CASTRO Simulations reveal an unusual death for ancient stars

This image is a slice through the interior of a supermassive star of 55,500 solar masses along the axis of symmetry. 

It shows the inner helium core in which nuclear burning is converting helium to oxygen, powering various fluid instabilities (swirling lines). 

This "snapshot" from a CASTRO simulation shows one moment a day after the onset of the explosion, when the radius of the outer circle would be slightly larger than that of the orbit of the Earth around the sun. 

Visualizations were done in VisIT. 

Credit: Ken Chen, University of California at Santa Cruz

Certain primordial stars, those 55,000 and 56,000 times the mass of our Sun, or solar masses, may have died unusually.

In death, these objects, among the Universe's first-generation of stars, would have exploded as supernovae and burned completely, leaving no remnant black hole behind.

Astrophysicists at the University of California, Santa Cruz (UCSC) and the University of Minnesota came to this conclusion after running a number of supercomputer simulations at the US Department of Energy's (DOE's) National Energy Research Scientific Computing Center (NERSC) and Minnesota Supercomputing Institute at the University of Minnesota.

They relied extensively on CASTRO, a compressible astrophysics code developed at DOE's Lawrence Berkeley National Laboratory's (Berkeley Lab's) Computational Research Division (CRD).

Their findings were recently published in Astrophysical Journal (ApJ).

First-generation stars are especially interesting because they produced the first heavy elements, or chemical elements other than hydrogen and helium.

In death, they sent their chemical creations into outer space, paving the way for subsequent generations of stars, solar systems and galaxies.

With a greater understanding of how these first stars died, scientists hope to glean some insights about how the Universe, as we know it today, came to be.

"We found that there is a narrow window where supermassive stars could explode completely instead of becoming a supermassive black hole, no one has ever found this mechanism before," says Ke-Jung Chen, a postdoctoral researcher at UCSC and lead author of the ApJ paper.

"Without NERSC resources, it would have taken us a lot longer to reach this result."

"From a user perspective, the facility is run very efficiently and it is an extremely convenient place to do science."

More information: Astrophysical Journal, iopscience.iop.org/0004-637X/790/2/162

NASA Terra Aqua MODIS: UK scientists reveal Amazon rainforest satellite imaging problem - Video

US Scientists have been puzzled by the apparent ‘greening up’ of the Amazon forest during its annual dry season.

However, Swansea University scientists, in research carried out in conjunction with NASA, have found that the Amazon is not as green in the dry season as researchers previously thought, because a trick of the light skews the satellite images.

The research is published in the latest issue of the scientific journal Nature; doi:10.1038/nature13006

This natural-colour satellite image shows the importance of correcting for sun-sensor geometry. 

On the left side, sunlight is backscattered by the Amazon rainforest, creating the appearance of brighter green leaves in some areas. 

To the right, sunglint makes the dark waters of the Amazon River and surrounding flooded wetlands appear silver or white compared to the darker forest. 

 Credit: NASA's Earth Observatory

The finding of the research yeam will help scientists develop a more accurate picture of changes in the Amazon, which is more important now than ever, given the enormous role the Amazon plays in regulating carbon dioxide, and influencing climate change.

NASA's Terra and Aqua satellites make daily observations over the huge expanse of Amazon forests.

The research team were investigating why previous satellite images seemed to show that the forests became greener during the dry season each year from June to October.

More greenery indicates productive, thriving vegetation, which would not be expected at a time of limited rainfall.

The new research shows that:

• The apparent greening of the Amazon in the dry season is an illusion. The forest does not become greener at all.
• It just looks that way due to a combination of shadowing within the forest canopy and the way that satellite sensors observe the Amazon during the dry season, which can create false “hot spots” in images.

Dr Jackie Rosette

‌Swansea researchers, working with NASA, developed a mathematical model which predicts how a forest will be seen from space, and how leaf area can be measured.

One of the Swansea team, Dr Jackie Rosette, spent 2 years at Goddard Space Flight Center, working closely with NASA colleagues.

Blue colours represent areas in Amazon forests where sensors and models can overestimate the green-up of vegetation; white represents areas that lack forest cover. 

The map is based on a model that extends the sun-sensor correction to all pixels in the southern Amazon. 

Credit: Doug Morton and NASA's Earth Observatory

Professor Peter North from the Department of Geography at Swansea University, one of the authors of the research paper, said:

"The Amazon is so vast that it’s only from space that we can properly observe it, so it’s very important that the satellite data gives us as accurate a picture as possible.

