NASA Spacecraft Reveal Mysteries Of Jupiter And Saturn Rings

upiter's ripple-producing culprit was comet Shoemaker-Levy 9. The comet's debris cloud hurtled through the thin Jupiter ring system on a collision course into the planet in July 1994. Scientists attribute Saturn's ripples to a similar object - likely another cloud of comet debris - plunging through the inner rings in 1983. The findings are detailed in two papers published Thursday in the journal Science.

"We're finding evidence that a planet's rings can be affected by specific, traceable events that happened in the last 30 years, rather than a hundred million years ago," said Matthew Hedman, a Cassini imaging team associate, lead author on one of the papers, and a research associate at Cornell University in Ithaca, N.Y. "The solar system is a much more dynamic place than we gave it credit for."

Scientists learned about the patchy patterns in Jupiter's rings in the late 1990s from Galileo's visit to Jupiter. Unfortunately, the images from that mission were fuzzy, and scientists didn't understand why such patterns would occur. Not until Cassini entered orbit around Saturn in 2004 and started sending back thousands of images did scientists have a better picture of the activity. A 2007 science paper by Hedman and colleagues first noted corrugations in Saturn's innermost ring, dubbed the D ring.

A group including Hedman and Mark Showalter, a Cassini co-investigator based at the SETI Institute in Mountain View, Calif., saw that the grooves in the D ring appeared to wind together more tightly over time. Playing the process backward, Hedman demonstrated the pattern originated when something tilted the D ring off its axis by about 300 feet (100 meters) in late 1983. The scientists found Saturn's gravity on the tilted area warped the ring into a tightening spiral.

Cassini imaging scientists received another clue around August 2009 when the sun shone directly along Saturn's equator and lit the rings edge-on. The unique lighting conditions highlighted ripples not previously seen in another part of the ring system. Whatever happened in 1983 was big - not a small, localized event.

The collision tilted a region more than 12,000 miles (19,000 kilometers) wide, covering part of the D ring and the next outermost ring, called the C ring. Unfortunately, spacecraft were not visiting Saturn at that time, and the planet was on the far side of the sun out of sight from ground or space-based telescopes.

Hedman and Showalter, the lead author on the second paper, wondered whether the long-forgotten pattern in Jupiter's ring system might illuminate the mystery. Using Galileo images from 1996 and 2000, Showalter confirmed a similar winding spiral pattern by applying the same math they had applied to Saturn and factoring in Jupiter's gravitational influence. Galileo was launched on a space shuttle in 1989 and studied Jupiter until 2003.

Unwinding the spiral pinpointed the date when Jupiter's ring was tilted off its axis between June and September 1994. Shoemaker-Levy plunged into the Jovian atmosphere in late July. The Galileo images also revealed a second spiral, which was calculated to have originated in 1990. Images taken by New Horizons in 2007, when the spacecraft flew by Jupiter on its way to Pluto, showed two newer ripple patterns, in addition to the fading echo of the Shoemaker-Levy impact.

"We now know that collisions into the rings are very common – a few times per decade for Jupiter and a few times per century for Saturn," Showalter said. "Now scientists know that the rings record these impacts like grooves in a vinyl record, and we can play back their history later."

Launched in Oct. 15, 1997, Cassini began orbiting Saturn in 2004 and sends back data daily.

"Finding these fingerprints still in the rings is amazing and helps us better understand impact processes in our solar system," said Linda Spilker, Cassini project scientist, based at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Cassini's long sojourn around Saturn has helped us tease out subtle clues that tell us about the history of our origins."

