Connect with us

(3 August 2020 – Carnegie Institution for Science) Work led by Carnegie’s Peng Ni and Anat Shahar has uncovered new details about our Solar System’s oldest planetary objects, which broke apart in long-ago collisions to form iron-rich meteorites.

Their findings reveal that the distinct chemical signatures of these meteorites can be explained by the process of core crystallization in their parent bodies, deepening our understanding of the geochemistry occurring in the Solar System’s youth. They are published by Nature Geoscience.

Many of the meteorites that shot through our planet’s atmosphere and crashed on its surface were once part of larger objects that broke up at some point in our Solar System’s history. The similarity of their chemical compositions tells scientists that they originated as part of common parent bodies, even if they arrived here centuries apart and in vastly different locations.

Deciphering the geologic processes that shaped these parent bodies could teach us more about our Solar System’s history and Earth’s formative years. To truly understand what makes our planet capable of sustaining life, and to look for habitable worlds elsewhere, it is crucial to understand its interior—past and present.

A back-scattered electron image showing one of the products of Chabot’s lab at APL mimicry of the core crystallization process. Liquid metal is on the right and solid metal is on the left. (courtesy: Nancy Chabot and Peng Ni)

iron 2

A beautiful illustration of the Widmanstatten pattern, which is characteristic of iron meteorites. (courtesy: Peng Ni)

“Like our Solar System’s rocky planets, these planetesimals accreted from the disk of dust and gas that surrounded our Sun in its youth,” explained lead author Ni. “And like on Earth, eventually, the densest material sank toward the center, forming distinct layers.”

Iron meteorites were thought to be the remnants of the cores of their ancient, broken-apart parent bodies.

“A history of how their layers differentiated is recorded in their chemical makeup, if we can read it,” said Shahar.

There are four stable isotopes of iron. (Each element contains a unique number of protons, but its isotopes have varying numbers of neutrons.) This means that each iron isotope has a slightly different mass than the others. As a result, some isotopes are preferred by certain chemical reactions—which, in turn, affects the proportion of that isotope in the reaction’s end products.

The traces of this favoritism can be found in rock samples and can help elucidate the processes that forged these meteorite parent bodies.

Previous research on the ratios of iron isotopes in iron meteorites led to a puzzling observation: compared to the raw material from which their parent bodies were constructed, they are enriched in heavy isotopes of iron.

Together with Nancy Chabot and Caillin Ryan of the Johns Hopkins University Applied Physics Laboratory, Ni and Shahar determined that this enrichment can be explained entirely by the crystallization of a parent object’s core.

The researchers use lab-based mimicry to simulate the temperatures of core crystallization in iron meteorite parent bodies. Sophisticated models of the crystallization process including other elemental concentrations—for example, of gold and iridium, as well as isotopes of iron—confirmed their findings.

“This improved understanding of core crystallization adds to our knowledge about our Solar System’s formative period,” Ni concluded.

Source link

0
Continue Reading

Space

Global helium abundance measurements in solar corona

Global helium abundance measurements in solar corona

(18 September 2020 – Naval Research Laboratory) Two U.S. Naval Research Laboratory Space Science Division (SSD) researchers joined an international cadre of scientists July 27 in presenting the results of the first simultaneous global solar corona images of the helium and hydrogen emission that is helping scientists to better understand the space environment.

The paper, “Global Helium Abundance Measurements in the Solar Corona,” was published online in Nature Astronomy and discusses the abundance of helium relative to hydrogen in the solar corona, the outer atmosphere of the sun, seen from earth only during eclipses.

NRL Astrophysicist Dennis Wang, Ph.D., software lead for the HElium Resonance Scattering in the Corona and HEliosphere (HERSCHEL) rocket flight, was responsible for flight and ground software. His NRL colleague, Research Physicist Martin Laming, Ph.D., managed the new model of element abundance fractionation, to include helium.

