Caption: After its encounter with Tempel 1 (green arc), the Deep Impact flyby spacecraft continued in its orbit (yellow ellipse) around the sun that will bring it past Earth for the first of three flybys. Along the way, there have been some trajectory correction maneuvers (TCMs) to adjust the spacecraft's path so that after the flyby it will be in an orbit (white circles) that will intersect with comet Hartley 2 (red arc) in 2010. During the flyby, the spacecraft will experience a gravity assist from Earth (blue circle) that will steal some of the orbital energy from the spacecraft, changing its orbit from the yellow path to the white one. Additional Earth flybys in 2008 and 2009 will refine the orbit even further.
2007 Earth Flyby
Image Credit: NASA/JPL-Caltech/UMD/GSFC/Tony Farnham