MESSENGER Mercury Flyby 3 - Maneuvers for the Neutron Spectrometer

This animation shows maneuvers of the MESSENGER spacecraft during a portion of the third Mercury flyby on September 29, 2009. Several of the maneuvers are designed to improve the capability of MESSENGER's Neutron Spectrometer (NS) to identify neutron-absorbing elements, most notably iron (Fe) and titanium (Ti), on Mercury's surface. Thermal neutrons are measured with the Doppler filter effect, which uses the spacecraft velocity (5 km/s) and orientation to identify the slower (2.2 km/s) thermal neutrons. The graph at lower right shows predicted neutron counting rates for three different average surface compositions; blue, green, and red curves denote counting rates for low, medium, and high amounts of Fe and Ti, respectively. The Doppler filter effect reaches its peak neutron enhancement during the spacecraft rotation maneuver at 21:46 UTC. It is at this time that neutrons provide the strongest discriminator of Mercury's surface composition, as seen by the separation among the three colored curves.

Category:

Science & Technology

Tags:

• MESSENGER
• Mercury
• Mercury flyby
• neutron spectrometer
• NASA
• space exploration