. 24/7 Space News .
IRON AND ICE
SwRI-led team produces a new Earth Bombardment Model
by Staff Writers
San Antonio TX (SPX) Oct 25, 2021

Illustration of large asteroids penetrating Earth's oxygen-poor atmosphere. Courtesy of SwRI/Dan Durda, Simone Marchi.

A team led by Southwest Research Institute has updated its asteroid bombardment model of the Earth with the latest geologic evidence of ancient, large collisions. These models have been used to understand how impacts may have affected oxygen levels in the Earth's atmosphere in the Archean eon, 2.5 to 4 billion years ago.

When large asteroids or comets struck early Earth, the energy released melted and vaporized rocky materials in the Earth's crust. The small droplets of molten rock in the impact plume would condense, solidify and fall back to Earth, creating round, globally distributed sand-size particles. Known as impact spherules, these glassy particles populated multiple thin, discrete layers in the Earth's crust, ranging in age from about 2.4 to 3.5 billion years old.

These Archean spherule layers are markers of ancient collisions. "In recent years, a number of new spherule layers have been identified in drill cores and outcrops, increasing the total number of known impact events during the early Earth," said Dr. Nadja Drabon, a professor at Harvard University and a co-author of the paper.

"Current bombardment models underestimate the number of late Archean spherule layers, suggesting that the impactor flux at that time was up to 10 times higher than previously thought," said SwRI's Dr. Simone Marchi, lead author of a paper about this research in Nature Geoscience. "What's more, we find that the cumulative impactor mass delivered to the early Earth was an important 'sink' of oxygen, suggesting that early bombardment could have delayed oxidation of Earth's atmosphere."

The abundance of oxygen in Earth's atmosphere is due to a balance of production and removal processes. These new findings correspond to the geological record, which shows that oxygen levels in the atmosphere varied but stayed relatively low in the early Archean eon. Impacts by bodies larger than six miles (10 km) in diameter may have contributed to its scarcity, as limited oxygen present in the atmosphere of early Earth would have been chemically consumed by impact vapors, further reducing its abundance in the atmosphere.

"Late Archean bombardment by objects over six miles in diameter would have produced enough reactive gases to completely consume low levels of atmospheric oxygen," said Dr. Laura Schaefer, a professor at Stanford University and a co-author of the paper.

"This pattern was consistent with evidence for so-called 'whiffs' of oxygen, relatively steep but transient increases in atmospheric oxygen that occurred around 2.5 billion years ago. We think that the whiffs were broken up by impacts that removed the oxygen from the atmosphere. This is consistent with large impacts recorded by spherule layers in Australia's Bee Gorge and Dales Gorge."

SwRI's results indicate that the Earth was subject to substantial numbers of large impacts throughout the late Archean era. Around 2.4 billion years ago, during the tail end of this bombardment, the Earth went through a major shift in surface chemistry triggered by the rise of atmospheric oxygen, dubbed the Great Oxidation Event (GOE), which is attributed to changes in the oxygen production-sink balance. Among the proposed scenarios are a presumed increase in oxygen production and decrease in gases capable of removing oxygen, either from volcanic sources or through their gradual loss to space.

"Impact vapors caused episodic low oxygen levels for large spans of time preceding the GOE," said Marchi, who also recently published a book about colliding worlds(link is external). "As time went on, collisions become progressively less frequent and too small to be able to significantly alter post-GOE oxygen levels. The Earth was on its course to become the current planet."

Research Report: "Delayed and variable late Archean atmospheric oxidation due to high collision rates on Earth"


Related Links
Southwest Research Institute
Asteroid and Comet Mission News, Science and Technology


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


IRON AND ICE
Astronomers detect signs of an atmosphere stripped from a planet during giant impact
Boston MA (SPX) Oct 21, 2021
Young planetary systems generally experience extreme growing pains, as infant bodies collide and fuse to form progressively larger planets. In our own solar system, the Earth and moon are thought to be products of this type of giant impact. Astronomers surmise that such smashups should be commonplace in early systems, but they have been difficult to observe around other stars. Now astronomers at MIT, the National University of Ireland Galway, Cambridge University, and elsewhere have discovered evi ... 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

IRON AND ICE
Humidity caused corrosion of Starliner capsule valves, Boeing, NASA say

Nanoracks, Voyager Space, and Lockheed Martin to develop commercial space module

Blue Origin, partners announce plans for private space station

Printable steak, insect protein, fungus among NASA space food idea winners

IRON AND ICE
Ten years of Soyuz at Europe's Spaceport

US targeting Feb. 2022 to launch new lunar program Artemis

SpaceX conducts 2 test firings of Starship 20 in Texas

South Korea launches own space rocket for the first time

IRON AND ICE
Ingenuity Mars Helicopter Flight 14 Successful

China's Mars orbiter resumes communications with Earth

Mars helicopter Ingenuity approaches 14th flight

Hear sounds from Mars captured by Perseverance Rover

IRON AND ICE
Chinese astronauts arrive at space station for longest mission

China's longest-yet crewed space mission impressive, expert says

Chinese astronaut bridges gender gap

Test conducted to verify spacecraft technology, FM says

IRON AND ICE
From Polar Bears to Polar Orbits

Conclusions from Satellite Constellations 2 Released

Russian Soyuz rocket launches 36 new UK satellites

Over half OneWeb constellation now deployed

IRON AND ICE
Energy-efficient separation of a greenhouse gas: New study from Pusan National University

Shape-shifting materials with infinite possibilities

Stronger than spider silk: Bagworm silk enables strong conducting fibers

Smart material switches between heating and cooling in minutes

IRON AND ICE
Permafrost thaw could release bacteria and viruses

Researchers call for armchair astronomers to help find unknown hidden worlds

Astronomers provide 'Field Guide' to Exoplanets known as Hot Jupiters

NEID Spectrometer Lights Up Path to Exoplanet Exploration

IRON AND ICE
Keeping our eyes on New Horizons

The unusual magnetic fields of Uranus and Neptune

Hubble Finds Evidence of Persistent Water Vapor in One Hemisphere of Europa

SwRI scientists confirm decrease in Pluto's atmospheric density









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.