|Greenhouse Asteroid? |
Ice Volcanoes on Enceladus!
Studying Stardust, Pluto's Moons!
The Other Side of the Sun!
|Greenhouse Asteroid? |
University of Leicester News Release
March 14, 2006 - A new theory to explain global warming was revealed at a meeting at the University of Leicester (UK) and is being considered for publication in the journal "Science First Hand".
The controversial theory has nothing to do with burning fossil fuels and atmospheric carbon dioxide levels. According to Vladimir Shaidurov of the Russian Academy of Sciences, the apparent rise in average global temperature recorded by scientists over the last hundred years or so could be due to atmospheric changes that are not connected to human emissions of carbon dioxide from the burning of natural gas and oil.
Shaidurov explained how changes in the amount of ice crystals at high altitude could damage the layer of thin, high altitude clouds found in the mesosphere that reduce the amount of warming solar radiation reaching the earth's surface.
Shaidurov has used a detailed analysis of the mean temperature change by year for the last 140 years and explains that there was a slight decrease in temperature until the early twentieth century. This flies in the face of current global warming theories that blame a rise in temperature on rising carbon dioxide emissions since the start of the industrial revolution.
Shaidurov, however, suggests that the rise, which began between 1906 and 1909, could have had a very different cause, which he believes was the massive Tunguska Event, which rocked a remote part of Siberia, northwest of Lake Baikal on the 30th June 1908.
Trees felled by the Tunguska blast. Photograph from Kulik's
1927 expedition. (Photo N. A. Strukov, 1928)
The Tunguska Event, sometimes known as the Tungus Meteorite is thought to have resulted from an asteroid or comet entering the earth's atmosphere and exploding. The event released as much energy as fifteen one-megaton atomic bombs. As well as blasting an enormous amount of dust into the atmosphere, felling 60 million trees over an area of more than 2000 square kilometres.
Shaidurov suggests that this explosion would have caused "considerable stirring of the high layers of atmosphere and change its structure." Such meteoric disruption was the trigger for the subsequent rise in global temperatures.
Global warming is thought to be caused by the "greenhouse effect". Energy from the sun reaches the earth's surface and warms it, without the greenhouse effect most of this energy is then lost as the heat radiates back into space.
However, the presence of so-called greenhouse gases at high altitude absorb much of this energy and then radiate a proportion back towards the earth's surface. Causing temperatures to rise.
Many natural gases and some of those released by conventional power stations, vehicle and aircraft exhausts act as greenhouse gases. Carbon dioxide, natural gas, or methane, and chlorofluorocarbons (CFCs) are all potent greenhouse gases.
Carbon dioxide and methane are found naturally in the atmosphere, but it is the gradual rise in levels of these gases since the industrial revolution, and in particular the beginning of the twentieth century, that scientists have blamed for the gradual rise in recorded global temperature. Attempts to reverse global warming, such as the Kyoto Protocol, have centred on controlling and even reducing CO2 emissions.
However, the most potent greenhouse gas is water, explains Shaidurov and it is this compound on which his study focuses. According to Shaidurov, only small changes in the atmospheric levels of water, in the form of vapour and ice crystals can contribute to significant changes to the temperature of the earth's surface, which far outweighs the effects of carbon dioxide and other gases released by human activities. Just a rise of 1% of water vapour could raise the global average temperature of Earth's surface more then 4 degrees Celsius.
Asteroid collision with Earth (NASA)
The role of water vapour in controlling our planet's temperature was hinted at almost 150 years ago by Irish scientist John Tyndall. Tyndall, who also provided an explanation as to why the sky is blue, explained the problem: "The strongest radiant heat absorber, is the most important gas controlling Earth's temperature. Without water vapour, he wrote, the Earth's surface would be 'held fast in the iron grip of frost'." Thin clouds at high altitude allow sunlight to reach the earth's surface, but reflect back radiated heat, acting as an insulating greenhouse layer.
Water vapour levels are even less within our control than CO2 levels. According to Andrew E. Dessler of the Texas A & M University writing in 'The Science and Politics of Global Climate Change', "Human activities do not control all greenhouse gases, however. The most powerful greenhouse gas in the atmosphere is water vapour, he says, "Human activities have little direct control over its atmospheric abundance, which is controlled instead by the worldwide balance between evaporation from the oceans and precipitation."
