2012: Fear No Supernova

Given the incredible amounts of energy in a supernova explosion - as much as the sun creates during its entire lifetime - another erroneous doomsday theory is that such an explosion could happen in 2012 and harm life on Earth. However, given the vastness of space and the long times between supernovae, astronomers can say with certainty that there is no threatening star close enough to hurt Earth.

Astronomers estimate that, on average, about one or two supernovae explode each century in our galaxy. But for Earth's ozone layer to experience damage from a supernova, the blast must occur less than 50 light-years away. All of the nearby stars capable of going supernova are much farther than this.

Any planet with life on it near a star that goes supernova would indeed experience problems. X- and gamma-ray radiation from the supernova could damage the ozone layer, which protects us from harmful ultraviolet light in the sun's rays. The less ozone there is, the more UV light reaches the surface. At some wavelengths, just a 10 percent increase in ground-level UV can be lethal to some organisms, including phytoplankton near the ocean surface. Because these organisms form the basis of oxygen production on Earth and the marine food chain, any significant disruption to them could cascade into a planet-wide problem.

First Global Image from VIIRS

The NPP satellite launched on October 28, 2011, and VIIRS acquired its first measurements on November 21. To date, the images are preliminary, used to gauge the health of the sensor as engineers continue to power it up for full operation.

Rising from the south and setting in the north on the daylight side of Earth, VIIRS images the surface in long wedges measuring 3,000 kilometers (1,900 miles) across. The swaths from each successive orbit overlap one another, so that at the end of the day, the sensor has a complete view of the globe. The Arctic is missing because it is too dark to view in visible light during the winter.

The NPP satellite was placed in a Sun-synchronous orbit, a unique path that takes the satellite over the equator at the same local (ground) time in every orbit. So, when NPP flies over Kenya, it is about 1:30 p.m. on the ground. When NPP reaches Gabon - about 3,000 kilometers to the west - on the next orbit, it is close to 1:30 p.m. on the ground. This orbit allows the satellite to maintain the same angle between the Earth and the Sun so that all images have similar lighting.

The consistent lighting is evident in the daily global image. Stripes of sunlight (sunglint) reflect off the ocean in the same place on the left side of every swath. The consistent angle is important because it allows scientists to compare images from year to year without worrying about extreme changes in shadows and lighting.

Clouds over the Indian Ocean

As citizens of northern countries ponder sculpted snow and ice, or icings for baked goods, the summer skies over the southern oceans offered their own vision in white in the early winter of 2011. The brush strokes of bright holiday swirls were made by winds and atmospheric eddies moving over the far southern reaches of the Indian Ocean.

The natural-color image was captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite on November 30, 2011. According to Patrick Minnis, a cloud expert at NASA’s Langley Research Center, there are at least three layers of clouds in the image.

The lowest layer is a marine stratus (stratocumulus) deck that covers the lower left two-thirds of the image. “The clouds look like whipped, mashed potatoes with swirls and bright peaks,” Minnis said. “The bright peaks indicate glaciations-freezing of the super-cooled cloud droplets. The swirls are reflective of eddies in the low-level wind fields.”

Just above (or perhaps continuous with) the marine layer, parallel wave patterns mark a brighter layer of stratus clouds that cover the other third of scene. Above it all, in the upper right quadrant, a high cirrus cloud throws shadows on the clouds below.

Tom Arnold, an atmospheric scientist based at NASA’s Goddard Space Flight Center, explained that marine stratus clouds can form (and persist) where there is a meeting between a cold ocean surface, some wind, and a strong temperature inversion at the top of the atmospheric boundary layer (about 2,000 to 3000 feet). “The cold ocean cools and moistens the low level air, making the low cloud base possible,” Arnold noted. “The wind helps lift the air, and the temperature inversion acts a kind of cap on the cloud layer, preventing much vertical mixing with the warmer, drier, and more stable air immediately above the boundary layer.”

The temperature inversion layer is a product of a large area of high pressure that causes air to slowly sink, Arnold added. The sinking air compresses the air-and thus warms and dry’s it-forming the temperature inversion layer over the top of the colder ocean-cooled air.

Trio of NASA Missions Named 'Best of What's New'

NASA's Dawn, Mars Science Laboratory and MESSENGER missions have earned recognition from Popular Science magazine as innovations worthy of the publication's "Best of What's New" Award in the aviation and space category.

