Curiosity on Mars

Il Curiosity Mars Rover della NASA ha incontrato delle strane striature ad andamento parallelo sul terreno di Marte alle falde di Monte Sharp (vedi foto). Sembra che nessun ricercatore autonomo sardo abbia ancora rivendicato le strane strutture rinvenute alla antica presenza Shardana sul posto.

NASA's Curiosity Mars Rover views striated ground 








NASA's Curiosity Mars rover has reached an area where orbital images had piqued researchers' interest in patches of ground with striations all oriented in a similar direction. 

NASA's Curiosity Mars rover used the Navigation Camera (Navcam) on its mast for this look back after finishing a drive of 328 feet (100 meters) on the 548th Martian day, or sol, of the rover's work on Mars (Feb. 19, 2014) 

[Credit: NASA/JPL-Caltech] 

A close-up look at some of the striations from the rover's Navigation Camera gains extra drama by including Mount Sharp in the background. The lower slopes of that layered mountain are the mission's long-term science destination.  

Martian Landscape With Rock Rows and Mount Sharp: This landscape scene photographed by NASA's Curiosity Mars rover shows rows of rocks in the foreground and Mount Sharp on the horizon 

[Credit: NASA/JPL-Caltech] 

The foreground rocks are in an outcrop called "Junda" which the rover passed during a drive of 328 feet (100 meters) on Feb. 19. It paused during the drive to take the component images of the scene, then finished the day's drive. A location still ahead, called "Kimberley," where researchers plan to suspend driving for a period of science investigations, also features ground with striations. NASA's Mars Science Laboratory Project is using Curiosity to assess ancient habitable environments and major changes in Martian environmental conditions. JPL, a division of the California Institute of Technology in Pasadena, built the rover and manages the project for NASA's Science Mission Directorate in Washington. 

For more information about Curiosity, visit http://www.jpl.nasa.gov/msl , http://www.nasa.gov/msl and http://mars.jpl.nasa.gov/msl/. 

Source: NASA/Jet Propulsion Laboratory [February 27, 2014]

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Le "SUPER TERRA" potrebbero essere pianeti morti.

Negli ultimi anni si sono moltiplicati i tentativi per trovare un altro pianeta che possa ospitare la vita come noi la conosciamo sulla Terra, nell'evenienza che un giorno quest' ultima sia troppo affollata per ospitarci tutti (secondo le teorie neo-Malthusiane). I giornali lanciano quasi quotidianamente entusiasti annunci del ritrovamento di una "Super Terra", ignorando che - con ogni probabilità - si tratta di pianeti morti.
Saranno necessari molti anni ancora - e probabilmente strumenti di nuova generazione - per trovare il posto giusto...

‘Super-Earths’ may be dead worlds

 In the last 20 years the search for Earth-like planets around other stars has accelerated, with the launch of missions like the Kepler space telescope. Using these and observatories on the ground, astronomers have found numerous worlds that at first sight have similarities with Earth. A few of these are even in the 'habitable zone' where the temperature is just right for water to be in liquid form and so are prime targets in the search for life elsewhere in the universe. 

The mass of the initial rocky core determines whether the final planet is potentially habitable. On the top row of the diagram, the core has a mass of more than 1.5 times that of the Earth. The result is that it holds on to a thick atmosphere of hydrogen (H), deuterium (H2) and helium (He). The lower row shows the evolution of a smaller mass core, between 0.5 and 1.5 times the mass of the Earth. It holds on to far less of the lighter gases, making it much more likely to develop an atmosphere suitable for life 
[Credit: NASA / H. Lammer] 



