Geochemist: Helium and Lead isotopes provide insight into Earth's core

This map of the Samoan hotspot shows its division into three parallel volcanic lineaments. 

Credit: UCSB

A UC Santa Barbara geochemist studying Samoan volcanoes has found evidence of the planet's early formation still trapped inside the Earth.

Known as hotspots, volcanic island chains such as Samoa can ancient primordial signatures from the early solar system that have somehow survived billions of years.

Matthew Jackson, an associate professor in UCSB's Department of Earth Science, and colleagues utilized high-precision lead and helium isotope measurements to unravel the chemical composition and geometry of the deep mantle plume feeding Samoa's volcanoes.

Their findings appear today in the journal Nature.

In most cases, volcanoes are located at the point where two tectonic plates meet, and are created when those plates collide or diverge.

Hotspot volcanoes, however, are not located at plate boundaries but rather represent the anomalous melting in the interior of the plates.

Such intraplate volcanoes form above a plume-fed hotspot where the Earth's mantle is melting.

The plate moves over time, at approximately the rate human fingernails grow (3 inches a year), and eventually the volcano moves off the hotspot and becomes extinct.

Another volcano forms in its place over the hotspot and the process repeats itself until a string of volcanoes evolves.

"So you end up with this linear trend of age-progressive volcanoes," Jackson said. "On the Pacific plate, the youngest is in the east and as you go to the west, the volcanoes are older and more deeply eroded."

"Hawaii has two linear trends of volcanoes, most underwater, which are parallel to each other. There's a southern trend and a northern trend."

Because the volcanic composition of parallel Hawaiian trends is fundamentally different, Jackson and his team decided to look for evidence of this in other hotspots.

In Samoa, they found three volcanic trends exhibiting three different chemical configurations as well as a fourth group of a late-stage eruption on top of the third trend of volcanoes. These different groups exhibit distinct compositions.

"Our goal was to figure out how we could use this distribution of volcano compositions at the surface to reverse-engineer how these components are distributed inside this upwelling mantle plume at depth," Jackson said.

Each of the four distinct geochemical compositions, or endmembers, that the scientists identified in Samoan lavas contained low Helium-3 (He-3) and Helium-4 (He-4) ratios.

The surprising discovery was that they all exhibited evidence for mixing with a fifth, rare primordial component consisting of high levels of He-3 and He-4.

"We have really strong evidence that the bulk of the plume is made of the high Helium-3, -4 component," Jackson said.

"That tells us that most of this plume is primordial material and there are other materials hosted inside of this plume with low Helium-3, -4, and these are likely crustal materials sent into the mantle at ancient subduction zones."

The unique isotopic topology revealed by the researchers' analysis showed that the four low-helium endmembers do not mix efficiently with one another. However, each of them mixes with the high He-3 and He-4 component.

"This unique set of mixing relationships requires a specific geometry for the four geochemical flavors within the upwelling plume: They must be hosted within a matrix that is composed of the rare fifth component with high He-3," Jackson explained.

"This new constraint on plume structure has important implications for how deep mantle material is entrained in plumes, and it gives us the clearest picture yet for the chemical structure of an upwelling mantle plume."

More Information
Helium and lead isotopes reveal the geochemical geometry of the Samoan plume - M. G. Jackson, S. R. Hart, J. G. Konter, M. D. Kurz, J. Blusztajn & K. A. Farley Corresponding Author: Nature 514, 355–358 (16 October 2014) doi:10.1038/nature13794

NASA's Messenger: Mercury's magnetic field reveals its interior is different from Earth's

Earth and Mercury are both rocky planets with iron cores, but Mercury's interior differs from Earth's in a way that explains why the planet has such a bizarre magnetic field, UCLA planetary physicists and colleagues report.

Measurements from NASA's Messenger spacecraft have revealed that Mercury's magnetic field is approximately three times stronger at its northern hemisphere than its southern one.

In the current research, scientists led by Hao Cao, a UCLA postdoctoral scholar working in the laboratory of Christopher T. Russell, created a model to show how the dynamics of Mercury's core contribute to this unusual phenomenon.

The magnetic fields that surround and shield many planets from the sun's energy-charged particles differ widely in strength.

While Earth's is powerful, Jupiter's is more than 12 times stronger, and Mercury has a rather weak magnetic field.

Venus likely has none at all. The magnetic fields of Earth, Jupiter and Saturn show very little difference between the planets' two hemispheres.

Within Earth's core, iron turns from a liquid to a solid at the inner boundary of the planet's liquid outer core; this results in a solid inner part and liquid outer part.

The solid inner core is growing, and this growth provides the energy that generates Earth's magnetic field. Many assumed, incorrectly, that Mercury would be similar.

