Cloud shape changes dramatically from the equator to the pole while the lower latitude cloud shape is fragmented due to vigorous convective movement. This movement is powered by the sun’s radiation heating the atmosphere. The bright white visible above the darker cloud deck is made of freshly formed droplets of sulphuric acid. Toward mid latitude, the convective clouds become streaky shapes. In higher latitudes, clouds appear dense and featureless, a type of haze. The dark, circular feature visible at the right edge of the image is a dark streak usually present in the polar region, indicating atmospheric spiralling towards the pole.
May 30, 2008
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April 11, 2008
The rock that orbits Mars is Phobos, one of its two moons. Taken at a distance of 6,800 km ( 4,200 mi), the picture below was captured by HiRISE (High Resolution Imaging Science Experiment) aboard NASA’s Mars Reconnaissance Orbiter.
Check out the large impact crater on the right side of Phobos. There are striations emanating from the edge of the crater moving from the lower bottom right to the upper left of the face of the moon. It looks like flames left a mark after the impact. Probably not flames of course, but it is mind boggling to consider what might have caused these striations. Possibly ejected debris from an impact?
The crater has a name, naturally. Named Stickney, it has a diameter of 9 km ( 5.6 mi). Scientists from the European Space Agency’s Mars Express believe these marks occurred from impacts on Mars which ejected debris high enough up from the planet to have impacted Phobos. Those were probably some massive hits that Mars took, but Earth likely experienced the same thing.
Inside the crater Stickney can be seen a series of textures which are landslides formed when material fell into the crater. Phobos gravity is less than 1/1000 of Earth’s. They look like someone used a large spoon and scooped material out of the wall of the crater.
Stickney reminds me of the crater on Saturn’s moon, Mimas. The crater is named Herschel and defines Mimas, shown in the picture at right.
Actually, the two moons of Mars really are essentially rocks. They are believed to be stray asteroids that wandered in too close to Mars and were captured by the planet’s gravity.
March 13, 2008
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The Venus Express space probe has been eyeing the southern polar region of Venus and has found an atmospheric phenomenon that looks very much like a hurricane with a center resembling an eye like those found in hurricanes on Earth. This hurricane is causing scientists to scratch their heads as the Venus version seems to morph and change shape rapidly over the course of several days.
The vortex of the hurricane is 2,000 km (1,240 mi) wide and was actually discovered in 1974 by the Mariner 10 spacecraft. A similar entity exists near the north pole of the planet, observed by the Pioneer spacecraft in 1979.
Scientists have been recently analyzing the southern polar hurricane in the thermal infrared wavelength hoping to understand the temperature in the upper reaches of the clouds. In this analysis, the vortex appears very bright, indicating the downward movement of atmospheric gases through the vortex creating a depression in the upper reaches and generating heat there. Various shapes of the vortex appear in the pictures at left.
In June 2006, the vortex was hourglass shaped matching the earlier observing in the north by the Pioneer mission. The images show the hurricane changes its shape in a matter of days. A video of the phenomenon can be viewed at the European Space Agency web site here: http://www.esa.int/esaCP/SEMIZFM5NDF_index_0.html
The changing dynamic of the vortex can be seen quite well in the video. The structure is very complex with different wind dynamics at different altitudes.
Scientists are uncertain how to account for the activities of the vortex. One theory is that gases in the atmosphere get heated by the Sun near the equator. These gases rise upward, then migrate to the polar regions. The gases cool, then sink down to the surface. As the gas moves toward the northern and southern poles, they are deflected due to the rotation of the planet. This is similar to the way winds at the center of Earth-born hurricanes operate. The planetary rotation adds to the unpredictability of the hurricane-like winds, just as the rotation of the Earth does for our hurricanes.
Venus Express was launched in November 2005 and its mission is scheduled to run through May 2009. Scientists plan to continue to monitor the hurricane and the wind activity in the polar regions of Venus.
A video illustrating the cloud structure of Venus can be found here: http://sci.esa.int/science-e/www/area/index.cfm?fareaid=64
March 6, 2008
The ATV Jules Verne has been cleared for launch for March 9 at Europe’s space port in Kourou, French Guiana. The vehicle is an unmanned European resupply ship for the International Space Station. The Russian space agency and NASA are partner’s in this endeavor.
Resupply items frequently needed on the ISS are propellant, water, air, other payloads and various experiments.
The ATV can also provide an orbital boost to the ISS. The space station’s orbit degrades due to drag encountered in the atmosphere which gradually slows the orbital speed. The ATV will be launched by an Ariane 5 rocket ; together, both the ATV and the launcher weigh 460 tons.
Ariane 5 (Wikipedia.org)
This is the first flight of the ATV after many delays. Designed to compliment the Progress spacecraft, it has 3x the capacity of Progress. It can carry bulk liquids in a pressurized environment.
The ATV itself weighs nearly 21 metric tons and has a cargo capacity of 9 metric tons. It is a successor to the Hermes mini-shuttle, similar to the U.S. proposed Dyna-Soar X20. Development of the Hermes was cancelled in 1993.
The spacecraft will be put into orbit at 186 miles (300km) above the Earth. The ATV will be an important resource to carry cargo into space especially since the space shuttle will soon be retired by NASA. Missions to resupply the ISS are planned for every 17 months.
The ATV is named after Jules Verne (1828 – 1905), a French author who was a pioneer in the development of science fiction stories. He authored Journey to the Center of the Earth; Twenty Thousand Leagues under the Sea; and, Around the World in Eighty Days .
February 21, 2008
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High energy X-rays emanating from a star 100 times more massive than the Sun and producing a million times more light, named Eta Carinae, has been discovered by the European Space Agency space probe Integral.
Currently the most massive nearby star that can be studied in detail, Eta Carinae is part of the bipolar Homunculus Nebula, which surrounds the star. The nebula was created by a supernova eruption of Eta Carinae whose light first reached Earth in 1843.
These star types are rare with only a few dozen found in galaxies the size of the Milky Way. Found in the constellation Carina, it is about 7,500 light years away. Violent winds of electrically charge particles bombard each other at thousands of miles per second emitting gamma rays and x-rays. The star is actually a binary system with a second large star orbiting the first.
Integral has provided instruments not previously available for measuring the high energy spectrum x-rays in addition to the gamma rays. The result of a shock wave effect produced when the individual star’s solar winds collide, these stars constantly shed particles off into space. Due to the colliding winds of radiation between these two stars, temperatures get extreme possibly reaching a billion plus degrees Kelvin.
Integral is examining the x-rays emissions of Eta Carinae to understand how stars evolve and create energy. Electrically-charged particles are trapped in the magnetic structure of the shock-wave and collide with low-energy photons, producing the emissions recently discovered by Integral. Astronomers believe this lies at the heart of many diverse phenomena in the universe.
Since Earth is relatively close to Eta Carinae at 7,500 light years, the radiation could possibly reach our planet. The gamma rays and x-rays would be absorbed by our upper atmosphere, with possible degradation of the ozone layer. This would be problematic for spacecraft and satellites however. If the Carina system were to supernova, a possibility due to it mass, the light from the explosion would be enough to be prominently seen from Earth.
What is needed for the star to supernova is for it to reach the Eddington limit. This describes the effect when the outward pressure of radiation and the heat of the star created by the amount of its mass is so great as to overcome the effects of gravity. At this point, the star will explode as gravity is incapable of holding everything together.