Scientists make first rough estimate of Mars’ internal structure


Genesis cover

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 ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit.

 
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

Artist's cutaway showing theorized Martian interior
Artist’s cutaway of theorized Martian interior

Using data from InSight’s seismometer, scientists have made their first approximation of the internal structure of Mars.

The first boundary Deng and Levander measured is the divide between Mars’ crust and mantle almost 22 miles (35 kilometers) beneath the lander.

The second is a transition zone within the mantle where magnesium iron silicates undergo a geochemical change. Above the zone, the elements form a mineral called olivine, and beneath it, heat and pressure compress them into a new mineral called wadsleyite. Known as the olivine-wadsleyite transition, this zone was found 690-727 miles (1,110-1,170 kilometers) beneath InSight. “The temperature at the olivine-wadsleyite transition is an important key to building thermal models of Mars,” Deng said. “From the depth of the transition, we can easily calculate the pressure, and with that, we can derive the temperature.”

The third boundary he and Levander measured is the border between Mars’ mantle and its iron-rich core, which they found about 945-994 miles (1,520-1,600 kilometers) beneath the lander. Better understanding this boundary “can provide information about the planet’s development from both a chemical and thermal point of view,” Deng said.

Because they only have one seismometer on the planet, this approximation has a great deal of uncertainty. Only when we have multiple such seismic instruments, scattered across the entire Martian globe, will scientists be able to hone their models more accurate of the planet’s interior.

Readers!
 

My July fund-raiser for Behind the Black is now over. The support from my readers was unprecedented, making this July campaign the best ever, twice over. What a marvelous way to celebrate the website's tenth anniversary!
 

Thank you! The number of donations in July, and continuing now at the beginning of August, is too many for me to thank you all personally. Please forgive me by accepting my thank you here, in public, on the website.
 

If you did not donate or subscribe in July and still wish to, note that the tip jar remains available year round.


 

Regular readers can support Behind The Black with a contribution via paypal:

Or with a subscription with regular donations from your Paypal or credit card account:


 

If Paypal doesn't work for you, you can support Behind The Black directly by sending your donation by check, payable to Robert Zimmerman, to
 
Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652

2 comments

  • LocalFluff

    The one seismometer contains multiple, I think eight, seismometers. And although they are within a couple of inch from each other, they can determine the direction of the seismic waves. Scientists and engineers have used their heads in the hard way in order to figure out how to make useful seismic measurements from a single landing site. I think that the problem they now face is that there is so very little seismic activity on Mars that one needs quantity, i.e. time, to get over the noise level. Time is very good for seismometry in general.

  • MadRocketSci

    I’m somewhat surprised that there’s any seismic activity to find on such a small planet. My intuition on the subject is pretty untrained, but you would think there would be some sort of L^3/L^2 law to how fast a planet’s core cools off over geological time.

Leave a Reply

Your email address will not be published. Required fields are marked *