- New Clues from the Dawn of the Solar System
- New Mercury Surface Composition Maps Illuminate the Planet’s History
- Lockheed Martin Presents Solution for NASA’s Commercial Resupply Services 2 Program
- Rosetta Detects Hints of Ice in the Comet’s Neck
- China's Yutu Rover Reveals Moon's 'Complex' Geological History
- ISRO to Build Third Launch Pad at Sriharikota
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Posted: 15 Mar 2015 06:43 AM PDT
A research group in the University of Arizona's (UA) Lunar and Planetary Laboratory has found evidence in meteorites that hint at the discovery of a previously unknown region within the swirling disk of dust and gas known as the protoplanetary disk – which gave rise to the planets in our solar system. Led by Kelly Miller, a doctoral student in the lab of Dante Lauretta, the principal investigator of NASA's OSIRIS-REx mission, the team has found evidence of minerals within meteorites that formed in an environment that was enhanced in oxygen and sulfur and date from a time before the particles stuck together, or "accreted," to form larger bodies such as asteroids and planets. Miller will present the data at the 46th Lunar and Planetary Science Conference, which is held March 16–20 in The Woodlands, Texas. The results are in preparation for publication in a journal, but have not been peer-reviewed yet.
The elements that later went on to constitute the major ingredients in life on Earth – such as carbon, oxygen, nitrogen and hydrogen – originated as volatile gases in the protoplanetary disk when the solar system was less than 10 million years old, Miller said.
"If we want to understand how those elements contributed to life, we have to understand where they occurred at the time the solar system formed," she said.
Miller and her team study meteorites called chondrites, which are thought to be the most primitive leftovers from the birth and infancy of the solar system about 4.6 billion years ago. They derive their name from their main component – chondrules, which formed as molten droplets floating in space.
"We think that chondrites represent the earliest building blocks of rocky planets such as Earth, Mars or Venus," Miller said.
Specifically, Miller and her co-workers studied sections about half as thin as a human hair that were cut from R chondrites, a rare type of meteorite so named after the location where the type specimen fell: Rumuruti in Kenya. R chondrites are thought to have formed somewhere between Earth and Jupiter. In one specimen, found in Antarctica, they discovered a new type of building block called sulfide chondrules. The samples were obtained from the U.S. collection of Antarctic meteorites – a cooperative effort among NASA, the National Science Foundation (NSF) and the Smithsonian Institution.
"Generally, chondrules are made up of minerals rich in silicon, but the chondrules we found in this meteorite are completely different in that they are composed of sulfide minerals," she explained. "This suggests that they formed in a region that was rich in sulfur, and provides evidence for a previously unknown type of environment in the early solar system."
"Our discovery of the sulfide chondrules will help us put a quantifiable number on how much sulfide was enhanced in that region of the protoplanetary disk," Miller added.
Obtaining a better understanding of the distribution of gases in the early solar system has been identified by the Planetary Science Decadal Survey as a primary objective for the study of primitive bodies. Published by the National Research Council for NASA and other government agencies such as the National Science Foundation, the document identifies key questions in planetary science and outlines plans for space- and ground-based exploration ten years into the future.
"What is exciting about this sample is that it has not been heated to high temperatures and thereby altered in its composition," Miller said. "We know it's a fragment of a larger asteroid, and some of that asteroid heated up to higher temperatures, erasing the signature of the original building blocks of the asteroid, but our piece retains the original building blocks."
"These sulfide chondrules help us pin down when and where that sulfur enhancement occurred and help us better understand the process," she added.
To learn more about the early stages of the solar system including the origin of the building blocks of life and water, the UA-led OSIRIS-REx mission is getting ready to launch a robotic spacecraft to asteroid Bennu in 2016 and bring a sample of at least 60 grams of pristine material back to Earth for study. The mission will provide ample amounts of sample material and, most importantly, from a known context.
"Unlike with meteorites that came to us serendipitously and we're lacking the context of where the material formed, with OSIRIS-REx we will know exactly where that piece came from, and we will know the travel history of Bennu – where it has been in the past," Miller said.
