The European Space Agency says its Rosetta spacecraft will fly by Earth for the last time this month, gaining speed for a 10-year journey to explore a comet.

The Rosetta's swing by Earth Nov. 13 will be the fourth planetary gravity assist that will provide the boost the spacecraft needs for its mission to the outer solar system and comet 67P/Churyumov-Gerasimenko. The spacecraft is scheduled for a close encounter with asteroid 21 Lutetia in July next year, before it goes into hibernation early in 2011, in advance of its early 2014 approach to 67P/Churyumov-Gerasimenko.

When it reaches the comet, Rosetta will become the first mission to orbit and deploy a lander on a comet, scientists said. It will help to reconstruct the history of the solar system.

The spacecraft, launched in 2004, is controlled by the ESA's European Space Operations Center in Darmstadt, Germany.