Astrobiologists have discovered regions in our galaxy which might have the greatest potential for producing very complex organic molecules, the starting point for the development of life. We’ve heard before about “follow the water” in the search for life; in this case it may be “follow the methanol”…
The scientists involved, from Rensselaer Polytechnic Institute in Troy, New York, began a search for methanol, a key ingredient in the synthesis of organic molecules. According to Douglas Whittet, lead researcher of the study, “Methanol formation is the major chemical pathway to complex organic molecules in interstellar space.” The idea is to look for areas where there is rich methanol production occurring. In the large clouds of dust and gas that give birth to new stars, there are simpler organic molecules like carbon monoxide. Under the right conditions, carbon monoxide on the surfaces of dust grains can interact with hydrogen, also found in the clouds, to create methanol. Methanol can then become a steppingstone to create the more complex organic molecules, the types needed for life itself. But how much methanol is out there, and where?
It appears to be most abundant around a small number of newly-formed stars, where it makes up to 30 percent of the material around those stars. In other areas though, it is in much smaller amounts, or none at all. In the cold dust and gas clouds that will eventually produce new stars, it was found to exist in the 1 to 2 percent range. Hence, there appear to be “sweet spots” where conditions are suitable for the chain reactions to occur, depending on how fast the needed molecules can reach the dust grains. It can mean the difference between a “dead end” for additional development or an “organic bloom.” As described by Whittet: “If the carbon monoxide molecules build up too quickly on the surfaces of the dust grains, they don’t get the opportunity to react and form more complex molecules. Instead, the molecules get buried in the ices and add up to a lot of dead weight. If the buildup is too slow, the opportunities for reaction are also much lower.”
So some places may be much more likely to have the conditions necessary for the development of life than others. What about our own solar system? How does it compare? By studying the methanol amounts in comets, relics from the beginning of the solar system, the scientists have concluded that the methanol abundance back then was about average. Not a dearth of the stuff, but not a “sweet spot” really, either. Yet here we are… or, as Whittet put it, “This means that our solar system wasn’t particularly lucky and didn’t have the large amounts of methanol that we see around some other stars in the galaxy. But, it was obviously enough for us to be here.”
The paper, titled “Observational constraints on methanol production in interstellar and preplanetary ices,” will be published in the Nov. 20 edition of The Astrophysical Journal and is a collaboration between Rensselaer, NASA Ames Research Center, the SETI Institute and Ohio State University.
A replication of the arsenic life experiment being done by biologist Rosie Redfield. Image credit: Rosie Redfield.
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One of the most vocal and ardent critics of the so-called ‘arsenic life’ experiment which was published in December 2010 was biologist Rosie Redfield from the University of British Columbia in Vancouver. The science paper by NASA astrobiologist Felisa Wolfe-Simon and her team reported that a type of bacteria in Mono Lake in California can live and grow almost entirely on arsenic, a poison, and incorporates it into its DNA. Redfield called the paper “lots of flim-flam, but very little reliable information.” Her opinion was quickly seconded by many other biologists/bloggers.
Redfield has been working on replicating the experiment done by Wolfe-Simon, and doing in her work in front of the world, so to speak. She is detailing her work in an open lab notebook on her blog. So far, she reports that her results contradict Wolfe-Simon et al.’s observations.
To date, Redfield is finding that the bacteria, called GFAJ-1, is not living and growing in arsenic, but dying. Redfield says her work refutes that cells from the GFAJ-1 could use arsenic for growth in place of phosphorus, and when arsenic was added to the low-phosphorus medium in which the bacteria was living, the bacteria was killed. Additionally, in other test viles, the growth properties Redfield is finding for GFAJ-1 don’t match those reported by Wolfe-Simon and her team, which claimed that the bacteria could not grow on a low concentration of phosphorus, and that the bacteria could grow on arsenic in the absence of phosphorus.
