A NASA Discovery mission to conduct the first orbital study
of the innermost planet
NASA logo carnegie institution logo JHU APL logo

Why Mercury?
The Mission
News Center
Science Operations
Who We Are
Related Links

Download iPhone/iPad app Information about Mercury Flybys Question and Answer End of Orbit Insertion Where is MESSENGER? Where is Mercury now? Subscribe to MESSENGER eNews

Mercury Flyby 3


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.

Information about Targeted Observations

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

Visualization Tool

visualization tool thumbnail 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"

Images and Data from the Flyby
images from the flyby thumbnail

View images and movies acquired by the MESSENGER spacecraft during its flyby of Mercury. Check back often to see the latest releases as they become available!

movie thumbnail

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)

Fellows at the Flyby

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.


Closest Approach Trajectory Highlights

See three views of the spacecraft trajectory near closest approach to the planet, as well as summary details of the spacecraft’s location when closest to the planet and the gravity-assist boost imparted to the spacecraft via the flyby.

Third Mercury flyby closest approach details:

Date and time: September 29, 2009, 21:54:56 UTC
Spacecraft distance to planet center: 2667.2 km
Altitude: 227.8 km
Sub-spacecraft surface latitude, longitude: 0.329° S, 211.653° E
Spacecraft velocity with respect to planet center: 5.289 km/s
Effective gravity-assist velocity change from flyby: 2.836 km/s

   Top  | Contacts
© 1999-2015 by JHU/APL