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Dawn Spacecraft Begins Approach To Dwarf Planet Ceres

December 29, 2014 Leave a comment

Artist's concept. Image credit: NASA/JPL-Caltech

Artist’s concept. Image credit: NASA/JPL-Caltech

NASA’s Dawn spacecraft has entered an approach phase in which it will continue to close in on Ceres, a Texas-sized dwarf planet never before visited by a spacecraft. Dawn launched in 2007 and is scheduled to enter Ceres orbit in March 2015.

Dawn recently emerged from solar conjunction, in which the spacecraft is on the opposite side of the sun, limiting communication with antennas on Earth. Now that Dawn can reliably communicate with Earth again, mission controllers have programmed the maneuvers necessary for the next stage of the rendezvous, which they label the Ceres approach phase. Dawn is currently 400,000 miles (640,000 kilometers) from Ceres, approaching it at around 450 miles per hour (725 kilometers per hour).

The spacecraft’s arrival at Ceres will mark the first time that a spacecraft has ever orbited two solar system targets. Dawn previously explored the protoplanet Vesta for 14 months, from 2011 to 2012, capturing detailed images and data about that body.

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A Simulation Of The Universe With Realistic Galaxies

December 29, 2014 Leave a comment

Credit: J. Schaye et al. 2015

Credit: J. Schaye et al. 2015

The simulations took several months to run at the “Cosmology Machine” in Durham and at “Curie” in Paris, among the largest computers used for scientific research in the U.K. and France, respectively. Astronomers can now use the results to study the development of galaxies from almost 14 billion years ago until now. The results will be published in Monthly Notices of the Royal Astronomical Society on 1 January.

or years, astronomers have studied the formation of galaxies using computer simulations, but with limited success. The galaxies that formed in previous simulations were often too massive, too small, too old and too spherical.

The galaxies formed in the EAGLE-simulation (Evolution and Assembly of GaLaxies and their Environments) are a much closer reflection of real galaxies thanks to the strong galactic winds, which blow away the gas supply needed for the formation of stars. EAGLE’s galaxies are lighter and younger because fewer stars form and they form later. In the EAGLE simulation these galactic winds – which are powered by stars, supernova explosions and supermassive black holes – are stronger than in earlier simulations.

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