On September 29, 2009, the MESSENGER spacecraft passed by Mercury for the third time, flying 141.7 miles above the planet’s rocky surface for a final gravity assist that will enable it to enter orbit about Mercury in 2011. During the encounter, the MESSENGER cameras imaged a portion of Mercury's never-before-seen surface and the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) observed Mercury's exospheric "tail" during approach. With more than 90 percent of the planet’s surface already imaged, MESSENGER’s science team had drafted an ambitious observation campaign designed to tease out additional details from features uncovered during the first two flybys. But an unexpected signal loss prior to closest approach hampered those plans. Read this Mission News story for more details about the flyby.

Visit this page to read about the special targeted observations that were planned for Mercury flyby 3.

Use this Mercury Flyby 3 Visualization Tool to see simulated views of the planned instrument observations for the flyby.

November 3, 2009, 1 pm EDT:
NASA Science Update with Mercury Flyby 3 Results

September 23, 2009, 1 pm EDT:
NASA Media Telecon Preview of the Flyby

September 29, 2009, 5:55 pm EDT:
MESSENGER's Closest Approach to Mercury

October 1, 2009, 5 pm EDT:
Public Talk at APL: "Highlights from Three Mercury Flybys"

Watch an animation (94.9 MB) of the spacecraft maneuvers and the instrument observations that were planned for MESSENGER's third flyby of Mercury. (Small version without labels: 31 MB)

During the flyby, MESSENGER Educator Fellows shared their experiences in real time via the web. Learn more by visiting this page.

View a timeline of the many spacecraft and instrument activities that were planned for the flyby in a graphical format.