Navigation
Powered by Squarespace
Twitter
Arquivos
Downloads

Entries in Terra (16)

Sunday
Sep222013

Evidence of Extraterrestrial Life found in Earth's Atmosphere --Challenged!

Scientists from the University of Sheffield claim they have discovered proof of extraterrestrial life. Their evidence? The team launched a balloon 16 miles into the stratosphere, and it came back carrying small biological organisms. Professor Milton Wainwright, who led the team, is "95 percent certain that these biological entities are of extraterrestrial origin."

"If we're right, it means that there's life in space, and it's coming to earth. It means that life on earth probably originated in space. Most people will assume that these biological particles must have just drifted up to the stratosphere from Earth, but it is generally accepted that a particle of the size found cannot be lifted from Earth to heights of, for example, 27 kilometers."

But astronomer Phil Plait say's it's looks like the 'biological material' the scientists found probably didn't come from outer space: "There are a lot of reasons to think this claim is unfounded, but one is right in their very paper. The diatom ... appears clean, even pristine. As they themselves say: It is noticeable that the diatom fragment is remarkably clean and free of soil or other solid material ... which would be incredibly unlikely if it did come from a comet or a meteoroid, he wrote in Slate.

Plait also doubts the idea that a microorganism from Earth couldn't be held aloft by wind and turbulence for a long period of time acccording to the University of Sheffield scientists' theory.

However, the scientist who led the research, Chandra Wickramasinghe, Director of the Buckingham Centre for Astrobiology, University of Buckingham, is a proponent of the theory of panspermia, which according to Plait, could affect his research. Wickramasinghe and the late English astronomer Sir Fred Hoyle co-developed a theory known as "panspermia," which suggests that life exists throughout the universe and is distributed by meteoroids and asteroids.

In a paper called "Fossil Diatoms In A New Carbonaceous Meteorite" that appeared in the controversila Journal of Cosmology, Wickramasinghe claimed to have found strong evidence that life exists throughout the universe based on his study of the reported remains of a large meteorite (see image below right) that fell near the Sri Lanka village of Polonnaruwa on Dec. 29, 2012.

"Wickramasinghe jumps on everything, with little or no evidence, and says it's from outer space, so I think there's a case to be made for a bias on his part," says Plait reported in Slate.

The scientists still have one more test to perform --"isotope fractionation"--which will determine whether the ratio of certain isotopes is consistent with that of organisms from earth. Professor Milton Wainwright is confident that they they be extraterrestrial in origin. Stay tuned!

The image at the top of the page shows organic carbon in a ordinary chondritic meteorite obtained using a scanning transmission X-ray microscope at the Advanced Light Source, Lawrence Berkeley Laboratory. The sample was obtained using a focused ion beam electron microscope (mill). In this image, carbon is highlighed in red, iron in blue and calcium is green.The history of the early Solar System is recorded in the molecular structure of extraterrestrial organic solids. 

The Daily Galaxy via Slate and PBS

Image credit: https://www.gl.ciw.edu/news/extraterrestrial_carbon, provided by George Cody, Conel Alexander, and Larry Nittler.

Source:

http://www.dailygalaxy.com/my_weblog/2013/09/claims-of-extraterrestrial-life-found-in-earths-stratosphere-challenged.html

Sunday
Jun092013

2011 Draconid Meteor Shower Deposited a Ton of Meteoritic Material On Earth

With more than 400 meteors per hour, the 2011 Draconid meteor shower was one of the most intense meteor showers in the last decade. (Credit: © F. Pruneda)

About a ton of material coming from comet 21P/Giacobini-Zinner was deposited in the Earth's atmosphere on October 8th and 9th, 2011 during one of the most intense showers of shooting starts in the last decade, which registered an activity of more than 400 meteors per hour.

