From Many Worlds: “Probing The Insides of Mars to Learn How Rocky Planets Are Formed”

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NASA NExSS

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From Many Worlds

2018-11-08
Marc Kaufman

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An artist illustration of the InSight lander on Mars. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is designed to look for tectonic activity and meteorite impacts, study how much heat is still flowing through the planet, and track Mars’ wobble as it orbits the sun. While InSight is a Mars mission, it will help answer key questions about the formation of the other rocky planets of the solar system and exoplanets beyond. (NASA/JPL-Caltech).

NASA/Mars InSight Lander

In the known history of our 4.5-billion-year-old solar system, the insides of but one planet have been explored and studied. While there’s a lot left to know about the crust, the mantle and the core of the Earth, there is a large and vibrant field dedicated to that learning.

Sometime next month, an extensive survey of the insides of a second solar system planet will begin. That planet is Mars and, assuming safe arrival, the work will start after the InSight lander touches down on November 26.

This is not a mission that will produce dazzling images and headlines about the search for life on Mars. But in terms of the hard science it is designed to perform, InSight has the potential to tell us an enormous am0unt about the makeup of Mars, how it formed, and possibly why is it but one-third the size of its terrestrial cousins, Earth and Venus.

“We know a lot about the surface of Mars, we know a lot about its atmosphere and even about its ionosphere,” says Bruce Banerdt, the mission’s principal investigator, in a NASA video. “But we don’t know very much about what goes on a mile below the surface, much less 2,000 miles below the surface.”

The goal of InSight is to fill that knowledge gap, helping NASA map out the deep structure of Mars. And along the way, learn about the inferred formation and interiors of exoplanets, too.

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Equitorial Mars and the InSight landing site, with noting of other sites. (NASA)

The lander will touch down at Elysium Planitia, a flat expanse due north of the Curiosity landing site. The destination was selected because it is about as safe as a Mars landing site could be, and InSight did not need to be a more complex site with a compelling surface to explore.

“While I’m looking forward to those first images from the surface, I am even more eager to see the first data sets revealing what is happening deep below our landing pads.” Barerdt said. “The beauty of this mission is happening below the surface. Elysium Planitia is perfect.”

By studying the size, thickness, density and overall structure of the Martian core, mantle and crust, as well as the rate at which heat escapes from the planet’s interior, the InSight mission will provide glimpses into the evolutionary processes of all of the rocky planets in the inner solar system.

That’s because in terms of fundamental processes that shape planetary formation, Mars is an ideal subject.

It is big enough to have undergone the earliest internal heating and differentiation (separation of the crust, mantle and core) processes that shaped the terrestrial planets (Earth, Venus, Mercury, our moon), but small enough to have retained the signature of those processes over the next four billion years.

So Mars may contain the most in-depth and accurate record in the solar system of these processes. And because Mars has been less geologically active than the Earth — it does not have plate tectonics, for example — it has retains a more complete evolutionary record in its own basic planetary building blocks. In terms of deep planet geophysics, it is often described as something of a fossil.

By using geophysical instruments like those used on Earth, InSight will measure the fingerprints of the processes of terrestrial planet formation, as well as measuring the planet’s “vital signs.” They include the “pulse” (seismology), “temperature” (heat flow probe), and “reflexes” (precision tracking).

One promising way InSight will peer into the Martian interior is by studying motion underground — what we know as marsquakes.

NASA has not attempted to do this kind of science since the Viking mission. Both Viking landers had their seismometers on top of the spacecraft, where they produced noisy data. InSight’s seismometer will be placed directly on the Martian surface, which will provide much cleaner data.

As described by the agency, “NASA have seen a lot of evidence suggesting Mars has quakes. But unlike quakes on Earth, which are mostly caused by tectonic plates moving around, marsquakes would be caused by other types of tectonic activity, such as volcanism and cracks forming in the planet’s crust.

“In addition, meteor impacts can create seismic waves, which InSight will try to detect.

“Each marsquake would be like a flashbulb that illuminates the structure of the planet’s interior. By studying how seismic waves pass through the different layers of the planet (the crust, mantle and core), scientists can deduce the depths of these layers and what they’re made of. In this way, seismology is like taking an X-ray of the interior of Mars.”

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The InSight seismometer, developed by European partners and JPL, consists of a total of six seismic sensors that record the vibrations of the Martian soil in three directions in space and at two different frequency ranges. ges allows them to be mathematically combined into a single extremely broadband seismometer. In order to protect the seismometer against wind and strong temperature fluctuations, a protective dome (Wind and Thermal Shield, WTS) will be placed over it. (German Aerospace Center [DLR])

Scientists think it’s likely they’ll see between a dozen and a hundred marsquakes over the course of two Earth years. The quakes are likely to be no bigger than a 6.0 on the Richter scale, which would be plenty of energy for revealing secrets about the planet’s interior.

Another area of scientific interest involves whether or not the core of Mars is liquid. InSight’s Rotation and Interior Structure Experiment, RISE, will help answer that question by tracking the location of the lander to determine just how much Mars’ North Pole wobbles as it orbits the sun.

These observations will provide information on the size of Mars’ iron-rich core and will help determine whether the core is liquid. It will also help determine which other elements, besides iron, may be present.

The InSight science effort includes a self-hammering heat probe that will burrow down to 16 feet into the Martian soil and will for the first time measure the heat flow from the planet’s interior. Combining the rate of heat flow with other InSight data will reveal how energy within the planet drives changes on the surface.

This is especially important in trying to understand the presence and size of some of the solar system’s largest shield volcanoes in the solar system, a region known as Tharsis Mons.

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The Tharsis region of Mars has some of the largest volcanoes in the solar system. They include Olympus Mons, which is 375 miles in diameter and as much as 16 miles high. (U.S. Geological Survey)

Heat escaping from deep within the planet drives the formation of these types of features, as well as many others on rocky planets.

InSight is not an astrobiology mission — no searching for life beyond Earth.

But it definitely is part of the process by which scientists will learn what planet formation and the dynamics of their interiors says about whether a planet can be home to life.

See the full article here .


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About Many Worlds
There are many worlds out there waiting to fire your imagination.

Marc Kaufman is an experienced journalist, having spent three decades at The Washington Post and The Philadelphia Inquirer, and is the author of two books on searching for life and planetary habitability. While the “Many Worlds” column is supported by the Lunar Planetary Institute/USRA and informed by NASA’s NExSS initiative, any opinions expressed are the author’s alone.

This site is for everyone interested in the burgeoning field of exoplanet detection and research, from the general public to scientists in the field. It will present columns, news stories and in-depth features, as well as the work of guest writers.

About NExSS

The Nexus for Exoplanet System Science (NExSS) is a NASA research coordination network dedicated to the study of planetary habitability. The goals of NExSS are to investigate the diversity of exoplanets and to learn how their history, geology, and climate interact to create the conditions for life. NExSS investigators also strive to put planets into an architectural context — as solar systems built over the eons through dynamical processes and sculpted by stars. Based on our understanding of our own solar system and habitable planet Earth, researchers in the network aim to identify where habitable niches are most likely to occur, which planets are most likely to be habitable. Leveraging current NASA investments in research and missions, NExSS will accelerate the discovery and characterization of other potentially life-bearing worlds in the galaxy, using a systems science approach.
The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.