Sept. 26, 2016
It’s small, it’s hot, and it’s shrinking. Surprising new NASA-funded research suggests that Mercury is contracting even today, joining Earth as a tectonically active planet.
Credits: NASA/JHUAPL/Carnegie Institution of Washington/USGS/Arizona State University
It’s small, it’s hot, and it’s shrinking. New NASA-funded research suggests that Mercury is contracting even today, joining Earth as a tectonically active planet.
Images obtained by NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft reveal previously undetected small fault scarps— cliff-like landforms that resemble stair steps. These scarps are small enough that scientists believe they must be geologically young, which means Mercury is still contracting and that Earth is not the only tectonically active planet in our solar system, as previously thought.
The findings are reported in a paper in the October issue of Nature Geoscience.
Small graben, or narrow linear troughs, have been found associated with small fault scarps (lower white arrows) on Mercury, and on Earth’s moon. The small troughs, only tens of meters wide (inset box and upper white arrows), likely resulted from the bending of the crust as it was uplifted, and must be very young to survive continuous meteoroid bombardment.
Credits: NASA/JHUAPL/Carnegie Institution of Washington/Smithsonian Institution
“The young age of the small scarps means that Mercury joins Earth as a tectonically active planet, with new faults likely forming today as Mercury’s interior continues to cool and the planet contracts,” said lead author Tom Watters, Smithsonian senior scientist at the National Air and Space Museum in Washington, D.C.
Large fault scarps on Mercury were first discovered in the flybys of Mariner 10 in the mid-1970s and confirmed by MESSENGER, which found the planet closest to the sun was shrinking. The large scarps were formed as Mercury’s interior cooled, causing the planet to contract and the crust to break and thrust upward along faults making cliffs up to hundreds of miles long and some more than a mile (over one-and-a-half kilometers) high.
In the last 18 months of the MESSENGER mission, the spacecraft’s altitude was lowered, which allowed the surface of Mercury to be seen at much higher resolution. These low-altitude images revealed small fault scarps that are orders of magnitude smaller than the larger scarps. The small scarps had to be very young, investigators say, to survive the steady bombardment of meteoroids and comets. They are comparable in scale to small, young lunar scarps that are evidence Earth’s moon is also shrinking.
This active faulting is consistent with the recent finding that Mercury’s global magnetic field has existed for billions of years and with the slow cooling of Mercury’s still hot outer core. It’s likely that the smallest of the terrestrial planets also experiences Mercury-quakes—something that may one day be confirmed by seismometers.
“This is why we explore,” said NASA Planetary Science Director Jim Green at Headquarters in Washington, D.C. “For years, scientists believed that Mercury’s tectonic activity was in the distant past. It’s exciting to consider that this small planet – not much larger than Earth’s moon – is active even today.”
Managed by the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, MESSENGER launched Aug. 3, 2004 and began orbiting Mercury March 18, 2011. The mission ended with a planned impact on the surface of Mercury on April 30, 2015.
Last Updated: Sept. 26, 2016
Editor: Bill Keeter
el dispensador dice:
soy el portal del mensajero,
habilito los mares para que naveguen los veleros,
portando señales para elegidos y necios,
algunos se acercan a los muelles en sus puertos,
otros divisan desde la costa para huir del faro y sus agoreros,
nada es casual en este ángulo del universo,
muchos dicen ser pero no califican ni para verso,
disfrazando la vergüenza como si fuese placebo,
negando la existencia de los mercaderes en sus reinos...
contengo el espíritu de los pastores,
de los oradores,
de los discurseros,
aquellos a quienes les sobran palabras,
pero andan faltos de hechos,
hay un Hermes detrás del tendero,
hay mentiras suficientes como para tejer un infierno,
por eso protejo el engaño,
y al ladrón de los viajeros,
vendiendo las fronteras,
donde se funden los senderos...
no te confundas que hay más de un Mercurio de los sueños,
hay inteligencia en el hacer de los cuatreros,
espías nocturnos de bosques y de miedos,
guardián de puertas de lo oculto y sus agujeros...
cuando veas un mendigo tocar a tu puerta,
ábrele la puerta y concédele cobijo,
abrigo y también alimento,
puede que te deje la señal inesperada,
de tormentas, tempestades y dramáticos truenos,
se trata de Dios disfrazado para evitar ser reconocido por quienes naufragarán sin encontrar lecho,
si has sido el elegido,
deberás darte por satisfecho.
SEPTIEMBRE 26, 2016.-
nota de el dispensador ► Un día, Zeus y Hermes, tras un viaje transformados en mendigos, llegaron a la ciudad de Tiana en medio de la tormenta, y allí pidieron a sus habitantes un lugar para pasar la noche. Tras la negativa del resto, sólo Filemón y Baucis les permitieron entrar en su humilde cabaña. Después de servir comida y vino a sus invitados, Baucis notó que a pesar de llenar varias veces los vasos de los visitantes, la jarra de vino estaba aún llena, de lo que dedujo que aquellos foráneos eran en realidad deidades. Pensando que la humilde comida servida no era digna de tales invitados, Filemón decidió ofrecerles el ganso que guardaban en casa (el cual era su único animal). Pero cuando el campesino se acercó al ave, el animal corrió hacia el regazo de Zeus, quien aseguró que no era necesario tal sacrificio, pues debían marcharse. El dios avisó al matrimonio que iba a destruir la ciudad y a todos aquellos que les habían negado la entrada. Les dijo que deberían subir a lo alto de la montaña con él, y no darse la vuelta hasta llegar a la cima. Ya allí, la pareja vio su ciudad destruida por una inundación que provocó Zeus. [Filemón y Baucis - Wikipedia, la enciclopedia libre]
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