Every 6.6 years, the comet Giacobini-Zinner circulates through the inner solar system and passes through the perihelion, the closest point to the Sun of its orbit. Then, the comet sublimates the ices and ejects a large number of particles that are distributed in filaments. The oldest of these particles have formed a swarm that Earth passes trough every year in early October. The result is a Draconid meteor shower -- meteors from this comet come from the northern constellation Draco -- which hits Earth's atmosphere at about 75,000 km/h, a relatively slow speed in comparison with other meteoric swarms.

Josep Maria Trigo, researcher from the CSIC Institute of Space Sciences (ICE), states: "When a comet approaches the Sun, it sublimates part of its superficial ice and the gas pressure drives a huge number of particles that adopt orbits around the Sun, forming authentic swarms. The study shows that in the evening from October 8th to 9th 2011, the Earth intercepted three dense spindles of particles left behind by the comet when it crossed through the perihelion."

The researchers, who published their results in the Monthly Notices of the Royal Astronomical Society magazine, have obtained the orbits of twenty meteors in the solar system. Thus, they have confirmed the origin of the particles that caused the outbreak in that periodic comet. For this, they have count on 25 video-detection stations operated by the Spanish Meteor and Firewall Network (SPMN) and the collaboration of amateur astronomers.

Two of those filaments of meteoroids, which had been theoretically predicted already, have been identified by scientists with those left by the comet in 1874, 1894 and 1900. Nevertheless, researchers have confirmed that there was another dense region intercepted by Earth which had not been predicted and that involves a new challenge for theoretical models.

In a second article, researchers analyze the chemical composition of six fireballs from that swarm of the comet recorded during the outbreak. José María Madiedo, researcher from the University of Huelva and coordinator of this second study, asserts: "One of them, with an initial mass of 6 kg and nearly half a meter in diameter, named Lebrija in honor of the city it over flew, came to compete with the brightness of the moon that night."

The six analyzed fragments have a possibly similar composition to the carbonaceous chondrites (a type of organic-rich meteorites) but they are much more fragile. Trigo emphasizes: "They don't seem to have suffered any chemical alteration during their brief stay in the interplanetary environment, which turns out to be very interesting to confirm the astrobiological role of these particles in the continuous transportation of water and organic material to the Earth."

Source:

http://www.sciencedaily.com/releases/2013/06/130606141046.htm

Sunday
Mar242013

Is Earth Undergoing a 6th Mass Extinction? --"99.9% of all Past Species Extinct"

Of all species that have existed on Earth, 99.9 percent are now extinct. Many of them perished in five cataclysmic events. The classical "Big Five" mass extinctions identified by Raup and Sepkoski are widely agreed upon as some of the most significant: End Ordovician, Late Devonian, End Permian, End Triassic, and End Cretaceous. According to a recent poll, seven out of ten biologists think we are currently in the throes of a sixth mass extinction. Some say it could wipe out as many as 90 percent of all species living today. Other scientists dispute such dire projections.

“If you look at the fossil record, it is just littered with dead bodies from past catastrophes,” observes University of Washington paleontologist Peter Ward. Ward says that only one extinction in Earth’s past was caused by an asteroid impact – the event 65 million years ago that ended the age of the dinosaurs. All the rest, he claims, were caused by global warming.

Ward's study, Under a Green Sky, explores extinctions in Earth’s past and predicts extinctions to come in the future. Ward demonstrates that the ancient past is not just of academic concern. Everyone has heard about how an asteroid did in the dinosaurs, and NASA and other agencies now track Near Earth objects.

Unfortunately, we may not be protecting ourselves against the likeliest cause of our species' demise. Ward explains how those extinctions happened, and then applies those chilling lessons to the modern day: expect drought, superstorms, poison–belching oceans, mass extinction of much life, and sickly green skies.

The significant points Ward stresses are geologically rapid climate change has been the underlying cause of most great "extinction" events. Those events have been, observed Harvard evolutionary biologist Stephen Gould, major drivers of evolution.

Drastic climate change has not always been gradual; there is solid empirical evidence of catastrophic warming events taking place in centuries, perhaps even decades. The impact of atmospheric warming is most potent in its modification of ocean chemistry and of circulating currents; warming inevitably leads to non-mixing anoxic dead seas.

