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Getting to know Rosetta’s comet

A section of the smaller of Comet 67P/Churyumov–Gerasimenko’s two lobes as seen through Rosetta’s narrow-angle camera from a distance of about 8 km to the surface on 14 October 2014. The resolution is 15 cm/pixel. The image is featured on the cover of 23 January 2015 issue of the journal Science. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

A section of the smaller of Comet 67P/Churyumov–Gerasimenko’s two lobes as seen through Rosetta’s narrow-angle camera from a distance of about 8 km to the surface on 14 October 2014. The resolution is 15 cm/pixel. The image is featured on the cover of 23 January 2015 issue of the journal Science. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Rosetta is revealing its host comet as having a remarkable array of surface features and with many processes contributing to its activity, painting a complex picture of its evolution.

In a special edition of the journal Science, initial results are presented from seven of Rosetta’s 11 science instruments based on measurements made during the approach to and soon after arriving at Comet 67P/Churyumov–Gerasimenko in August 2014.

The familiar shape of the dual-lobed comet has now had many of its vital statistics measured: the small lobe measures 2.6 × 2.3 × 1.8 km and the large lobe 4.1 × 3.3 × 1.8 km. The total volume of the comet is 21.4 km3 and the Radio Science Instrument has measured its mass to be 10 billion tonnes, yielding a density of 470 kg/m3.

The 19 regions identified on Comet 67P/Churyumov–Gerasimenko are separated by distinct geomorphological boundaries. Following the ancient Egyptian theme of the Rosetta mission, they are named for Egyptian deities. They are grouped according to the type of terrain dominant within each region. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

The 19 regions identified on Comet 67P/Churyumov–Gerasimenko are separated by distinct geomorphological boundaries. Following the ancient Egyptian theme of the Rosetta mission, they are named for Egyptian deities. They are grouped according to the type of terrain dominant within each region. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

By assuming an overall composition dominated by water ice and dust with a density of 1500–2000 kg/m3, the Rosetta scientists show that the comet has a very high porosity of 70–80%, with the interior structure likely comprising weakly bonded ice-dust clumps with small void spaces between them.

The OSIRIS scientific camera, has imaged some 70% of the surface to date: the remaining unseen area lies in the southern hemisphere that has not yet been fully illuminated since Rosetta’s arrival.

The scientists have so far identified 19 regions separated by distinct boundaries and, following the ancient Egyptian theme of the Rosetta mission, these regions are named for Egyptian deities, and are grouped according to the type of terrain dominant within.

Features in the Hapi region show evidence of local gas-driven transport producing dune-like ripples (left) and boulders with ‘wind-tails’ (right) – where the boulder has acted as a natural obstacle to the direction of the gas flow, creating a streak of material ‘downwind’ of it. Credits: ESA/Rosetta/MPS

Features in the Hapi region show evidence of local gas-driven transport producing dune-like ripples (left) and boulders with ‘wind-tails’ (right) – where the boulder has acted as a natural obstacle to the direction of the gas flow, creating a streak of material ‘downwind’ of it. Credits: ESA/Rosetta/MPS

Five basic – but diverse – categories of terrain type have been determined: dust-covered; brittle materials with pits and circular structures; large-scale depressions; smooth terrains; and exposed more consolidated (‘rock-like’) surfaces.

Much of the northern hemisphere is covered in dust. As the comet is heated, ice turns directly into gas that escapes to form the atmosphere or coma. Dust is dragged along with the gas at slower speeds, and particles that are not travelling fast enough to overcome the weak gravity fall back to the surface instead.

Some sources of discrete jets of activity have also been identified. While a significant proportion of activity emanates from the smooth neck region, jets have also been spotted rising from pits.

The gases that escape from the surface have also been seen to play an important role in transporting dust across the surface, producing dune-like ripples, and boulders with ‘wind-tails’ – the boulders act as natural obstacles to the direction of the gas flow, creating streaks of material ‘downwind’ of them.

Active pit detected in Seth region of Comet 67P/Churyumov–Gerasimenko. Credits: ESA/Rosetta/MPS

Active pit detected in Seth region of Comet 67P/Churyumov–Gerasimenko. Credits: ESA/Rosetta/MPS

The dusty covering of the comet may be several metres thick in places and measurements of the surface and subsurface temperature by the Microwave Instrument on the Rosetta Orbiter, or MIRO, suggest that the dust plays a key role in insulating the comet interior, helping to protect the ices thought to exist below the surface.

Small patches of ice may also be present on the surface. At scales of 15–25 m, Rosetta’s Visible, InfraRed and Thermal Imaging Spectrometer, or VIRTIS, finds the surface to be compositionally very homogenous and dominated by dust and carbon-rich molecules, but largely devoid of ice. But smaller, bright areas seen in images are likely to be ice-rich. Typically, they are associated with exposed surfaces or debris piles where collapse of weaker material has occurred, uncovering fresher material.

On larger scales, many of the exposed cliff walls are covered in randomly oriented fractures. Their formation is linked to the rapid heating–cooling cycles that are experienced over the course of the comet’s 12.4-hour day and over its 6.5-year elliptical orbit around the Sun. One prominent and intriguing feature is a 500 m-long crack seen roughly parallel to the neck between the two lobes, although it is not yet known if it results from stresses in this region.

OSIRIS images of Comet 67P/Churyumov–Gerasimenko showing the details of a 500 m-long crack running through the Hapi region. Credits: ESA/Rosetta/MPS

OSIRIS images of Comet 67P/Churyumov–Gerasimenko showing the details of a 500 m-long crack running through the Hapi region. Credits: ESA/Rosetta/MPS

Some very steep regions of the exposed cliff faces are textured on scales of roughly 3 m with features that have been nicknamed ‘goosebumps’. Their origin is yet to be explained, but their characteristic size may yield clues as to the processes at work when the comet formed.

And on the very largest scale, the origin of the comet’s overall double-lobed shape remains a mystery. The two parts seem very similar compositionally, potentially favouring the erosion of a larger, single body. But the current data cannot yet rule out the alternative scenario: two separate comets formed in the same part of the Solar System and then merged together at a later date.

This key question will be studied further over the coming year as Rosetta accompanies the comet around the Sun.

Close-ups of a curious surface texture nicknamed ‘goosebumps’. Credits: ESA/Rosetta/MPS

Close-ups of a curious surface texture nicknamed ‘goosebumps’. Credits: ESA/Rosetta/MPS

How to grow an atmosphere

Their closest approach to the Sun occurs on 13 August at a distance of 186 million kilometres, between the orbits of Earth and Mars. As the comet continues to move closer to the Sun, an important focus for Rosetta’s instruments is to monitor the development of the comet’s activity, in terms of the amount and composition of gas and dust emitted by the nucleus to form the coma.

Images from the scientific and navigation cameras have shown an increase in the amount of dust flowing away from the comet over the past six months, and MIRO showed a general rise in the comet’s global water vapour production rate, from 0.3 litres per second in early June 2014 to 1.2 litres per second by late August. MIRO also found that a substantial portion of the water seen during this phase originated from the comet’s neck.

Water is accompanied by other outgassing species, including carbon monoxide and carbon dioxide. The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis, ROSINA, is finding large fluctuations in the composition of the coma, representing daily and perhaps seasonal variations in the major outgassing species. Water is typically the dominant outgassing molecule, but not always.

