NASA's MErcury Surface, Space ENvironment, GEochemistry,
and Ranging (MESSENGER) spacecraft will make its closest pass to Venus on Tuesday, June 5. This will place the spacecraft on target for a flyby of Mercury in January 2008. MESSENGER will be the first probe to visit the innermost planet in more than 30 years.
Threading its path through an aim point 209 miles above the surface ofVenus, MESSENGER will use the pull of the planet's gravity to guide it closer to Mercury. During this flyby, Venus's gravity will change the spacecraft's direction around the sun and decelerate it from 22.7 to 17.3 miles per second.
"Typically, spacecraft have used planetary flybys to speed toward the outer solar system," said Andy Calloway, MESSENGER mission operations manager, Johns Hopkins University Applied Physics Laboratory (APL), Laurel, Md. "MESSENGER, headed in the opposite direction, needs to slow down enough to slip into orbit around Mercury."