NASA probe detects likely ‘marsquake’ — an interplanetary first

A life-size model of the spaceship Insight, NASA's first robotic lander dedicated to studying the deep interior of Mars, is shown at Jet Propulsion Laboratory (JPL) in Pasadena, California, U.S. November 26, 2018. (REUTERS)
Updated 24 April 2019
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NASA probe detects likely ‘marsquake’ — an interplanetary first

  • A more distant quake would yield greater information about Mars’ interior because seismic waves would “penetrate deeper into the planet before they come back up to the seismometer,” he said

CALIFORNIA: NASA’s robotic probe InSight has detected and measured what scientists believe to be a “marsquake,” marking the first time a likely seismological tremor has been recorded on another planet, the Jet Propulsion Laboratory in California reported on Tuesday.
The breakthrough came nearly five months after InSight, the first spacecraft designed specifically to study the deep interior of a distant world, touched down on the surface of Mars to begin its two-year seismological mission on the red planet.
The faint rumble characterized by JPL scientists as a likely marsquake, roughly equal to a 2.5 magnitude earthquake, was recorded on April 6 — the lander’s 128th Martian day, or sol.
It was detected by InSight’s French-built seismometer, an instrument sensitive enough to measure a seismic wave just one-half the radius of a hydrogen atom.
“We’ve been collecting background noise up until now, but this first event officially kicks off a new field: Martian seismology,” InSight principal investigator Bruce Banerdt said in a news release.
Scientists are still examining the data to conclusively determine the precise cause of the signal, but the trembling appeared to have originated from inside the planet, as opposed to being caused by forces above the surface, such as wind.
“The high frequency level and broad band is very similar to what we get from a rupture process. So we are very confident that this is a marsquake,” Philippe Lognonné, a geophysics and planetary science professor at University Paris Diderot in France and lead researcher for InSight’s seismometer, said in an email.
Still, a tremor so faint in Southern California would be virtually lost among the dozens of small seismic crackles that occur there every day.
“Our informed guesswork is that this a very small event that’s relatively close, maybe from 50 to 100 kilometers away” from the lander, Banerdt told Reuters by telephone.

A more distant quake would yield greater information about Mars’ interior because seismic waves would “penetrate deeper into the planet before they come back up to the seismometer,” he said.
 
The size and duration of the marsquake also fit the profile of some of the thousands of moonquakes detected on the lunar surface between 1969 and 1977 by seismometers installed there by NASA’s Apollo missions, said Lori Glaze, planetary science division director at NASA headquarters in Washington.
The lunar and Martian surfaces are extremely quiet compared with Earth, which experiences constant low-level seismic noise from oceans and weather as well as quakes that occur along subterranean fault lines created by shifting tectonic plates in the planet’s crust.
Mars and the moon lack tectonic plates. Their seismic activity is instead driven by a cooling and contracting process that causes stress to build up and become strong enough to rupture the crust.
Three other apparent seismic signals were picked up by InSight on March 14, April 10 and April 11 but were even smaller and more ambiguous in origin, leaving scientists less certain they were actual marsquakes.
Lognonné said he expected InSight to eventually detect quakes 50 to 100 times larger than the April 6 tremor.


Space telescope offers rare glimpse of Earth-sized rocky exoplanet

Updated 20 August 2019
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Space telescope offers rare glimpse of Earth-sized rocky exoplanet

  • LHS 3844b, an exoplanet about 1.3 times the size of Earth, is locked in a tight orbit around a small, relatively cool star called a red dwarf

Direct observations from a NASA space telescope have for the first time revealed the atmospheric void of a rocky, Earth-sized world beyond our own solar system orbiting the most common type of star in the galaxy, according to a study released on Monday.
The research, published in the scientific journal Nature, also shows the distant planet’s surface is likely to resemble the barren exterior of the Earth’s moon or Mercury, possibly covered in dark volcanic rock.
The planet lies about 48.6 light years from Earth and is one of more than 4,000 so-called exoplanets identified over the past two decades circling distant stars in our home galaxy, the Milky Way.
Known to astronomers as LHS 3844b, this exoplanet about 1.3 times the size of Earth is locked in a tight orbit — one revolution every 11 hours — around a small, relatively cool star called a red dwarf, the most prevalent and long-lived type of star in the galaxy.
The planet’s lack of atmosphere is probably due to intense radiation from its parent red dwarf, which, though dim by stellar standards, also emits high levels of ultraviolet light, the study says.
The study will likely add to a debate among astronomers about whether the search for life-sustaining conditions beyond our solar system should focus on exoplanets around red dwarfs — accounting for 75% of all stars in the Milky Way — or less common, larger, hotter stars more like our own sun.
The principal finding is that it probably possesses little if any atmosphere — a conclusion reached by measuring the temperature difference between the side of the planet perpetually facing its star, and the cooler, dark side facing away from it.
A negligible amount of heat carried between the two sides indicates a lack of winds that would otherwise be present to transfer warmth around the planet.
“The temperature contrast on this planet is about as big as it can possibly be,” said researcher Laura Kreidberg of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. She is lead author of the study. Similar analysis previously was used to determine that another exoplanet, 55 Cancri e, about twice as big as Earth and believed to be half-covered in molten lava, likely possesses an atmosphere thicker than Earth’s. This exoplanet, unlike LHS 3844b, orbits a sun-like star.
The planet in the latest study was detected last year by NASA’s newly launched Transiting Exoplanet Survey Satellite, an orbiting telescope that pinpoints distant worlds by spotting periodic, dips in the light observed from their parent stars when an object passes in front of them.
But it was follow-up observations from another orbiting instrument, the Spitzer Space Telescope, which can detect infrared light directly from an exoplanet, that provided new insights about its features.