Redfield’s two major early criticisms of the original paper were that the authors had not ruled out the possibility that the bacteria were feeding on phosphorus contaminating their growth medium; and that the bacterial DNA was not properly purified, so that the arsenic detected might not actually have been in DNA.
An article in Nature reports that other researchers also working on replicating the experiment with GFAJ-1 laud Redfield’s efforts, but say it is too early to conclude that she has debunked the original work.
Additionally, one problem is that Redfield she did not replicate the experiment exactly, as she had to add one nutrient not used by the authors of the original arsenic life paper in order for the bacteria to grow.
This is not the first time scientists have written open notebooks during the replication of controversial findings, but it might be one of the more notable, given the amount of media attention the arsenic life paper received.
Redfield is also hoping that her work will highlight the benefits of open notebook-type research.
An image combining orbital imagery with 3-D modeling shows flows that appear in spring and summer on a slope inside Mars' Newton crater. Image credit: NASA/JPL-Caltech/Univ. of Arizona
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In a news conference today, NASA announced discoveries that provide additional evidence of seasonal water flows on Mars. Using data collected by the Mars Reconnaissance Orbiter, the MRO team presented images of dark lines that form on slopes during the martian spring/summer and fade in winter.
During the news conference, HIRISE principal investigator Alfred McEwen (University of Arizona), discussed that these “finger-like” features were found in Mars’ mid-southern latitudes. “The best explanation for these observations so far is the flow of briny water,” he said.
McEwen based his explanation on several key facts: First, salt lowers the freezing point of water (“plain” water would simply stay frozen on Mars) Secondly, the temperature on Mars during these flows ranges from -23 to +27 degrees Celsius, which rules out CO2. While there is significant evidence of flowing water, the team did state that there is no direct detection of water since it evaporates quickly on Mars.
Regarding the dark color of the flows, McEwen added, “The flows are not dark because of being wet, they are dark for some other reason.” McEwen also mentioned that researchers will need to re-create Mars-like conditions in the lab to better understand these flows, stating, “It’s a mystery now, but I think it’s a solvable mystery with further observations and laboratory experiments.”
MRO Project Scientist Richard Zurek (JPL) offered his thoughts as well. “These dark lineations are different from other types of features on Martian slopes,” he said, “and repeated observations show they extend ever farther downhill with time during the warm season.”
This series of images shows warm-season features that might be evidence of salty liquid water active on Mars today. Image credit: NASA/JPL-Caltech/Univ. of Arizona (click to view full animation)
What also proves intriguing to the team is that while gullies are very abundant on colder slopes that face the poles, the dark flows discussed in today’s news conference are found on warmer slopes which face the equator.
During the conference, Philip Christensen (Arizona State University) presented a map showing concentrations of “salts” in the same locations that the dark, “finger-like” flows were found.
McEwen reiterated during the Q&A session that the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), hasn’t detected any signs of water and that laboratory simulations will be necessary to gain a better understanding of these features – basically the team is seeing signs of flowing water, but not the water itself.
If you’d like to learn more about the Mars Reconnaissance Orbiter and today’s announcement, you can visit: http://www.nasa.gov/mro
This map of Mars shows relative locations of three types of findings related to salt or frozen water, plus a new type of finding that may be related to both salt and water. Credit: NASA/JPL-Caltech/ASU/UA/LANL/MSSS
Enceladus' signature ice geysers in action. NASA / JPL / SSI
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Researchers on the Cassini mission team have identified large salt grains in the plumes emanating from Saturn’s icy satellite Enceladus, making an even stronger case for the existence of a salty liquid ocean beneath the moon’s frozen surface.
Cassini first discovered the jets of water ice particles in 2005; since then scientists have been trying to learn more about how they behave, what they are made of and – most importantly – where they are coming from. The running theory is that Enceladus has a liquid subsurface ocean of as-of-yet undetermined depth and volume, and pressure from the rock and ice layers above combined with heat from within force the water up through surface cracks near the moon’s south pole. When this water reaches the surface it instantly freezes, sending plumes of ice particles hundreds of miles into space.
