggest a hypothesis that the Helena’s impact created the Thyrsus bulge on the opposite side of the planet. The fractured “thick” crust allowed the volcanoes to relieve the pressure as the fragments of the surface pushed softly, over millions of years, back into their resting possibly floating position.
This occurred long after the entire northern hemisphere was flattened thousands of feet lower than the southern hemisphere by what could’ve been an immense impact, or a minutes long plunge through an atmosphere of a gas giant… or through the edge of the sun itself if Mars was a moon of a theoretical missing planet where the astroid belt is now. (something happened to cover Mars with craters… )
Either way, Mars has had a good reason to still have a molten core.