Science Seminars

8/29/2011 – The MESSENGER Mission: 325 Orbits of Mercury and Counting

Speaker: Ralph McNutt, Johns Hopkins University, Applied Physics Laboratory
Date: Monday, Aug 29, 2011
Time: 11:45 AM
Location: Duane D-142

Seminar Abstract:

NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft is now well into its primary mission to initiate a new era in our understanding of the innermost planet. MESSENGER became the first spacecraft to orbit Mercury on 18 March 2011. MESSENGER’s Mercury Dual Imaging System is acquiring a global monochrome image mosaic at better than 90% coverage and at least 250 m average resolution, a global color image mosaic at better than 90% coverage and at least 1 km average resolution, and global stereo imaging at better than 80% coverage and at least 250 m average resolution. Higher-resolution images are also obtained of pre-selected targeted areas. The elemental remote sensing instruments are being operated nearly continuously and will ascertain the average abundances of most major elements. The Visible and Infrared Spectrograph channel of MESSENGER’s Mercury Atmospheric and Surface Composition Spectrometer (MASCS) is acquiring a global map of spectral reflectance from 300 to 1450 nm at a range of incidence and emission angles. Targeted areas have been selected for spectral coverage into the ultraviolet with the Ultraviolet and Visible Spectrometer, which is also being used to obtain observations of Mercury’s exospheric neutral species via their emission lines. MESSENGER’s Mercury Laser Altimeter is acquiring topographic profiles when the slant range to Mercury’s surface is 1500 km, encompassing the northern hemisphere. Topography over most of the southern hemisphere will be derived from stereo imaging, radio occultations, and limb profiles. MESSENGER’s radio science experiment is ascertaining Mercury’s gravity field from Doppler signals during downlinks MESSENGER’s Magnetometer is measuring the vector magnetic field at an instrument sampling rate of 20 samples/s or in a triggered burst mode to capture magnetospheric when downlink collection is limited. During each spacecraft orbit, the Energetic Particle Spectrometer measures energetic electrons and ions, and the Fast Imaging Plasma Spectrometer measures the energies and mass per charge of thermal plasma components, both within Mercury’s magnetosphere and in Mercury’s solar-wind environment.