Open-source Software Designed to Minimize Synthetic Biology Risks

Virginia Tech has licensed GenoTHREAT, a software tool that helps detect the use of synthetic DNA as bioterrorism agents. Developed as an open-source project by a team led by Jean Peccoud, associate professor at Virginia Bioinformatics Institute at Virginia Tech, it is being released using the Apache License Version 2.0 to ensure broad accessibility.
GenoTHREAT implements the “best match” screening protocol method recommended by the federal government to minimize the risk that unauthorized individuals or those with malicious intent will obtain toxins and other potentially dangerous materials from DNA synthesis providers. The process of developing GenoTHREAT allowed Peccoud’s team to conduct a rigorous bioinformatic analysis of the strengths and limitations of the best match method which was published in the March issue of Nature Biotechnology.
“It was natural to start developing GenoTHREAT around the federal guidance on synthetic DNA,” said Peccoud. “Since this regulation is only one of many regulations and policies that providers of synthetic DNA need to comply with, our current efforts aim at developing a more comprehensive biosecurity solution that can be customized for a variety of users.”
Five of the report’s co-authors – Arunima Srivastava of Delhi, India, a sophomore majoring in computer science in the College of Science; Michael Kozar of Harwich, Mass., a junior majoring in biology in the College of Science and French in the College of Liberal Arts and Human Sciences; Tyler Stewart of Springfield, Va., a junior majoring in biological sciences and biochemistry in the College of Science; and Gaelle Letort and Olivier Mirat, visiting students from ENSIMAG, an engineering school in Grenoble, France – are undergraduate students who worked with Peccoud and were part of a team of undergraduate students enrolled in the 2010 International Genetically Engineered Machines (iGEM) competition. The other two authors are Laura Adam, graduate research assistant, and Mandy Wilson, database administrator with Peccoud’s group
“This project exemplifies how it is possible to train students to use interdisciplinary strategies to confront today’s most important scientific problems,” said Virginia Tech Vice President and Dean for Undergraduate Education Daniel Wubah. “By breaking down the separation of basic and applied research, and by combining engineering and life science expertise, this team has made a valuable contribution to a real-world problem directly related to the security of our nation.”
Since the first synthetic cell in May 2010, the security and ethical aspects of synthetic biology have been debated in congressional hearings and by the Presidential Commission for the Study of Bioethical Issues and the National Academy of Science, among others.
“While the U.S. government does not endorse any particular tools, as stated in the Guidance, the U.S. government is supportive of efforts to develop new and improved methods to screen double-stranded DNA sequences for biosecurity purposes,” explained Capt. Theresa Lawrence of the U.S. Department of Health and Human Services. “We applaud efforts to advance this important field of science and enhance security.”

The Virginia Bioinformatics Institute at Virginia Tech is a premier bioinformatics, computational biology, and systems biology research facility that uses transdisciplinary approaches to science combining information technology, biology, and medicine. These approaches are used to interpret and apply vast amounts of biological data generated from basic research to some of today’s key challenges in the biomedical, environmental, and agricultural sciences. With more than 240 highly trained multidisciplinary, international personnel, research at the institute involves collaboration in diverse disciplines such as mathematics, computer science, biology, plant pathology, biochemistry, systems biology, statistics, economics, synthetic biology, and medicine. The large amounts of data generated by this approach are analyzed and interpreted to create new knowledge that is disseminated to the world’s scientific, governmental, and wider communities.

Hurricane Season 2011: Tropical Depression 91S (South Pacific)

Australia's Northern Territory has been experiencing rainfall and winds from the low pressure system called "System 91S" for several days this week. Today, NASA's Tropical Rainfall Measuring Mission satellite spotted light to moderate rainfall in the system as continues tracking southwest and bringing rains and winds to the northern coast of Western Australia this weekend.

System 91S was located in the Timor Sea, west-southwest of Darwin, Australia (Northern Territory) and was moving in a west-southwesterly direction. System 91S is forecast to continue traveling in that direction and its center is expected to remain at sea over the next several days as it heads toward the Southern Indian Ocean.

As it continues to track along coastal areas of the Northern Territory and Western Australia, cyclone warnings are in effect. A Cyclone Warning is in effect for Western Australian coastal and island areas from Kuri Bay to the Western Australia/Northern Territory border, including Kalumburu and Wyndham. In addition, a cyclone watch is in effect from Kuri Bay to Cape Leveque, not including Derby.