As such, Shaidurov has concluded that only an enormous natural phenomenon, such as an asteroid or comet impact or airburst, could seriously disturb atmospheric water levels, destroying persistent so-called 'silver', or noctilucent, clouds composed of ice crystals in the high altitude mesosphere (50 to 85km). The Tunguska Event was just such an event, and coincides with the period of time during which global temperatures appear to have been rising the most steadily - the twentieth century. There are many hypothetical mechanisms of how this mesosphere catastrophe might have occurred, and future research is needed to provide a definitive answer.
Professor Vladimir Shaidurov is an expert in Numerical Analysis and Mathematical Modelling, and the Corresponding member of Russian Academy of Sciences. For development of multigrid methods he achieved the highest Russian prize in science (together with Profs Fedorenko and Bachvalov) - the State Prize (2004). He visited University of Leicester in April 2005.
Shaidurov's paper "Atmospheric hypotheses of Earth's global warming" is available online at http://arxiv.org/abs/physics/0510042
University of Leicester - http://www.leicester.ac.uk
|Ice Volcanoes on Enceladus! |
Saturn’s moon Enceladus. (NASA)
Max Planck Society News Release
March 14, 2006 - Scientists from the Max Planck Institute for Nuclear Physics and the University of Potsdam have found ice volcanoes - or what could be called "ice geysers" - on the surface of Saturn’s moon Enceladus.
They made the discovery using a combination of computer simulations and measurements from the dust detector on the space probe CASSINI. The ice volcanoes are located at geologically young, warm structures in the icy moon’s southern polar region. The ice particles probably are created from steam deep in crevices.
Volcanic activity is now known to exist in three bodies in our solar system: Enceladus, Earth, and Jupiter’s moon Io (Science, March 10, 2006).
Saturn’s E ring, the largest ring around any planet in our solar system, is not only remarkable for its huge size. What is also astounding is that current optical measurements show it to be made of ice particles of nearly equal size - a radius of 0.3 to 2 micrometres.
The icy moon Enceladus was, however, expected to feed the ring with significantly larger pieces. The ring’s mass distribution must thus somehow be tied up with the dynamics of the particles. Until now, however, scientists did not know how. Directly measuring ice particles near Enceladus promised to deliver a better understanding of the E Ring’s complex nature.
On July 14, 2005, the CASSINI space probe came within 175 kilometres of Enceladus, which is suspected of being the source of Saturn’s E Ring. This made it possible to measure dust distribution deep inside the area of Enceladus’ gravitational pull. The scientists could thus investigate how the moon refreshed the ring with dust particles.
An artificially colored image of Saturn’s moon Enceladus. Clearly
visible over the southern polar region are dust fountains, caused
by ice volcanic activity (lower left corner). (NASA)
Until now, it was assumed that new ice particles were created by interplanetary micrometeorites, or ring particles themselves, bombarding the moon’s surface. In this model, most of the fresh particles form a nearly isotopic dust cloud around the moon. In the other model, faster particles feed the ring. Indeed, the dust detector on the space probe GALILEO had already discovered dust clouds surrounding Jupiter’s Galilean moons.
Measurements from the High Rate Detector (HRD) of CASSINI’s "Cosmic Dust Analyser" (CDA), taken by scientists from the Max Planck Institute for Nuclear Physics in Heidelberg and the University of Chicago are however not consistent with this assumption. Observations showed that the maximum rate of impact was reached before the probe moved to its closest point to Enceladus.
This can only be explained if there exists a strong anisotropic - that is, directionally dependent - dust distribution on the moon.
The dust detector was not the only instrument which came to show unexpected discoveries. Photographs of Enceladus’ southern polar region clearly showed geologically young structures. Infrared images also indicated a warmer area - a "hot spot" - in that southern region.
This led scientists from the University of Potsdam to model dust distribution on the moon under the assumption that there is an additional, tightly confined, dust source on its surface. The models indicated a contained dust source in the southern polar region. This turned out to be consistent with the probe’s measurements.
This convincing match between models and HRD measurements (see image 2) led the Cassini camera team to look for, and find, volcanic activity. Enceladus is thus the second moon in our solar system where volcanic activity has been discovered
Max Planck Society - http://www.mpg.de/english
|Studying Stardust |
This image illustrates one of several ways scientists have begun
extracting comet particles from the Stardust spacecraft's collector.
