MESSENGER Operational Influences and Environment

After a busy 6.6-year interplanetary trajectory through the inner solar system, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft was inserted into a highly eccentric, near-polar orbit about Mercury on 18 March 2011 UTC. It conducted uninterrupted operations until, after depleting its propellant, it impacted Mercury's surface on 30 April 2015. The spacecraft faced a number of operational, power-related, and thermal challenges throughout its mission, including the extreme and highly variable thermal environment at Mercury, the collection of a wide variety of science observations, frequent orbit-correction maneuvers, radio occultations, solar conjunctions, and power and thermal constraints on the spacecraft and its instruments. The MESSENGER team met these challenges over the course of the mission's orbital phase, which lasted more than 17 Mercury years. With the team's constant vigilance and analysis, the spacecraft safely and productively completed its primary and two extended missions. The tools and talents of the entire team contributed to the successful accomplishment of that goal without a single safing event during the entire orbital phase, enabling the return of unprecedented data from the innermost planet of the solar system.