2011. július 24., vasárnap

from Earth to the Solar System - FETTSS find on Facebook

Astrobiology: Life in the Universe

Mars Chasma Boreale

LIFE IN ICE? Chasma Boreale is a long valley that cuts deep into the north polar icecap of Mars. Where the ice cap has retreated, sand from earlier, ice-free climate cycles is exposed that winds have shaped into dunes. In 2007, NASA’s Phoenix mission landed in the northern arctic plains of Mars to study the history of water and potential habitability in the ice-rich soil. Phoenix verified the presence of water ice in the Martian sub-surface, and found calcium carbonate, an indicator of a less acidic (more potentially habitable) planet in the past. Phoenix even observed snow falling from clouds in the Martian atmosphere! This eerily Earth-like vista was made by combining data from NASA's Mars Odyssey and Global Surveyor orbiters. Image Credit: NASA/JPL-Caltech/Arizona State University, Thermal Emission Imaging System (THEMIS)

Mars Globe

THE RED PLANET: Mars has been the subject of intense study for the past two centuries. Its exploration has been wrought with success and failure, and has witnessed a dramatic evolution in knowledge. Speculations about the famous “irrigation canals” on Mars in the late 1800’s were finally put to rest by images returned from NASA’s Mariner 4 mission in 1965. Revealing impact craters and a barren landscape, they dispelled thoughts of thriving, agricultural civilizations. In the 1970’s NASA’s Viking mission carried out life-detection experiments on the surface. The results, indicating a lifeless planet, raised more questions than answers. The next two decades were met with struggle as several spacecraft from the US, Japan, Europe, and former USSR were lost. Success resurfaced in the late 1990’s with the ESA orbiter Mars Express and NASA’s Pathfinder rover, and Global Surveyor and Odyssey orbiters—heralding the mantra “Follow the Water.” In 2004, NASA’s twin rovers Spirit and Opportunity began their work, which is still ongoing today. NASA’s Mars Reconnaissance Orbiter and Phoenix lander followed. As data from these robotic explorers piled up, so did evidence that Mars preserves a record of surface liquid water and possibly habitable environments. NASA’s Mars Science Laboratory, launching in late 2011 and arriving in August, 2012 will carry an unprecedented suite of instruments that will bring us one step closer to determining if life ever started on Mars. Image Credit: NASA/Mars Global Surveyor

Mars Crater Ice

WATERING HOLE: ESA's Mars Express obtained this view of an unnamed impact crater located on Vastitas Borealis, a broad plain that covers much of Mars's far northern latitudes. The circular patch of bright material located at the center of the crater is residual water ice. The colors are very close to natural, but the vertical relief is exaggerated three times. This patch of ice is present all year round, remaining after frozen carbon dioxide overlaying it disappears during the Martian Summer. Image Credit: ESA/DLR/FU Berlin (G. Neukum)

Mars Polar Dunes

DUNES AT THE MARTIAN NORTH POLE: A sea of dunes, sculpted by the wind into long lines, surrounds the northern polar cap of Mars, covering an area as big as Texas. In this false-color image, areas with cooler temperatures are recorded in blue tints, while warmer features are depicted in yellows and oranges. This scene combines images taken between 2002—2004 by the Thermal Emission Imaging System (THEMIS) instrument onboard NASA's Mars Odyssey orbiter. In December, 2010, Mars Odyssey became the longest-serving spacecraft at the Red Planet. Image Credit: NASA/JPL-Caltech/Arizona State University, Thermal Emission Imaging System (THEMIS)

Venus Globe 1

EARTH’S TWIN? Radar data collected over many years from multiple sources were used to create this beautiful, color-coded portrait of Venus. Venus has roughly the same size, mass, density, and composition as Earth. Until the 1960’s, scientists speculated that Venus may have been very Earth-like, and home to lush, tropical forests. That view changed when new observations confirmed a superheated surface with temperatures over 400˚C (750˚F) and pressures nearly a hundred times that of Earth. But the biggest difference with Earth lies within Venus’ atmosphere. Clouds on Venus are made not of water like they are on Earth, but rather of concentrated sulfuric acid—essentially battery acid. About 700 million years ago, Venus experienced tremendous volcanic activity, flooding the surface with new lava and filling the atmosphere with greenhouse gases, causing a runaway greenhouse effect. Image Credit: NASA/JPL-Caltech

