Solar Sailing to Mercury

NASA released information about ‘solar sailing’ as a new technology in their advancement of broad planetary exploration. NASA plans to send the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft on its second mission October 6th to orbit the planet closest to the sun, Mercury. During the encounter, the probe will swing just 125 miles (200 kilometers) above the cratered surface of Mercury, snapping 1,278 pictures and collecting a variety of other data from the planet as it gains a critical gravity assist that keeps the probe on track to become the first spacecraft ever to orbit the innermost planet beginning in March 2011.

Daniel J. O’Shaughnessy, Lead for MESSENGER’s Guidance and Control subsystem, explained the technology behind solar sailing. O’Shaughnessy said, “sunlight exerts a small but perceptible force on MESSENGER at all times. Rather than let the MESSENGER trajectory be pushed around by the force due to sunlight, operators planned an intricate sequence of solar, ray, and body attitude changes, helping to deflect the light in a way that allows the push from the sun to drive the MESSENGER closer to the flyby target.”

The only previous probe to visit Mercury was the Mariner 10, which completed its mission in March 1975. The Mariner 10 mapped only about 45% of the planet’s surface from 1974 to 1975. The MESSENGER mapped approximately 30% of the planet on its first mission. As Marilyn Lindstrom from NASA’s Washington headquarters said, “it’s not very easy getting into Mercury’s orbit. We need to have six planetary flybys to provide gravity assist to slow us down and ease us into orbit in 2011.” NASA proposes ‘solar sailing’ as a differentiator between this upcoming mission and past missions, which will bring great advancements in broad planetary exploration.