Enceladus inside the E ring
Much of the ice ends up in orbit around Saturn, creating the hazy E ring in which Enceladus resides.
Although the discovery of the plumes initially came as a surprise, it’s the growing possibility of liquid water that’s really intriguing – especially that far out in the Solar System and on a little 504-km-wide moon barely the width of Arizona. What’s keeping Enceladus’ water from freezing as hard as rock? It could be tidal forces from Saturn, it could be internal heat from its core, a combination of both – or something else entirely… astronomers are still hard at work on this mystery.
Now, using data obtained from flybys in 2008 and 2009 during which Cassini flew directly through the plumes, researchers have found that the particles in the jets closest to the moon contain large sodium- and potassium-rich salt grains. This is the best evidence yet of the existence of liquid salt water inside Enceladus – a salty underground ocean.
“There currently is no plausible way to produce a steady outflow of salt-rich grains from solid ice across all the tiger stripes other than salt water under Enceladus’s icy surface.”
– Frank Postberg, Cassini team scientist, University of Heidelberg, Germany
Looking down into a jetting "tiger stripe"
If there indeed is a reservoir of liquid water, it must be pretty extensive since the numerous plumes are constantly spraying water vapor at a rate of 200 kg (400 pounds) every second – and at several times the speed of sound! The plumes are ejected from points within long, deep fissures that slash across Enceladus’ south pole, dubbed “tiger stripes”.
Recently the tiger stripe region has also been found to be emanating a surprising amount of heat, even further supporting a liquid water interior – as well as an internal source of energy. And where there’s liquid water, heat energy and organic chemicals – all of which seem to exist on Enceladus – there’s also a case for the existence of life.
“This finding is a crucial new piece of evidence showing that environmental conditions favorable to the emergence of life can be sustained on icy bodies orbiting gas giant planets.”
– Nicolas Altobelli, ESA project scientist for Cassini
Enceladus has intrigued scientists for many years, and every time Cassini takes a closer look some new bit of information is revealed… we can only imagine what other secrets this little world may hold. Thankfully Cassini is going strong and more than happy to keep on investigating!
“Without an orbiter like Cassini to fly close to Saturn and its moons — to taste salt and feel the bombardment of ice grains — scientists would never have known how interesting these outer solar system worlds are.”
– Linda Spilker, Cassini project scientist at JPL
The findings were published in this week’s issue of the journal Nature.
Image credits: NASA / JPL / Space Science Institute
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Jason Major is a graphic designer, photo enthusiast and space blogger. Visit his website Lights in the Dark and follow him on Twitter @JPMajor or on Facebook for the most up-to-date astronomy awesomeness!
Image of permineralized remains in the one of the meteorites studied by Richard Hoover. Credit: Journal of Cosmology
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A recent paper published by a NASA scientist claims the discovery evidence of fossil bacteria in a rare subclass of carbonaceous meteorite. The claims are extraordinary, and were the paper published somewhere other than the Journal of Cosmology, (and given an “exclusive preview” on Fox News) more people might be taking this seriously. But, even so, the topic went viral over the weekend.
Titled “Fossils of Cyanobacteria in CI1 Carbonaceous Meteorites” and written by NASA scientist Dr. Richard Hoover of the Marshall Space Flight Center, the paper makes the bold claim that meteorites found in France and Tanzania in the 1800s (the Alais, Ivuna, and Orgueil CI1 meteorites) have clear evidence pointing to space-dwelling microbes, with inferences of panspermia — the theory that microbes brought to Earth in comets and meteorites could have started life on our planet. “The implications,” says an online synopsis of the paper, “are that life is everywhere, and that life on Earth may have come from other planets.”