Our model has helped to identify the flaws in the previous interpretation. As a result, we can be much more confident that what we are seeing is a real pattern across the Amazon, not a trick of the light.

Having an accurate picture of the Amazon is essential if we are to understand its key role in shaping the climate."

Aboard the NASA satellites are sensors called MODIS (Moderate Resolution Imaging Spectroradiometer) which measure the amount of infrared light reflected from the Amazon.

Scientists use the ratio of red and near-infrared light as a measure of vegetation.

Doug Morton, NASA’s Goddard Space Flight Center said.

"We think we have uncovered the mechanism for the appearance of seasonal greening of Amazon forests – shadowing within the canopy that changes the amount of near-infrared light observed by MODIS"

The research implies that the previous hypothesis of increased productivity during dry seasons is likely to be false, and Amazon productivity may be more limited by water availability than sunlight.

This is critical for predicting the response of the Amazon to future climate change.

IBEX: Scientists reveal cosmic roadmap to galactic magnetic field

Cosmic ray intensities (left) compared with predictions (right) from IBEX. 

The similarity between these observations and predictions—as evidenced by the similar colour regions—supports the local galactic magnetic field direction determined from IBEX observations made from particles at vastly lower energies than the cosmic ray observations shown here. 

The blue area represents regions of lower fluxes of cosmic rays. 

The gray and white lines separate regions of different energies—lower energies above the lines, high energies below. 

Credit: Nathan Schwadron, UNH-EOS.

Scientists on NASA's Interstellar Boundary Explorer (IBEX) mission, including a team leader from the University of New Hampshire, report that recent, independent measurements have validated one of the mission's signature findings—a mysterious "ribbon" of energy and particles at the edge of our solar system that appears to be a directional "roadmap in the sky" of the local interstellar magnetic field.

Unknown until now, the direction of the galactic magnetic field may be a missing key to understanding how the heliosphere—the gigantic bubble that surrounds our solar system—is shaped by the interstellar magnetic field and how it thereby helps shield us from dangerous incoming galactic cosmic rays.

"Using measurements of ultra-high energy cosmic rays on a global scale, we now have a completely different means of verifying that the field directions we derived from IBEX are consistent," says Nathan Schwadron, lead scientist for the IBEX Science Operations Center at the UNH Institute for the Study of Earth, Oceans, and Space.

Schwadron and IBEX colleagues published their findings online today in Science Express.

Establishing a consistent local interstellar magnetic field direction using IBEX low-energy neutral atoms and galactic cosmic rays at ten orders of magnitude higher energy levels has wide-ranging implications for the structure of our heliosphere and is an important measurement to be making in tandem with the Voyager 1 spacecraft, which is in the process of passing beyond our heliosphere.

An all-sky map made by the IBEX spacecraft shows a surprising bright ribbon of emission coming from the edge of the solar system. 

Credit: Southwest Research Institute (SwRI)

"The cosmic ray data we used represent some of the highest energy radiation we can observe and are at the opposite end of the energy range compared to IBEX's measurements," says Schwadron.

"That it's revealing a consistent picture of our neighbourhood in the galaxy with what IBEX has revealed gives us vastly more confidence that what we're learning is correct."

How magnetic fields of galaxies order and direct galactic cosmic rays is a crucial component to understanding the environment of our galaxy, which in turn influences the environment of our entire solar system and our own environment here on Earth, including how that played into the evolution of life on our planet.

David McComas, principal investigator of the IBEX mission at Southwest Research Institute and coauthor on the Science Express paper says, "We are discovering how the interstellar magnetic field shapes, deforms, and transforms our entire heliosphere."

More information: "Global Anisotropies in TeV Cosmic Rays Related to the Sun's Local Galactic Environment from IBEX," by N.A. Schwadron et al. Science, 2014. www.sciencemag.org/content/early/2014/02/12/science.1245026

Iran unveils new home-made communication satellites

This file photo released June 16, 2011, shows launching the Safir, or Ambassador, satellite carrier, which carries Iran's Rasad, or Observation, satellite into earth orbit. Credit: Alalam news

Iran on Monday unveiled two domestically-made communication satellites, one to bolster its wireless connections and the other capable of taking high-resolution pictures, media reported.