First, a particle and its track are cut out of the collector material,
called aerogel, in a wedge-shaped slice called a keystone. A
specialized silicon pickle fork is then used to remove the keystone
from the remaining aerogel for further analysis. (NASA/ JPL-
Caltech/ University of California, Berkeley)
University of Washington News Release
March 13, 2006 - Scientists analyzing recent samples of comet dust have discovered minerals that formed near the sun or other stars. That means materials from the innermost part of the solar system could have traveled to the outer reaches, where comets formed.
"The interesting thing is we are finding these high-temperature minerals in materials from the coldest place in the solar system," said Donald Brownlee, a University of Washington astronomer who is principal investigator, or lead scientist, for NASA's Stardust mission.
Among the finds in material brought back by Stardust is olivine, a mineral that is the primary component of the green sand found on some Hawaiian beaches.
It is among the most common minerals in the universe, but finding it in comet Wild 2 could challenge a common view of how such crystalline materials form.
Olivine is a compound of iron, magnesium and other elements, in which the iron-magnesium mixture ranges from being nearly all iron to nearly all magnesium. The Stardust sample is primarily magnesium.
Many astronomers believe olivine crystals form from glass when it is heated close to stars, Brownlee said. One puzzle is why such crystals came from Wild 2, a comet that formed beyond the orbit of Neptune when the solar system began some 4.6 billion years ago.
This image shows a comet particle collected by the
Stardust spacecraft. The particle is made up of the
silicate mineral forsterite, which can found on Earth
in gemstones called peridot. It is surrounded by a thin
rim of melted aerogel, the substance used to collect
the comet dust samples. The particle is about 2
micrometers across. (NASA)
"It's certain such materials never formed inside this icy, cold body," Brownlee said.
The comet traveled the frigid environs of deep space until 1974, when a close encounter with Jupiter brought it to the inner solar system. Besides olivine, the dust from Wild 2 also contains exotic, high-temperature minerals rich in calcium, aluminum and titanium.
"I would say these materials came from the inner, warmest parts of the solar system or from hot regions around other stars," Brownlee said.
"The issue of the origin of these crystalline silicates still must be resolved. With our advanced tools, we can examine the crystal structure, the trace element composition and the isotope composition, so I expect we will determine the origin and history of these materials that we recovered from Wild 2."
Brownlee is among scientists presenting the first concrete findings from the Stardust sample this week at the annual Lunar and Planetary Science Conference in League City, Texas.
Stardust's captured dust from comet Wild 2 in January 2004, and the sample-return capsule parachuted to the Utah desert on Jan. 15 to complete the seven-year mission. The samples from Wild 2 were taken to the National Aeronautics and Space Administration's Johnson Space Center in Houston, and from there they have been sent to about 150 scientists around the world, who are using a variety of techniques to determine the properties of the comet grains.
A heart-shaped comet particle extracted from aerogel.
Returned to Earth by Stardust. (NASA/JPL)
The grains are very tiny, most much smaller than a hair's width. But there appear to be thousands of them embedded in the unique glassy substance called aerogel that was used to snare the particles propelled from the body of the comet. A grain of 10 microns – one-hundredth of a millimeter – can be sliced into hundreds of samples for scientists to study.
"It's not much, but still it's so much that we're almost overwhelmed," Brownlee said, noting that his lab has only worked on two particles so far. "The first grain we worked on, we haven't even cut into the main part of the particle yet."
The material, which came from the very outer edges of the solar system, has been preserved since the start of the solar system in the deep freeze of space 50 times farther away from the sun than Earth is. Brownlee believes the material will provide key information about how the solar system was formed.
"A fundamental question is how much of the comet material came from outside the solar system and how much of it came from the solar nebula, from which the planets were formed," he said. "We should be able to answer that question eventually."
High-resolution images available through this release at http://www.uwnews.org or at http://www.nasa.gov/stardust
|The World's Fastest Robot! |
|Fatronik News Release |
March 14, 2006 - Fatronik has launched the most rapid robot in the world at the BIEMH (International Machine-Tool Biennial) in Bilbao.
What is involved here is a high-performance handling robot the structure of which is basically four actuators working in a coordinated manner with the goal of achieving maximum dynamic performances.
The robot has four degrees of freedom, displacements along three translations and rotates on its vertical axis. It is a cylinder with a diameter of 1200mm and a height of 250mm. Its rotational capacity covers ±200º, which enables positioning an object in any orientation-position.
This robot is characterized by its high dynamics, with accelerations of 15G, enabling it to pick up and position over 200 items per minute. Its workload capacity is aimed at the manipulation of variously shaped objects up to a weight of 2 Kg.