A composite image of the Sun showing the hydrogen (left) and helium (center and right) in the low corona. The helium at depletion near the equatorial regions is evident. (courtesy: NASA)

“Understanding space weather is important for space situational awareness, that is, forecasting and mitigating the effects of solar activity on Navy and Defense Department satellites,” said Laming. “This was one case where instead of explaining the observations after the fact, I was able to see a prediction I had made come true.”

The HERSCHEL sounding rocket, launched Sep. 14, 2009, provided a number of technological advances in space-based remote sensing. Using a concept developed at NRL for a coronagraph functioning in the extreme ultraviolet regime of the electromagnetic spectrum, the helium coronagraph obtained the first images of the solar atmosphere in the region of the solar wind source surface from light resonantly scattered from helium ions.

The leading model for solar wind variability used by the Department of Defense and National Oceanic and Atmospheric Administration space weather forecasters is an NRL SSD product, known as the Wang, Sheely, Arge Model which is based on simple assumptions about the relation of the solar magnetic field structure and the solar wind, and is reasonably successful in predicting the overall variability of the solar wind as it reaches Earth.

Geomagnetic storms impact radio frequency transmission at frequencies refracted, or reflected, by the ionosphere. The Navy uses magnetic sensors in various battlespace applications, which could be disrupted during large geomagnetic storms and Coronal Mass Ejections. These are major reasons why the Navy is interested in disruptions of the Earth’s magnetic field structure in these measurements.

“There is a long chain of work efforts that go from fundamental understanding of the solar atmosphere, to specifying the observables that need to be monitored before we eventually get to reliable Space Weather forecasts,” said Laming. “In the future, service members should anticipate more reliable satellite-based Command, Control, Communications, Computers, Intelligence, Surveillance, and Reconnaissance.”

Laming demonstrates a strong belief in his model’s prediction capability and his understanding of the sun’s corona adding, “I think we all have more confidence in my model and the conclusions one might draw from it.”

About the U.S. Naval Research Laboratory

NRL is a scientific and engineering command dedicated to research that drives innovative advances for the Navy and Marine Corps from the seafloor to space and in the information domain. NRL headquarters is located in Washington, D.C., with major field sites in Stennis Space Center, Mississippi; Key West, Florida; and Monterey, California, and employs approximately 2,500 civilian scientists, engineers and support personnel.

Source link

0
Continue Reading

Space

hints of fresh ice in northern hemisphere

hints of fresh ice in northern hemisphere

(18 September 2020 – JPL) New composite images made from NASA’s Cassini spacecraft are the most detailed global infrared views ever produced of Saturn’s moon Enceladus. And data used to build those images provides strong evidence that the northern hemisphere of the moon has been resurfaced with ice from its interior.

Cassini’s Visible and Infrared Mapping Spectrometer (VIMS) collected light reflected off Saturn, its rings and its ten major icy moons – light that is visible to humans as well as infrared light. VIMS then separated the light into its various wavelengths, information that tells scientists more about the makeup of the material reflecting it.

The VIMS data, combined with detailed images captured by Cassini’s Imaging Science Subsystem, were used to make the new global spectral map of Enceladus.

In these detailed infrared images of Saturn’s icy moon Enceladus, reddish areas indicate fresh ice that has been deposited on the surface. (courtesy: NASA/JPL-Caltech/University of Arizona/LPG/CNRS/University of Nantes/Space Science Institute)

Cassini scientists discovered in 2005 that Enceladus – which looks like a highly reflective, bright white snowball to the naked eye – shoots out enormous plumes of ice grains and vapor from an ocean that lies under the icy crust. The new spectral map shows that infrared signals clearly correlate with that geologic activity, which is easily seen at the south pole. That’s where the so-called “tiger stripe” gashes blast ice and vapor from the interior ocean.

But some of the same infrared features also appear in the northern hemisphere. That tells scientists not only that the northern area is covered with fresh ice but that the same kind of geologic activity – a resurfacing of the landscape – has occurred in both hemispheres. The resurfacing in the north may be due either to icy jets or to a more gradual movement of ice through fractures in the crust, from the subsurface ocean to the surface.