Iran's space programme has prompted concern among Western governments, which fear Tehran is trying to master the technology required to deliver a nuclear warhead.

The Islamic republic insists that its nuclear programme is entirely peaceful and denies its space programme is linked in any way to its disputed nuclear ambitions.

The state-run IRNA news agency named the two satellites as Khalije Fars (Persian Gulf) and Tadbir (wisdom) and said they were built by scientists at local universities.

"Khalije Fars, designed and manufactured by researchers at Malek Ashtar University, is a small satellite which provides secure satellite wireless connections at national or regional scope," IRNA said.

"Tadbir was built by Tehran's University of Science and Industry and is capable of conducting photographic assignments with a resolution of 100 meters (yards)," the agency added.

The deputy head of Iran's space agency, Hamid Fazeli, meanwhile told Fars news agency that the Islamic republic will launch a satellite into orbit by the end of the Iranian year, which ends on March 21.

Fazeli said that Tadbir is among a number of satellites that are ready to be launched into space. He did not give further details.

In December, Iran said that it had safely returned a monkey to Earth after blasting it into space in the second such launch.

An earlier attempt had failed in September 2011.

Iran has already launched three satellites into space since 2009 and plans to send a human into orbit by 2020.

LLCD: Laser demo reveals bright future for space communication

Compared to the days of dial-up, today's web-sites load at lightning speed. 

Just like you need your web-pages load quickly and securely, NASA scientists and engineers want the same quick connectivity with their data-gathering spacecraft. 

To meet these demands NASA is moving away from their form of dial-up (radio frequency-based communication), to their own version of high-speed Internet; using laser communications. 

Credit: NASA

The completion of the 30-day Lunar Laser Communication Demonstration (LLCD) mission has revealed that the possibility of expanding broadband capabilities in space using laser communications is as bright as expected.

Hosted aboard the Lunar Atmosphere and Dust Environment Explorer (LADEE), for its ride to lunar orbit, the LLCD was designed to confirm laser communication capabilities from a distance of almost a quarter-of-a-million miles.

In addition to demonstrating record-breaking data download and upload speeds to the moon at 622 megabits per second (Mbps) and 20 Mbps, respectively, LLCD also showed that it could operate as well as any NASA radio system.

"Throughout our testing we did not see anything that would prevent the operational use of this technology in the immediate future," said Don Cornwell, LLCD mission manager at NASA's Goddard Space Flight Center in Greenbelt, Md.

For example, LLCD demonstrated error-free communications during broad daylight, including operating when the moon was to within three degrees of the sun as seen from Earth.

LLCD also demonstrated error-free communications when the moon was low on the horizon, less than 4 degrees, as seen from the ground station, which also demonstrated that wind and atmospheric turbulence did not significantly impact the system. LLCD was even able to communicate through thin clouds, an unexpected bonus.

Operationally, LLCD demonstrated the ability to download data from the LADEE spacecraft itself. "We were able to download LADEE's entire stored science and spacecraft data [1 gigabyte] in less than five minutes, which was only limited to our 40 Mbps connection to that data within LADEE" said Cornwell.

Using LADEE's onboard radio system would take several days to complete a download of the same stored data.

Additionally, LLCD was to prove the integrity of laser technology to send not only error-free data but also uncorrupted commands and telemetry or monitoring messages to and from the spacecraft over the laser link.

NASA Administrator Charles Bolden congratulates the LLCD team on their successful demonstration of laser communications in a video that was relayed via laser to and from the moon. 

Credit: NASA's Goddard Space Flight Center

LLCD also demonstrated the ability to "hand-off" the laser connection from one ground station to another, just as a cellphone does a hand-off from one cell tower to another.

An additional achievement was the ability to operate LLCD without using LADEE's radio at all.

"We were able to program LADEE to awaken the LLCD space terminal and have it automatically point and communicate to the ground station at a specific time without radio commands. This demonstrates that this technology could serve as the primary communications system for future NASA missions," said Cornwell.

NASA and NOAA help reveal melt secrets of Great Lakes ice

A colour-coded image of major ice types on Lake Superior, made from a RADARSAT1 radar backscatter image using a new NASA and NOAA-developed technique. 

Credit: NOAA Great Lakes Environmental Research Laboratory and NASA/JPL-Caltech

Two scientists from NASA and NOAA have developed a new space-based technique for monitoring the ice cover of the Great Lakes that is so accurate it can identify a narrow channel of open water cut through the ice by an icebreaker—even at night.