We are already in the middle, not the beginning, of an anthropogenic global warming, caused by agriculture and deforestation, which began some 10,000 years ago but which is now accelerating exponentially; though the earliest wave of anthropogenic warming has been stabilizing and beneficial to human development, it appears to have the potential for catastrophic effects within a lifetime or two.

Looking at the ancient evidence, Ward notes that ice caps began to shrink. "Melting all the ice caps causes a 75-meter increase in sea level will remove every coastal city on our planet." It will also cover earth's most productive farmland, the author warns, adding, "It will happen if we do not somehow control CO2 rise in the atmosphere."

An analysis of the geological record of the Earth's sea level, carried out by scientists at Princeton and Harvard universities supports Ward using a novel statistical approach that reveals the planet's polar ice sheets are vulnerable to large-scale melting even under moderate global warming scenarios. Such melting would lead to a large and relatively rapid rise in global sea level.

According to the analysis, an additional 2 degrees of global warming could commit the planet to 6 to 9 meters (20 to 30 feet) of long-term sea level rise. This rise would inundate low-lying coastal areas where hundreds of millions of people now reside. It would permanently submerge New Orleans and other parts of southern Louisiana, much of southern Florida and other parts of the U.S. East Coast, much of Bangladesh, and most of the Netherlands, unless unprecedented and expensive coastal protection were undertaken. And while the researchers' findings indicate that such a rise would likely take centuries to complete, if emissions of greenhouse gases are not abated, the planet could be committed during this century to a level of warming sufficient to trigger this outcome.

The last interglacial stage provides a historical analog for futures with a fairly moderate amount of warming; the high sea levels during the stage suggest that significant chunks of major ice sheets could disappear over a period of centuries in such futures.

Previous geological studies of sea level benchmarks such as coral reefs and beaches had shown that, at many localities, local sea levels during the last interglacial stage were higher than today. But local sea levels differ from those in this earlier stage; one major contributing factor is that the changing masses of the ice sheets alter the planet's gravitational field and deform the solid Earth.

As a consequence, inferring global sea level from local geological sea level markers requires a geographically broad data set, a model of the physics of sea level, and a means to integrate the two. The study's authors provide all three, integrating the data and the physics with a statistical approach that allows them to assess the probability distribution of past global sea level and its rate of change.

The findings indicate that sea level during the last interglacial stage rose for centuries at least two to three times faster than the recent rate, and that both the Greenland and West Antarctic ice sheet likely shrank significantly and made important contributions to sea level rise. However, the relative timing of temperature change and sea level change during the last interglacial stage is fairly uncertain, so it is not possible to infer from the analysis how long an exposure to peak temperatures during this stage was needed to commit the planet to peak sea levels.

A similar study by a team of scientists from Bristol, Cardiff and Texas A&M universities braved the lions and hyenas of a small East African village to extract microfossils from rocks which have revealed the level of CO2 in the Earth’s atmosphere at the time of the formation of the ice-cap. New carbon dioxide data confirm that formation of the Antarctic ice-cap some 33.5 million years ago was due to declining carbon dioxide in the atmosphere.

Professor Paul Pearson from Cardiff University’s School of Earth and Ocean Sciences, who led the mission to the remote East Africa village of Stakishari said: “About 34 million years ago the Earth experienced a mysterious cooling trend. Glaciers and small ice sheets developed in Antarctica, sea levels fell and temperate forests began to displace tropical-type vegetation in many areas.

“The period culminated in the rapid development of a continental-scale ice sheet on Antarctica, which has been there ever since. We therefore set out to establish whether there was a substantial decline in atmospheric carbon dioxide levels as the Antarctic ice sheet began to grow.”