“The infrared shows us that the surface of the south pole is young, which is not a surprise because we knew about the jets that blast icy material there,” said Gabriel Tobie, VIMS scientist with the University of Nantes in France and co-author of the new research published in Icarus.

“Now, thanks to these infrared eyes, you can go back in time and say that one large region in the northern hemisphere appears also young and was probably active not that long ago, in geologic timelines.”

Managed by NASA’s Jet Propulsion Laboratory in Southern California, Cassini was an orbiter that observed Saturn for more than 13 years before exhausting its fuel supply. The mission plunged it into the planet’s atmosphere in September 2017, in part to protect Enceladus, which has the potential of holding conditions suitable for life, with its ocean likely heated and churned by hydrothermal vents like those on Earth’s ocean floors.

The Cassini-Huygens mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. JPL, a division of Caltech in Pasadena, manages the mission for NASA’s Science Mission Directorate in Washington. JPL designed, developed and assembled the Cassini orbiter.

Source link

0
Continue Reading

Space

Rocket Lab completes final dress rehearsal at Launch Complex 2 ahead of first Electron mission from U.S. soil

Rocket Lab completes final dress rehearsal at Launch Complex 2

(17 September 2020 – Rocket Lab) Rocket Lab has successfully completed a wet dress rehearsal of the Electron vehicle at Rocket Lab Launch Complex 2 (LC-2) at the Mid-Atlantic Regional Spaceport in Wallops Island, Virginia.

With this major milestone complete, the Electron launch vehicle, launch team, and the LC-2 pad systems are now ready for Rocket Lab’s first launch from U.S. soil. The mission is a dedicated launch for the United States Space Force in partnership with the Department of Defense’s Space Test Program and the Space and Missile Systems Center’s Small Launch and Targets Division.

(courtesy: Rocket Lab)

The wet dress rehearsal is a crucial final exercise conducted by the launch team to ensure all systems and procedures are working perfectly ahead of launch day. The Electron launch vehicle was rolled out to the pad, raised vertical and filled with high grade kerosene and liquid oxygen to verify fueling procedures. The launch team then flowed through the integrated countdown to T-0 to carry out the same operations they will undertake on launch day. Before a launch window can be set, NASA is conducting the final development and certification of its Autonomous Flight Termination System (AFTS) software for the mission. This flight will be the first time an AFTS has been has flown from the Mid-Atlantic Regional Spaceport and represents a valuable new capability for the spaceport.

Launch Complex 2 supplements Rocket Lab’s existing site, Launch Complex 1 in New Zealand, from which 14 Electron missions have already launched. The two launch complexes combined can support more than 130 launch opportunities every year to deliver unmatched flexibility for rapid, responsive launch to support a resilient space architecture. Operating two launch complexes in diverse geographic locations provides an unrivalled level of redundancy and assures access to space regardless of disruption to any one launch site.

“Responsive launch is the key to resilience in space and this is what Launch Complex 2 enables,” said Peter Beck, Rocket Lab founder and Chief Executive. “All satellites are vulnerable, be it from accidental or deliberate actions. By operating a proven launch vehicle from two launch sites on opposite sides of the world, Rocket Lab delivers unmatched flexibility and responsiveness for the defense and national security community to quickly replace any disabled satellite. We’re immensely proud to be delivering reliable and flexible launch capability to the U.S. Space Force and the wider defense community as space becomes an increasingly contested domain.”

While the launch team carried out this week’s wet dress rehearsal, construction is nearing completion on the Rocket Lab Integration and Control Facility (ICF) within the Wallops Research Park, adjacent to NASA Wallops Flight Facility Main Base. The ICF houses a launch control center, state-of-the-art payload integration facilities, and a vehicle integration department that enables the processing of multiple Electron vehicles to support multiple launches in rapid succession. The build has been carried out in just a few short months thanks to the tireless support of Virginia Space, Governor Northam, Virginia Secretary of Transportation Shannon Valentine, and Accomack County.

Source link

0
Continue Reading

Trending