The Book Of THoTH

NASA astrobiologists studying the origin of life have reproduced uracil, a key component of RNA, in the laboratory. They discovered that an ice sample containing pyrimidines exposed to ultraviolet radiation under space-like conditions produces this essential ingredient of life. The study appears in the September issue of Astrobiology.

“We have demonstrated for the first time that we can make uracil, a component of RNA, non-biologically in a laboratory under conditions found in space,” said Michel Nuevo, research scientist at NASA’s Ames Research Center. “We are showing that these laboratory processes, which simulate occurrences in outer space, can make a fundamental building block used by living organisms on Earth.”

It is widely accepted that around 2.4 billion years ago, the Earth’s atmosphere underwent a dramatic change when oxygen levels rose sharply. Called the “Great Oxidation Event” (GOE), the oxygen spike marks an important milestone in Earth’s history, the transformation from an oxygen-poor atmosphere to an oxygen-rich one paving the way for complex life to develop on the planet.

Two questions that remain unresolved in studies of the early Earth are when oxygen production via photosynthesis got started and when it began to alter the chemistry of Earth’s ocean and atmosphere.

A research team that includes members of NAI’s Arizona State University team corroborates recent evidence that oxygen production began in Earth’s oceans at least 100 million years before the GOE, and goes a step further in demonstrating that even very low concentrations of oxygen can have profound effects on ocean chemistry. Their study is published in the current issue of Science.

To arrive at their results, the researchers analyzed 2.5 billion-year-old black shales from Western Australia, samples provided through the NAI’s Astrobiology Drilling Program. Essentially representing fossilized pieces of the ancient seafloor, the fine layers within the rocks allowed the researchers to page through ocean chemistry’s evolving history.

Specifically, the shales revealed that episodes of hydrogen sulfide accumulation in the oxygen-free deep ocean occurred nearly 100 million years before the GOE and up to 700 million years earlier than such conditions were predicted by past models for the early ocean. Scientists have long believed that the early ocean, for more than half of Earth’s 4.6 billion-year history, was characterized instead by high amounts of dissolved iron under conditions of essentially no oxygen.

Said Timothy Lyons of UC Riverside who led the study, “This is important because oxygen-poor and sulfidic conditions almost certainly impacted the availability of nutrients essential to life, such as nitrogen and trace metals. The evolution of the ocean and atmosphere were in a cause-and-effect balance with the evolution of life.”

Scanning electron images of two dust particles E1 (panel A) and G4 (B) and secondary ion mass spectrometry isotopic ratio maps (C–D). Oxygen isotope maps of particles E1 (C) and G4 (D) show four and seven isotopically anomalous regions, indicated by circles, which have been identified as presolar grains. The scale bars are 2 microns.

Dust samples collected by high-flying aircraft in the upper atmosphere have yielded an unexpectedly rich trove of relicts from the ancient cosmos, report scientists from NAI’s Carnegie Institution of Washington team in Earth and Planetary Science Letters. The stratospheric dust includes minute grains that likely formed inside stars that lived and died long before the birth of our sun, as well as material from molecular clouds in interstellar space. This “ultra-primitive” material likely wafted into the atmosphere after the Earth passed through the trail of an Earth-crossing comet in 2003, giving scientists a rare opportunity to study cometary dust in the laboratory.

At high altitudes, most dust in the atmosphere comes from space, rather than the Earth’s surface. Thousands of tons of interplanetary dust particles (IDPs) enter the atmosphere each year. “We’ve known that many IDPs come from comets, but we’ve never been able to definitively tie a single IDP to a particular comet,” says study coauthor Larry Nittler, of Carnegie’s Department of Terrestrial Magnetism. “The only known cometary samples we’ve studied in the laboratory are those that were returned from comet 81P/Wild 2 by the Stardust mission.” NASA’s Stardust mission collected samples of comet dust, returning to Earth in 2006.

Comets are thought to be repositories of primitive, unaltered matter left over from the formation of the solar system. Material held for eons in cometary ice has largely escaped the heating and chemical processing that has affected other bodies, such as the planets. However, the Wild 2 dust returned by the Stardust mission included more altered material than expected, indicating that not all cometary material is highly primitive.

The IDPs used in the current study were collected by NASA aircraft in April 2003, after the Earth passed through the dust trail of comet Grigg-Skjellerup. The research team, which included Carnegie scientists Nittler, Henner Busemann (now at the University of Manchester, U.K.), Ann Nguyen, George Cody, and seven other colleagues, analyzed a sub-sample of the dust to determine the chemical, isotopic and microstructural composition of its grains.

