. 24/7 Space News .
EXO WORLDS
Planetary collisions can drop the internal pressures in planets
by Staff Writers
Pasadena CA (SPX) Sep 05, 2019

illustration only

A new study from Caltech shows that giant impacts can dramatically lower the internal pressure of planets, a finding that could significantly change the current model of planetary formation.

The impacts, such as the one that is thought to have caused the formation of the earth's moon roughly 4.5 billion years ago, could cause random fluctuations in core and mantle pressures that would explain some puzzling geochemical signatures in Earth's mantle.

"Previous studies have incorrectly assumed that a planet's internal pressure is simply a function of the mass of the planet, and so it increases continuously as the planet grows. What we've shown is that the pressure can temporarily change after a major impact, followed by a longer term increase in pressure as the post-impact body recovers.

This finding has major implications for the planet's chemical structure and subsequent evolution," says Simon Lock, postdoctoral researcher at Caltech and lead author of a paper explaining the new model that was published by Science Advances on September 4.

Lock authored the paper with colleague Sarah Stewart (PhD '02), professor of planetary science at the University of California, Davis, a 2018 MacArthur Fellow, and an alumna of the Caltech Division of Geological and Planetary Sciences.

Planetary systems typically begin as a disk of dust that slowly accretes into rocky bodies. The end of the main stage of this process is characterized by high-energy collisions between planet-sized bodies as they coalesce to form the final planets.

The shock energy of these impacts can vaporize significant portions of a planet and even, as is thought to have happened with the impact that formed the moon, temporarily turn the two colliding bodies into a rotating donut of planetary material known as a "synestia," which later cools back into one or more spherical bodies.

Lock and Stewart used computational models of giant impacts and planetary structures to simulate collisions that formed bodies with masses of between 0.9 and 1.1 Earth masses and found that, immediately after a collision, their internal pressures were much lower than had been expected.

They found that the decrease in pressure was due to a combination of factors: the rapid rotation imparted by the collision, which generated a centrifugal force that acted against gravity, in essence pushing material away from the spin axis; and the low density of the hot, partially vaporized body.

"We have no direct observations of the growth of Earth-like planets. It turns out that the physical properties of a planet can vary wildly during their growth by collisions. Our new view of planet formation is much more variable and energetic than previous models which opens the door for new explanations of previous data," Stewart says.

The final result is that major impacts can lower a planet's internal pressure significantly. The pressure right after an impact like the one that is thought to have formed the moon could have been half of that of present-day Earth.

If true, the finding could help reconcile a long-standing contradiction between the geochemistry of the earth's mantle and physical models of planet formation.

As the proto-Earth grew, each object that collided with it delivered metal into the mantle. After each impact, the metal absorbed small amounts of other elements from the mantle, and then sank to the core - dragging those elements with it.

The amount of each element that dissolved into the metal was determined, in part, by the earth's internal pressures. As such, the chemical composition of the mantle today records the mantle pressure during the planet's formation.

Studies of the metals in the earth's mantle today indicate that this absorption process occurred at pressures found in the middle of the mantle today. However, giant impact models show that such impacts melt most of the mantle, and so the mantle should have recorded a much higher pressure - equivalent to what we now see just above the core. This anomaly between the geochemical observation and physical models is one that scientists have long sought to explain.

By showing that the pressures after giant impacts were lower than previously thought, Lock and Stewart may have found the physical mechanism to solve this conundrum.

Next, Lock and Stewart plan to use their results to calculate how stochastic changes in pressure during formation affect the chemical structure of planets. Lock says that they will also continue to study how planets recover from the trauma of giant impacts "We have shown that the pressures in planets can increase dramatically as a planet recovers, but what effect does that have on how the mantle solidifies or how Earth's first crust formed? This is a whole new area that has yet to be explored," he says.

Research Report: "Giant impacts stochastically change the internal pressures of terrestrial planets."


Related Links
California Institute of Technology
Lands Beyond Beyond - extra solar planets - news and science
Life Beyond Earth


Thanks for being there;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Monthly Supporter
$5+ Billed Monthly


paypal only
SpaceDaily Contributor
$5 Billed Once


credit card or paypal


EXO WORLDS
Deep-sea sediments reveal solar system chaos: An advance in dating geologic archives
Manoa HI (SPX) Aug 30, 2019
A day is the time for Earth to make one complete rotation on its axis, a year is the time for Earth to make one revolution around the Sun - reminders that basic units of time and periods on Earth are intimately linked to our planet's motion in space relative to the Sun. In fact, we mostly live our lives to the rhythm of these astronomical cycles. The same goes for climate cycles. The cycles in daily and annual sunlight cause the familiar diel swings in temperature and the seasons. On geologic time ... read more

Comment using your Disqus, Facebook, Google or Twitter login.



Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

EXO WORLDS
Company Claims Orbital Hotel to Host 400 Space Tourists Will Be Operational By 2025

Europe Unlikely to Abandon Soyuz Once US Revives Space Shuttles - German Space Center

UAE Wants to Train More Astronauts for Arab World - Emirati Official

Space Station science return and spacecraft shuffle

EXO WORLDS
Russia Launches Rokot Space Rocket to Orbit Military Satellite

Dynetics, Raytheon producing glide bodies for hypersonic weapon prototypes

Trump says US 'not involved' in Iranian rocket failure

Study tests performance of electric solid propellant

EXO WORLDS
ESA Chief says discussed ExoMars 2020 launch with Roscosmos

NASA engineers attach Mars Helicopter to Mars 2020 rover

NASA Invites Students to Name Next Mars Rover

NASA's Mars Helicopter Attached to Mars 2020 Rover

EXO WORLDS
China's KZ-1A rocket launches two satellites

China's newly launched communication satellite suffers abnormality

China launches first private rocket capable of carrying satellites

Chinese scientists say goodbye to Tiangong-2

EXO WORLDS
Iridium and Thales Expand Partnership to Deliver Aircraft Connectivity Services

ESA re-routes satellite to avoid SpaceX collision risk

Cutting-edge Chinese satellite malfunctions after launch

Private Chinese firms tapping international space market

EXO WORLDS
Russia says radioactive isotopes released by missile test blast

ESA spacecraft dodges large constellation

China's Tianhe-2 Supercomputer to Crunch Space Data From New Radio Telescope

Chipping away at how ice forms could keep windshields, power lines ice-free

EXO WORLDS
Deep-sea sediments reveal solar system chaos: An advance in dating geologic archives

Exoplanets Can't Hide Their Secrets from Innovative New Instrument

Hints of a volcanically active exomoon

Canadian astronomers determine Earth's fingerprint

EXO WORLDS
Storms on Jupiter are disturbing the planet's colorful belts

ALMA shows what's inside Jupiter's storms

Young Jupiter was smacked head-on by massive newborn planet

Mission to Jupiter's icy moon confirmed









The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.