How a comet grows a magnetosphere: 1. The comet approaches the Sun 2. Water molecules sublimate from the comet as it thaws 3. The water molecules are ionised by ultraviolet light from the Sun 4. Newborn ions are accelerated by the solar wind electric field and are detected by the RPC-ICA instrument 5. The solar wind accelerates the water ions in one direction, but is itself deflected in the opposite direction 6. In due time sharp boundaries will form, shielding the comet atmosphere from direct interaction with the solar wind. This is a well-known situation observed at active comets and planets Copyright ESA/Rosetta/RPC-ICA

How a comet grows a magnetosphere:
1. The comet approaches the Sun
2. Water molecules sublimate from the comet as it thaws
3. The water molecules are ionised by ultraviolet light from the Sun
4. Newborn ions are accelerated by the solar wind electric field and are detected by the RPC-ICA instrument
5. The solar wind accelerates the water ions in one direction, but is itself deflected in the opposite direction
6. In due time sharp boundaries will form, shielding the comet atmosphere from direct interaction with the solar wind. This is a well-known situation observed at active comets and planets
Copyright ESA/Rosetta/RPC-ICA

By combining measurements from MIRO, ROSINA and GIADA (Rosetta’s Grain Impact Analyzer and Dust Accumulator) taken between July and September, the Rosetta scientists have made a first estimate of the comet’s dust-to-gas ratio, with around four times as much mass in dust being emitted than in gas, averaged over the sunlit nucleus surface.

However, this value is expected to change once the comet warms up further and ice grains – rather than pure dust grains – are ejected from the surface.

GIADA has also been tracking the movement of dust grains around the comet, and, together with images from OSIRIS, two distinct populations of dust grains have been identified. One set is outflowing and is detected close to the spacecraft, while the other family is orbiting the comet no closer than 130 km from the spacecraft.

It is thought that the more distant grains are left over from the comet’s last closest approach to the Sun. As the comet moved away from the Sun, the gas flow from the comet decreased and was no longer able to perturb the bound orbits. But as the gas production rate increases again over the coming months, it is expected that this bound cloud will dissipate. However, Rosetta will only be able to confirm this when it is further away from the comet again – it is currently in a 30 km orbit.

Summary of properties of Comet 67P/Churyumov–Gerasimenko, as determined by Rosetta’s instruments during the first few months of its comet encounter. Credit: ESA

Summary of properties of Comet 67P/Churyumov–Gerasimenko, as determined by Rosetta’s instruments during the first few months of its comet encounter. Credit: ESA

As the gas–dust coma continues to grow, interactions with charged particles of the solar wind and with the Sun’s ultraviolet light will lead to the development of the comet’s ionosphere and, eventually, its magnetosphere. The Rosetta Plasma Consortium, or RPC, instruments have been studying the gradual evolution of these components close to the comet.

“Rosetta is essentially living with the comet as it moves towards the Sun along its orbit, learning how its behaviour changes on a daily basis and, over longer timescales, how its activity increases, how its surface may evolve, and how it interacts with the solar wind,” says Matt Taylor, ESA’s Rosetta project scientist.

“We have already learned a lot in the few months we have been alongside the comet, but as more and more data are collected and analysed from this close study of the comet we hope to answer many key questions about its origin and evolution.”

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Helicopter Could be ‘Scout’ for Mars Rovers

A proposed helicopter could triple the distances that Mars rovers can drive in a Martian day and help pinpoint interesting targets for study. Credit: NASA

A proposed helicopter could triple the distances that Mars rovers can drive in a Martian day and help pinpoint interesting targets for study. Credit: NASA

Getting around on Mars is tricky business. Each NASA rover has delivered a wealth of information about the history and composition of the Red Planet, but a rover’s vision is limited by the view of onboard cameras, and images from spacecraft orbiting Mars are the only other clues to where to drive it. To have a better sense of where to go and what’s worth studying on Mars, it could be useful to have a low-flying scout.

Enter the Mars Helicopter, a proposed add-on to Mars rovers of the future that could potentially triple the distance these vehicles currently drive in a Martian day, and deliver a new level of visual information for choosing which sites to explore.

The helicopter would fly ahead of the rover almost every day, checking out various possible points of interest and helping engineers back on Earth plan the best driving route.

Scientists could also use the helicopter images to look for features for the rover to study in further detail. Another part of the helicopter’s job would be to check out the best places for the rover to collect key samples and rocks for a cache, which a next-generation rover could pick up later.

The vehicle is envisioned to weigh 2.2 pounds (1 kilogram) and measure 3.6 feet (1.1 meters) across from the tip of one blade to the other. The prototype body looks like a medium-size cubic tissue box.

The current design is a proof-of-concept technology demonstration that has been tested at NASA’s Jet Propulsion Laboratory, Pasadena, California.

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Mysteries in Nili Fossae

The Nili Fossae graben system, part of which is shown in this image, is an area of great geological interest near the giant Isidis impact basin, northeast of the Syrtis Major volcanic province. Copyright ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

The Nili Fossae graben system, part of which is shown in this image, is an area of great geological interest near the giant Isidis impact basin, northeast of the Syrtis Major volcanic province. Copyright ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

These new images from the high-resolution stereo camera on ESA’s Mars Express show Nili Fossae, one of the most enticing regions on Mars. This ‘graben system’ lies northeast of the volcanic region of Syrtis Major on the northwestern edge of the large Isidis impact basin – and intriguing hints of methane have been seen here.

Grabens are blocks of land that have fallen between parallel faults, sometimes forming rift valleys. The graben system in Nili Fossae contains numerous troughs oriented concentrically around the edges of an impact basin, as can be seen in the context map.

The easternmost of these troughs is partially visible at the lower left of the images. It is perhaps most obvious as a depression in the topography map from Mars Express.

A wider contextual image showing the region around Nili Fossae. Copyright NASA MGS MOLA Science Team

A wider contextual image showing the region around Nili Fossae. Copyright NASA MGS MOLA Science Team

The graben is most likely associated with the formation of the Isidis impact basin. Flooding of the basin with basaltic lava may have resulted in subsidence, which added stress to the planet’s crust and was then released through fracturing and trough formation.

Mars Express and other spacecraft have shown that the region displays a fascinating mineral diversity, drawing the attention of many planetary scientists. The minerals include phyllosilicates (clays), carbonates and opaline silica. These indicate a diverse history for this area resulting from the huge geological and tectonic forces that have been at play.

Water has played an important role here, too. The visible trough’s flanks are very steep (see the topography map) and some layered materials can be spotted at the walls. On the plateau, several depressions can be observed. Some of them appear to extend into the trough and show a resemblance to small ‘sapping valleys’.

Sapping valleys develop when groundwater removes material from underneath the surface. This gradually relocates the spring line further upstream, carving a valley in the process.

The images also contain evidence for percolating hydrothermal fluids in the subsurface of the region. A large, 55 km-diameter impact crater with a central pit is clearly seen in the main colour, topography and 3D images. The pit is believed to have been excavated when water or ice, trapped below the surface, was rapidly heated by the impact that shaped the crater. The sudden heating caused a violent steam explosion that either weakened the rocky surface, leading to its collapse, or it may even have blasted it away, leaving the rocky hole and rocky debris.

Perspective view of Nili Fossae. Copyright ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

Perspective view of Nili Fossae. Copyright ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

In addition to the variety of interesting geological features, Nili Fossae is of particular interest because it is a site where atmospheric methane may have been detected by Earth-based telescopes. Methane may be produced here, but its origin remains mysterious, and could be geological or perhaps even biological.

There is certainly a huge amount to study here. Nili Fossae was on the shortlist of landing sites for NASA’s Curiosity rover, even though ultimately the choice was made to send the robotic explorer to Gale Crater.

The awful-smelling comet 67P/C-G. Credit: ESA/Rosetta/NAVCAM

Rosetta Comet ‘Pouring’ More Water Into Space

This animation comprises 24 montages based on images acquired by the navigation camera on the European Space Agency's Rosetta spacecraft orbiting Comet 67P/Churyumov-Gerasimenko between Nov. 19 and Dec. 3, 2014. Image Credit: ESA/Rosetta/NAVCAM

This animation comprises 24 montages based on images acquired by the navigation camera on the European Space Agency’s Rosetta spacecraft orbiting Comet 67P/Churyumov-Gerasimenko between Nov. 19 and Dec. 3, 2014.
Image Credit: ESA/Rosetta/NAVCAM

There has been a significant increase in the amount of water “pouring” out of comet 67P/Churyumov-Gerasimenko, the comet on which the Rosetta mission’s Philae lander touched down in November 2014.

