The Space Engineering Spacecraft “Hayabusa” (MUSES-C) launched on May 9, 2003, by the Japan Aerospace Exploration Agency (JAXA) has been flying smoothly in a heliocentric orbit for about a year using its ion engines.
On May 19, Hayabusa came close to the Earth, and successfully carried out an earth swing-by to place it in a new elliptical orbit toward the asteroid “ITOKAWA”.
The earth swing-by is a technique to significantly change direction of an orbit and/or speed by using the Earth’s gravity without consuming onboard propellant. Hayabusa came closest to the Earth at 3:22 p.m. on May 19 (Japan Standard Time) at an altitude of approximately 3700 km.The combination of acceleration by the ion engines and the earth swing-by performed this time was the first technological verification in the world, both in the sense of plot and implementation. After its precise orbit is determined in a week, Hayabusa will restart its ion engines to fly toward “ITOKAWA”.
Hayabusa acquired earth images using its onboard optical navigation camera (which is for detecting a relative position to an asteroid and for scientific observations) as it neared the Earth. You can find these images at the following websites:
Institute of Space and Astronautical Science (ISAS)
http://www.isas.jaxa.jp/e/index.shtml
Hayabusa Earth Swing-by
http://www.jaxa.jp/press/2004/05/20040520_hayabusa_e.html