"In the dark, it's difficult to read a map that's right in front of you," said Son Nghiem of NASA's Jet Propulsion Laboratory, Pasadena, Calif., one of the developers of the new technique.

Son Nghiem

"Yet we now have a way to use satellite radars almost 500 miles [800 kilometers] out in space to see through clouds and darkness and map ice across the Great Lakes."

Ice on the Great Lakes puts a big chill on the U.S. and Canadian economies, affecting shipping, fishing and also public safety when winter and spring flooding are caused by ice jams.

It has a significant impact on the regional environment and ecological systems as well. Yet previous techniques of analyzing satellite observations of the ice sometimes misidentified ice as water and vice versa.

The new method, co-developed by Nghiem and his colleague George Leshkevich of NOAA's Great Lakes Environmental Research Laboratory, Ann Arbor, Mich., not only corrects that problem, it also gives a more accurate analysis of ice characteristics, such as whether the ice is dense or full of bubbles, and whether it has melted and refrozen.

Leshkevich said the method has now been transitioned to NOAA for routine use in generating ice maps across the Great Lakes.

"These maps will provide important information for environmental management, ice forecasting and modeling, off-shore wind farm development, operational icebreaking activities in support of winter navigation, and science research."

The more accurate classification of ice will also be useful for scientific research into such questions as how the Great Lakes are responding to, and leading, climate change in the upper Midwest.

More information: www.iaglr.org/jglr/release/39/2013.05.003_leshkevich.php

Astronomers reveal contents of mysterious black hole jets

This is a model of the black hole system with the jets that have been found to contain atomic matter. 

Credit: J. Miller-Jones (ICRAR) using software created by R. Hynes.

An international team of astronomers has answered a long standing question about the enigmatic jets emitted by black holes, in research published today in prestigious journal Nature.

Jets are narrow beams of matter spat out at high speed from near a central object, like a black hole.

"Although they have been observed for decades, we're still not sure what they are made of, or what powers them," ESO astronomer Dr María Díaz Trigo, lead author of the study, said.

The team studied the radio waves and X-rays emitted by a small black hole a few times the mass of the Sun.

The black hole in question was known to be active, but the team's radio observations did not show any jets, and the X-ray spectrum didn't reveal anything unusual.

However, a few weeks later, the team took another look and this time saw radio emissions corresponding to the sudden appearance of these jets, and even more interestingly, lines had appeared in the X-ray spectrum – the tell-tale signature of ordinary atoms – around the black hole.

During the first observation the X-ray emission can be fully described by emission from a standard accretion disc. 

Credit: Riccardo Lanfranchi

"Intriguingly, we found the lines were not where they should be, but rather were shifted significantly," Dr James Miller Jones from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), who led the radio observations, said.

The same effect occurs when a siren from a vehicle changes pitch as it moves towards or away from us, as the sound wave is shortened or lengthened by the movement.

During the second observation the appearance of a jet is detected in radio emission and the X-ray spectrum requires an additional component attributed to coronal emission above the disc and three narrow emission lines indicating the presence of baryons. 

Credit: Riccardo Lanfranchi

"It led us to conclude the particles were being accelerated to fast speeds in the jets, one directed towards Earth, and the other one in the opposite direction," team member Dr Simone Migliari from the University of Barcelona said.

Dr Miller-Jones said this is the first strong evidence of such particles in jets from a typical small black hole.

"We've known for a long time that jets contain electrons, but haven't got an overall negative charge, so there must be something positively charged in them too," Dr Miller Jones said.

"Until now it wasn't clear whether the positive charge came from positrons, the antimatter 'opposite' of electrons, or positively charged atoms. Since our results found nickel and iron in these jets, we now know ordinary matter must be providing the positive charge."

Positively charged atoms are much heavier than the positrons astronomers thought might make up the jets, and therefore the jets can carry away far more energy from the black hole than previously confirmed.

What's more, astronomers aren't sure whether the jets are powered by the spin of the rotating black hole itself, or whether they are instead launched directly from the disk of matter that surrounds the black hole.

"Our results suggest it's more likely the disk is responsible for channelling the matter into the jets, and we are planning further observations to try and confirm this," Dr Miller-Jones said.

Using the X-ray data, the team also determined the jets were moving at 66% of the speed of light, or 198,000 km/s, the most accurate determination to date of the jet speed from a run-of-the-mill black hole that's a few times the mass of the Sun.