The TRMM satellite, operated by both NASA and the Japanese Space Agency, passed over the system at 1451 UTC on April 1. The U.S. Navy and Naval Research Laboratory's Monterey Marine Meteorology Division, Calif. overlaid TRMM rainfall rate imagery on top of Japan's METSAT-2 infrared imagery to provide a complete picture of the low pressure areas cloud extent and rainfall rates. TRMM's precipitation radar instrument measured rainfall rates close to 1 inch (25 mm) per hour.

Surface winds on April 1 are estimated between 25 and 30 knots (29 to 34 mph / 46 to 55 kmh). Satellite imagery indicated that the center of Depression 91S' circulation was located near 13.2 South latitude and 128.9 East longitude. It is moving in a southwesterly direction near 4 knots (5 mph/7 kmh).

Infrared satellite imagery shows that the low-level center of circulation appears to be consolidating, and there is improved banding of thunderstorms wrapping into the center of the storm. Both of those factors hint at a storm organizing and strengthening. The only challenge in the forecast is that there is a moderate wind shear battering the storm which is inhibiting further strengthening into a tropical storm today. That vertical wind shear is expected to decrease as System 91S tracks along the northern coast this weekend.

There is a good chance that System 91S could become a tropical storm over the weekend. Regardless, residents of the northern coastal areas of Western Australia should expect some heavy rainfall, gusty winds and rough surf at the beaches this weekend.

NASA Satellites Eyeing 4 Tropical Systems Around the World For Possible Development

There are four low pressure areas in the tropics today that NASA satellites are all keeping an eye on for possible development. They are Systems 90S, 91S and 99S in the Southern Pacific, and System 93B in the Northern Indian Ocean. Despite a poor chance for development in all of them, one has triggered warnings in northern Australia because of its proximity to land.

NASA and the Japanese Space Agency manage the Tropical Rainfall Measuring Mission or TRMM satellite and TRMM passed over two of those four systems today. TRMM captured light to moderate rainfall in the low pressure area called "System 90S" on March 30 at 01:49 UTC. Rainfall rates were between 5 and 20 millimeters (0.2 and 0.8 inches) per hour within the storm. System 90S is located 500 miles north-northwest of Port Hedland, Australia, near 12.0 South latitude and 116.0 East longitude.

Infrared satellite imagery from the Atmospheric Infrared Sounder (AIRS) instrument aboard NASA's Aqua satellite revealed that the low has consolidated during the morning hours, while the Advanced Microwave Scanning Radiometer-E instrument showed deep convection on the north and south sides of the center of circulation. Despite these developments atmospheric dynamics are not currently favorable, so the Joint Typhoon Warning Center currently gives this low a poor chance for development.

The second tropical low pressure area NASA satellites are watching is also 500 miles away from land, and that's System 99S. System 99S is 500 miles north of the Cocos Islands today, near 9.8 South and 99.4 East. The TRMM satellite measured rainfall rates between 5 and 20 millimeters (0.2 and 0.8 inches) per hour within the System 99S early today. The AIRS infrared imagery captured from NASA's Aqua satellite shows that areas of deep convection exist on all sides of the low pressure center, but it's not uniform. Vertical wind shear is currently light and sea surface temperatures are warm enough to support development, however, the chance that it will develop into a tropical storm in the next 24 hours is poor. As the week progresses, perhaps the chance will improve with the environmental conditions.

The third tropical low pressure area isn't a tropical storm but it has triggered a watch for Australia's Northern Territories. Because of System 91S' location, about 200 miles northeast of Darwin, Australia (near 10.0 South and 133.1 East), a tropical cyclone Watch has been issued for the coastal communities between Cape Hotham, Port Keats, including Darwin and the Tiwi Islands. The Tiwi Islands include Melville and Bathurst Islands and are part of Australia's Northern Territory, 25 miles (40 km) north of Darwin where the Arafura Sea joins the Timor Sea. In addition, a Strong Wind Warning has been issued from Milingimbi to Troughton Island.

System 91S is expected to move in a southwesterly direction over the next several days and track over Snake Bay, Mellville Island and Cape Fourcroy, Bathurst Island.