The paper states: “Filaments found in the CI1 meteorites have also been detected that exhibit structures consistent with the specialized cells and structures used by cyanobacteria for reproduction (baeocytes, akinetes and hormogonia), nitrogen fixation (basal, intercalary or apical heterocysts) and attachment or motility (fimbriae).”
Dr. Chris McKay, a planetary scientist and astrobiologist at NASA Ames Research Center, pointed out to Universe Today that Hoover’s claims are “extraordinary, because of the ecological setting implied. Cyanobacteria live in liquid water and are photosynthetic.”
McKay said finding heterocysts (cells formed by some filamentous cyanobacteria) would certainly be indicative of life from an actively thriving environment. “The implication of these results is that the meteorite hosted a liquid water environment in contact with sunlight and high oxygen,” he told Universe Today in an email.
Image at 1000 X of multiple filaments and sheaths embedded in Orgueil meteorite. Credit: Journal of Cosmology
There have been previous reports of bacteria in meteorites, but most have turned out to be contamination or misunderstanding of the microscopic structures within rocks (remember the Alan Hills Meteorite claim from 1996 –which is still widely controversial.) It turns out that Dr. Hoover has reported fossil bacteria previously, but none have actually been proven. And, it also turns out that Hoover’s paper was submitted to the Astrobiology Journal in 2007, but the review was never completed.
“Richard Hoover is a careful and accomplished microscopist so there is every reason to believe that the structures he sees are present and are not due to contamination,” McKay said. “If these structures had been reported from sediments from a lake bottom there would be no question that they were classified correctly as biological remains.”
There are two possibilities, McKay said. “One, the structures are not biological but are chance shapes. In a millimeter square area of meteorite there are million possible 1 micron squares. Perhaps any diversity of shapes can be found if searching is extensive.”
Or the second possibility, McKay said is that “the environments on meteorites are, or were, radically different from what we would expect. There are suggestions for how meteorite parent bodies could have sustained interior liquid water. But not in a way that could have the liquid water exposed to sunlight. It also seems unlikely that high oxygen concentrations would be implied.”
There’s also the question of why Hoover would choose to publish in the somewhat dubious Journal of Cosmology, an open access, but supposedly peer-reviewed online journal, which has come under fire for errors found in some of their articles, and for the rather sensational claims made by some of the papers published within.
But word also was released by the Journal of Cosmology that they will cease publication in May 2011. In a press release titled, “Journal of Cosmology To Stop Publishing–Killed by Thieves and Crooks,” (posted by journalist David Dobbs), the press release said that the “JOC threatened the status quo at NASA,” and that “JOC’s success posed a direct threat to traditional subscription based science periodicals, such as “science” magazine; just as online news killed many newspapers. Not surprisingly, JOC was targeted by science magazine and others who engaged in illegal, criminal, anti-competitive acts to prevent JOC from distributing news about its online editions and books.”
UPDATE: NASA has released a statement on Hoover’s paper, saying that “NASA cannot stand behind or support a scientific claim unless it has been peer-reviewed or thoroughly examined by other qualified experts. This paper was submitted in 2007 to the International Journal of Astrobiology. However, the peer review process was not completed for that submission. NASA also was unaware of the recent submission of the paper to the Journal of Cosmology or of the paper’s subsequent publication. Additional questions should be directed to the author of the paper.” – Dr. Paul Hertz, chief scientist of NASA’s Science Mission Directorate in Washington
But Hoover’s work is generating a huge buzz.
The journal’s editor in chief, Rudy Schild of the Harvard-Smithsonian Centre for Astrophysics, said Hoover is a “highly respected scientist and astrobiologist with a prestigious record of accomplishment at NASA. Given the controversial nature of his discovery, we have invited 100 experts and have issued a general invitation to over 5,000 scientists from the scientific community to review the paper and to offer their critical analysis.”
“No other paper in the history of science has undergone such a thorough analysis, and no other scientific journal in the history of science has made such a profoundly important paper available to the scientific community, for comment, before it is published,” Schild added. Those commentaries will be published March 7 through March 10, and can be found here.