“What we found is that they are very different from typical IDPs” says Nittler. “They are more primitive, with higher abundances of material whose origin predates the formation of the solar system.” The distinctiveness of the particles, plus the timing of their collection after the Earth’s passing through the comet trail, point to their source being the Grigg-Skjellerup comet.

“This is exciting because it allows us to compare on a microscopic scale in the laboratory dust particles from different comets,” says Nittler. “We can use them as tracers for different processes that occurred in the solar system four-and-a-half billion years ago.”

The biggest surprise for the researchers was the abundance of so-called presolar grains in the dust sample. Presolar grains are tiny dust particles that formed in previous generations of stars and in supernova explosions before the formation of the solar system. Afterwards, they were trapped in our solar system as it was forming and are found today in meteorites and in IDPs. Presolar grains are identified by having extremely unusual isotopic compositions compared to anything else in the solar system. But presolar grains are generally extremely rare, with abundances of just a few parts per million in even the most primitive meteorites, and a few hundred parts per million in IDPs. “In the IDPs associated with comet Grigg-Skjellerup they are up to the percent level,” says Nittler. “This is tens of times higher abundances than we see in other primitive materials.”

Also surprising is the comparison with the samples from Wild 2 collected by the Stardust mission. “Our samples seem to be much more primitive, much less processed, than the samples from Wild 2,” says Nittler, “which might indicate that there is a huge diversity in the degree of processing of materials in different comets.”

Scanning electron images of two dust particles E1 (panel A) and G4 (B) and secondary ion mass spectrometry isotopic ratio maps (C–D). Oxygen isotope maps of particles E1 (C) and G4 (D) show four and seven isotopically anomalous regions, indicated by circles, which have been identified as presolar grains. The scale bars are 2 microns.

Dust samples collected by high-flying aircraft in the upper atmosphere have yielded an unexpectedly rich trove of relicts from the ancient cosmos, report scientists from NAI’s Carnegie Institution of Science team in Earth and Planetary Science Letters. The stratospheric dust includes minute grains that likely formed inside stars that lived and died long before the birth of our sun, as well as material from molecular clouds in interstellar space. This “ultra-primitive” material likely wafted into the atmosphere after the Earth passed through the trail of an Earth-crossing comet in 2003, giving scientists a rare opportunity to study cometary dust in the laboratory.

At high altitudes, most dust in the atmosphere comes from space, rather than the Earth’s surface. Thousands of tons of interplanetary dust particles (IDPs) enter the atmosphere each year. “We’ve known that many IDPs come from comets, but we’ve never been able to definitively tie a single IDP to a particular comet,” says study coauthor Larry Nittler, of Carnegie’s Department of Terrestrial Magnetism. “The only known cometary samples we’ve studied in the laboratory are those that were returned from comet 81P/Wild 2 by the Stardust mission.” NASA’s Stardust mission collected samples of comet dust, returning to Earth in 2006.

Comets are thought to be repositories of primitive, unaltered matter left over from the formation of the solar system. Material held for eons in cometary ice has largely escaped the heating and chemical processing that has affected other bodies, such as the planets. However, the Wild 2 dust returned by the Stardust mission included more altered material than expected, indicating that not all cometary material is highly primitive.

The IDPs used in the current study were collected by NASA aircraft in April 2003, after the Earth passed through the dust trail of comet Grigg-Skjellerup. The research team, which included Carnegie scientists Nittler, Henner Busemann (now at the University of Manchester, U.K.), Ann Nguyen, George Cody, and seven other colleagues, analyzed a sub-sample of the dust to determine the chemical, isotopic and microstructural composition of its grains.

“What we found is that they are very different from typical IDPs” says Nittler. “They are more primitive, with higher abundances of material whose origin predates the formation of the solar system.” The distinctiveness of the particles, plus the timing of their collection after the Earth’s passing through the comet trail, point to their source being the Grigg-Skjellerup comet.

“This is exciting because it allows us to compare on a microscopic scale in the laboratory dust particles from different comets,” says Nittler. “We can use them as tracers for different processes that occurred in the solar system four-and-a-half billion years ago.”

The biggest surprise for the researchers was the abundance of so-called presolar grains in the dust sample. Presolar grains are tiny dust particles that formed in previous generations of stars and in supernova explosions before the formation of the solar system. Afterwards, they were trapped in our solar system as it was forming and are found today in meteorites and in IDPs. Presolar grains are identified by having extremely unusual isotopic compositions compared to anything else in the solar system. But presolar grains are generally extremely rare, with abundances of just a few parts per million in even the most primitive meteorites, and a few hundred parts per million in IDPs. “In the IDPs associated with comet Grigg-Skjellerup they are up to the percent level,” says Nittler. “This is tens of times higher abundances than we see in other primitive materials.”