NASA AIRS infrared imagery revealed today that the convection (rapidly rising air that produces the thunderstorms that power a tropical cyclone) are intensifying and expanding around System 91S' center. The convection, however appears disorganized in the low and the maximum sustained winds are between 15 and 20 knots (17-23 mph/27-37 kmh). The chance for development into a tropical storm in the next 24 hours remains poor, but the areas under the watch may feel System 91S' rains and some gusty winds.

The fourth area is in the northern hemisphere and in a different ocean. Tropical low 93B is located in the Northern Indian Ocean. Last night it was only 50 miles north of Phuket, Thailand near 9.0 North latitude and 98.7 East longitude. However, today, infrared satellite imagery from NASA's AIRS instrument showed that the low level circulation center has drifted inland. When a low is inland, its center of circulation is cut off from the warm waters that power the tropical cyclone. Because of weak steering winds, however, the low may move back seaward and redevelop in the warm waters offshore.

Currently the system's maximum sustained winds are between 15 and 20 knots (17-23 mph/27-37 kmh). The chance for development into a tropical storm in the next 24 hours remains poor, but coastal Thailand are already experiencing rains and some gusty winds from System 93B.

NASA's TRMM and Aqua satellites continue to provide data to forecasters who are keeping a watchful eye on all of these tropical low pressure areas.

Evolutionary 'Winners' and 'Losers' Revealed in Collaborative Study

March 22, 2011-Houston-

In a study that literally analyzed competing bacteria fighting it out to the death, a University of Houston (UH) researcher and his colleagues identified evolutionary ‘winners’ and ‘losers.’ Continuing research to understand the basis of these fates may become a useful tool is designing roadblocks to antibiotic resistance.

In collaboration with scientists at Michigan State University (MSU), UH evolutionary biologist Timothy Cooper and his graduate student Utpala Shrestha were co-authors on a paper titled “Second-Order Selection for Evolvability in a Large Escherichia coli Population.” The report appeared March 18 in Science, the world’s leading journal of original scientific research, global news and commentary.

“The project found that bacteria growing for thousands of generations in an environment containing glucose as the only food had evolved to be better at getting better,” Cooper said. “We found that two lineages of bacteria arose and competed in a single experimental population. The lineage that initially grew more slowly, yet had the potential to evolve more rapidly, was the evolutionary ‘winner.’ This is surprising because it’s usually thought that competition is decided by what competitors can do now and not what they are capable of in the future.”

As genetic changes occurred, making some individuals better competitors on the glucose food, other individuals that did not quickly get their own beneficial mutations were outcompeted and went extinct. Down the line, understanding the benefits of evolving quickly like this will be a useful tool to predict such things as antibiotic resistance and the evolution of infectious disease. Cooper said this knowledge may one day help scientists design intervention strategies that make the evolution of these traits less likely to occur.

The work done by Cooper and Shrestha at UH established the specific genetic changes occurring during this bacterial evolution experiment that caused the change in their ability to evolve further. They discovered the genetic change that was important for determining which bacteria would prevail and which were destined to become extinct.

“Our collaborators isolated individual bacteria from a population that had evolved for 500 generations and sequenced their entire DNA genome to determine all the changes that had occurred,” Cooper said. “By isolating these changes and adding them in defined combinations back into the original ancestral strain, we were able to determine their individual effects.”

Reminiscent of Aesop’s lesson that ‘slow and steady wins the race,’ Cooper adds that even bacteria can benefit from a long-term view, with their experiment showing that bacteria that adapted, slowly but consistently, outcompeted those that initially grew quickly but then ran out of ways to improve.

With much of his work based on experimental evolution, which is the lab-based study of evolving populations, Cooper’s motivation for this experiment comes from wanting to understand the factors involved in evolution of organisms to better fit their environments. Using bacterial and computational experimental systems he aims to identify and integrate these mechanisms and examine how they depend on genetic and environmental factors.

“Bacteria provide an ideal model system to address these questions, because they evolve so quickly, undergoing thousands of generations in only a few years,” Cooper said. “Additionally, we can now sequence their entire genomes and determine the genetic changes that lead to improvements in their ability to grow.”

