Bob Moler's Ephemeris Blog

Ephemeris for Monday, March 2nd.  The sun will rise at 7:19.  It’ll be up for 11 hours and 12 minutes, setting at 6:31.   The moon, 3 days before full, will set at 6:00 tomorrow morning.

On Thursday March 5th NASA’s Dawn spacecraft will fall under the gravitational influence of the asteroid, or actually recently promoted dwarf planet Ceres and enter orbit.  The journey took 7 years including an intermediate year-long stop at the asteroid Vesta.  Dawn uses the latest in ion thrusters, or latest when it was launched.  Using power generated by its solar panels it ejects xenon ions from one of its three ion thrusters to produce a thrust comparable to the weight of a piece of paper.  It can accelerate the spacecraft from zero to 60 miles per hour in a few days.  In the tale of the hare and the tortoise it’s in the tortoise class, at least to start.  Ion engines are 10 times as efficient as chemical rockets and they can thrust for years.

Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.

Addendum

Artist’s rendition of the Dawn spacecraft at Vesta. Credit: NASA/JPL

Ion engine test. Xenon ions glow blue. Credit NASA.