Show an ad over header. AMP

I am the FIRST

Movements on Mars unlock the Red Planet's interior

Seismic action on Mars is revealing new details about the inner structure of the Red Planet.

Why it matters: Mars' interior holds the key to understanding how the planet and its atmosphere formed — and provides clues about how other rocky planets, like Earth, become habitable.

  • "Mars is a second laboratory in planetary formation," says Bruce Banerdt, principal investigator of NASA's InSight mission to study the interior of Mars.
  • "We're just starting to understand basic processes. If theories don’t explain the situation we find on Mars, we'll have to tweak them."

Driving the news: A trio of new studies published today in the journal Science reports the first direct measurements of the interior of Mars and, for that matter, another planet.

  • The InSight mission measures seismic waves from fractures in Mars' surface thought to be caused by heat escaping the planet's still-cooling core.
  • The low-frequency waves created by these Marsquakes are picked up directly by the seismometer or after they travel through the planet, bouncing off the core and surface.

What they found: The teams of researchers measured the strength and speed of the reflected waves from 8–11 Marsquakes to determine key aspects of the size and composition of Mars' interior.

Core: They estimateMars' core has a radius of about 1,140 miles, which is 100 miles larger than theories predicted and about half the radius of the planet.

  • That means the density of the mostly iron and nickel core is less than previously thought and the center of Mars likely includes other elements, like sulfur, carbon, hydrogen and oxygen.
  • The scientists also confirmed the core is still liquid, likely because of the other elements dissolved in it.
  • The large size of Mars' core creates a "shadow zone" so that some waves don't reach the seismometer. Banerdt says he hopes future missions can capture more data by going to a different region of Mars and placing another seismometer on the planet.
  • The intrigue: The estimated size of the core implies it is 15–18% sulfur, about twice what can be accounted for in existing models, according to Banerdt. "We don't know how to get that much sulfur," he says, adding it may have to do with the density of the mantle.

Mantle: Mars' middle layer, which insulates the core, is relatively thin, which may explain why the planet cooled more quickly than Earth and lost its protective magnetic field.

  • On top of the mantle, there is a thick lithosphere — the rigid outer shell that makes up the crust and upper mantle — about 310 miles below the surface, the researchers report. The thickness of the lithosphere might explain why plate tectonics — or volcanic activity — isn't seen on the Red Planet today.
  • The mantle, which the data suggest consists of just one rocky layer compared to Earth's two, makes up the bulk of the planet. "We have to understand the mantle to understand the planet," Banerdt says.

Crust: The outermost layer of the planet is estimated to be between 15 and 45 miles thick — not as thick and dense as researchers earlier predicted from satellite data — and made up of two or three layers.

  • The researchers also found the crust is 13–21 times more enriched in radioactive elements that produce heat, which hints at its composition and how it formed through early volcanic activity.
"It's been a long road, but we finally got these key numbers we’ve been pursuing all these years."
Bruce Banerdt, NASA JPL, who began working on a seismology mission to Mars in the early 1990s

Background: NASA's InSight lander touched down on the Elysium Planitia region of Mars in November of 2018 and the seismometer began taking measurements in February 2019.

  • A key instrument designed to drill into the martian soil and measure how much heat is flowing from the planet's interior to its surface failed multiple times before NASA called it quits on the probe earlier this year.
  • How a planet loses heat — from radioactive elements decaying or from the cooling of its core — influences its volcanic and tectonic activity. Those measurements would have helped to independently validate the seismometer data, but Banerdt says they're able to self-verify the seismometer system in other ways.

What's next: InSight received a mission extension until at least the end of 2022.

  • In that time, Banerdt says they'll focus on detecting more quakes, collecting data to understand seasonal and annual variations in weather, and looking at whether some types of seismic events vary between seasons on the planet.

4 ffp

Why the startup world needs to ditch "unicorns" for "dragons"

When Aileen Lee originally coined the term "unicorn" in late 2013, she was describing the 39 "U.S.-based software companies started since 2003 and valued at over $1 billion by public or private market investors."

Flashback: It got redefined in early 2015 by yours truly and Erin Griffith, in a cover story for Fortune, as any privately-held startup valued at $1 billion or more. At the time, we counted 80 of them.

Keep reading... Show less

Scoop: Facebook's new moves to lower News Feed's political volume

Facebook plans to announce that it will de-emphasize political posts and current events content in the News Feed based on negative user feedback, Axios has learned. It also plans to expand tests to limit the amount of political content that people see in their News Feeds to more countries outside of the U.S.

Why it matters: The changes could reduce traffic to some news publishers, particularly companies that post a lot of political content.

Keep reading... Show less

Scoop: Amazon quietly getting into live audio business

Amazon is investing heavily in a new live audio feature that's similar to other live audio offerings like Clubhouse, Twitter Spaces and Spotify's new live audio platform, sources tell Axios.

Why it matters: As with Amazon's efforts in podcasting and music subscriptions, the company sees live audio as a way to bolster the types of content it can offer through its voice assistant, Alexa, and its smart speaker products.

Keep reading... Show less

Hurricane Ida exposes America's precarious energy infrastructure

The powerful hurricane that plunged New Orleans into darkness for what could be weeks is the latest sign that U.S. power systems are not ready for a warmer, more volatile world.

The big picture: “Our current infrastructure is not adequate when it comes to these kinds of weather extremes,” Joshua Rhodes, a University of Texas energy expert, tells Axios.

Keep reading... Show less

"We must go further": 70% of adults in European Union are fully vaccinated

About 70% of adults in the European Union are fully vaccinated against COVID-19, Ursula von der Leyen, the president of the European Commission, said Tuesday.

Why it matters: The milestone makes the E.U. one of the world's leaders in inoculations, after an initially lagging vaccine campaign, the New York Times notes.

Keep reading... Show less

What Elizabeth Holmes jurors will be asked ahead of fraud trial

Jury selection begins today in USA v. Elizabeth Holmes, with the actual jury trial to get underway on Sept. 8.

Why it matters: Theranos was the biggest fraud in Silicon Valley history, putting both hundreds of millions of dollars and thousands of patients' health at risk.

Keep reading... Show less



Get Goodhumans in your inbox

Most Read

More Stories