Funded by the National Science Foundation and the Defense Advanced Research Projects Agency, this work was a multidisciplinary effort done in collaboration with researchers in zoology, microbiology and molecular genetics at MSU. In addition to UH’s Cooper and Shrestha, the MSU team consisted of Richard Lenski, Jeffrey Barrick, Robert Woods and Mark Kauth. Woods has since moved on to the University of Michigan and Barrick is currently at the University of Texas at Austin.

iMobot Rolls, Crawls and Creeps

An intelligent, reconfigurable modular robot invented by a UC Davis alumnus and a professor of mechanical and aerospace engineering is headed for commercial development with the help of a grant from the National Science Foundation.
Graham Ryland and Professor Harry Cheng hope their “iMobot” will be a useful research and teaching tool. They also say the technology could be used in industrial applications for rapidly prototyping complex robotics — and may eventually form the basis of robots for search-and-rescue operations in difficult terrain. The university has filed a patent on the robot.
Ryland and Cheng developed the iMobot while Ryland was studying for his master's degree in mechanical engineering and conducting research in Cheng’s Integration Engineering Laboratory at UC Davis.
A single iMobot module has four controllable degrees of freedom, with two joints in the center section and two wheels, one on each end. An individual module can drive on its wheels, crawl like an inchworm, or raise one end of its body and pan around as a camera platform.
Individual modules could be assembled into larger robots for particular tasks, such as a snakelike robot that could get into confined spaces, or a larger, wheeled robot for smoother terrain.
"We wanted to create a robot that was modular and could be assembled together, but was also mobile and useful by itself. We feel this hardware platform could drastically speed up university and industry research in the field of robotics," Ryland said.
Commercial robots are usually built for a specific application. But there is a lot of interest in modular robots -- machines made up of durable subunits that can function alone or be configured for a specific task.
The iMobot could be used as a testbed tool for engineers studying control systems for individual robots or groups of robots, Cheng said.
"It's very difficult to build the kind of robot with flexibility, modularity, and reconfigurability that people want to use for research and teaching," he said.
By using an off-the-shelf commercial robot like iMobot, researchers can focus on solving problems in areas such as artificial intelligence, robot collaboration, and reconfigurable and adaptive systems, without having to first develop the hardware part of the robot.
Currently, there are no commercial research-grade modular robots available, Ryland said.
Cheng and Ryland have formed a company, Barobo Inc., to develop the robot commercially. Ryland is the company’s president. Barobo recently received a small-business innovation research grant from the National Science Foundation to begin commercial development. The initial grant is for $150,000 over six months, with the opportunity to apply for another $500,000. The inventors hope to have the robot on the market by the end of this year.