Jupiter Surface 1

THE GREAT RED SPOT: Here’s a close up of The Great Red Spot of Jupiter. It’s a vast anticyclone located in Jupiter’s southern hemisphere, and is about three times the size of Earth. Visible even through small backyard telescopes, its color changes as different chemicals and gases are churned from the bottom layers up to the surface. The winds at the edge of the spot can reach up to 350 miles per hour. The Great Red Spot was probably first observed by astronomer Giovanni Cassini in the late 1600’s, but it wasn’t observed up close until NASA’s Pioneer 10 spacecraft made its flyby in 1974. Image Credit: JPL/NASA

Jupiter Surface 2

CLOUD CITY: Everything visible in this image is a cloud. Unlike on Earth where only water condenses to form clouds, Jupiter's clouds are made of ammonia, hydrogen sulfide, and water. Jupiter's many jet streams shear clouds apart, forming characteristic streaks. The fastest jet stream winds blow eastward at 480km (300 miles) per hour. The most energetic features are the small, bright clouds to the left of the Great Red Spot—they grow and disappear over a few days and generate lightning. The striking colors in this image of Jupiter, taken by NASA’s Cassini spacecraft in 2000, are very close to the way the human eye would see them. Image Credit: NASA/JPL/Space Science Institute


HYPERION: Sponge or moon? This stunning, false-color image of Saturn's moon Hyperion reveals crisp details across the strange, tumbling moon’s surface. Although somewhat potato-shaped, Hyperion's average diameter is 270km (168 miles). Scientists think Hyperion's unique appearance can be attributed to the fact that it has an unusually low density for such a large object, giving it weak surface gravity and high porosity. Hyperion’s craters are particularly deep and there appears to have been landslides inside many of the bigger craters. The result is a curious look, somewhat like the surface of a sponge or a wasp nest. Many of the crater walls on Hyperion are bright, suggesting an abundance of water ice. Image Credit: NASA/JPL/Space Science Institute

Saturn Globe 2

SPECTACULAR SATURN: Saturn is the second largest planet in the Solar System, behind Jupiter. Its stunning ring system glows with scattered sunlight in this image made by NASA’s Cassini spacecraft as it passed behind the planet in 2006. Saturn has almost four-dozen moons, ranging in size from just under 3km (2 miles) wide to about the width of the continental U.S. Two of the moons, Titan and Enceladus, are of great interest to astrobiologists: Titan provides an analogue to the chemistry of early Earth, and Enceladus’ inner heat and jets of ice and water vapor could be a habitat for extraterrstrial life. This image also shows Earth—it’s the white dot at the ten o'clock position between the bright main rings and the thinner, light brown ring. Image Credit: NASA/JPL/Space Science Institute.

Sun Globe 2

SPACE WEATHER: What is a storm on the Sun like? Most of the time when we talk about “the weather,” we are referring to the state of Earth’s atmosphere that gives us rain, wind, and temperature changes. The “space weather” produced by the Sun extends deep into the Solar System. It drives some of the greatest changes in our local space environment—affecting our magnetosphere, ionosphere, atmosphere, and potentially our climate. The Sun contains very powerful magnetic fields and they can become twisted and tangled, storing enormous amounts of energy. When the Sun becomes stormy, all that pent-up energy erupts in the form of the Solar System's largest explosions: solar flares and coronal mass ejections. These blasts of light and charged gas rip through the solar wind and sometimes impact the bodies of the Solar System. Luckily, Earth’s magnetosphere acts as a shield, and its atmosphere absorbs the dangerous radiation, protecting us.. Image Credit: NASA/ESA/SOHO


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