Dawn and Mars Science Laboratory are managed by NASA's Jet Propulsion Laboratory in Pasadena, Calif. Dawn is currently orbiting and exploring the massive main-belt asteroid Vesta. The Mars Science Laboratory and its Curiosity rover launched on Nov. 26 on a journey to the Red Planet, where the rover will look for signs of past or present habitability.

The MESSENGER mission is currently orbiting Mercury.

More information on the award winners is online at: http://www.popsci.com/bown/2011/category/aviation-amp-space .

JPL, a division of the California Institute of Technology in Pasadena, manages Dawn and Mars Science Laboratory for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Ala. UCLA is responsible for overall Dawn mission science. Orbital Sciences Corp. in Dulles, Va., designed and built the spacecraft. The German Aerospace Center, the Max Planck Institute for Solar System Research, the Italian Space Agency and the Italian National Astrophysical Institute are international partners on the mission team.

Sean Solomon, of the Carnegie Institution of Washington, leads the MESSENGER mission as principal investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft for NASA.

Asteroid Research Begins Under the Sea

NASA is using a capability-driven approach to new concepts of human exploration for multiple destinations in our solar system; one of those destinations are near-Earth asteroids. Across the agency, experts are being called into action to develop solutions to this new challenge. In particular, the NEEMO 15 analog field test, slated for mid-October this year, will test new tools, techniques, time lining approaches and communication technologies which could be useful when humans approach asteroids in space.

During the week of May 9-15, 2011, the NEEMO 15 support team is conducting engineering evaluations in the Aquarius undersea research laboratory in Key Largo, Fla. The purpose of these engineering tests is to understand the equipment, techniques and test concepts that will be implemented in the October NEEMO 15 mission, to make sure that all systems are ready for more rigorous testing when the crew will be living full-time in the Aquarius undersea habitat.

The specific operations for visiting an asteroid have not been considered in great detail before. Gravity on an asteroid is negligible, so walking around on one isn't really an option. Anchoring to the surface will probably be necessary, but asteroids are made up of different materials - some solid metal, some piles of rubble and some, a combination of rock, pebbles and dust.

Weak gravity and diverse materials present problems whose solutions can be experimented with on the ocean floor, which is what the NEEMO 15 mission is trying to do. NEEMO 15 will focus on three different aspects of a mission to an asteroid surface. The first is anchoring to the surface of the asteroid.

Athabasca Oil Sands

Buried under Canada’s boreal forest is one of the world’s largest reserves of oil. Bitumen—a very thick and heavy form of oil (also called asphalt)—coats grains of sand and other minerals in a deposit that covers about 142,200 square kilometers (54,900 square miles) of northwest Alberta. According to a 2003 estimate, Alberta has the capacity to produce 174.5 billion barrels of oil.

Only 20 percent of the oil sands lie near the surface where they can easily be mined, and these deposits flank the Athabasca River. The rest of the oil sands are buried more than 75 meters below ground and are extracted by injecting hot water into a well that liquefies the oil for pumping. In 2010, surface mines produced 356.99 million barrels of crude oil, while in situ production (the hot water wells) yielded 189.41 million barrels of oil.

This series of images from the Landsat satellite shows the growth of surface mines over the Athabasca oil sands between 1984 and 2011. The Athabasca River runs through the center of the scene, separating two major operations. To extract the oil at these locations, oil producers remove the sand in big, open-pit mines, which are tan and irregularly shaped. The sand is rinsed with hot water to separate the oil, and then the sand and wastewater are stored in “tailings ponds,” which have smooth tan or green surfaces in satellite images.

The process of extracting oil from the sand is expensive. It takes two tons of sand to produce one barrel of crude oil. Great Canadian Oil Sands opened the first large-scale mine in 1967, but growth was slow until 2000 because the global cost of a barrel of oil was too low to make oil sands profitable.

The images above show slow growth between 1984 and 2000, followed by a decade of more rapid development. The first mine (from 1967, now part of the Millennium Mine) is visible near the Athabasca River in the 1984 image. The only new development visible between 1984 and 2000 is the Mildred Lake Mine (west of the river), which began production in 1996.

For more info, visit http://earthobservatory.nasa.gov/Features/WorldOfChange/athabasca.php?src=features-hp