(Before It's News)
between May 21, 2014 and August 5, 2014 the Rosetta spacecraft will perform crucial orbit correction maneuvers.
These are required to slow down the spacecraft's speed relative to comet 67P/Churyumov-Gerasimenko – from 750 meters per-second to just one meter per-second. This will reduce Rosetta's distance from the comet from one million kilometers to just under 200 kilometers.
Source:
http://stargazernation.blogspot.com/2014/05/rosetta-slowing-for-monumental.html