Nice quote below. By orienting the craft toward the sun, the MESSENGER team was able to use the resulting solar pressure - in effect, a solar sailing technique - to fine tune the trajectory of the spacecraft on its second flyby of Mercury, achieving a record for precision. It missed its targeted altitude by only .6 kilometers, according to the blog, Musings of a MESSENGER Fellow.
That’s pretty remarkable targeting, given that MESSENGER has traveled 668 million kilometers since its last deep space maneuver in March, [MESSENGER Mission Design Lead Jim] McAdams says. 'It’s as if we shot an arrow from New York to a target in Los Angeles – nudged it three times mid-stream with a soft breath – and arrived within the width of the arrow’s shaft at the target.'
Above is an artist's impression of the long, steep cliffs that extend for hundreds of kilometers on Mercury¹s surface in both Mariner 10 and MESSENGER images. These giant cliffs are believed to have formed when Mercury's interior cooled and the entire planet shrank slightly as a result.
Credit: Michael Carroll/Alien Volcanoes by Lopes and Carroll, The Johns Hopkins University Press, 2008.