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MESSENGER Neutron Spectrometer data from flybys 1 and 3

MESSENGER Neutron Spectrometer data from flybys 1 and 3
MESSENGER Neutron Spectrometer data from flybys 1 and 3 During MESSENGER's closest approaches to Mercury on January 14, 2008 ("M1") and September 29, 2009 ("M3"), it used its Neutron Spectrometer to determine the abundance of the elements iron and titanium in the surface. Near closest approach on both of these flybys, the spacecraft was commanded to rotate in a way that would increase its sensitivity to the neutrons flowing off of the surface. On these two diagrams, black dots represent the neutron spectrometer data; bars above and below the dots are the measurement uncertainty. The blue, red, and green lines are the predicted neutron counts for surfaces containing low, high, and very high abundances of iron and titanium, respectively. MESSENGER counted unexpectedly low numbers of neutrons, indicating that the surface has much higher iron and titanium abundance than previously thought. NASA / JHUAPL / CIW