Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists present new long-term ecological research

05.02.2018

Highlights include the health of US East Coast salt marshes; influence of sea ice patterns on penguins; diet of blue whales in the California Current

Mars developed in as little as two to four million years after the birth of the solar system, far more quickly than Earth, according to results of a new study published in this week's issue of the journal Nature.


The Pacific sardine is an important species in NSF's California Current Ecosystem LTER Site.

Credit: NSF California Current Ecosystem LTER Site


What lives in seawater? Scientists at NSF's Northeast US Shelf LTER Site are finding new answers.

Credit: Northeast U.S. Shelf LTER Site

The red planet's rapid formation helps explain why it is so small, say the study's co-authors, Nicolas Dauphas at the University of Chicago and Ali Pourmand at the University of Miami.

Their research was funded by the National Science Foundation (NSF).

Mars probably is not a terrestrial planet like Earth, which grew to its full size over 50 to 100 million years via collisions with other small bodies in the solar system, said Dauphas, a geophysicist.

"Earth was made of embryos like Mars, but Mars is a stranded planetary embryo that never collided with other embryos to form an Earthlike planet," Dauphas said.

The new work provides evidence for this idea, which was first proposed 20 years ago on the basis of planetary growth simulations.

It likely will change the way planetary scientists view Mars, said Pourmand, a marine geologist and geophysicist. "We thought that there were no embryos in the solar system to study, but when we study Mars, we are studying embryos that eventually made planets like Earth."

There had been large uncertainties in the formation history of Mars because of the unknown composition of its mantle, the rock layer that underlies the crust.

"Now we can shrink those uncertainties to the point where we can do interesting science," Dauphas said.

Dauphas and Pourmand were able to refine the age of Mars by using the radioactive decay of hafnium to tungsten in meteorites.

Hafnium 182 decays into tungsten 182 in a half-life of nine million years. This relatively rapid decay means that almost all hafnium 182 will disappear in 50 million years, providing a way to assemble a fine-scale chronology of early events in the solar system.

"To apply that system you need two gradients," Pourmand explained. "You need the hafnium-tungsten ratio of the mantle of Mars and you need the tungsten isotopic composition of the mantle of Mars."

The latter was well known from analyses of martian meteorites, but not the former.

Previous estimates of the formation of Mars ranged as high as 15 million years because the chemical composition of the martian mantle was largely unknown.

Scientists still wrestle with large uncertainties in the composition of Earth's mantle because of processes such as melting.

"We have the same problem for Mars," Dauphas said.

Analyses of martian meteorites provide clues about the mantle composition of Mars, but their compositions also have changed.

Solving some lingering unknowns about the composition of chondrites, a common type of meteorites, provided the data needed.

As essentially unaltered debris left over from the birth of the solar system, chondrites serve as a Rosetta stone for deducing planetary chemical composition.

Cosmochemists have intensively studied chondrites, but still poorly understand the abundances of two categories of elements they contain, including uranium, thorium, lutetium and hafnium.

Dauphas and Pourmand analyzed the abundances of these elements in more than 30 chondrites, and compared those to the compositions of another 20 martian meteorites.

"Once you solve the composition of chondrites you can address many other questions," Dauphas said.

Hafnium and thorium both are refractory or non-volatile elements, meaning that their compositions remain relatively constant in meteorites.

They also are lithophile elements, those that would have stayed in the mantle when the core of Mars formed. If scientists could measure the hafnium-thorium ratio in the martian mantle, they would have the ratio for the whole planet, which they need to reconstruct its formation history.

The relationships between hafnium, thorium and tungsten dictated that the hafnium-thorium ratio in the mantle of Mars must be similar to the same ratio in chondrites.

To derive the martian mantle's hafnium-tungsten ratio, they divided the thorium-tungsten ratio of the martian meteorites by the thorium-hafnium ratio of the chondrites.

"Why do you do that? Because thorium and tungsten have very similar chemical behavior," Dauphas said.

Once Dauphas and Pourmand had determined this ratio, they were able to calculate how long it took Mars to develop into a planet.

A computer simulation based on these data showed that Mars must have reached half its present size only two million years after the formation of the solar system.

"New application of radiogenic isotopes to both chondrite and martial meteorites provides data on the age and mode of formation of Mars," said Enriqueta Barrera, program director in NSF's Division of Earth Sciences. "That is consistent with models that explain Mars' small mass in comparison to that of Earth."

A quickly-forming Mars would help explain the puzzling similarities in the xenon content of its atmosphere and that of Earth's.

"Maybe it's just a coincidence, but maybe the solution is that part of the atmosphere of Earth was inherited from an earlier generation of embryos that had their own atmospheres, maybe a Marslike atmosphere," Dauphas said.

The short formation history of Mars further raises the possibility that aluminum 26, which is known from meteorites, turned the red planet into a magma ocean early in its history.

Aluminum 26 has a half-life of 700,000 years, so it would have disappeared too quickly to contribute to the internal heat of Earth.

If Mars formed in two million years, however, significant quantities of aluminum 26 would remain. "When aluminum 26 decays it releases heat and can completely melt the planet," Pourmand said.

The research was also funded by the National Aeronautics and Space Administration and the Packard Foundation.

Media Contact

cheryl dybas
cdybas@nsf.gov

 @NSF

http://www.nsf.gov 

Cheryl Dybas |

More articles from Earth Sciences:

nachricht Novel method for investigating pore geometry in rocks
18.06.2018 | Kyushu University, I2CNER

nachricht Decades of satellite monitoring reveal Antarctic ice loss
14.06.2018 | University of Maryland

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Creating a new composite fuel for new-generation fast reactors

20.06.2018 | Materials Sciences

Game-changing finding pushes 3D-printing to the molecular limit

20.06.2018 | Materials Sciences

Could this material enable autonomous vehicles to come to market sooner?

20.06.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>