"Hao's breakthrough is in understanding how Mercury is different from the Earth so we could understand Mercury's strongly hemispherical magnetic field," said Russell, a co-author of the research and a professor in the UCLA College's department of Earth, planetary and space sciences.

"We had figured out how the Earth works, and Mercury is another terrestrial, rocky planet with an iron core, so we thought it would work the same way but it's not working the same way."

Mercury's peculiar magnetic field provides evidence that iron turns from a liquid to a solid at the core's outer boundary, say the scientists, whose research currently appears online in the journal Geophysical Research Letters and will be published in an upcoming print edition.

"It's like a snow storm in which the snow formed at the top of the cloud and middle of the cloud and the bottom of the cloud too," said Russell.

"Our study of Mercury's magnetic field indicates iron is snowing throughout this fluid that is powering Mercury's magnetic field."

The research implies that planets have multiple ways of generating a magnetic field.

Hao and his colleagues conducted mathematical modeling of the processes that generate Mercury's magnetic field.

In creating the model, Hao considered many factors, including how fast Mercury rotates and the chemistry and complex motion of fluid inside the planet.

The cores of both Mercury and Earth contain light elements such as sulfur, in addition to iron; the presence of these light elements keeps the cores from being completely solid and "powers the active magnetic field–generation processes," Hao said.

Hao's model is consistent with data from Messenger and other research on Mercury and explains Mercury's asymmetric magnetic field in its hemispheres.

He said the first important step was to "abandon assumptions" that other scientists make.

"Planets are different from one another," said Hao, whose research is funded by a NASA fellowship. "They all have their individual character."

More Information: 'A dynamo explanation for Mercury's anomalous magnetic field.' Authors: Hao Cao, Christopher Russell, et al. - Article first published online: 19 JUN 2014 DOI: 10.1002/2014GL060196

Boeing CST-100: Future Commercial Spacecraft Interior revealed

Boeing has unveiled a new commercial interior of its Crew Space Transportation (CST-100) next-generation manned space capsule, showing how people other than NASA astronauts may one day travel to space.

Boeing's new commercial interior of its Crew Space Transportation (CST-100) next-generation manned space capsule, showing how people other than NASA astronauts may one day travel to space.

Credit: Boeing

Boeing and partner Bigelow Aerospace highlighted the future commercial interior of the capsule it is developing for NASA, while Bigelow showcased a full-scale model of its BA 330 commercial space habitat.

Chris Ferguson

"We are moving into a truly commercial space market and we have to consider our potential customers, beyond NASA, and what they need in a future commercial spacecraft interior," said Chris Ferguson, former Space Shuttle Atlantis commander and current Boeing director of Crew and Mission Operations for the Commercial Crew Program.

Engineers from across Boeing leveraged the company's decades of experience in commercial and government aerospace to design the capsule's interior.

Full-scale model of the BA 330 inflatable space habitat, as seen at Bigelow Aerospace’s Las Vegas facilities, Wednesday, April 30, 2014.

Credit: Space.com/Robert Z. Pearlman

"Boeing's teams have been designing award-winning and innovative interiors for our airplanes since the dawn of commercial aviation," said Rachelle Ornan, regional director of Sales and Marketing for Boeing Commercial Airplanes.

"Designing the next-generation interior for commercial space is a natural progression."

"A familiar daytime blue sky scene helps passengers maintain their connection with Earth."

CST-100, developed as part of NASA's Commercial Crew Integrated Capability initiative, is designed to transport up to seven crew members or a mix of crew and cargo to low-Earth-orbit destinations such as the International Space Station and a planned Bigelow station.

NASA SDO: Bright points in Sun's atmosphere mark patterns deep in its interior

Brightpoints in the sun's atmosphere, left, correspond to magnetic parcels on the sun's surface, seen in the processed data on the right. 

Green spots show smaller parcels, red and yellow much bigger ones. 

Credit: NASA/SDO

Like a balloon bobbing along in the air while tied to a child's hand, a tracer has been found in the sun's atmosphere to help track the flow of material coursing underneath the sun's surface.

New research that uses data from NASA's Solar Dynamics Observatory (SDO), to track bright points in the solar atmosphere and magnetic signatures on the sun's surface offers a way to probe the star's depths faster than ever before.

The technique opens the door for near real-time mapping of the sun's roiling interior – movement that affects a wide range of events on the sun from its 22-year sunspot cycle to its frequent bursts of X-ray light called solar flares.

"There are all sorts of things lurking below the surface," said Scott McIntosh, first author of a paper on these results in the April 1, 2014, issue of the Astrophysical Journal Letters.