The 2.5-mile-wide (4-kilometer) comet was releasing the earthly equivalent of 40 ounces (1.2 liters) of water into space every second at the end of August 2014. The observations were made by NASA’s Microwave Instrument for Rosetta Orbiter (MIRO), aboard the European Space Agency’s Rosetta spacecraft.  Science results from the MIRO team were released today as part of a special Rosetta-related issue of the journal Science.

“In observations over a period of three months [June through August, 2014], the amount of water in vapor form that the comet was dumping into space grew about tenfold,” said Sam Gulkis, principal investigator of the MIRO instrument at NASA’s Jet Propulsion Laboratory in Pasadena, California, and lead author of a paper appearing in the special issue.

“To be up close and personal with a comet for an extended period of time has provided us with an unprecedented opportunity to see how comets transform from cold, icy bodies to active objects spewing out gas and dust as they get closer to the sun.”

The MIRO instrument is a small and lightweight spectrometer that can map the abundance, temperature and velocity of cometary water vapor and other molecules that the nucleus releases. It can also measure the temperature up to about one inch (two centimeters) below the surface of the comet’s nucleus.

One reason the subsurface temperature is important is that the observed gases likely come from sublimating ices beneath the surface. By combining information on both the gas and the subsurface, MIRO will be able to study this process in detail.

Also in the paper released today, the MIRO team reports that 67P spews out more gas from certain locations and at certain times during its “day.” The nucleus of 67P consists of two lobes of different sizes (often referred to as the “body” and “head” because of its duck-like shape), connected by a neck region. A substantial portion of the measured outgassing from June through September 2014 occurred from the neck region during the afternoon.

“That situation may be changing now that the comet is getting warmer,” said Gulkis. “MIRO observations would need to be carefully analyzed to determine which factors in addition to the sun’s warmth are responsible for the cometary outgassing.”

Artist's impression of Rosetta and Philae at the comet. Credit: ESA - C. Carreau/ATG medialab

Artist’s impression of Rosetta and Philae at the comet. Credit: ESA – C. Carreau/ATG medialab

Observations are continuing to search for variability in the production rate and changes in the parts of the nucleus that release gas as the comet’s distance from the sun changes. This information will help scientists understand how comets evolve as they orbit and move toward and then away from the sun. The gas production rate is also important to the Rosetta navigation team controlling the spacecraft, as this flowing gas can alter the trajectory of the spacecraft.

In another 67P paper released today, it was revealed that the comet’s atmosphere, or coma, is much less homogenous than expected and that comet outgassing varies significantly over time.

“If we would have just seen a steady increase of gases as we closed in on the comet, there would be no question about the heterogeneity of the nucleus,” said Myrtha Hässig, a NASA-sponsored scientist from the Southwest Research Institute in San Antonio. “Instead we saw spikes in water readings, and a few hours later, a spike in carbon dioxide readings. This variation could be a temperature effect or a seasonal effect, or it could point to the possibility of comet migrations in the early solar system.”

The measurements on the coma were made by the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis Double Focusing Mass Spectrometer (ROSINA DFMS) instrument. Measuring the in situ coma composition at the position of the spacecraft, ROSINA data indicate that the water vapor signal is strongest overall. However, there are periods when the carbon monoxide and carbon dioxide abundances rival that of water.

“Taken together, the MIRO outgassing results and results about heterogeneous fountains from ROSINA suggest fascinating new details to be learned about how comets work,”said Claudia Alexander, NASA project scientist for the U.S. Rosetta team, from JPL. “These results are helping us move the field forward on how comets operate on a fundamental level.”

Rosetta is currently about 107 million miles (171 million kilometers) from Earth and about 92 million miles (148 million kilometers) from the sun. Comets are time capsules containing primitive material left over from the epoch when the sun and its planets formed.

By studying the gas, dust and structure of the nucleus and organic materials associated with the comet, via both remote and in situ observations, the Rosetta mission should become a key to unlocking the history and evolution of our solar system, as well as answering questions regarding the origin of Earth’s water and perhaps even life. Rosetta is the first mission in history to rendezvous with a comet, escort it as it orbits the sun, and deploy a lander to its surface.

https://intern.nasa.gov/

NASA Scholarships for Students of Space

https://intern.nasa.gov/

https://intern.nasa.gov/

NASA’s Office of Education is now accepting applications from undergraduate students for the NASA Scholarship and Research Opportunities. The deadline is March 31, 2015, so any aspiring space scientists and engineers out there should get typing!

The scholarships are made to individuals pursuing degrees that could help NASA fill deficiencies in the agency’s Science, Technology, Engineering, and Mathematics workforce. There are two opportunities to apply:

  • Minority University Research and Education Project (MUREP) which awards scholarships for individuals in one or more relevant NASA related, STEM disciplines. Students must currently attend or plan to attend an accredited Minority Serving Institution (MSI) in the United States.
  • Aeronautics Undergraduate Scholarships (AUS) which awards scholarships for individuals in areas related to aeronautics. These scholarships are directed toward enhancing the state of aeronautics for the nation, transforming the nation’s air transportation system, and developing the knowledge, tools, and technologies to support future air and space vehicles.

There is a lot more Information available at the NASA One Stop Shopping Initiative at https://intern.nasa.gov . Visit the website and select “Scholarship.”

The United Launch Alliance Delta IV Heavy rocket, with NASA’s Orion spacecraft mounted atop, lifts off from Cape Canaveral Air Force Station's Space Launch Complex 37 at at 7:05 a.m. EST, Friday, Dec. 5, 2014, in Florida. The Orion spacecraft will orbit Earth twice, reaching an altitude of approximately 3,600 miles above Earth before landing in the Pacific Ocean. No one is aboard Orion for this flight test, but the spacecraft is designed to allow us to journey to destinations never before visited by humans, including an asteroid and Mars. Credit: NASA/Bill Ingalls

The United Launch Alliance Delta IV Heavy rocket, with NASA’s Orion spacecraft mounted atop, lifts off from Cape Canaveral Air Force Station’s Space Launch Complex 37 at at 7:05 a.m. EST, Friday, Dec. 5, 2014, in Florida. Credit: NASA/Bill Ingalls

For students pursuing a Masters or Doctoral degree, the Aeronautics Graduate Scholarship Program is also awarding individual scholarships. You must be studying at an accredited United States academic institution.

According to the announcment:

“Aeronautics Graduate Scholarships are directed toward enhancing the state of aeronautics for the nation, transforming the nation’s air transportation system, and developing the knowledge, tools, and technologies to support future air and space vehicles. This scholarship opportunity, with a timeline of two years, is required by the NASA Authorization Act of 2005 in support of research degrees relevant to the Aeronautics Research Mission Directorate.”

Information on the Aeronautics Graduate Scholarship Program can also be found at the NASA One Stop Shopping Initiative at https://intern.nasa.gov, by selecting “Scholarship”.

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NASA, Microsoft Collaboration Will Allow Scientists to ‘Work on Mars’

A screen view from OnSight, a software tool developed by NASA's Jet Propulsion Laboratory in collaboration with Microsoft. OnSight uses real rover data to create a 3-D simulation of the Martian environment where mission scientists can "meet" to discuss rover operations. Image credit: NASA/JPL-Caltech

A screen view from OnSight, a software tool developed by NASA’s Jet Propulsion Laboratory in collaboration with Microsoft. OnSight uses real rover data to create a 3-D simulation of the Martian environment where mission scientists can “meet” to discuss rover operations. Image credit: NASA/JPL-Caltech

NASA and Microsoft have teamed up to develop software called OnSight, a new technology that will enable scientists to work virtually on Mars using wearable technology called Microsoft HoloLens.