Co-author Dr Bridget Wade from Texas A&M University Department of Geology and Geophysics added: “This was the biggest climate switch since the extinction of the dinosaurs 65 million years ago. Our study is the first to provide a direct link between the establishment of an ice sheet on Antarctica and atmospheric carbon dioxide levels and therefore confirms the relationship between carbon dioxide levels in the atmosphere and global climate.”

Geologists have long speculated that the formation of the Antarctic ice-cap was caused by a gradually diminishing natural greenhouse effect. The study’s findings, published in Nature online, confirm that atmospheric CO2 started to decline about 34 million years ago, during the period known to geologists as the Eocene - Oligocene climate transition, and that the ice sheet began to form about 33.5 million years ago when CO2 in the atmosphere reached a tipping point of around 760 parts per million.

The team mapped large expanses of bush and wilderness and pieced together the underlying local rock formations using occasional outcrops of rocks and stream beds. Eventually they discovered sediments of the right age near a traditional African village called Stakishari. By assembling a drilling rig and extracting hundreds of meters of samples from under the ground they were able to obtain exactly the piece of Earth's history they had been searching for.

Ward is encouraged that we are beginning to make changes in their daily lives and demanding action from their leaders -"that we are on a planet that has violent convulsions, and that we humans are playing with nature in such a way that we could recreate what were some really awful times in earth's history, that we really tinker with the earth's atmosphere at our peril."

The image at the top of the page shows a a very well-preserved example of a Paleoniscoid fish thought related to Rhabdolepis. The paleoniscoids were the first ray-finned fish, a feature readily seen here. Some 40 or more families appeared during the Carboniferous and Permian Periods. This taxon went extinct during the Lower Permian.

Source: 

www.dailygalaxy.com

Friday
Mar012013

Radiation ring around Earth mysteriously appears, then dissipates

RING AROUND THE WORLD In September, a third ring appeared between the two known Van Allen radiation belts that girdle the Earth thousands of miles above. Johns Hopkins Univ. Applied Physics Laboratory/Univ. of Colorado Boulder Laboratory for Atmospheric and Space Physics

High above Earth’s surface float two rings of energetic charged particles, and for about four weeks in September, they were joined by a third. The temporary ring may have formed in response to a solar shock wave that passed by Earth, researchers report online February 28 in Science.

The discovery could force scientists to revisit decades of ideas about the structure of the Van Allen belts, donut-shaped rings of radiation trapped in orbit by the planet’s magnetic field. Those revisions could improve predictions of space weather and scientists’ understanding of the space environment near Earth, resulting in better protection for manned and unmanned spacecraft that navigate those areas.

“It's a very important discovery,” says Yuri Shprits of the University of California, Los Angeles, who wasn’t involved in the study. “Over half a century after the discovery of the radiation belts, this most important region of space where most of the satellites operate presents us with new puzzles.”

Until the discovery, researchers thought the Van Allen belts always contained two zones of high-energy particles: an inner zone made mostly of protons and some electrons, and an outer zone dominated by electrons. A sparsely populated area separates the zones. The belts run from the top of the atmosphere, some 1,000 kilometers above Earth’s surface, to as far as five or six Earth radii from the planet’s surface.

NASA’s early Explorer and Pioneer spacecraft discovered and mapped the belts in 1958. Scientists have since learned that the radiation reservoirs can fluctuate dramatically, especially in the outer zone. Disturbances such as solar storms that disrupt Earth’s magnetic field can cause the outer zone to change shape or to gain or lose particles.

On August 30, NASA launched twin space probes to study the fine details of such disruptions and take a closer look at the belts’ composition. The probes repeatedly pass through the belts, completing an orbit about every nine hours. Just days after the probes launched, researchers led by Daniel Baker of the University of Colorado Boulder watched a third ring grow between the two existing belts, and the outer ring to expand. After a month, it disappeared, as did the outer zone, temporarily leaving only one ring. In the following months, the normal two-ring structure gradually returned.

“I'm delighted that observations so early in the program could reveal such new things,” Baker says.