Now a team of scientists have looked at how these worlds form and suggest that many of them may be a lot less clement than was though. They find that planets that form from less massive cores can become benign habitats for life, whereas the larger objects instead end up as 'mini-Neptunes' with thick atmospheres and probably stay sterile. The researchers, led by Dr. Helmut Lammer of the Space Research Institute (IWF) of the Austrian Academy of Sciences, publish their results in Monthly Notices of the Royal Astronomical Society. 
Planetary systems, including our own Solar system, are thought to form from hydrogen, helium and heavier elements that orbit their parent stars in a so-called protoplanetary disk. Dust and rocky material is thought to clump together over time, eventually forming rocky cores that go on to be planets. 
The gravity of these cores attracts hydrogen from the disk around them, some of which is stripped away by the ultraviolet light of the young star they orbit. Dr. Lammer and his team modelled the balance of capture and removal of hydrogen for planetary cores between 0.1 and 5 times the mass of Earth, located in the habitable zone of a Sun-like star. In their model, they found that protoplanets with the same density of Earth, but less than 0.5 times its mass will not capture much gas from the disk. Depending on the disk and assuming that the young star is much brighter in ultraviolet light than the Sun is today, planetary cores with a similar mass to Earth can capture but also lose their enveloping hydrogen. But the highest mass cores, similar to the 'super Earths' found around many stars, hold on to almost all of their hydrogen. These planets end up as 'mini Neptunes' with far thicker atmospheres than our home planet. The results suggest that for some of the recently discovered super-Earths, such as Kepler-62e and -62f, being in the habitable zone is not enough to make them habitats. 
Dr. Lammer comments "Our results suggest that worlds like these two super-Earths may have captured the equivalent of between 100 and 1000 times the hydrogen in the Earth's oceans, but may only lose a few percent of it over their lifetime. With such thick atmospheres, the pressure on the surfaces will be huge, making it almost impossible for life to exist." 
The ongoing discovery of low (average) density super-Earths supports the results of the study. Scientists will need to look even harder to find places where life could be found, setting a challenge for astronomers using the giant telescopes that will come into use in the next decade. 
The study was carried out by researchers within the Austrian FWF Research Network "Pathways to Habitability." 

Source: Royal Astronomical Society (RAS) [February 26, 2014]

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Figli delle stelle

Discoveries suggest icy cosmic start 

for amino acids and DNA ingredients

Using new technology at the telescope and in laboratories, researchers have discovered an important pair of prebiotic molecules in interstellar space. The discoveries indicate that some basic chemicals that are key steps on the way to life may have formed on dusty ice grains floating between the stars.

The Green Bank Telescope and some of the molecules it has discovered [Credit: Bill Saxton, NRAO/AUI/NSF]

The scientists used the National Science Foundation's Green Bank Telescope (GBT) in West Virginia to study a giant cloud of gas some 25,000 light-years from Earth, near the center of our Milky Way Galaxy. The chemicals they found in that cloud include a molecule thought to be a precursor to a key component of DNA and another that may have a role in the formation of the amino acid alanine.

One of the newly-discovered molecules, called cyanomethanimine, is one step in the process that chemists believe produces adenine, one of the four nucleobases that form the "rungs" in the ladder-like structure of DNA. The other molecule, called ethanamine, is thought to play a role in forming alanine, one of the twenty amino acids in the genetic code.

"Finding these molecules in an interstellar gas cloud means that important building blocks for DNA and amino acids can 'seed' newly-formed planets with the chemical precursors for life," said Anthony Remijan, of the National Radio Astronomy Observatory (NRAO).

In each case, the newly-discovered interstellar molecules are intermediate stages in multi-step chemical processes leading to the final biological molecule. Details of the processes remain unclear, but the discoveries give new insight on where these processes occur.

Previously, scientists thought such processes took place in the very tenuous gas between the stars. The new discoveries, however, suggest that the chemical formation sequences for these molecules occurred not in gas, but on the surfaces of ice grains in interstellar space.

"We need to do further experiments to better understand how these reactions work, but it could be that some of the first key steps toward biological chemicals occurred on tiny ice grains," Remijan said.

The discoveries were made possible by new technology that speeds the process of identifying the "fingerprints" of cosmic chemicals. Each molecule has a specific set of rotational states that it can assume. When it changes from one state to another, a specific amount of energy is either emitted or absorbed, often as radio waves at specific frequencies that can be observed with the GBT.

New laboratory techniques have allowed astrochemists to measure the characteristic patterns of such radio frequencies for specific molecules. Armed with that information, they then can match that pattern with the data received by the telescope. Laboratories at the University of Virginia and the Harvard-Smithsonian Center for Astrophysics measured radio emission from cyanomethanimine and ethanamine, and the frequency patterns from those molecules then were matched to publicly-available data produced by a survey done with the GBT from 2008 to 2011.

A team of undergraduate students participating in a special summer research program for minority students at the University of Virginia (U.Va.) conducted some of the experiments leading to the discovery of cyanomethanimine. The students worked under U.Va. professors Brooks Pate and Ed Murphy, and Remijan. The program, funded by the National Science Foundation, brought students from four universities for summer research experiences. They worked in Pate's astrochemistry laboratory, as well as with the GBT data.

"This is a pretty special discovery and proves that early-career students can do remarkable research," Pate said.

The findings have been published in The Astrophysical Journal Letters. 

Source: National Radio Astronomy Observatory [February 28, 2013]