A Messenger to Mercury
by Paul Deans
|An artist's impression of MESSENGER in orbit at Mercury. Because of the extreme heat, a sunshade made of heat-resistant ceramic fabric protects the spacecraft's instruments. Courtesy NASA / JHUAPL / Carnegie Institution.|
Scientists involved in the spacecraft exploration of the solar system are patient bunch. They have to be. For instance, after liftoff in August 1977, it took Voyager 2 two years to reach Jupiter; three to get to Saturn; seven to reach Uranus; and more than 10 years to arrive at Neptune.Add on the pre-launch years required for mission concept and development, plus time for spacecraft construction, and it's no surprise that some astronomers devoted most of their career to the Voyager missions. Equally daunting is the New Horizons journey to Pluto. Launched in January 2006, the spacecraft will not fly past this dwarf planet until July 2015 -- a wait of nearly a decade.
By comparison, the MESSENGER mission to Mercury has been a whirlwind of activity. Launched in August 2004, the spacecraft is now on its final approach to an orbital rendezvous with the closest planet to the Sun. But along the way, it flew past Earth once, Venus twice, and Mercury three times.
Those three Mercury flybys helped settle MESSENGER (an acronym for MErcury Surface, Space ENvironment, GEochemistry, and Ranging) into a solar orbit that is conducive to an orbital-insertion maneuver when it approaches the tiny planet for the fourth time.
If you enjoyed this excerpt from a feature article and would like to receive our quarterly Mercury magazine, we invite you to join the ASP and receive 4 issues a year.