July 6 News Items

Pratt & Whitney Rocketdyne Gets Contract Expansion (Source: Hartford Business)
DARPA has awarded East Hartford-based Pratt & Whitney’s Rocketdyne division a $2.2 million contract for the fabrication and ground test of a solar thermal propulsion engine for in-space use. This contract extends an existing High Delta-V Experiment Program, or HiDVE for short, an additional six months and follows a successful critical design review last March. “The solar thermal propulsion engine encompasses an innovative new technology that allows it to use less fuel by harnessing the sun’s energy,” said a PWR official. “This gives the satellite greater ability to maneuver in space and conduct longer missions by extending the use of its fuel.” (7/6)

Fresh Puzzle Over Dark Energy Supernovae (Source: New Scientist)
It's an embarrassing gap in astronomers' knowledge. Despite relying on type Ia supernovae as tools to measure the dark energy speeding up the universe's expansion, they still don't know exactly what causes the blasts. Now the picture has got even fuzzier. In the standard scenario, a white dwarf pulls matter from a companion star, and this extra mass triggers a supernova. Heavy white dwarfs were thought more likely to explode, since it takes less to push them over the edge.

Now Christopher Pritchet of the University of Victoria in British Columbia, Canada, and colleagues have observed galaxies dominated by lightweight white dwarfs producing type Ia supernovae just as efficiently as those dominated by heavier white dwarfs. These cases may be down to the collision of two white dwarfs, says co-author Andrew Howell of the University of Toronto. (7/6)