Certainly, further review of Hoover’s work needs to be conducted.
A wider range of asteroids were capable of creating the kind of amino acids used by life on Earth, according to new NASA research. Amino acids are used to build proteins, which are used by life to make structures like hair and nails, and to speed up or regulate chemical reactions. Amino acids come in two varieties that are mirror images of each other, like your hands. Life on Earth uses the left-handed kind exclusively. Since life based on right-handed amino acids would presumably work fine, scientists are trying to find out why Earth-based life favored left-handed amino acids.
In March, 2009, researchers at NASA’s Goddard Space Flight Center in Greenbelt, Md., reported the discovery of an excess of the left-handed form of the amino acid isovaline in samples of meteorites that came from carbon-rich asteroids. This suggests that perhaps left-handed life got its start in space, where conditions in asteroids favored the creation of left-handed amino acids. Meteorite impacts could have supplied this material, enriched in left-handed molecules, to Earth. The bias toward left-handedness would have been perpetuated as this material was incorporated into emerging life.
In the new research, the team reports finding excess left-handed isovaline (L-isovaline) in a much wider variety of carbon-rich meteorites. “This tells us our initial discovery wasn’t a fluke; that there really was something going on in the asteroids where these meteorites came from that favors the creation of left-handed amino acids,” says Dr. Daniel Glavin of NASA Goddard. Glavin is lead author of a paper about this research published online in Meteoritics and Planetary Science January 17.
This is a photo of a carbon-rich meteorite analyzed in the study. Credit: Antarctic Meteorite Laboratory/NASA Johnson Space Center
“This research builds on over a decade of work on excesses of left-handed isovaline in carbon-rich meteorites,” said Dr. Jason Dworkin of NASA Goddard, a co-author on the paper.
“Initially, John Cronin and Sandra Pizzarello of Arizona State University showed a small but significant excess of L-isovaline in two CM2 meteorites. Last year we showed that L-isovaline excesses appear to track with the history of hot water on the asteroid from which the meteorites came. In this work we have studied some exceptionally rare meteorites which witnessed large amounts of water on the asteroid. We were gratified that the meteorites in this study corroborate our hypothesis,” explained Dworkin.
L-isovaline excesses in these additional water-altered type 1 meteorites (i.e. CM1 and CR1) suggest that extra left-handed amino acids in water-altered meteorites are much more common than previously thought, according to Glavin. Now the question is what process creates extra left-handed amino acids. There are several options, and it will take more research to identify the specific reaction, according to the team.
However, “liquid water seems to be the key,” notes Glavin. “We can tell how much these asteroids were altered by liquid water by analyzing the minerals their meteorites contain. The more these asteroids were altered, the greater the excess L-isovaline we found. This indicates some process involving liquid water favors the creation of left-handed amino acids.”
Another clue comes from the total amount of isovaline found in each meteorite. “In the meteorites with the largest left-handed excess, we find about 1,000 times less isovaline than in meteorites with a small or non-detectable left-handed excess. This tells us that to get the excess, you need to use up or destroy the amino acid, so the process is a double-edged sword,” says Glavin.
Whatever it may be, the water-alteration process only amplifies a small existing left-handed excess, it does not create the bias, according to Glavin. Something in the pre-solar nebula (a vast cloud of gas and dust from which our solar system, and probably many others, were born) created a small initial bias toward L-isovaline and presumably many other left-handed amino acids as well.
One possibility is radiation. Space is filled with objects like massive stars, neutron stars, and black holes, just to name a few, that produce many kinds of radiation. It’s possible that the radiation encountered by our solar system in its youth made left-handed amino acids slightly more likely to be created, or right-handed amino acids a bit more likely to be destroyed, according to Glavin.
It’s also possible that other young solar systems encountered different radiation that favored right-handed amino acids. If life emerged in one of these solar systems, perhaps the bias toward right-handed amino acids would be built in just as it may have been for left-handed amino acids here, according to Glavin.