For their observations, the team used the European Space Agency's XMM-Newton satellite to observe X-ray emission from the black hole, as well as CSIRO's Australia Telescope Compact Array for the radio observations.

More information: Nature paper: dx.doi.org/10.1038/nature12672

Area 51 Declassified: Documents Reveal Cold War 'Hide-and-Seek

Warning signs tell people to stay away from Area 51.

Newly declassified documents reveal more detail about past use of the mysterious Nevada test site known as Area 51 and the concern for maintaining secrecy about the work done at the facility.

The recently released papers, which date mostly from the early 1960s into the 1970s, spotlight the U.S. government's desire for tight security at Area 51, also known as Groom Lake.

The area was photographed with American reconnaissance assets to better assess what the Soviet Union's spy satellites might be able to discern.

The documents also detail the debate over the possible release of a photograph "inadvertently" taken of the secret facility by NASA astronauts aboard the Skylab space station in 1974.

Stealthy work
More than 60 declassified documents in an Area 51 file were posted on the Internet by the National Security Archive late last month, compiled and edited by archive senior fellow Jeffrey Richelson.

The archive is located at The George Washington University in Washington, D.C.

Those of you hoping for information about captured aliens and flying saucers will be disappointed.

A number of documents focus on the quest to develop stealth capability in aircraft. Others report on another type of activity at Area 51 — the exploitation of covertly acquired Soviet MiG fighter jets.

American engineers assessed the design, performance and limitations of MiGs in an attempt to learn their vulnerabilities — knowledge that could come in handy during combat situations.

Hubble images reveal Neptune's 'lost' inner moon

Naiad is the encircled point of light just to the left of Neptune.

Neptune's tiny, innermost moon, Naiad, has now been seen for the first time since it was discovered by Voyager's cameras in 1989.

Dr. Mark Showalter, a senior research scientist at the SETI Institute in Mountain View, California, announced the result today in Denver, Colorado, at the annual meeting of the Division for Planetary Sciences of the American Astronomical Society.

He and collaborators Dr. Jack Lissauer of the NASA Ames Research Center, Dr. Imke de Pater of UC Berkeley, and Robert French of the SETI Institute, also released a dramatic new image of Neptune's puzzling rings and ring-arcs, which were first imaged by Voyager.

Mark Showalter

"Naiad has been an elusive target ever since Voyager left the Neptune system," said Dr. Showalter. From Earth, Neptune is 2 million times brighter than Naiad, andthetwo are separated by only one arcsecond.

"This is equivalent to the width of a human hair from 50 feet away," noted collaborator Lissauer. The team of astronomers needed to develop new techniques to suppress Neptune's glare.

Naiad was finally revealed, moving across a sequence of eight images taken during December 2004.

Strangely, Naiad appears to have veered significantly off course. The astronomers are puzzled by the fact that Naiad is now far ahead of its predicted orbital position.

They wonder whether gravitational interactions with one of Neptune's other moons may have caused it to speed up, although the details remain mysterious.

Further observations will be needed in order to understand Naiad's motion.

In addition to its moons, Neptune hosts a family faint rings and ring-arcs. The arcs have been changing slowly in the years since their discovery.

Whereas Voyager saw a set of four closely-spaced arcs, the leading two arcs have been fading away, and are completely absent from the newest images.

The trailing arcs, however, are essentially unchanged. This system of arcs is probably confined by the gravitational effects of the nearby moon Galatea, but the reason for the long-term changes is unknown.

Dr. de Pater has also been following the ongoing evolution of the arcs from the 10-meter W. M. Keck telescope in Hawaii.

SpaceX reveal news of Hyperloop transportation system

Musk of SpaceX unveiled his idea for the potentially revolutionary "Hyperloop" transportation system.

Hubble Reveal Spiral galaxies are bigger than originally thought

A new CU-Boulder study indicates spiral galaxies like our Milky Way, and the M74 Galaxy shown here, are larger and more massive than previously believed. Credit: NASA

Let's all fist bump: Spiral galaxies like our own Milky Way appear to be much larger and more massive than previously believed, according to a new University of Colorado Boulder study by researchers using the Hubble Space Telescope.

CU-Boulder Professor John Stocke, study leader, said new observations with Hubble's $70 million Cosmic Origins Spectrograph, or COS, designed by CU-Boulder show that normal spiral galaxies are surrounded by halos of gas that can extend to over 1 million light-years in diameter.