Also surprising is the comparison with the samples from Wild 2 collected by the Stardust mission. “Our samples seem to be much more primitive, much less processed, than the samples from Wild 2,” says Nittler, “which might indicate that there is a huge diversity in the degree of processing of materials in different comets.”

Scientist Dale Andersen prepares to dive in Lake Untersee in Queen Maud Land in Antarctica. Photo: Dale Andersen
The ice-covered lakes of Antarctica’s McMurdo Dry Valleys have long been of interest to astrobiologists. These remote and extreme environments harbor unique microbial ecosystems that could provide clues about how life might survive on other worlds – such as Jupiter’s icy moon, Europa. Recently, a team of scientists funded by the NASA Exobiology Program began exploring the unique habitat of the ice-crusted Lake Joyce.

Lake Joyce is of special interest, because it’s waters harbor carbonate structures known as microbialites. These unique structures are formed with layers of cyanobacteria. The research team is interested in how these organisms are able to grow in the dark, cold waters of Lake Joyce.


A recent report concerning the study is available from OnOrbit.com at http://www.onorbit.com/node/1619


Follow field reports from the scientists on twitter at: Dale Andersen: http://twitter.com/daleandersen and Dawn Sumner: http://twitter.com/sumnerd

Lake Joyce, foreground, in the McMurdo Dry Valleys.

Members of NAI’s team at Georgia Tech have a new paper in Molecular Biology and Evolution describing an analysis of ribosomal structure and sequence. Their approach chronicles the ribosome’s evolution, effectively interpreting the ribosome as a fossil. Using the highest resolution structures available, of two species that represent disparate regions of the evolutionary tree, they have sectioned the large subunit of each ribosome into concentric shells, like an onion, using the site of peptidyl transfer as the origin. Their results suggest that the structure and interactions of both RNA and protein can be described as changing, in an observable manner, over evolutionary time.

Exploring Ice in the Solar System is a series of lessons for K-5 classrooms developed by the NAI Carnegie Institution of Science Team and the NASA MESSENGER mission. Twelve lessons span topics from ice in everyday life, to exploring ice in the polar regions of Earth, to icy places on Mars and Europa, to life in ice. Each standards-aligned lesson consists of substantive background information, inquiry-based activities, teaching tips, resources, a photo gallery, and strategies for differentiated instruction and evaluation.

Adrian Ponce, deputy manager for JPL’s planetary science section, has devised a new microscope-based method to quickly validate — from days to minutes — a spacecraft’s cleanliness. The method will help in decontaminating spacecraft before launch, and could have medical and pharmaceutical uses on Earth.

Throughout most of the month of August, an international team of scientists participated in the Arctic Mars Analogue Svalbard Expedition (AMASE) in Norway, conducting scientific research and testing instruments for future NASA and European Space Agency (ESA) Mars robotic missions.

The Svalbard archipelago is unique in the diversity of geological formations it contains. Few places in the world include a record of so many geological eras exposed in outcrops that can be studied without moving significant amounts of soil and vegetation. Some of these formations are considered interesting analogues for Mars terrains. AMASE 2009 test sites ranged from volcanic rocks with carbonate deposits similar to those found on some Martian meteorites, to ancient sediments with fossilized microbial mats similar to the oldest known fossil remnants of life on Earth.
AMASE Principal Investigator Andrew Steele on site with his Svalbard field team. Image Credit: Kjell Ove Storvik

NASA funding for AMASE 2009 was provided by the Agency’s Astrobiology Science and Technology for Exploring Planets (ASTEP) program. This expedition was the sixth NASA-funded AMASE campaign since 2003.

NASA-sponsored members of the AMASE 2009 team included ASTEP Principal Investigator and AMASE science leader Andrew Steele of the Carnegie Institution for Science in Washington, D.C.; NASA Senior Scientist for Astrobiology (Interim) Mary A. Voytek; NASA Ames Research Center astrobiologist David Blake; NASA Goddard Space Flight Center astrobiologists Paul Mahaffey, Jennifer Eigenbrode, and Amy McAdam; Mars Science Laboratory team member Pamela Conrad of the Jet Propulsion Laboratory; and Cornell University’s Steven Squyres, Principal Investigator for the Mars Exploration Rover (MER) mission’s Athena Science Payload.