A sun-produced shock wave that passed Earth in early September may have created the third ring, the researchers propose. Another shock wave came through in early October and may have obliterated the outer two rings.

Researchers don’t know how often a third ring forms. “I would be amazed if in the past 4.5 billion years this hasn't happened before,” Baker says. The probes could provide answers about the third ring’s frequency.

No reports have emerged of satellite damage from the third ring’s brief existence, though operators often do not reveal that information, says Joe Kunches of the National Weather Service’s Space Weather Prediction Center.

Scientists will continue to comb through data from the probes to refine theoretical and observational knowledge of the belts. The probes’ findings could also help engineers design spacecraft better protected against the belts’ harmful radiation. And forecasters could use real-time data feeds from the probes to give satellite operators better warnings and predictions about the belts’ activity. “That's what we're really excited about,” Kunches says.

Source:

http://www.sciencenews.org/view/generic/id/348664/title/Radiation_ring_around_Earth_mysteriously_appears_then_dissipates


Wednesday
Feb272013

NASA's Aquarius Sees Salty Shifts

NASA has released the first full year of validated ocean surface salinity data from the agency's Aquarius instrument aboard the Aquarius/SAC-D spacecraft. The data cover the period from Dec. 2011 through Dec. 2012. Red colors represent areas of high salinity, while blue shades represent areas of low salinity. Among the prominent salinity features visible in this view are the large area of highly saline water across the North Atlantic. This area, the saltiest anywhere in the open ocean, is analogous to deserts on land, where little rainfall and much evaporation occur. Aquarius is a focused effort to measure ocean surface salinity and will provide the global view of salinity variability needed for climate studies. The mission is a collaboration between NASA and the Space Agency of Argentina (Comision Nacional de Actividades Espaciales). Image credit: NASA/GSFC/JPL-Caltech

The colorful images chronicle the seasonal stirrings of our salty world: Pulses of freshwater gush from the Amazon River's mouth; an invisible seam divides the salty Arabian Sea from the fresher waters of the Bay of Bengal; a large patch of freshwater appears in the eastern tropical Pacific in the winter. These and other changes in ocean salinity patterns are revealed by the first full year of surface salinity data captured by NASA's Aquarius instrument. 

"With a bit more than a year of data, we are seeing some surprising patterns, especially in the tropics," said Aquarius Principal Investigator Gary Lagerloef, of Earth & Space Research in Seattle. "We see features evolve rapidly over time." 

Launched June 10, 2011, aboard the Argentine spacecraft Aquarius/Satelite de Aplicaciones Cientificas (SAC)-D, Aquarius is NASA's first satellite instrument specifically built to study the salt content of ocean surface waters. Salinity variations, one of the main drivers of ocean circulation, are closely connected with the cycling of freshwater around the planet and provide scientists with valuable information on how the changing global climate is altering global rainfall patterns. 

The salinity sensor detects the microwave emissivity of the top approximately 1 inch (1 to 2 centimeters) of ocean water - a physical property that varies depending on temperature and saltiness. The instrument collects data in 240-mile-wide (386 kilometers) swaths in an orbit designed to obtain a complete survey of global salinity of ice-free oceans every seven days. 

The Changing Ocean 

The animated version of Aquarius' first year of data unveils a world of varying salinity patterns. The Arabian Sea, nestled up against the dry Middle East, appears much saltier than the neighboring Bay of Bengal, which gets showered by intense monsoon rains and receives freshwater discharges from the Ganges and other large rivers. Another mighty river, the Amazon, releases a large freshwater plume that heads east toward Africa or bends up north to the Caribbean, depending on the prevailing seasonal currents. Pools of freshwater carried by ocean currents from the central Pacific Ocean's regions of heavy rainfall pile up next to Panama's coast, while the Mediterranean Sea sticks out in the Aquarius maps as a very salty sea. 

