A new terrestrial bombardment model developed by an international group of scientists led by Southwest Research Institute (SwRI) indicates that Earth’s surface was heavily reprocessed — or melted, mixed and buried — as a result of giant asteroid impacts more than four billion years ago.
The model, calibrated using existing lunar and terrestrial data, sheds light on the role asteroid collisions played in the geological evolution of the uppermost layers of Earth during the geologic eon call the “Hadean,” or first geologic eon, approximately four to 4.5 billion years ago.
The team, which also included academic and government researchers, published its findings in a paper, “Widespread Mixing and Burial of Earth’s Hadean Crust by Asteroid Impacts,” in the July 31, 2014, issue of the journal Nature.
An artistic conception of the early Earth, showing a surface pummeled by large impacts, resulting in extrusion of deep-seated magma onto the surface. At the same time, the distal portion of the surface could have retained liquid water.
“Prior to approximately four billion years ago, no large region of Earth’s surface could have survived untouched by impacts and their effects,” said Dr. Simone Marchi, lead author of the paper and a planetary scientist in SwRI’s Planetary Science Directorate in Boulder, Colo. “The new picture of the Hadean Earth emerging from this work has important implications for its habitability,” Marchi said.
Large impacts had particularly severe effects on existing ecosystems. Researchers found that on average, Hadean Earth more than four billion years ago could have been hit by one to four impactors that were more than 600 miles wide and capable of global sterilization, and by three to seven impactors more than 300 miles wide and capable of global ocean vaporization.
“During that time, the lag between major collisions was long enough to allow intervals of more clement conditions, at least on a local scale,” Marchi said. “Any life emerging during the Hadean eon likely needed to be resistant to high temperatures and could have survived such a violent period in Earth’s history by thriving in niches deep underground or in the ocean’s crust.”
The research was supported in part by NASA’s Solar System Exploration Research Virtual Institute (SSERVI) at NASA’s Ames Research Center in Moffett Field, Calif.
“A large asteroid impact could have buried a substantial amount of Earth’s crust with impact-generated melt,” said Dr. Yvonne Pendleton, SSERVI director at Ames. “This new model helps explain how repeated asteroid impacts may have buried Earth’s earliest and oldest rocks.”
Terrestrial planet formation models indicate Earth went through a sequence of major growth phases: initially accretion of planetesimals — planetary embryos — over many tens of millions of years; then a giant impact that led to the formation of the Moon; followed by the late bombardment when giant asteroids several tens to hundreds of miles in size periodically hit ancient Earth, dwarfing the one that presumably killed the dinosaurs (estimated to be six miles in size), only 65 million years ago.
Researchers estimate that accretion during the late bombardment contributed less than one percent of Earth’s present-day mass, but the giant asteroid impacts still had a profound effect on the geological evolution of early Earth. Prior to four billion years ago Earth was resurfaced over and over by voluminous, impact-generated melt.
Furthermore, large collisions as late as about four billion years ago may have repeatedly boiled away existing oceans into steamy atmospheres. Despite the heavy bombardment, the findings are compatible with the claim of liquid water on Earth’s surface as early as about 4.3-4.4 billion years ago based on geochemical data.
The new research reveals that asteroidal collisions not only severely altered the geology of the Hadean eon Earth, but also likely played a major role in the evolution of life on early Earth as well.
The team was comprised of Marchi and Dr. William Bottke from SwRI; L. Elkins-Tanton from Carnegie Institution for Science in Washington; M. Bierhaus and K. Wünnemann from the Museum fur Naturkunde in Berlin, Germany; A. Morbidelli from Observatoire de la Côte d’Azur in Nice, France; and D. Kring from the Universities Space Research Association and the Lunar and Planetary Institute in Houston.
SSERVI is a virtual institute that, with international partnerships, brings science and exploration researchers together in a collaborative virtual setting. SSERVI is funded by the Science Mission Directorate and Human Exploration and Operations Mission Directorate at NASA Headquarters in Washington. For more information about SSERVI and selected member teams, visit: http://sservi.nasa.gov.
Editors: An artistic conception of the early Earth is available at: http://www.swri.org/press/2014/hadean-earth.htm.
For more information, contact Joe Fohn, (210) 522-4630, Communications Department, Southwest Research Institute, PO Drawer 28510, San Antonio, TX 78228-0510.
Joe Fohn | Eurek Alert!
Tracking the amount of sea ice from the Greenland ice sheet
28.09.2016 | Ca' Foscari University of Venice
A perfect sun-storm
28.09.2016 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ
Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of light metals.
Scientists at the University of Stuttgart have now developed two new process variants that will considerably expand the areas of application for friction stir welding.
Technologie-Lizenz-Büro (TLB) GmbH supports the University of Stuttgart in patenting and marketing its innovations.
Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of...
Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.
Optical quantum computers are what people are pinning their hopes on for tomorrow’s computer technology – whether for tap-proof data encryption, ultrafast...
The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.
“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...
With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.
Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...
For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.
Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...
28.09.2016 | Event News
27.09.2016 | Event News
23.09.2016 | Event News
28.09.2016 | Medical Engineering
28.09.2016 | Materials Sciences
28.09.2016 | Business and Finance