Credit: uanews.org
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Posted: 15 Mar 2015 03:19 AM PDT
Two new papers from members of the MESSENGER Science Team provide global-scale maps of Mercury’s surface chemistry that reveal previously unrecognized geochemical terranes — large regions that have compositions distinct from their surroundings. The presence of these large terranes has important implications for the history of the planet. The MESSENGER mission was designed to answer several key scientific questions, including the nature of Mercury’s geological history. Remote sensing of the surface’s chemical composition has a strong bearing on this and other questions. Since MESSENGER was inserted into orbit about Mercury in March 2011, data from the spacecraft’s X-Ray Spectrometer (XRS) and Gamma-Ray Spectrometer (GRS) have provided information on the concentrations of potassium, thorium, uranium, sodium, chlorine, and silicon, as well as ratios relative to silicon of magnesium, aluminum, sulfur, calcium, and iron.
Until now, however, geochemical maps for some of these elements and ratios have been limited to one hemisphere and have had poor spatial resolution. In “Evidence for geochemical terranes on Mercury: Global mapping of major elements with MESSENGER's X-Ray Spectrometer,” published this week in Earth and Planetary Science Letters, the authors used a novel methodology to produce global maps of the magnesium/silicon and aluminum/silicon abundance ratios across Mercury’s surface from data acquired by MESSENGER’s XRS.
These are the first global geochemical maps of Mercury, and the first maps of global extent for any planetary body acquired via the technique of X-ray fluorescence, by which X-rays emitted from the Sun’s atmosphere allow the planet’s surface composition to be examined. The global magnesium and aluminum maps were paired with less spatially complete maps of sulfur/silicon, calcium/silicon, and iron/silicon, as well as other MESSENGER datasets, to study the geochemical characteristics of Mercury’s surface and to investigate the evolution of the planet’s thin silicate shell.
The most obvious of Mercury’s geochemical terranes is a large feature, spanning more than 5 million square kilometers. This terrane “exhibits the highest observed magnesium/silicon, sulfur/silicon, and calcium/silicon ratios, as well as some of the lowest aluminum/silicon ratios on the planet’s surface,” writes Shoshana Weider, a planetary geologist and Visiting Scientist at the Carnegie Institution. Weider and colleagues suggest that this “high-magnesium region” could be the site of an ancient impact basin. By this interpretation, the distinctive chemical signature of the region reflects a substantial contribution from mantle material that was exposed during a large impact event.
A second paper, “Geochemical terranes of Mercury’s northern hemisphere as revealed by MESSENGER neutron measurements,” now available online in Icarus, presents the first maps of the absorption of low-energy (“thermal”) neutrons across Mercury’s surface. The data used in this second study were obtained with the GRS anti-coincidence shield, which is sensitive to neutron emissions from the surface of Mercury.
“From these maps we may infer the distribution of thermal-neutron-absorbing elements across the planet, including iron, chlorine, and sodium,” writes lead author Patrick Peplowski of The Johns Hopkins University Applied Physics Laboratory. “This information has been combined with other MESSENGER geochemical measurements, including the new XRS measurements, to identify and map four distinct geochemical terranes on Mercury.”
According to Peplowski, the results indicate that the smooth plains interior to the Caloris basin, Mercury’s largest well-preserved impact basin, have an elemental composition that is distinct from other volcanic plains units, suggesting that the parental magmas were partial melts from a chemically distinct portion of Mercury’s mantle. Mercury’s high-magnesium region, first recognized from the XRS measurements, also contains high concentrations of unidentified neutron-absorbing elements.
“Earlier MESSENGER data have shown that Mercury’s surface was pervasively shaped by volcanic activity,” notes Peplowski. “The magmas erupted long ago were derived from the partial melting of Mercury’s mantle. The differences in composition that we are observing among geochemical terranes indicate that Mercury has a chemically heterogeneous mantle.”
“The consistency of the new XRS and GRS maps provides a new dimension to our view of Mercury’s surface,” Weider adds. “The terranes we observe had not previously been identified on the basis of spectral reflectance or geological mapping.”
“The crust we see on Mercury was largely formed more than three billion years ago,” says Carnegie’s Larry Nittler, Deputy Principal Investigator of the mission and co-author of both studies. “The remarkable chemical variability revealed by MESSENGER observations will provide critical constraints on future efforts to model and understand Mercury’s bulk composition and the ancient geological processes that shaped the planet’s mantle and crust.”
