The Brightness of the Sun

The bright Sun, a portion of the International Space Station and Earth's horizon are featured in this image photographed during the STS-134 mission's fourth spacewalk in May 2011. The image was taken using a fish-eye lens attached to an electronic still camera. 

Image Credit: NASA

Churning Out Stars

W3 is an enormous stellar nursery about 6,200 light-years away in the Perseus Arm, one of the Milky Way galaxy’s main spiral arms, which hosts both low- and high-mass star formation. In this image from the Herschel space observatory, the low-mass forming stars are seen as tiny yellow dots embedded in cool red filaments, while the highest-mass stars - with greater than eight times the mass of our Sun - emit intense radiation, heating up the gas and dust around them and appearing here in blue. 

This three-color image of W3 combines Herschel bands at 70 microns (blue), 160 microns (green) and 250 microns (red). The image spans about 2 by 2 degrees. North is up and east is to the left. 

Image Credit: ESA/PACS & SPIRE consortia, A. Rivera-Ingraham & P.G. Martin, Univ. Toronto, HOBYS Key Programme (F. Motte)
Explanation from: http://www.nasa.gov/mission_pages/herschel/multimedia/pia16881.html

Building a Lunar Base with 3D Printing

Building a base on the Moon could theoretically be made much simpler by using a 3D printer to construct it from local materials.

The concept was recently endorsed by the European Space Agency (ESA) which is now collaborating with architects to gauge the feasibility of 3D printing using lunar soil.

“Terrestrial 3D printing technology has produced entire structures,” explained Laurent Pambaguian, heading the project for ESA. “Our industrial team investigated if it could similarly be employed to build a lunar habitat.”

According to Pambaguian, ESA’s partners have devised a weight-bearing “catenary” dome design with a cellular structured wall to help shield against micrometeoroids and space radiation – incorporating a pressurized inflatable to shelter astronauts.

Meanwhile, a hollow closed-cell structure – somewhat reminiscent of bird bones – provides a combination of strength and weight. The base’s design was guided in turn by the properties of 3D-printed lunar soil, with a 1.5 ton building block produced as a demonstration.

“3D printing offers a potential means of facilitating lunar settlement with reduced logistics from Earth,” said Scott Hovland of ESA’s human spaceflight team. “The new possibilities this work opens up can then be considered by international space agencies as part of the current development of a common exploration strategy.”

Essentially, 3D “printouts” are built up layer by layer. A mobile printing array of nozzles on a 6 m frame sprays a binding solution onto a sand-like building material. First, the simulated lunar material is mixed with magnesium oxide to turn it into ‘paper’ to print with. Then for the structural ‘ink’ a binding salt is applied to convert the material to a stone-like solid.

Current 3D printers build at a rate of around 2 m per hour, while next-gen designs should attain 3.5 m per hour, completing an entire building in a week.

Images Credit: ESA/Foster + Partners
Explanation from: http://lunarscience.nasa.gov/articles/building-a-lunar-base-with-3d-printing/

Mammatus Clouds over Saskatchewan

Normal cloud bottoms are flat. This is because moist warm air that rises and cools will condense into water droplets at a specific temperature, which usually corresponds to a very specific height. As water droplets grow, an opaque cloud forms. Under some conditions, however, cloud pockets can develop that contain large droplets of water or ice that fall into clear air as they evaporate. Such pockets may occur in turbulent air near a thunderstorm. Resulting mammatus clouds can appear especially dramatic if sunlit from the side. These mammatus clouds were photographed over Regina, Saskatchewan, Canada in 2011.

Image Credit: Craig Lindsay
Explanation from: http://apod.nasa.gov/apod/ap121023.html