Developed by NASA’s Jet Propulsion Laboratory in Pasadena, California, OnSight will give scientists a means to plan and, along with the Mars Curiosity rover, conduct science operations on the Red Planet.

“OnSight gives our rover scientists the ability to walk around and explore Mars right from their offices,” said Dave Lavery, program executive for the Mars Science Laboratory mission at NASA Headquarters in Washington. “It fundamentally changes our perception of Mars, and how we understand the Mars environment surrounding the rover.”

OnSight will use real rover data and extend the Curiosity mission’s existing planning tools by creating a 3-D simulation of the Martian environment where scientists around the world can meet. Program scientists will be able to examine the rover’s worksite from a first-person perspective, plan new activities and preview the results of their work firsthand.

“We believe OnSight will enhance the ways in which we explore Mars and share that journey of exploration with the world,” said Jeff Norris, JPL’s OnSight project manager.

Until now, rover operations required scientists to examine Mars imagery on a computer screen, and make inferences about what they are seeing. But images, even 3-D stereo views, lack a natural sense of depth that human vision employs to understand spatial relationships.

Scientist Katie Stack Morgan examines rover images on her computer. Images, even 3-D stereo views, lack a natural sense of depth that human vision employs to understand spatial relationships. Image credit: NASA/JPL-Caltech

Scientist Katie Stack Morgan examines rover images on her computer. Images, even 3-D stereo views, lack a natural sense of depth that human vision employs to understand spatial relationships. Image credit: NASA/JPL-Caltech

The OnSight system uses holographic computing to overlay visual information and rover data into the user’s field of view. Holographic computing blends a view of the physical world with computer-generated imagery to create a hybrid of real and virtual.

To view this holographic realm, members of the Curiosity mission team don a Microsoft HoloLens device, which surrounds them with images from the rover’s Martian field site. They then can stroll around the rocky surface or crouch down to examine rocky outcrops from different angles. The tool provides access to scientists and engineers looking to interact with Mars in a more natural, human way.

“Previously, our Mars explorers have been stuck on one side of a computer screen. This tool gives them the ability to explore the rover’s surroundings much as an Earth geologist would do field work here on our planet,” said Norris.

The OnSight tool also will be useful for planning rover operations. For example, scientists can program activities for many of the rover’s science instruments by looking at a target and using gestures to select menu commands.

The joint effort to develop OnSight with Microsoft grew from an ongoing partnership to investigate advances in human-robot interaction. The JPL team responsible for OnSight specializes in systems to control robots and spacecraft. The tool will assist researchers in better understanding the environment and workspace of robotic spacecraft — something that can be quite challenging with their traditional suite of tools.

JPL plans to begin testing OnSight in Curiosity mission operations later this year. Future applications may include Mars 2020 rover mission operations, and other applications in support of NASA’s journey to Mars.

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Death of a dynamo — A hard drive from space

Hidden magnetic messages contained within ancient meteorites are providing a unique window into the processes that shaped our solar system, and may give a sneak preview of the fate of the Earth’s core as it continues to freeze.

The Esquel pallasite from the Natural History Museum collections, consists of gem-quality crystals of the silicate mineral olivine embedded in a matrix of iron-nickel alloy. Credit: Copyright the Natural History Museum

The Esquel pallasite from the Natural History Museum collections, consists of gem-quality crystals of the silicate mineral olivine embedded in a matrix of iron-nickel alloy. Credit: Copyright the Natural History Museum

The dying moments of an asteroid’s magnetic field have been successfully captured by researchers, in a study that offers a tantalising glimpse of what may happen to the Earth’s magnetic core billions of years from now.

Using a detailed imaging technique, the research team were able to read the magnetic memory contained in ancient meteorites, formed in the early solar system over 4.5 billion years ago. The readings taken from these tiny ‘space magnets’ may give a sneak preview of the fate of the Earth’s magnetic core as it continues to freeze. The findings are published today (22 January) in the journal Nature.

Using an intense beam of x-rays to image the nanoscale magnetisation of the meteoritic metal, researchers led by the University of Cambridge were able to capture the precise moment when the core of the meteorite’s parent asteroid froze, killing its magnetic field. These ‘nano-paleomagnetic’ measurements, the highest-resolution paleomagnetic measurements ever made, were performed at the BESSY II synchrotron in Berlin.

The researchers found that the magnetic fields generated by asteroids were much longer-lived than previously thought, lasting for as long as several hundred million years after the asteroid formed, and were created by a similar mechanism to the one that generates the Earth’s own magnetic field. The results help to answer many of the questions surrounding the longevity and stability of magnetic activity on small bodies, such as asteroids and moons.

“Observing magnetic fields is one of the few ways we can peek inside a planet,” said Dr Richard Harrison of Cambridge’s Department of Earth Sciences, who led the research. “It’s long been assumed that metal-rich meteorites have poor magnetic memories, since they are primarily composed of iron, which has a terrible memory – you wouldn’t ever make a hard drive out of iron, for instance. It was thought that the magnetic signals carried by metal-rich meteorites would have been written and rewritten many times during their lifetime, so no-one has ever bothered to study their magnetic properties in any detail.”

The particular meteorites used for this study are known as pallasites, which are primarily composed of iron and nickel, studded with gem-quality silicate crystals. Contained within these unassuming chunks of iron however, are tiny particles just 100 nanometres across – about one thousandth the width of a human hair – of a unique magnetic mineral called tetrataenite, which is magnetically much more stable than the rest of the meteorite, and holds within it a magnetic memory going back billions of years.

“We’re taking ancient magnetic field measurements in nanoscale materials to the highest ever resolution in order to piece together the magnetic history of asteroids – it’s like a cosmic archaeological mission,” said PhD student James Bryson, the paper’s lead author.

The researchers’ magnetic measurements, supported by computer simulations, demonstrate that the magnetic fields of these asteroids were created by compositional, rather than thermal, convection – meaning that the field was long-lasting, intense and widespread. The results change our perspective on the way magnetic fields were generated during the early life of the solar system.

These meteorites came from asteroids formed in the first few million years after the formation of the Solar System. At that time, planetary bodies were heated by radioactive decay to temperatures hot enough to cause them to melt and segregate into a liquid metal core surrounded by a rocky mantle. As their cores cooled and began to freeze, the swirling motions of liquid metal, driven by the expulsion of sulphur from the growing inner core, generated a magnetic field, just as the Earth does today.

“It’s funny that we study other bodies in order to learn more about the Earth,” said Bryson. “Since asteroids are much smaller than the Earth, they cooled much more quickly, so these processes occur on shorter timescales, enabling us to study the whole process of core solidification.”

Scientists now think that the Earth’s core only began to freeze relatively recently in geological terms, maybe less than a billion years ago. How this freezing has affected the Earth’s magnetic field is not known. “In our meteorites we’ve been able to capture both the beginning and the end of core freezing, which will help us understand how these processes affected the Earth in the past and provide a possible glimpse of what might happen in the future,” said Harrison.

However, the Earth’s core is freezing rather slowly. The solid inner core is getting bigger, and eventually the liquid outer core will disappear, killing the Earth’s magnetic field, which protects us from the Sun’s radiation. “There’s no need to panic just yet, however,” said Harrison. “The core won’t completely freeze for billions of years, and chances are, the Sun will get us first.”

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Gullies on Vesta Suggest Past Water-Mobilized Flows

This image shows Cornelia Crater on the large asteroid Vesta. On the right is an inset image showing an example of curved gullies, indicated by the short white arrows, and a fan-shaped deposit, indicated by long white arrows. Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

This image shows Cornelia Crater on the large asteroid Vesta. On the right is an inset image showing an example of curved gullies, indicated by the short white arrows, and a fan-shaped deposit, indicated by long white arrows. Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Protoplanet Vesta, visited by NASA’s Dawn spacecraft from 2011 to 2013, was once thought to be completely dry, incapable of retaining water because of the low temperatures and pressures at its surface. However, a new study shows evidence that Vesta may have had short-lived flows of water-mobilized material on its surface, based on data from Dawn.