Credit: carnegiescience.edu
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Posted: 14 Mar 2015 04:00 PM PDT
The technologies behind Lockheed Martin’s proposal for NASA’s Commercial Resupply Services 2 (CRS-2) program contain three major elements: a reusable space servicing vehicle called Jupiter; a large, versatile cargo container named the Exoliner; and a robotic arm. Unveiled March 12 in Washington, the company’s approach to the CRS-2 program offers NASA extensive cargo capacity and the opportunity to host commercial payloads, and builds a foundation for future deep space exploration systems. CRS-2 is a NASA program to resupply the International Space Station (ISS) with food, equipment and other critical supplies.
“We know how important it is to get astronauts on the ISS the supplies they need on time, every time,” said Wanda Sigur, vice president and general manager of Lockheed Martin Space Systems’ Civil Space line of business. “Our approach is designed to deliver a large volume of critical supplies and cargo with each flight, and do so on schedule. That’s why we’re bringing together flight-proven technologies that are reliable, safe and cost-effective.”
The Jupiter spacecraft builds upon the design of MAVEN, now in orbit around Mars, and OSIRIS-REx, currently under construction for an asteroid sample return mission. The Exoliner container is based upon teammate Thales Alenia Space’s cargo carrier used on the Automated Transfer Vehicle. The robotic arm, built by teammate MacDonald Dettwiler and Associates, draws from technology used on the International Space Station and the Space Shuttle for more than 30 years.
The Lockheed Martin CRS-2 solution brings many affordability benefits with it. Not only does it employ a reusable spacecraft and create the option to host commercial payloads, it’s also designed to support future exploration missions in deep space. Jupiter and the Exoliner cargo carrier can be pre-positioned with supplies of food, fuel, water and equipment for astronauts to use as they travel on manned missions farther into space than ever before.
“Our top priority is safe, reliable and affordable delivery of cargo to the ISS,” said Jim Crocker, vice president and general manager of Lockheed Martin Space Systems’ International line of business. “At the same time, as NASA continues on the journey to Mars, we’re excited by the possibilities CRS-2 can offer to accelerate that goal.”
Credit: lockheedmartin.com
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Posted: 14 Mar 2015 03:38 PM PDT
When seen with the human eye, comet 67P/Churyumov-Gerasimenko is grey – all over. With its color filters Rosetta’s scientific imaging system OSIRIS, however, can discern tiny differences in reflectivity. To this effect, scientists from the OSIRIS team image the same region on the comet’s surface using different color filters. If, for example, the region appears especially bright in one of these images, it reflects light of this wavelength especially well. “Even though the color variations on 67P’s surface are minute, they can give us important clues”, says OSIRIS Principal Investigator Holger Sierks from the Max Planck Institute for Solar System Research (MPS) in Germany. In a recent analysis performed by the OSIRIS team, the Hapi region clearly stands out from the rest of the comet: while most parts of 67P display a slightly reddish reflectivity spectrum as is common for cometary nuclei and other primitive bodies, the reflection of red light is somewhat lower in this region.
“We know that the reflectivity properties are closely correlated to the surface morphology”, says OSIRIS scientist Sonia Fornasier from the Paris Observatory. Where the smooth surface of the Hapi region gives way to the more rugged terrain of the surrounding areas, the reflectivity, too, changes. The scientists believe that Hapi’s special reflectivity properties hint at a higher abundance of frozen water at or near the surface. Earlier comet missions had observed similar behavior on comets 103P/Hartley 2 and 9P/Temple 1 and associated the bluish spectrum to the presence of frozen water. While OSIRIS can only study a limited number of spectral bands, Rosetta is equipped with other instruments such as VIRTIS than can unambiguously identify the spectral signature of water molecules in infrared reflection. “We are excited to see, whether our suspicion will be confirmed”, says Sierks.
The Hapi region differs from the rest of 67P’s surface in many respects. Not only is it much smoother, it is one of the main sources of activity in the Northern hemisphere. Early dust jets originated there. “During perihelion when 67P heats up significantly Hapi is hidden in Northern polar night. Outbound on the comet’s orbit, from March 2016, Hapi will receive solar heat again”, says Fornasier. “At this large distance from the Sun it will then be very cold. Hapi might therefore be a region that has been able to retain ices on its surface during past orbits around the Sun and has thus enough “fuel” left to create the fireworks of activity we have witnessed in the past months.”