“It was a privilege to be a working member of the AMASE field expedition this year,� said Dr. Voytek, a microbiologist by training. “We gathered extensive data on sampling and analysis techniques and robotic operations that will help mission planners increase science returns on MSL, ExoMars, and other missions and speed the search for evidence of past or present life on Mars.�
Swabbing rover scoops to test a cleaning procedure before collecting a sample: part of a Mars sample return simulation. Image Credit: Kjell Ove Storvik

“Extreme environments present a tremendous opportunity for scientists and engineers to develop and hone exploration protocols for Mars and to broaden our understanding of life, and the clues it may leave behind,� said NASA Mars Exploration Program Lead Scientist Michael A. Meyer.

AMASE researchers simulated rover operations on Mars using field prototypes of instruments that will fly on future NASA and ESA missions. Prototype instruments included MSL’s mineral and organic chemistry sensors CheMin and SAM; and the ExoMars panoramic camera (PanCam), ground penetrating radar (WISDOM), and mineral and organic chemistry spectrometer.
NASA Ames’s David Blake celebrating his 60th birthday while working at Sigurfjella Peak. Image Credit: Kjell Ove Storvik

“Our teams learned a lot about how these instruments perform and how they can be used together to meet common science goals FOR BOTH FUTURE ROBOTIC AND SAMPLE RETURN MISSIONS,� said AMASE science leader Steele.

A further exercise involved a blind test with a remote science control center aboard the Norwegian Polar Institute research vessel Lance, which served as a home base for the AMASE team. This exercise simulated several days of Mars rover activities under realistic operating conditions. A field team supplied measurements requested by the remote science team on the ship. The time pressure of receiving data from Mars, assessing the information, making key decisions on how to continue, and uploading instructions to the spacecraft was intense.
NASA and ESA scientists plan the Mars sample return exercise. Image Credit: Kjell Ove Storvik

“The instruments were deployed on geologically relevant targets and were used in a sequence similar to that planned for ExoMars and MSL,� said ESA’s ExoMars Project Scientist Jorge Vago. After field measurements were completed, samples were collected and taken aboard for cataloguing and further tests. The information obtained during this exercise was then compared with data collected during more detailed observations performed in the laboratories aboard the Lance. This exercise was helpful in learning what might have been overlooked on the field, Vago explained. The results of such an exercise can be used to optimize rover investigation protocols, toward maximizing science returns within the constraints imposed by a real Mars mission.

THE AMASE 2009 expedition involved researchers from different universities and research centers, providing an excellent opportunity to perform science in environments similar to Mars, allowing interdisciplinary teams from the United States and Europe to work together. While NASA and ESA are discussing options for robotic Mars exploration, AMASE campaigns are contributing to preparing the science groundwork and forging long-lasting bonds among scientists and institutions. AMASE relies on the incredible help and infrastructure from Norwegian science institutions (Norwegian Space Agency, Norwegian Polar Institute, Kings Bay, University centre of Svalbard) and the governor and people of Svalbard.
Cornell University’s Steve Squyres returning from glacier sampling. Image Credit: Kjell Ove Storvik NASA Goddard’s Jennifer Eigenbrode in the doorway of her portable science clean lab. Image Credit: Kjell Ove Storvik R.V. (Research Vessel) Lance: residence, lab, and recreation center for the AMASE 2009 team. Image Credit: Kjell Ove Storvik Helicopter aid in the field, AMASE 2009. Image Credit: Kjell Ove Storvik Svalbard has no penguins, but it does have people, when AMASE is on the march. Image Credit: Kjell Ove Storvik Luxury accommodations at Svalbard, AMASE 2009. Image Credit: Kjell Ove Storvik Physical fitness is a scientific requirement on AMASE expeditions. NASA Senior Scientist Mary Voytek goes after samples. Image Credit: Kjell Ove Storvik Setting up shop in the field, AMASE 2009. Image Credit: Kjell Ove Storvik Cryptoendoliths – microbial life inside rocks, found on Svalbard. Image Credit: Kjell Ove Storvik Mars on Earth: Svalbard, 2009. Image Credit: Kjell Ove Storvik Looking out for polar bears while scientists do their thing, AMASE 2009. Image Credit: Kjell Ove Storvik

The search for life-friendly real estate around distant stars doesn’t have to be limited to planets. New research shows that habitable exomoons can be detected with a new method using current technology – including NASA’s recently launched Kepler spacecraft.