The research was funded by the NASA Astrobiology Institute (NAI), which is administered by NASA’s Ames Research Center in Moffett Field, Calif.; the NASA Cosmochemistry program, the Goddard Center for Astrobiology, and the NASA Post Doctoral Fellowship program. The team includes Glavin, Dworkin, Dr. Michael Callahan, and Dr. Jamie Elsila of NASA Goddard.
We don’t like to cover news on Astronomy Cast, but sometimes there’s a news story that’s interesting, complicated, and rapidly unfolding – and it happens to cover an area that we haven’t talked much about. So today we thought we’d talk about the discovery of arsenic-based life, and exotic forms of life in general. Maybe we need to redefine our definition of life. Or maybe we just got introduced to some distant cousins.
Backlash from the “arsenic life” paper that was published on December 2, is still ongoing. Some of the criticism has been about the science, while much more criticism has been about the coverage of the news and also how NASA introduced, or “teased” the public with news, using the words “astrobiology” and “extraterrestrial life” in their announcement of an upcoming press conference. Today, at the American Geophysical Union conference, one of the team scientists, Ron Oremland discussed the fallout from the news coverage, and I’ll be providing an overview of that shortly. At about the same time, the science team released a statement and some FAQ’s about the science paper. Below is that statement and the information the science team provided.
Trees on an alien world? No, a dune field on Mars with sand flows. Credit: NASA/JPL/U of Arizona
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Excitingly, we’ve been able to detect the composition of atmospheres on a handful of planets orbiting other stars. But if next-generation space observatories go online within the next couple of decades, some scientists propose using a new technique to determine details such as tree-like multicellular life on extrasolar planets.
While previous studies have discussed the likelihood of detecting life on exoplanets through signs of biogenic gases in the atmosphere, or seeing “glints” of light off oceans or lakes, those technique are limited in that, for example, biogenic gases could be signs of either single-celled or multicellular life – not providing much detail — and as we’ve seen from Titan, glints off planetary bodies do not necessarily come from water-filled lakes.
Researchers Christopher Doughty and Adam Wolf from the Carnegie Institution propose using a technique that Earth-orbiting satellites already use to in order to determine types of crops and land cover, as well as cloud detection, atmospheric conditions and other applications.
Called Bidirectional Reflectance Distribution Function (BRDF), this type of remote sensing determines the causes of differing reflectance at different sun- and view-angles. For example, trees cast shadows on the planet, and the large-scale pattern of shadows would make the light reflected off the vegetation to take on specific brightness and color characteristics.
“BRDF arises from the changing visibility of the shadows cast by objects,” the researchers wrote in their paper, “and the presence of tree-like structures is clearly distinguishable from flat ground with the same reflectance spectrum. We examined whether the BRDF could detect the existence of tree-like structures on an extrasolar planet by using changes in planetary albedo as a planet orbits its star.”
BRDF and different light reflection for various planetary sufaces. Credit: Wolfgang Lucht.
They used a computer model to simulate vegetation reflectance at different planetary phase angles and added both simulated and real cloud cover to calculate the planetary albedo for a vegetated and non-vegetated planet with abundant liquid water.
Depending on how accurately planetary cloud cover can be resolved, as well as the sensitivity instruments on proposed missions such as the Terrestrial Planet Finder, this technique could theoretically detect tree-like multicellular life on exoplanets in about 50 nearby stellar systems.
The angles of the spacecraft, the planet and its sun would have to be taken into account but the team says these characteristics would change in predictable ways over time, producing a detectable pattern.
If vegetation on the exoplanet was wide¬spread enough, it would affect the reflective properties of the whole planet.
“We found that even if the entire planetary albedo were rendered to a single pixel, the rate of increase of albedo as a planet approaches full illumination would be comparatively greater on a vegetated planet than on a non-vegetated planet,” they said.