"And we've found a marker for this deep rooted activity. This is kind of a gateway to the interior, and we don't need months of data to get there."

One of the most common ways to probe the sun's interior is through a technique called helioseismology in which scientists track the time it takes for waves – not unlike seismic waves on Earth—to travel from one side of the sun to the other.

From helioseismology solar scientists have some sense of what's happening inside the sun, which they believe to be made up of granules and super-granules of moving solar material.

The material is constantly overturning like boiling water in a pot, but on a much grander scale: A granule is approximately the distance from Los Angeles to New York City; a super-granule is about twice the diameter of Earth.

SDO contains three instruments; Helioseismic and Magnetic Imager (HMI), Atmospheric Imaging Assembly (AIA), and Extreme Ultraviolet Variablity Experiment (EVE) -- for observations leading to a more complete understanding of the solar dynamics that drive variability in the Earth's environment. 

Credit: NASA/Goddard Space Flight Center

Instead of tracking seismic waves, the new research probes the solar interior using the Helioseismic Magnetic Imager (HMI) on SDO, which can map the dynamic magnetic fields that thread through and around the sun.

Since 2010, McIntosh has tracked the size of different magnetically-balanced areas on the sun, that is, areas where there are an even number of magnetic fields pointing down in toward the sun as pointing out.

Think of it like looking down at a city from above with a technology that observed people, but not walls, and recording areas that have an even number of men and women.

Even without seeing the buildings, you'd naturally get a sense for the size of rooms, houses, buildings, and whole city blocks – the structures in which people naturally group.

More Information: 'Identifying Potential Markers of the Sun's Giant Convective Scale' Astrophysical Journal April 2014: Authors: Scott W. McIntosh, Xin Wang, Robert J. Leamon, and Philip H. Scherrer: doi:10.1088/2041-8205/784/2/L32

Windows Into Jupiter's moon Europa's Interior

This graphic of Jupiter's moon Europa maps a relationship between the amount of energy deposited onto the moon from charged-particle bombardment and the chemical contents of ice deposits on the surface in five areas of the moon (labeled A through E). 

Credit: NASA/JPL-Caltech/Univ. of Ariz./JHUAPL/Univ. of Colo.

The surface of Jupiter's moon Europa exposes material churned up from inside the moon and also material resulting from matter and energy coming from above.

If you want to learn about the deep saltwater ocean beneath this unusual world's icy shell -- as many people do, certainly those who are interested in possible extraterrestrial life -- you might target your investigation of the surface.

New analysis of observations made more than a decade ago by NASA's Galileo mission to Jupiter helps identify the deposits that have emanated from 'below' the surface rather than those deposited 'on' the surface.

In particular the report examines Sulphuric Acid Hydrate production on Europa's surface.

J. Brad Dalton

"We have found the regions where charged electrons and ions striking the surface would have done the most, and the least, chemical processing of materials emplaced at the surface from the interior ocean," said J. Brad Dalton of NASA's Jet Propulsion Laboratory, Pasadena, Calif., lead author of the report published recently in the journal Planetary and Space Science.

"That tells us where to look for materials representing the most pristine ocean composition, which would be the best places to target with a lander or study with an orbiter."

Europa is about the size of Earth's moon and, like our moon, keeps the same side toward the planet it orbits.

Picture a car driving in circles around a mountain with its left-side windows always facing the mountain.

Europa's orbit around Jupiter is filled with charged, energetic particles tied to Jupiter's powerful magnetic field.

Jupiter's Moon Io

Besides electrons, these particles include ions of sulphur and oxygen originating from volcanic eruptions on Io, a neighbouring Jupiter moon.

The magnetic field carrying these energetic particles sweeps around Jupiter faster than Europa orbits Jupiter, in the same direction: about 10 hours per circuit for the magnetic field versus about 3.6 days for Europa's orbit.

So, instead of our mountain-circling car getting bugs on the front windshield, the bugs are plastered on the back of the car by a "wind" from behind going nearly nine times faster than the car.

Europa has a "leading hemisphere" in front and a "trailing hemisphere" in back.

NASA's Galileo Satellite

Earlier studies had found more sulphuric acid hydrate being produced towards the center of the trailing hemisphere than elsewhere on Europa's surface, interpreted as resulting from chemistry driven by sulphur ions bombarding the icy surface.

Surface deposits in these areas are most likely to preserve the original chemical compounds that erupted from the interior.

Dalton suggests that any future spacecraft missions to Europa should target these deposits for study from orbit, or even attempt to land there.

