Tuesday, May 31, 2016

Water droplets vaporized by world's most powerful X-ray laser


The SLAC National Accelerator Laboratory's Linac Coherent Light Source (LCLS) is the world's most powerful X-ray laser. The two-mile-long linear accelerator is used to produce ultrafast pulses of light (30 femtoseconds) in order to take stop-motion pictures of atoms and molecules in motion. The laser's wavelength (0.151nm) is comparable to that of an atom, which provides extremely high resolution imaging capabilities. Here, a pulse of the X-ray laser can be seen vaporizing 40µm droplets of water. Because of the speed of the interaction, imagery is captured in stop-motion over many repeated experiments and combined to produce a video. A secondary, time-delayed pulsed laser is used to illuminated the scene following the primary X-ray laser interaction.

Source:
https://youtu.be/v5bH01qNN0Y PhysOrg

Article:
http://phys.org/news/2016-05-movies-droplets-blown-x-ray-laser.html Nature

Physics publication:
http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys3779.html

Valles Marineris: The Grand Canyon of Mars


Mars will look good in Earth's skies over the next few days -- but not this good. To get a view this amazing, a spacecraft had to actually visit the red planet. Running across the image center, though, is one the largest canyons in the Solar System. Named Valles Marineris, the grand valley extends over 3,000 kilometers long, spans as much as 600 kilometers across, and delves as much as 8 kilometers deep.

By comparison, the Earth's Grand Canyon in Arizona, USA is 800 kilometers long, 30 kilometers across, and 1.8 kilometers deep. The origin of the Valles Marineris remains unknown, although a leading hypothesis holds that it started as a crack billions of years ago as the planet cooled. Several geologic processes have been identified in the canyon. The featured mosaic was created from over 100 images of Mars taken by Viking Orbiters in the 1970s. Tomorrow, Mars and Earth will pass the closest in 11 years, resulting in the red planet being quite noticeable toward the southeast after sunset.


Image & Info via APOD
http://apod.nasa.gov/apod/astropix.html

Image Credit: Viking Project, USGS, NASA

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