Since its launch in August 2004, the MESSENGER spacecraft has traveled 2.40 billion miles (3.85 billion kilometers). That’s the mileage as of March 19, although it grows about 18 miles (29 km) every second. Back on January 14, the probe had traversed merely 2.23 billion miles (3.59 billion km) — just enough to get it to Mercury. It marked the first flyby of the innermost planet since Mariner 10 skimmed past for its third and final time in 1975.
Message from the innermost planet
The MESSENGER spacecraft flew past Mercury January 14, giving scientists their first close-up view of the planet in 33 years.