Epigenomic Findings Illuminate Veiled Variants

Genes make up only a tiny percentage of the human genome. The rest, which has remained measurable but mysterious, may hold vital clues about the genetic origins of disease. Using a new mapping strategy, a collaborative team led by researchers at the Broad Institute of MIT and Harvard, Massachusetts General Hospital (MGH), and MIT has begun to assign meaning to the regions beyond our genes and has revealed how minute changes in these regions might be connected to common diseases. The researchers’ findings appear in the March 23 advance online issue of Nature.
The results have implications for interpreting genome-wide association studies – large-scale studies of hundreds or thousands of people in which scientists look across the genome for single “letter” changes or SNPs (single nucleotide polymorphisms) that influence the risk of developing a particular disease. The majority of SNPs associated with disease reside outside of genes and until now, very little was known about the functions of most of them.
“Our ultimate goal is to figure out how our genome dictates our biology,” said co-senior author Manolis Kellis, a Broad associate member and associate professor of computer science at MIT. “But 98.5 percent of the genome is non-protein coding, and those non-coding regions are generally devoid of annotation.”
The term “epigenome” refers to a layer of chemical information on top of the genetic code, which helps determine when and where (and in what types of cells) genes will be active. This layer of information consists of chemical modifications, or “chromatin marks,” that appear across the genetic landscape of every cell, and can differ dramatically between cell types.
In a previous study, the authors showed that specific combinations of these chromatin marks (known as “chromatin states”) can be used to annotate parts of the genome – namely to attach biological meaning to the stretches of As, Cs, Ts, and Gs that compose our DNA. However, many questions remained about how these annotations differ between cell types, and what these differences can reveal about human biology.
In the current study, the researchers mapped chromatin marks in nine different kinds of cells, including blood cells, liver cancer cells, skin cells, and embryonic cells. By looking at the chemical marks, the researchers were able to create maps showing the locations of key control elements in each cell type. The researchers then asked how chromatin marks change across cell types, and looked for matching patterns of activity between controlling elements and the expression of neighboring genes.
“We first annotated the elements and figured out which cell types they are active in,” said co-senior author Bradley Bernstein, a Broad senior associate member and Harvard Medical School (HMS) associate professor at Massachusetts General Hospital (MGH). “We could then begin to link the elements and put together a regulatory network.”
Having pieced together these networks connecting non-coding regions of the genome to the genes they control, the researchers could begin to interpret data from disease studies. The team studied a large compendium of genome-wide association studies (GWAS), looking to characterize non-coding SNPs associated with control regions in specific cell types.
“Across 10 association studies of various human diseases, we found a striking overlap between previously uncharacterized SNPs and the control region annotations in specific cell types,” said Kellis. “This suggests that these DNA changes are disrupting important regulatory elements and thus play a role in disease biology.”
The researchers confirmed the reliability of their approach by showing that SNPs were associated with the appropriate cell types. For example, SNPs from autoimmune diseases such as rheumatoid arthritis and lupus sit in regions that are only active in immune cells, and SNPs associated with cholesterol and metabolic disease sit in regions active in liver cells. While more in-depth, follow-up studies will be needed to confirm the biological significance of these connections, the current study can help guide the direction of these investigations.
“GWAS has identified hundreds of non-coding regions of the genome that influence human disease, but a major barrier to progress is that we remain quite ignorant of the functions of these non-coding regions,” said David Altshuler, deputy director at the Broad and an HMS professor at MGH, who was not involved in the study. “This remarkable and much-needed resource is a major step forward in helping researchers address that challenge.”
SNPs in the non-coding regions of the genome may have subtler biological effects than their counterparts that arise in genes because they can influence how much protein is produced. The researchers mainly focused on SNPs in enhancer regions, which help boost a gene’s expression, and their network connections to regulators that control them and genes that they target. Follow-up efforts can then focus on specific pieces of this network that could be targeted with drugs.
The team involved in this study hopes to expand its analysis to include many other cell types and map additional marks to expand their networks beyond enhancer regions. In the meantime, researchers involved in genome-wide association studies will be able to use the maps from this project to analyze non-coding SNPs in a new light.
“These maps can be used to come up with hypotheses about how the variants themselves are working and which ones are causal,” said Bernstein. “This resource now goes back to the GWAS community, which can use the maps to form and test new functional models.”
This research was supported by the National Human Genome Research Institute under an ENCODE grant, the Howard Hughes Medical Institute, the National Science Foundation, and the Sloan Foundation.
About the Broad Institute of Harvard and MIT
The Eli and Edythe L. Broad Institute of Harvard and MIT was launched in 2004 to empower this generation of creative scientists to transform medicine. The Broad Institute seeks to describe all the molecular components of life and their connections; discover the molecular basis of major human diseases; develop effective new approaches to diagnostics and therapeutics; and disseminate discoveries, tools, methods and data openly to the entire scientific community.
Founded by MIT, Harvard and its affiliated hospitals, and the visionary Los Angeles philanthropists Eli and Edythe L. Broad, the Broad Institute includes faculty, professional staff and students from throughout the MIT and Harvard biomedical research communities and beyond, with collaborations spanning over a hundred private and public institutions in more than 40 countries worldwide. For further information about the Broad Institute, go to http://www.broadinstitute.org.