“Nobody expected to find evidence of water on Vesta. The surface is very cold and there is no atmosphere, so any water on the surface evaporates,” said Jennifer Scully, postgraduate researcher at the University of California, Los Angeles. “However, Vesta is proving to be a very interesting and complex planetary body.”

The study has broad implications for planetary science.

“These results, and many others from the Dawn mission, show that Vesta is home to many processes that were previously thought to be exclusive to planets,” said UCLA’s Christopher Russell, principal investigator for the Dawn mission. “We look forward to uncovering even more insights and mysteries when Dawn studies Ceres.”

Dawn is currently in the spotlight because it is approaching dwarf planet Ceres, the largest object in the main asteroid belt between Mars and Jupiter. It will be captured into orbit around Ceres on March 6. Yet data from Dawn’s exploration of Vesta continue to capture the interest of the scientific community.

Scully and colleagues, publishing in the journal “Earth and Planetary Science Letters,” identified a small number of young craters on Vesta with curved gullies and fan-shaped (“lobate”) deposits.

“We’re not suggesting that there was a river-like flow of water. We’re suggesting a process similar to debris flows, where a small amount of water mobilizes the sandy and rocky particles into a flow,” Scully said.

This artist's concept shows NASA's Dawn spacecraft heading toward the dwarf planet Ceres. Dawn spent nearly 14 months orbiting Vesta, the second most massive object in the main asteroid belt between Mars and Jupiter, from 2011 to 2012. It is heading towards Ceres, the largest member of the asteroid belt. When Dawn arrives, it will be the first spacecraft to go into orbit around two destinations in our solar system beyond Earth. Image credit: NASA/JPL-Caltech

This artist’s concept shows NASA’s Dawn spacecraft heading toward the dwarf planet Ceres. Dawn spent nearly 14 months orbiting Vesta, the second most massive object in the main asteroid belt between Mars and Jupiter, from 2011 to 2012. It is heading towards Ceres, the largest member of the asteroid belt. When Dawn arrives, it will be the first spacecraft to go into orbit around two destinations in our solar system beyond Earth. Image credit: NASA/JPL-Caltech

The curved gullies are significantly different from those formed by the flow of purely dry material, scientists said. “These features on Vesta share many characteristics with those formed by debris flows on Earth and Mars,” Scully said.

The gullies are fairly narrow, on average about 100 feet (30 meters) wide. The average length of the gullies is a little over half a mile (900 meters). Cornelia Crater, with a width of 9 miles (15 kilometers), contains some of the best examples of the curved gullies and fan-shaped deposits.

The leading theory to explain the source of the curved gullies is that Vesta has small, localized patches of ice in its subsurface. No one knows the origin of this ice, but one possibility is that ice-rich bodies, such as comets, left part of their ice deep in the subsurface following impact. A later impact would form a crater and heat up some of the ice patches, releasing water onto the walls of the crater.

“If present today, the ice would be buried too deeply to be detected by any of Dawn’s instruments,” Scully said. “However, the craters with curved gullies are associated with pitted terrain, which has been independently suggested as evidence for loss of volatile gases from Vesta.” Also, evidence from Dawn’s visible and infrared mapping spectrometer and gamma ray and neutron detector indicates that there is hydrated material within some rocks on Vesta’s surface, suggesting that Vesta is not entirely dry.

It appears the water mobilized sandy and rocky particles to flow down the crater walls, carving out the gullies and leaving behind the fan-shaped deposits after evaporation. The craters with curvy gullies appear to be less than a few hundred million years old, which is still young compared to Vesta’s age of 4.6 billion years.

Laboratory experiments performed at NASA’s Jet Propulsion Laboratory, Pasadena, California, indicate that there could be enough time for curved gullies to form on Vesta before all of the water evaporated. “The sandy and rocky particles in the flow help to slow the rate of evaporation,” Scully said.

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Doubt cast on global firestorm generated by dino-killing asteroid

This is the fire propagation apparatus recreating the impact induced thermal pulse at the Cretaceous-Palaeogene (K-Pg) boundary. Halogen lamps are delivering the thermal radiation. Credit: University of Exeter

This is the fire propagation apparatus recreating the impact induced thermal pulse at the Cretaceous-Palaeogene (K-Pg) boundary. Halogen lamps are delivering the thermal radiation. Credit: University of Exeter

Pioneering new research has debunked the theory that the asteroid that is thought to have led to the extinction of dinosaurs also caused vast global firestorms that ravaged planet Earth.

A team of researchers from the University of Exeter, University of Edinburgh and Imperial College London recreated the immense energy released from an extra-terrestrial collision with Earth that occurred around the time that dinosaurs became extinct. They found that the intense but short-lived heat near the impact site could not have ignited live plants, challenging the idea that the impact led to global firestorms.

These firestorms have previously been considered a major contender in the puzzle to find out what caused the mass extinction of life on Earth 65 million years ago.

The researchers found that close to the impact site, a 200 km wide crater in Mexico, the heat pulse – that would have lasted for less than a minute – was too short to ignite live plant material. However they discovered that the effects of the impact would have been felt as far away as New Zealand where the heat would have been less intense but longer lasting – heating the ground for about seven minutes – long enough to ignite live plant matter.

The experiments were carried out in the laboratory and showed that dry plant matter could ignite, but live plants including green pine branches, typically do not.

Dr Claire Belcher from the Earth System Science group in Geography at the University of Exeter said: “By combining computer simulations of the impact with methods from engineering we have been able to recreate the enormous heat of the impact in the laboratory. This has shown us that the heat was more likely to severely affect ecosystems a long distance away, such that forests in New Zealand would have had more chance of suffering major wildfires than forests in North America that were close to the impact. This flips our understanding of the effects of the impact on its head and means that palaeontologists may need to look for new clues from fossils found a long way from the impact to better understand the mass extinction event.”

Plants and animals are generally resistant to localised fire events – animals can hide or hibernate and plants can re-colonise from other areas, implying that wildfires are unlikely to be directly capable of leading to the extinctions. If however some animal communities, particularly large animals, were unable to shelter from the heat, they may have suffered serious losses. It is unclear whether these would have been sufficient to lead to the extinction of species.

Dr Rory Hadden from the University of Edinburgh said: “This is a truly exciting piece of inter-disciplinary research. By working together engineers and geoscientists have tackled a complex, long-standing problem in a novel way. This has allowed a step forward in the debate surrounding the end Cretaceous impact and will help Geoscientists interpret the fossil record and evaluate potential future impacts. In addition, the methods we developed in the laboratory for this research have driven new developments in our current understanding of how materials behave in fires particularly at the wildland-urban-interface, meaning that we have been able to answer questions relating to both ancient mass extinctions at the same time as developing understanding of the impact of wildfires in urban areas today.”

Image of the the ultracompact H II (ionized hydrogen) region G34.26+0.15 as seen by the Spitzer Space Telescope. Credit: NASA/JPL-CalTech

The Cosmic Chemistry That Gave Rise to Water

The European Space Agency's Herschel Space Telescope was able to examine the far-infrared light of star-forming regions until it was retired in 2013. Credit: ESA

The European Space Agency’s Herschel Space Telescope was able to examine the far-infrared light of star-forming regions until it was retired in 2013. Credit: ESA

Earth’s water has a mysterious past stretching back to the primordial clouds of gas that birthed the Sun and other stars. By using telescopes and computer simulations to study such star nurseries, researchers can better understand the cosmic chemistry that has influenced the distribution of water in star systems across the Universe.

Much water takes the form of the familiar chemical formula H2O with two hydrogen atoms and one oxygen atom. But some water also takes the form of the less familiar “heavy water,” known as deuterated water with the chemical formula HDO. That ratio of H2O to HDO represents a unique signature that can reveal the history of water within star nurseries, the clouds of gas that eventually spawn star systems and their respective planets.