The current estimated diameter of the Milky Way, for example, is about 100,000 light-years. One light-year is roughly 6 trillion miles.

The material for galaxy halos detected by the CU-Boulder team originally was ejected from galaxies by exploding stars known as supernovae, a product of the star formation process, said Stocke of CU-Boulder's astrophysical and planetary sciences department.

"This gas is stored and then recycled through an extended galaxy halo, falling back onto the galaxies to reinvigorate a new generation of star formation," he said.

"In many ways this is the 'missing link' in galaxy evolution that we need to understand in detail in order to have a complete picture of the process."

Stocke gave a presentation on the research June 27 at the University of Edinburgh's Higgs Centre for Theoretical Physics in Scotland at a conference titled "Intergalactic Interactions."

Read the full article here

Obese Black-Hole Galaxies Could Reveal Quasar Secrets

Obese black-hole galaxies could be a stepping stone to the quasars we see today. 

CREDIT: NASA/ESA 

Gluttonous black holes in the center of some galaxies could be precursors to the brightest objects in the known universe.

A recently proposed type of galaxy with an overwhelmingly large black hole in its center could give astronomers a better understanding of the formation of quasars — bright objects in galaxies with supe-rmassive black holes.

The centers of these obese black-hole galaxies (OBGs) could harbour black holes so massive that radiation from where the black hole accretes would overwhelm that of the stars within its galaxy.

New research indicates that some of the most luminous quasars seen from Earth were likely OBGs first before something "lit up" the black hole and had it pump out energy visible from Earth.

The simulations indicate there could be a million OBGs in the observable universe, making the team behind the work ask, why don't we see them?

Tanking up
The team, led by scientists from the Max Planck Institute for Extraterrestrial Physics in Germany, was trying to figure out why astronomers can see quasars from a very far away, at the beginning of the universe. (More distant objects are older and have less metal in them.)

"People have hypothesized there could be these black holes forming from this metal-free gas reservoir ... which is completely free of stars," said Bhaskar Agarwal, a doctoral research fellow at Max Planck who led the research.

This means the black holes in OBGs could have formed separately from the stars surrounding them, contradicting recent observations by the Herschel Space Observatory.

In that earlier finding, astronomers suggested that galaxies that have black holes in their center — including the Milky Way — see the stars and black holes evolve together.

Other research, including observational research, also shows OBG-like objects with a very massive black hole at the center of the galaxy, Agarwal told reporters.

But if the black holes in OBGs formed solo from a reservoir of gas, the stars must have come from somewhere.

The simulations suggested the black hole would have remained on its own until a merger between galaxies brought stars within its vicinity.

The results were published in the Monthly Notices of the Royal Astronomical Society by Oxford University Press on May 29.

Participating researchers came from Max Planck, Yale University and the University of Edinburgh.

NASA Scientists Reveal Moon and Asteroids Share History

Scientists have now discovered that studying meteorites from the giant asteroid Vesta helps them understand the event known as the "lunar cataclysm," when a repositioning of the gas giant planets destabilized a portion of the asteroid belt and triggered a solar-system-wide bombardment. 

Credit: NASA/GSFC/ASU/JPL-Caltech/UCLA/MPS/DLR/IDA

NASA and international researchers have discovered that Earth's moon has more in common than previously thought with large asteroids roaming our solar system.

Asteroid Vesta

Scientists from NASA's Lunar Science Institute (NLSI) in Moffett Field, Calif., discovered that the same population of high-speed projectiles that impacted our lunar neighbor four billion years ago, also hit the giant asteroid Vesta and perhaps other large asteroids.

The research unveils an unexpected link between Vesta and the moon, and provides new means for studying the early bombardment history of terrestrial planets. The findings are published in the March issue of Nature Geoscience.

"It's always intriguing when interdisciplinary research changes the way we understand the history of our solar system," said Yvonne Pendleton, NLSI director.

Yvonne Pendleton

"Although the moon is located far from Vesta, which is in the main asteroid belt between the orbits of Mars and Jupiter, they seem to share some of the same bombardment history."

The findings support the theory that the repositioning of gas giant planets like Jupiter and Saturn from their original orbits to their current location destabilised portions of the asteroid belt and triggered a solar system-wide bombardment of asteroids billions of years ago, called the lunar cataclysm.

