MESSENGER spacecraft maps of the planet Mercury
 

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

The US space agency, NASA, has released the first complete map of Mercury, the innermost and smallest planet. NASA’s MESSENGER spacecraft, which has been orbiting Mercury since March 2011, has ultimately imaged the entire surface of the planet. The map has been produced from thousands of MESSENGER’s images.

Mariner 10, the first spacecraft ever to visit Mercury, during three flybys of the planet, performed in 1974 and 1975, managed to map only 45% of its surface. 

"It's a huge accomplishment – we've gone from having more than half of the planet a complete mystery prior to MESSENGER to a full coverage that will enable a better understanding of the global processes that shaped Mercury's formation and evolution," said Brett Denevi, a member scientist of the MESSENGER program.

"Completing the initial imaging of the entire surface of our solar system's innermost planet is an important milestone," adds Sean Solomon, MESSENGER Principal Investigator. "Those global images have produced many important discoveries about how Mercury's crust formed and evolved, but all of those discoveries have raised new questions.  With ongoing and planned targeted observations, conducted synergistically with all of MESSENGER's instruments, we can look forward to further discoveries and new understanding."

During its one-year main mission, MESSENGER acquired 88,746 images and extensive data. It is now nearing completion of a yearlong extended mission, during which the space probe has obtained over 80,000 new images and other measurements, to support the science targets.

MESSENGER launched toward Mercury on 3 August 2004, from Cape Canaveral Air Force Station, aboard a powerful Delta II rocket. It flew by Mercury on 14 January 2008, then performed two more Mercury flybys, on 6 October 2008 and 29 September 2009. Eventually, MESSENGER became the first spacecraft to enter Mercury orbit, on 18 March 2011.

Interestingly, during its spectacular voyage to Mercury, MESSNEGER flew by Earth, on 2 August 2005, almost one year after its launch, and flew by Venus twice, on 24 October 2006 and on 5 June 2007. 

References
NASA
MESSENGER Website
Wikipedia

Aymen Mohamed Ibrahem
Senior Astronomy Specialist