“The HDO/H2O ratio is a very important tool, as it keeps memory of the water formation conditions and mechanisms,” says Audrey Coutens, a postdoctoral researcher in astrophysics and planetary science at the University of Copenhagen in Denmark.

By looking at water ratios, Coutens and her colleagues have been trying to better understand a star nursery called G34.26+0.15. The target of their recent research is a region leading to the formation of stars more massive than our sun. The processes leading to the formation of such high-mass stars are not yet fully understood.

Interstellar fingerprints

The new study aimed to shed new light on high-mass star formations by looking at how the water ratios changed within high-mass star-forming regions such as G34. Doing so required ground and space telescopes capable of detecting the light signatures of water and other chemicals in G34 at a distance of 11 light-years from Earth.

Image of the the ultracompact H II (ionized hydrogen) region G34.26+0.15 as seen by the Spitzer Space Telescope. Credit: NASA/JPL-CalTech

Image of the the ultracompact H II (ionized hydrogen) region G34.26+0.15 as seen by the Spitzer Space Telescope. Credit: NASA/JPL-CalTech

Perhaps the most crucial telescope data came from Europe’s Herschel Space Telescope, which ended its scientific mission in 2013. As a space observatory, Herschel was able to look at the far-infrared light of distant star-forming regions unfiltered by Earth’s atmosphere. The telescope was able to observe water and other chemical molecules in space based on their light emissions by using the HIFI spectrometer — an instrument that can detect the light wavelengths and display them as spectral lines representing the “fingerprints” of each molecule.

By using both Herschel and ground telescopes, the team detected 10 HDO spectral lines (used to derive the HDO abundance) and three H218O spectral lines (used to derive the H2O abundance). Some of the lines didn’t need much energy to get excited and mainly gave off their telltale signatures in the colder regions of G34. Others required higher temperatures in the inner, warmer region of G34 to reveal their signature.

“To determine the water distribution, it is therefore important to have a lot of lines with different excitation levels to probe the different regions,” Coutens says.

The spectral line profiles also reveal details on the motion, temperature and other characteristics of such molecules. Broader lines often mean higher temperature or turbulence, Coutens explains. Brighter lines signal a greater abundance of molecules.

Simulating star nurseries

The researchers compared the observations from the telescopes with their own chemical computer simulations of the G34 high-mass star-forming region. Such simulations assumed that G34 has a roughly spherical shape with an inner hot core that has the highest density and temperature, which sits inside a larger, colder envelope.

“In reality, it is probably more complex than a simple sphere,” Coutens says. “But it helps us to have an idea of how water is distributed in these types of high-mass sources.”

The study results revealed that the HDO/H2O ratio decreased within the hot, inner core of G34 over time as various chemical reactions destroyed and reformed the water molecules. By comparison, the HDO/H2O ratio is higher in the colder outer envelope of G34. Such results suggest strong similarities in water distribution between high-mass and low-mass star-forming regions, because the latter also have a decreased HDO/H2O ratio in the core and an increased HDO/H2O ratio in the outer envelope.

“We see a decrease of the HDO/H2O ratio in the inner regions compared to the outer regions,” Coutens says. “It is the first time that this trend has been shown in a high-mass source.”

Still looking to the stars

The findings involving G34 could boost scientific understanding of the interstellar chemistry that creates water in high-mass star forming regions. It has also helped refine the simulations used to predict water distribution among the stars. Still, researchers still need to look at more examples of similar regions to make sure that G34 represents the norm for high-mass star nurseries rather than an exception.

The Atacama Large Millimeter/submillimeter Array (ALMA) in Chile is designed to search for astronomical phenomena such as complex molecules in protoplanetary discs. Credit: ALMA (ESO/NAOJ/NRAO)/B. Tafreshi (twanight.org)

The Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. Credit: ALMA (ESO/NAOJ/NRAO)/B. Tafreshi (twanight.org)

Luckily, there is no shortage of information from both space observatories and ground instruments at the moment. Coutens and her colleagues have access to data from five to six other high-mass star nurseries collected by the Herschel Space Telescope’s HIFI spectrometer before the space telescope was retired.

“We have other HIFI observations of HDO towards a few other high-mass star forming regions, but the radiative transfer modeling is quite time-consuming,” Coutens says. “So we need more time to know if this trend is also present in these sources.”

There are alternatives to examining the water distribution in the warm, inner regions of star nurseries. Such work could be done by the powerful arrays of interferometer antennas at the ALMA telescope facility in Chilean Andes, or the Plateau de Bure Interferometer in the French Alps.

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Telescope To Seek Dust Where Other Earths May Lie

The Large Binocular Telescope Interferometer (LBTI) instrument set its eyes on a dusty star system called Eta Corvi, depicted here in this artist's concept. Recent collisions between comets and rocky bodies within the star system are thought to have generated the surplus of dust. Image Credit: Large Binocular Telescope Observatory

The Large Binocular Telescope Interferometer (LBTI) instrument set its eyes on a dusty star system called Eta Corvi, depicted here in this artist’s concept. Recent collisions between comets and rocky bodies within the star system are thought to have generated the surplus of dust. Image Credit: Large Binocular Telescope Observatory

The NASA-funded Large Binocular Telescope Interferometer, or LBTI, has completed its first study of dust in the “habitable zone” around a star, opening a new door to finding planets like Earth. Dust is a natural byproduct of the planet-formation process, but too much of it can block our view of planets.

The findings will help in the design of future space missions that have the goal of taking pictures of planets similar to Earth, called exo-Earths.

“Kepler told us how common Earth-like planets are,” said Phil Hinz, the principal investigator of the LBTI project at the University of Arizona, Tucson, referring to NASA’s planet-hunting Kepler mission, which has identified more than 4,000 planetary candidates around stars. “Now we want to find out just how dusty and obscured planetary environments are, and how difficult the planets will be to image.”

The new instrument, based at the Large Binocular Telescope Observatory at the top of Mount Graham in southeastern Arizona, will obtain the best infrared images yet of dust permeating a star’s habitable zone, the region around the star where water — an essential ingredient for life as we know it — could pool on a planet. Earth sits comfortably within our sun’s habitable zone, hence its glistening surface of oceans.

Scientists want to take pictures of exo-Earths and break up their light into a rainbow of colors. This color information is displayed in plots, called spectra, which reveal chemical clues about whether a planet could sustain life. But dust — which comes from colliding asteroids and evaporating comets — can outshine the feeble light of a planet, making this task difficult.

“Imagine trying to view a firefly buzzing around a lighthouse in Canada from Los Angeles,” said Denis Defrère of the University of Arizona, lead author of the new study that appears in the Jan. 14 issue of the Astrophysical Journal. “Now imagine that fog is in the way. The fog is like our stardust. We want to eliminate the stars with fog from our list of targets to study in the future.”

A previous NASA project, called the Keck Interferometer, had a similar task of seeking out this dust, finding good news for planet hunters: The stars they observed didn’t seem to be all that dusty on average. LBTI is taking the research a step further, more precisely quantifying the amount of dust around stars. It will be 10 times more sensitive than the Keck Interferometer, and is specially designed to target a star’s inner region — its sweet spot, the habitable zone.

This artist's conception illustrates a storm of comets around a star near our own, called Eta Corvi. Image credit: NASA/JPL-Caltech

This artist’s conception illustrates a storm of comets around a star near our own, called Eta Corvi. Image credit: NASA/JPL-Caltech

The new study reports LBTI’s first test observations of stardust, in this case around a mature, sun-like star called eta Corvi known to be unusually dusty. According to the science team, this star is 10,000 times dustier than our own solar system, likely due to a recent impact between planetary bodies in its inner regions. The surplus of dust gives the telescope a good place to practice its dust-detecting skills.