Quickplacer - not pretty, but pretty fast.
This robot is aided by a vision system capable of guiding its movements. The vision system, available in both black and white and in color, is responsible for locating the shape and the orientation-position of the objects and, as a function of the received programming, gives orders for the robots movements. It is also possible to co-ordinate the whole system with moving belts in such a way that the robot can pick up a moving object and also position it on a moving belt.
The Quickplacer robot is the most rapid in the world. Its high acceleration and braking capacity, 5 times more than that of a Formula 1 racing car, makes it world leader in production capacity.
It special structure and the characteristics of the elements make its speed and acceleration optimum, increasing productivity by 20% with respect to currently existing solutions.
The technological structure and capacities of this robot make it ideal for handling tasks in a multitude of sectors such as in food and agriculture, the hygiene sector, beauty care, health care or electronic components.
Its design is optimized for small-sized objects – up to 2 Kg – in very varied tasks. The possible tasks to which this robot can be applied are as varied as the following:
• Positioning of chocolates in individually-shaped places
• Packaging of bars of chocolate/turron
• Packaging of biscuits individually or in groups
• Quality control in the processing of vegetables (combined with a colour vision system)
• Packaging of peppers
• Packaging of lipstick bars
• Packaging of baby towelettes
• Feeding various products (fish, meat, CDs,…) to flowpack machines.
Fatronik - http://www.fatronik.com
|Pluto’s Moons |
This pair of NASA Hubble Space Telescope images shows the motion of
Pluto's satellites between February 15th and March 2nd, 2006. (NASA)
Johns Hopkins University Applied Physics Laboratory News Release
March 10, 2006 - Using new Hubble Space Telescope observations, a research team led by Dr. Hal Weaver of the Johns Hopkins University Applied Physics Laboratory and Dr. Alan Stern of Southwest Research Institute has found that Pluto’s three moons are essentially the same color – boosting the theory that the Pluto system formed in a single, giant collision.
Publishing their findings in an International Astronomical Union Circular (No. 8686), the team determined that Pluto’s two “new” satellites, discovered in May 2005 and provisionally called S/2005 P 1 and S/2005 P 2, have identical colors to one another and are essentially the same, neutral color as Charon, Pluto’s large moon discovered in 1978.
All three satellites have surfaces that reflect sunlight with equal efficiency at all wavelengths, which means they have the same color as the Sun or Earth's moon. In contrast, Pluto has more of a reddish hue.
The new observations were obtained March 2 with the high-resolution channel of the Hubble’s Advanced Camera for Surveys. The team determined the bodies’ colors by comparing the brightness of Pluto and each moon in images taken through a blue filter with those taken through a green/red filter.
Pluto, Charon and the two new moons. Credit: NASA, ESA,
A. Stern(SwRI) and Z. Levay (STScI)
"The high quality of the new data leaves little doubt that the hemispheres of P1 and P2 that we observed have essentially identical, neutral colors," says Weaver.
The new results further strengthen the hypothesis that Pluto and its satellites formed after a collision between two Pluto-sized objects nearly 4.6 billion years ago. “Everything now makes even more sense,” says Stern. “If all three satellites presumably formed from the same material lofted into orbit around Pluto from a giant impact, you might well expect the surfaces of all three satellites to have similar colors.”
The researchers hope to make additional Hubble color observations, in several more filters, to see if the similarity among the satellites persists to longer (redder) wavelengths.
They have proposed to obtain compositional information on the new satellites by observing them at near-infrared wavelengths, where various ice and mineral absorptions are located. The researchers also hope to better refine the orbits of P1 and P2 and measure the moons’ shapes and rotational periods.
The Hubble observations were made in support of NASA’s New Horizons mission to Pluto and the Kuiper Belt. New Horizons launched on Jan. 19, 2006, and will fly through the Pluto system in July 2015, providing the first close-up look at the ninth planet and its moons.
Stern leads the mission and science team as principal investigator; Weaver serves as the mission’s project scientist. The Johns Hopkins University Applied Physics Laboratory, Laurel, Md., manages the mission for NASA’s Science Mission Directorate and operates the New Horizons spacecraft.
For more information on the mission, visit http://pluto.jhuapl.edu
|The Other Side of the Sun |
The sun that we see. (NASA)
Stanford University News Release
March 13, 2006 - The hidden face of the sun is fully visible for the first time, thanks to a new technique developed at Stanford University.