One of the features that stand out most clearly is a large patch of highly saline water across the North Atlantic. This area, the saltiest anywhere in the open ocean, is analogous to deserts on land, where little rainfall and a lot of evaporation occur. A NASA-funded expedition, the Salinity Processes in the Upper Ocean Regional Study (SPURS), traveled to the North Atlantic's saltiest spot last fall to analyze the causes behind this high salt concentration and to validate Aquarius measurements. 

"My conclusion after five weeks out at sea and analyzing five weekly maps of salinity from Aquarius while we were there was that indeed, the patterns of salinity variation seen from Aquarius and by the ship were similar," said Eric Lindstrom, NASA's physical oceanography program scientist, NASA Headquarters, Washington, and a participant of the SPURS research cruise. 

Future Goals 

"The Aquarius prime mission is scheduled to run for three years but there is no reason to think that the instrument could not be able to provide valuable data for much longer than that," said Gene Carl Feldman, Aquarius project manager at NASA's Goddard Space Flight Center in Greenbelt, Md. "The instrument has been performing flawlessly and our colleagues in Argentina are doing a fantastic job running the spacecraft, providing us a nice, stable ride." 

In future years, one of the main goals of the Aquarius team is to figure out ways to fine-tune the readings and retrieve data closer to the coasts and the poles. Land and ice emit very bright microwave emissions that swamp the signal read by the satellite. At the poles, there's the added complication that cold polar waters require very large changes in their salt concentration to modify their microwave signal. 

Still, the Aquarius team was surprised by how close to the coast the instrument is already able to collect salinity measurements. 

"The fact that we're getting areas, particularly around islands in the Pacific, that are not obviously badly contaminated is pretty remarkable. It says that our ability to screen out land contamination seems to be working quite well," Feldman said. 

Another factor that affects salinity readings is intense rainfall. Heavy rain can affect salinity readings by attenuating the microwave signal Aquarius reads off the ocean surface as it travels through the soaked atmosphere. Rainfall can also create roughness and shallow pools of freshwater on the ocean surface. In the future, the Aquarius team wants to use another instrument aboard Aquarius/SAC-D, the Argentine-built Microwave Radiometer, to gauge the presence of intense rain simultaneously to salinity readings, so that scientists can flag data collected during heavy rainfall. 

An ultimate goal is combining the Aquarius measurements with those of its European counterpart, the Soil Moisture and Ocean Salinity satellite (SMOS) to produce more accurate and finer maps of ocean salinity. In addition, the Aquarius team, in collaboration with researchers at the U.S. Department of Agriculture, is about to release its first global soil moisture dataset, which will complement SMOS' soil moisture measurements. 

"The first year of the Aquarius mission has mostly been about understanding how the instruments and algorithms are performing," Feldman said. "Now that we have overcome the major hurdles, we can really begin to focus on understanding what the data are telling us about how the ocean works, how it affects weather and climate, and what new insights we can gain by having these remarkable salinity measurements." 

Aquarius was built by NASA's Jet Propulsion Laboratory, Pasadena, Calif.; and NASA Goddard. JPL managed Aquarius through its commissioning phase and is archiving mission data. Goddard now manages Aquarius mission operations and processes science data. Argentina's space agency, Comision Nacional de Actividades Espaciales (CONAE), provided the SAC-D spacecraft, optical camera, thermal camera with Canada, microwave radiometer, sensors from various Argentine institutions and the mission operations center. France and Italy also contributed instruments. For more information about NASA's Aquarius mission, visit: http://www.nasa.gov/aquarius . 

For a narrated global tour of Aquarius ocean surface salinity measurements, see: http://www.youtube.com/watch?v=5xQP_B18vMw . A visualization showing changes in global ocean surface salinity as measured by Aquarius from Dec. 2011 through Dec. 2012 can be seen at: http://www.youtube.com/watch?v=RJVnZnZUUYc . - See more at: http://www.jpl.nasa.gov/news/news.php?release=2013-074&cid=release_2013-074#sthash.B43H9PQd.dpuf

Source:

http://www.jpl.nasa.gov/news/news.php?release=2013-074&cid=release_2013-074