The results showed the telescope works as intended, but also yielded a surprise: The dust was observed to be significantly closer to the star than previously thought, lying between the star and its habitable zone. NASA’s Spitzer Space Telescope has previously estimated the dust to be farther out, based on models of the size of the dust grains.

“With LBTI, we can really see where the dust is,” said Hinz. “This star is a not a good candidate for direct imaging of planets, but it demonstrates what LBTI is good for: We are figuring out the architecture of planetary systems in a way that has not been done before.”

LBTI will begin its official science operations this spring, and will operate for at least three years. One of the project’s goals is to find stars 10 times less dusty than our solar system — the good candidates for planet imaging. These survey results will inform designs and strategies for upcoming exo-Earth imaging missions now in early planning stages. The journey to find worlds ripe for life begins in part by following a trail of dust.

The Astrophysical Journal paper is online at: http://iopscience.iop.org/0004-637X/799/1/42/article

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A voyage from the Earth’s crust to its mantle and back again

Image Credit: leonello calvetti / Shutterstock

Image Credit: leonello calvetti / Shutterstock

From the beginning of time, uranium has been part of the Earth and, thanks to its long-lived radioactivity, it has proven ideal to date geological processes and deduce Earth’s evolution.

Natural uranium consists of two long-lived isotopes uranium-238 and the lighter uranium-235. A new study of the global cycle of these uranium isotopes brings additional perspectives to the debate on how the Earth has changed over billions of years as revealed in a recently published study in the journal Nature.

From early Earth history, the continental crust (the Earth’s thick solid outer skin that we live on) has accumulated mass from the underlying hot mantle. Most of the newly formed crust, however, is lost again. At mid-ocean ridges at the bottom ocean, where plates drift apart, new oceanic crust is constantly produced as basaltic rocks when hot volcanic lava emerges from the mantle and solidifies. The oceanic crust moves away from the mid-ocean-ridges and ultimately gets transported back into the underlying mantle through “subduction” at ocean trenches.

Uranium is enriched in the rocks of the continental crust; however, at Earth’s surface, different environments over time have influenced its mobility. In an oxygen-free atmosphere, as prevailed on early Earth, uranium stayed immobile in rocks as tetravalent uranium (IV). Only after atmospheric oxygen was formed did uranium become oxidised to its mobile hexavalent uranium (VI).

This more mobile uranium may then be released during the weathering and break-down of rocks and transported to the oceans in aqueous form. As the cooling oceanic crust moves away from the mid-ocean-ridges in the oceans, seawater eventually percolates through cracks in its rock and in the process uranium gets incorporated into the oceanic crust, in a similar way that a sponge takes up water.

“The radioactive nature of uranium isotopes has long been key in reconstructing early Earth history, but we now see that they also have another story to tell” explains Morten Andersen, a geochemist in the Department of Earth Sciences at ETH Zurich.

Uranium isotopes form specific signatures 

For this work, conducted at the University of Bristol including Morten Andersen (now Earth Science, ETH Zurich) along with researchers from the Durham (UK), Wyoming and Rhode Island (US), used the ‘fingerprint’ carried in the ratio of the two uranium isotopes.

The specific “fingerprint” derived from the ratio of the uranium isotopes, relates to uranium oxidation processes at the Earth’s surface. In particular, the researchers found that a higher ratio of uranium-238 to uranium-235 is incorporated into the modern oceanic crust, when compared to the uranium isotope signature found in meteorites.

The meteorites represent the Earth’s “building blocks” and, thus, yield the original uranium isotope composition of the Earth as a whole, and also the undisturbed mantle. This uranium isotope “fingerprint” of the altered oceanic crust provides a way to trace uranium that has moved from the surface and back into the Earth’s interior through subduction.

A mantle plume rising from within the Earth can create a flood basalt eruption. Credit: Tasa Graphic Arts

A mantle plume rising from within the Earth can create a flood basalt eruption. Credit: Tasa Graphic Arts

In order to examine the uranium cycle (and the rock cycle), the researchers analysed mid-ocean ridge basalts (MORBs), the hot volcanic lava that is produced from the upper and well-mixed part of the mantle. The ratio of the uranium isotopes in MORBs can be compared with those found in ocean island basalts in places such as Hawaii and the Canary Islands. These islands are so-called “hot-spots” with lava formed from hot mantle plumes that up-well beneath the oceanic crust. Compared to the MORB mantle, the island basalts are made up of material transported to the surface from a much deeper, less well-mixed, mantle sources.

Heavy uranium from surface to the deep

The isotope ratios for uranium-238 to uranium-235 are significantly greater for MORBs than for ocean island basalts. The ratios are also higher than that found in meteorites. This suggests that the MORBs contain a “fingerprint” of the uranium from the oceanic crust, drawn down from the surface and into the upper part of the Earth’s mantle through subduction, according to Andersen.

Through convection – slow movements of material in the upper mantle – the material was eventually mixed around and carried to the area of the mid-ocean ridges and transported back to the surface in the lavas that make up MORBs.

In contrast, the island basalts’ ratios of uranium-238 to uranium-235 correspond to those of the meteorites used in the study and showed that these rocks could not have the same mantle source as the MORBs. The researchers explain that ocean island lavas comes from a deeper, less mixed, mantle source and therefore any uranium added from the surface originates from a much earlier time in Earth’s history, when the surface environment was very different from today.

A drill core of altered oceanic crust near a mid-ocean ridge with uranium-bearing in-fillings (rust-brown areas) Credit: IODP

A drill core of altered oceanic crust near a mid-ocean ridge with uranium-bearing in-fillings (rust-brown areas) Credit: IODP

Study co-author Heye Freymuth of the University of Bristol explains: “Although uranium was incorporated into the oceanic crust since the initial rise in atmospheric oxygen about 2.4 billion years ago, the ocean crust did not incorporate higher amounts of uranium-238 as the oceans did not yet have adequate supplies of oxygen.”

Only during the second marked increase in atmospheric oxygen content 600 million years ago did the deep ocean become fully oxidised, which allowed the oceanic crust to gain the “fingerprint” of high uranium-238. So, despite the oceanic crust having been transported into the Earth’s mantle for a long time, the uranium isotope ratio of the subducted oceanic crust first differed from the Earth’s mantle only after the full oxidation of the oceans.

“An important result of this study is how changing conditions on the Earth’s surface and the increase of oxygen in the atmosphere influenced the composition of deep Earth. Our results suggest that due to changes over the past 600 million years, uranium was mobilised from the surface, transported into the Earth’s interior and distributed within the mantle,” says Andersen.

Hot debate about Earth’s early days

The study of uranium and the crust’s cycle brings new perspectives to the debate about how the face of the Earth has changed over billions of years. “This is currently one of the hottest research topics for Earth scientists,” Andersen points out.

Particularly lively debates take place on how the concentration of oxygen in the atmosphere evolved; after all, it is associated with many other geological weathering processes, including the fate of uranium. The current study is mainly fundamental research in a relatively young research area. The identified uranium isotope signatures could in future be used commercially to detect unknown uranium deposits and help understand processes of uranium mobility.

The first basic scientific work pointing to the potential of uranium-238 to uranium-235 variation on Earth was published in 2007. The study by Andersen and his colleagues is the first to use the uranium isotope ratio for the examination of igneous rock and apply it to the recycling process in deep Earth.

Colour image of Beagle-2 on Mars. Credit: ESA

Lost Lander Found on Mars

Colour image of Beagle-2 on Mars. Credit: ESA

Colour image of Beagle-2 on Mars. Credit: ESA

NASA’s Mars Reconnaissance Orbiter has spotted the European Beagle-2 on Mars, 12 years after the lander lost contact during its descent to the red planet.

If Beagle 2 had landed on Mars successfully, could it have discovered life? Credit: All Rights Reserved Beagle 2, www.beagle2.com

If Beagle 2 had landed on Mars successfully, could it have discovered life? Credit: All Rights Reserved Beagle 2, www.beagle2.com

Beagle-2 hitched a ride to Mars onboard the European Space Agency’s (ESA) Mars Express mission in 2003. The stationary lander was small, just 30 kg, but carried a sophisticated chemical laboratory. It was designed as Europe’s first life-hunting mission to Mars.