Rosetta is an ESA mission with contributions from its member states and NASA. Rosetta's Philae lander is provided by a consortium led by DLR, MPS, CNES and ASI. 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.
The scientific imaging system OSIRIS was built by a consortium led by the Max Planck Institute for Solar System Research (Germany) in collaboration with CISAS, University of Padova (Italy), the Laboratoire d'Astrophysique de Marseille (France), the Instituto de Astrofísica de Andalucia, CSIC (Spain), the Scientific Support Office of the European Space Agency (The Netherlands), the Instituto Nacional de Técnica Aeroespacial (Spain), the Universidad Politéchnica de Madrid (Spain), the Department of Physics and Astronomy of Uppsala University (Sweden), and the Institute of Computer and Network Engineering of the TU Braunschweig (Germany). OSIRIS was financially supported by the national funding agencies of Germany (DLR), France (CNES), Italy (ASI), Spain (MEC), and Sweden (SNSB) and the ESA Technical Directorate.
Credit: mps.mpg.de
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Posted: 14 Mar 2015 08:37 AM PDT
The moon's geological history is more complex than previously thought, preliminary results from China's first lunar rover, Yutu, suggested Thursday. Ground-penetrating radar measurements taken by Yutu, also known as Jade Rabbit, revealed at least nine subsurface layers beneath its landing site, indicating that multiple geologic processes have taken place there. "We have for the first time detected multiple subsurface layers (on the moon)," said lead author Xiao Long, professor of the China University of Geosciences in Wuhan, attributing these layers to ancient lava flows and the weathering of rocks and boulders into regolith, or loose layers of dust, over the past 3.3 billion years or so.
One of the most interesting findings is a layer at depths of 140 meters to 240 meters, said Xiao, who is also professor of Macau University of Science and Technology.
"We think this layer is probably pyroclastic rocks which formed during the course of volcanic eruptions," Xiao told Xinhua via email. "It reveals the diversity of volcanic activity, but what's more important is that it shows there are plenty of volatile contents inside the moon."
Yutu is part of China's Chang'e-3 moon mission, which delivered the rover and a stationary lander to the lunar surface on Dec. 14, 2013, marking the first moon landing since the Soviet Union's Luna 24 mission in 1976.
It touched down on the northern Mare Imbrium, also called Sea of Rains, a region not directly sampled before and far from the U. S. Apollo and Luna landings sites.
Yutu traveled a total of 114 meters following a zigzagging route, then came to a halt about 20 meters to the southwest of the landing site due to mechanical problems.
So the rover just surveyed a small area using two radar antennas capable of penetrating the Moon's crust to depths of about 400 meters.
The data, however, were enough to show its landing site is compositionally distinct from previous Moon-landing sites, the researchers said.
"Overall, we have already had a general scientific understanding of the moon thanks to these lunar missions," Xiao said. "But if we want to have a comprehensive understanding of moon's geological structure, material composition and formation, as well as its evolution, a large number of exploration events are still needed. Meanwhile, effective international cooperation is a must considering the high cost of these activities."
The findings were published in the U.S. journal Science.
Credit: xinhuanet.com
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Posted: 14 Mar 2015 08:20 AM PDT
Indian space agency has proposed to set up its third rocket launch pad at Satish Dhawan Space Centre, Sriharikota, in Andhra Pradesh, parliament was informed on Thursday. In a written reply to a question raised in the Rajya Sabha, Minister of State for Science and Technology Jitendra Singh said: "Indian Space Research Organisation (ISRO) proposes to set up a new launch pad, referred as third launch pad, at Satish Dhawan Space Centre, Sriharikota." The third launch pad is intended to support increased launch frequency, launching requirements of future advanced launch vehicles and also serve as a redundant launch pad for the GSLV MIII class of rockets.
Detailed studies on possible concepts/options and preliminary configuration have been carried out, he said.
The possible site for the third launch pad has been identified in Sriharikota taking into account the safety distances and maximal utilisation of existing launch pad facilities.
However, further work on design of the launch pad will be taken up at an appropriate time after finalising the configuration of the advanced launch vehicle, operationalisation of geosynchronous satellite launch vehicle (GSLV MIII) rocket, programmatic requirements and resource availability.
Currently ISRO has two rocket launch pads at Sriharikota to launch GSLV and polar satellite launch vehicle (PSLV).
Credit: ndtv.com
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