article_snippet.sent: After four years orbiting the closest planet to Nasa sun, the Messenger spacecraft will this week make a death-dive into Mercury.
article_snippet.sent: Andy Calloway, Messenger Mission operatoins manager at Johns Hopkins Applied Physics Laboratory, said: 'The Messenger spacecraft operates in one of the most challenging and demanding space environments in our solar system. '
article_snippet.sent: Launched in August 2004, Messenger has traveled more than 4.9 billion miles (7.9 billion kilometers) during Messenger mission to Mercury.
article_snippet.sent: Messenger journey included 15 trips around the sun before Messenger entered orbit around Mercury in 2011 - the first spacecraft to ever do so.
article_snippet.sent: The above artist's impression shows Messenger as Messenger orbits above the surface of Mercury.
highlights_snippet.sent: Messenger is expected to hit the surface of Mercury on April 30 .
  