The research provides new constraints on the start and duration of the lunar cataclysm, and demonstrates that the cataclysm was an event that affected not only the inner solar system planets, but the asteroid belt as well.

The moon rocks brought back by NASA Apollo astronauts have long been used to study the bombardment history of the moon.

Now the ages derived from meteorite samples have been used to study the collision history of main belt asteroids.

In particular, howardite and eucrite meteorites, which are common species found on Earth, have been used to study asteroid Vesta, their parent body.

With the aid of computer simulations, researchers determined that meteorites from Vesta recorded high-speed impacts which are now long gone.

Researchers have linked these two datasets and found that the same population of projectiles responsible for making craters and basins on the moon were also hitting Vesta at very high velocities, enough to leave behind a number of telltale, impact-related ages.

The team's interpretation of the howardites and eucrites was augmented by recent close-in observations of Vesta's surface by NASA's Dawn spacecraft.

In addition, the team used the latest dynamical models of early main belt evolution to discover the likely source of these high velocity impactors.

The team determined that the population of projectiles that hit Vesta had orbits that also enabled some objects to strike the moon at high speeds.

"It appears that the asteroidal meteorites show signs of the asteroid belt losing a lot of mass four billion years ago, with the escaped mass beating up on both the surviving main belt asteroids and the moon at high speeds" says lead author Simone Marchi, who has a joint appointment between two of NASA's Lunar Science Institutes, one at the Southwest Research Institute in Boulder, Colo., and another at the Lunar and Planetary Institute in Houston.

"Our research not only supports the current theory, but it takes it to the next level of understanding."

Reference
High-velocity collisions from the lunar cataclysm recorded in asteroidal meteorites. Nature Geoscience, 2013; DOI: 10.1038/ngeo1769

NASA Mars Rover Curiosity breaks Tintina rock reveals dazzling white interior

When Curiosity drove over Tintina, the rock broke apart and exposed a fresh, bright white surface

A rock crushed under the Curiosity Mars rover's wheels has dazzled mission scientists in more ways than one.

Mars is supposed to be the Red Planet, but the rock - dubbed "Tintina" - is a brilliant shade of white.

The unusual colour indicates the presence of hydrated minerals that formed when water flowed through the robot's landing site in ancient times.

Water-bearing minerals in Tintina and elsewhere add to the growing catalogue of water evidence at this location.

Rover team members have been presenting mission findings at the 44th Lunar and Planetary Science Conference (LPSC) in The Woodlands, Texas.

It was also announced that the rover has suffered another computer glitch; Curiosity had already been recovering from a memory problem discovered earlier in the month.

The description of hydrated minerals at Gale Crater follows an announcement last week that Curiosity had found clay minerals in a rock it had drilled.

These clays indicate formation in, or substantial alteration by, neutral water.

That is significant for showing that conditions on the Red Planet could have supported life in the distant past, because many rocks studied previously were probably deposited in acidic water.

Speaking here in The Woodlands, near Houston, chief scientist John Grotzinger described Curiosity's landing site as the first truly habitable environment found on Mars.

"What we're really excited about is that this is the first time we've been able to follow through with a whole suite of different measurements that really demonstrate the place we found at Gale Crater was a very viable, habitable environment," he reported.

Prof Grotzinger added that the team "felt really good" about the Martian location.

The one-tonne Nasa rover has been exploring Gale Crater, near the Martian equator, since touching down in August 2012. It drove over Tintina on 17 January, breaking it open to expose the dazzling white interior.

"This is one of the brightest and whitest things we've seen with the Mastcam at the Gale Crater site," said Melissa Rice, from the California Institute of Technology (Caltech), in Pasadena.

"This rock, Tintina, has a very strong hydration signal that corresponds to all that white material we see inside the rock. But that hydration signal doesn't show up anywhere else in the image.

"The first time we tried to take the image [of Tintina], it saturated the detector, because we had no idea we'd have something so bright," said Jim Bell, from Arizona State University in Tempe.

Using filters on the rover's Mast camera (Mastcam) and an instrument which shoots neutrons into the ground to probe for hydrogen, researchers have detected more hydrated minerals near the clay-bearing rock than at locations Curiosity visited earlier in its mission.

Melissa Rice explained: "What Mastcam is seeing is water that is bound in the mineral structure of the rocks. This water is left over from a previous wet era and is now trapped and preserved in these hydrated minerals."