Only half of the sun--the near side--is directly observable. The far side always faces away from Earth and is therefore out of view. But the new technology allows anyone with a computer to download images of the entire solar surface--an important advance with practical applications, say researchers, because potentially damaging solar storms that form on the far side now can be detected days, or even weeks, before they wreak havoc on Earth.
"Sunspots, solar flares and other active regions on the surface of the sun emit radiation that can interfere with orbiting satellites, telecommunications and power transmission," says Philip Scherrer, research professor in the Stanford Department of Physics.
"This new method allows more reliable warning of magnetic storms brewing on the far side that could rotate with the sun and threaten the Earth."
This image shows two active regions crossing
the solar east limb in November 2003. The right
side, in yellow, are white light images showing
sunspots. The left side (blue) shows the prediction
of sunspots on the farside. Since the white light
observations are images made "straight on", they
are stretched into blurry lines when they are
projected to show the view over the limb. This is
simply because we do not have a camera above
the east limb (yet). (Stanford University)
It takes about 27 days for the sun to rotate on its axis, so an active region that forms on the far side can remain hidden for up to 13 days, surprising Earth-bound observers when it finally rotates into view.
That's what happened in October 2003, when active regions from the back side suddenly appeared on the eastern edge of the sun, spewing X-rays, ultraviolet radiation and high-energy particles into space.
"We were not able to make a public prediction about the intensity of that activity, because at the time we could only image about a quarter to a third of the far side," Scherrer says. "The new method allows us to see the entire far side, including the poles."
Scherrer and his Stanford colleagues study the sun using data from the Solar and Heliospheric Observatory (SOHO), a research satellite launched in 1995 by NASA and the European Space Agency. On board SOHO is the Michelson Doppler Imager (MDI), an electronic instrument that creates images of the sun's interior by measuring the velocity of sound waves produced by hot, bubbling gases that well up to the surface--a technique called acoustic helioseismology.
"Heliosesimology works on the same principle as medical ultrasound, which can create an image of a fetus inside a pregnant woman," Scherrer explains. "In this case, we're looking through a star with sound waves."
Positioned about 1 million miles above Earth, the SOHO satellite always faces the visible front side of the sun. In 2000 and 2001, scientists Charles Lindsey and Doug Braun--now at NorthWest Research Associates Inc.--developed two techniques that resulted in the first pictures of the sun's back side. However, both techniques had limitations. One method only produced images near the center of the far side, while the other was restricted to views at the edges. To get complete image, researchers would have to combine both methods, but that proved to be a major technical challenge.
The problem was finally overcome last summer when a new computer algorithm was developed by the Stanford SOHO/MDI team in collaboration with Kenneth Oslund, an undergraduate at the California Institute of Technology. Their work resulted in the MDI Farside Graphics Viewer, which displays the first full images of the far side of the sun.
The viewer is available online at http://soi.stanford.edu/press/farside_Feb2006/web
"This new method is a vast improvement," Scherrer says. "It should be especially important during the next solar maximum, which should begin in 2011, when solar activity will be at its peak."
He points out that during the last "solar max," which lasted from 2000 to 2003, solar storms temporarily knocked out power in the northern parts of Sweden and Canada and destroyed a satellite that was used to verify credit card payments at numerous gas stations in the United States. Air transportation also can be disrupted when solar radiation interferes with the operation of Global Positioning System satellites, or when aircraft that take short cuts over the North Pole have to take longer routes to prevent passengers and crew from being exposed to intense X-ray radiation.
"Our goal is to give pilots and air traffic controllers a day or two notice of a possible solar event," Scherrer says, adding that missions to Mars and other planets also can be affected when solar storms interfere with satellite communications to Earth. Last week, researchers at the National Center for Atmospheric Research in Colorado released new computer models predicting that the next solar cycle will be 30 to 50 percent stronger than last time.
In 2008, SOHO is scheduled to be replaced by NASA's Solar Dynamics Observatory (SDO), a more advanced satellite designed to provide new data about the magnetic forces inside the sun that drive the 11-year solar cycle. Stanford, the University of Colorado and the Lockheed Martin Corp. will lead the SDO research effort.
"With cell phones and other devices, we've gotten more and more dependent on the space environment, so there are real economic reasons for missions like SOHO and SDO," Scherrer says.
Videos and high-resolution images of the far side of the sun are available at http://sohowww.nascom.nasa.gov
Stanford University - http://www.stanford.edu