Dalton stated "While investigating the products of surface chemistry driven by charged particles is still interesting from a scientific standpoint, there is a strong push within the community to characterize the contents of the ocean and determine whether it could support life. These kinds of places just might be the windows that allow us to do that."

Jupiter's Moon Europa: Interior Saline Sea flows onto the surface

Based on new evidence from Jupiter's moon Europa, astronomers hypothesize that chloride salts bubble up from the icy moon's global liquid ocean and reach the frozen surface where they are bombarded with sulphur from volcanoes on Jupiter's innermost large moon Io. 

The new findings propose answers to questions that have been debated since the days of NASA's Voyager and Galileo missions. 

This illustration of Europa (foreground), Jupiter (right) and Io (middle) is an artist's concept. 

Credit: NASA/JPL-Caltech

Kevin Hand

Mike Brown

A new paper by Mike Brown, an astronomer at the California Institute of Technology in Pasadena, Calif., and Kevin Hand from NASA's Jet Propulsion Laboratory, also in Pasadena, details the strongest evidence yet that salty water from the vast liquid ocean beneath Europa's frozen exterior actually makes its way to the surface.

The finding, based on some of the best data of its kind since NASA's Galileo mission (1989 to 2003) to study Jupiter and its moons, suggests there is a chemical exchange between the ocean and surface, making the ocean a richer chemical environment.

The work is described in a paper that has been accepted for publication in the Astronomical Journal.

The exchange between the ocean and the surface, Brown said, "means that energy might be going into the ocean, which is important in terms of the possibilities for life there. It also means that if you'd like to know what's in the ocean, you can just go to the surface and scrape some off."

Europa's ocean is thought to cover the moon's whole globe and is about 60 miles (100 kilometers) thick under a thin ice shell. Since the days of NASA's Voyager and Galileo missions, scientists have debated the composition of Europa's surface.

The infrared spectrometer aboard Galileo was not capable of providing the detail needed to identify definitively some of the materials present on the surface.

Now, using the Keck II Telescope on Mauna Kea, Hawaii, and its OSIRIS spectrometer, Brown and Hand have identified a spectroscopic feature on Europa's surface that indicates the presence of a magnesium sulfate salt, a mineral called epsomite, that could have formed by oxidation of a mineral likely originating from the ocean below.

Brown and Hand started by mapping the distribution of pure water ice versus anything else. The spectra showed that even Europa's leading hemisphere contains significant amounts of non-water ice.

Then, at low latitudes on the trailing hemisphere-the area with the greatest concentration of the non-water ice material-they found a tiny, never-before-detected dip in the spectrum.

The two researchers tested everything from sodium chloride to Drano in Hand's lab at JPL, where he tries to simulate the environments found on various icy worlds. At the end of the day, the signature of magnesium sulfate persisted.

The magnesium sulfate appears to be generated by the irradiation of sulfur ejected from the Jovian moon Io and, the authors deduce, magnesium chloride salt originating from Europa's ocean.

Chlorides such as sodium and potassium chlorides, which are expected to be on the Europa surface, are in general not detectable because they have no clear infrared spectral features but magnesium sulfate is detectable. The authors believe the composition of Europa's ocean may closely resemble the salty ocean of Earth.

Europa is considered a premier target in the search for life beyond Earth, Hand said.

"If we've learned anything about life on Earth, it's that where there's liquid water, there's generally life," Hand said. "And of course our ocean is a nice, salty ocean. Perhaps Europa's salty ocean is also a wonderful place for life."

NASA, ESA Cassini Fly-by: Titan's Cool and Sluggish Interior

This artist's illustration shows the likely interior structure of Saturn's moon Titan deduced from gravity field data collected by NASA's Cassini spacecraft.

The investigation by Cassini's radio science team suggests that Titan's interior is a cool mix of ice studded with rock, though the outermost 500 kilometers (300 miles) appear to be ice essentially devoid of any rock.

Many planets and moons, including the Earth, evolve into a body with a clearly distinct rocky core. This radio science investigation suggests Titan's interior, cool and sluggish, failed to allow the interior to separate into completely differentiated layers of ice and rock.

In addition to the hazy surface of Titan (yellow), the layers in the cutaway show an ice layer starting near the surface (light gray), an internal ocean hypothesized from other Cassini data (blue), another layer of ice (light gray) and the mix of rock and ice in the interior (dark gray). In the background are the Cassini spacecraft and Saturn, not to scale.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of Caltech, manages the project for NASA's Science Mission Directorate in Washington.

The Cassini orbiter was designed, developed and assembled at JPL. Cassini's radio science subsystem has been jointly developed by NASA and the Italian Space Agency.

For more information about the Cassini-Huygens mission visit http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov/.

Image credit: NASA/JPL