When Beagle-2 touched down on the surface of Mars, it was meant to send back a faint 5-watt signal… but that signal never came. For months after the landing, scientists on Earth hunted for Beagle-2 with images from ESA’s Mars Express orbiter and NASA’s Mars Odyssey mission. However, Beagle-2 was nowhere to be found.
For a recap of the events in 2003, here are some stories from the astrobio.net archives, including an interview with Beagle-2 scientist Colin Pillinger.

Beagle Hunt for Mars

More than a decade later, tiny Beagle-2 has been spotted on Mars using the high-resolution camera on NASA’s Mars Reconnaissance Orbiter. The lander appears to be partially deployed, proving that Beagle-2 made a successful entry, descent and landing. Now the question is “What went wrong?”

Beagle 2 : Europe’s Mars Lander. Credit: ESA

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An Ecosystem in a Box

Ecosystem Earth. Credit: ESA/NASA

Ecosystem Earth. Credit: ESA/NASA

An unusual package was delivered to a hotel in Beijing, China, in 1987 containing a batch of blue–green algae that would spend five days in space in a capsule. The ESA-led MELiSSA project was on its way.

The algae survived their trip around the world and, a quarter of a century later, the teams are close to testing a nearly closed ecosystem that will support life forms with almost no external resources or waste.

Along the way, the project has spawned spin-offs that purify water with little energy, improved wine-making and created new foods for astronauts.

MELiSSA (Micro-Ecological Life Support System Alternative) is investigating ways of producing food, water and oxygen on long manned space missions with limited supplies. The goal is to support the human exploration of the Solar System, as well as meeting pressing challenges on Earth.

“MELiSSA is a good example of how we do things right,” notes Franco Ongaro, ESA’s Director of Technical and Quality Management.

Nostoc algae sent to space in 1987. Creative Commons: CC-BY Attribution-NonCommercial-ShareAlike 2.0 Generic (CC BY-NC-SA 2.0) https://flic.kr/p/8enSCx

Nostoc algae sent to space in 1987. Creative Commons: CC-BY Attribution-NonCommercial-ShareAlike 2.0 Generic (CC BY-NC-SA 2.0) https://flic.kr/p/8enSCx

Working towards closed-loop life-support relies on scientists from diverse disciplines and MELiSSA covers a large community of industrial companies, universities, research centres, scientists and students from all over Europe, and has produced more than 200 peer-review scientific papers.

A productive cycle

Although MELiSSA aims to keep astronauts alive and well on deep missions into our Solar System, 25 years of research is bringing results and benefiting people on Earth right now.

More than 1.8 million cubic metres of water are treated daily in Europe using its technology, and the sparkling wine industry has improved their products with biomass sensors derived from MELiSSA.

Bacteria that it has earmarked for astronauts to grow in space for food is now showing potential for lowering cholesterol levels around the world.

The team’s knowledge of bacteria made them ESA’s experts on ensuring microbial cleanliness of ESA’s supply ferries for the International Space Station.

Testing the System in Spain

A new facility is now being built in Barcelona, Spain to demonstrate how fresh food, water and air can be produced through biological processes with no waste or external inputs.

A view inside the MELiSSA pilot plant at the University Autònoma of Barcelona. Credit: UAB

A view inside the MELiSSA pilot plant at the University Autònoma of Barcelona. Credit: UAB

“The high-tech facility has the highest quality standards to comply with industry and space requirements,” says Christophe Lasseur, ESA’s project manager. “What we are doing is the essence of sustainable development: recycling, water recovery and industrial ecology.”

“We are busy right now preparing experiments for ESA missions to the International Space Station.”

ESA astronaut Andreas Mogensen will fly his 10-day mission in May, tasting a series of protein-rich snacks made from Spirulina algae and basic crops, as well as monitoring fluids at microscopic levels and bringing biological samples back to Earth.

Soon afterwards, ESA astronaut Tim Peake will test ArtEMISS on the Station, a mini-photobioreactor that will verify the use of algae in spacecraft life-support systems. Algae show potential for producing both oxygen to breathe and food to eat for astronauts in space.

“We are looking into the future. Let’s give MELiSSA another 25 years,” concludes Christophe.

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Snapshot of cosmic burst of radio waves

This is a schematic illustration of CSIRO's Parkes radio telescope receiving the polarised signal from the new 'fast radio burst'. Credit: Swinburne Astronomy Productions

This is a schematic illustration of CSIRO’s Parkes radio telescope receiving the polarised signal from the new ‘fast radio burst’. Credit: Swinburne Astronomy Productions

A strange phenomenon has been observed by astronomers right as it was happening – a ‘fast radio burst’. The eruption is described as an extremely short, sharp flash of radio waves from an unknown source in the universe. The results have been published in the Monthly Notices of the Royal Astronomical Society.

Over the past few years, astronomers have observed a new phenomenon, a brief burst of radio waves, lasting only a few milliseconds. It was first seen by chance in 2007, when astronomers went through archival data from the Parkes Radio Telescope in Eastern Australia. Since then we have seen six more such bursts in the Parkes telescope’s data and a seventh burst was found in the data from the Arecibo telescope in Puerto Rico. They were almost all discovered long after they had occurred, but then astronomers began to look specifically for them right as they happen.

Radio-, X-ray- and visible light 

A team of astronomers in Australia developed a technique to search for these ‘Fast Radio Bursts’, so they could look for the bursts in real time. The technique worked and now a group of astronomers, led by Emily Petroff (Swinburne University of Technology), have succeeded in observing the first ‘live’ burst with the Parkes telescope. The characteristics of the event indicated that the source of the burst was up to 5.5 billion light years from Earth.

Now that they had the burst location and as soon as it was observed, a number of other telescopes around the world were alerted – on both ground and in space, in order to make follow-up observations on other wavelengths.

“Using the Swift space telescope we can observe light in the X-ray region and we saw two X-ray sources at that position,” explains Daniele Malesani, astrophysicist at the Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen.

The intensity profile of the fast radio burst, showing how quickly it evolved in time, last only a few milliseconds. Before and after the burst, only noise from the sky was detected. Credit: Malesani/Petroff

The intensity profile of the fast radio burst, showing how quickly it evolved in time, last only a few milliseconds. Before and after the burst, only noise from the sky was detected. Credit: Malesani/Petroff

Then the two X-ray sources were observed using the Nordic Optical Telescope on La Palma. “We observed in visible light and we could see that there were two quasars, that is to say, active black holes. They had nothing to do with the radio wave bursts, but just happen to be located in the same direction,” explains astrophysicist Giorgos Leloudas, Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen and Weizmann Institute, Israel.

Further investigation

So now what? Even though they captured the radio wave burst while it was happening and could immediately make follow-up observations at other wavelengths ranging from infrared light, visible light, ultraviolet light and X-ray waves, they found nothing. But did they discover anything?

“We found out what it wasn’t. The burst could have hurled out as much energy in a few milliseconds as the Sun does in an entire day. But the fact that we did not see light in other wavelengths eliminates a number of astronomical phenomena that are associated with violent events such as gamma-ray bursts from exploding stars and supernovae, which were otherwise candidates for the burst,” explains Daniele Malesani.

But the burst left another clue. The Parkes detection system captured the polarisation of the light. Polarisation is the direction in which electromagnetic waves oscillate and they can be linearly or circularly polarised. The signal from the radio wave burst was more than 20 percent circularly polarised and it suggests that there is a magnetic field in the vicinity.

“The theories are now that the radio wave burst might be linked to a very compact type of object – such as neutron stars or black holes and the bursts could be connected to collisions or ‘star quakes’. Now we know more about what we should be looking for,” says Daniele Malesani.