Other
Scientific paper
Sep 2009
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009dps....41.1101c&link_type=abstract
American Astronomical Society, DPS meeting #41, #11.01
Other
Scientific paper
Even before insertion into orbit about Mercury, MESSENGER has altered our understanding of the innermost planet. Images from MESSENGER's first Mercury flyby, in January 2008, revealed abundant evidence for widespread volcanism. Newly imaged lobate scarps and other tectonic landforms confirm that Mercury contracted globally in response to interior cooling. The 1500-km-diameter Caloris basin, first fully viewed by MESSENGER, has been the focus for numerous volcanic centers, some with pyroclastic deposits. Smooth plains interior and exterior to Caloris are demonstrably younger than the basin-forming event, and the basin interior experienced widespread contractional and extensional deformation. Reflectance spectra of Mercury's surface showed no evidence for FeO in surface silicates. MESSENGER observations support earlier inferences that Mercury's surface consists dominantly of iron-poor, calcium-magnesium silicates plus spectrally neutral opaque minerals. MESSENGER's second flyby, in October 2008, documented neutral Mg and Ca in Mercury's anti-sunward tail and differing distributions of Mg, Ca, and Na in the nightside exosphere, resulting from different combinations of time-variable source, transfer, and loss processes. Accompanying a southward interplanetary magnetic field (IMF) were magnetic reconnection rates 10 times typical at Earth; combined with the more quiescent conditions under northward IMF seen during the first flyby, these results indicate that Mercury's magnetosphere is more responsive to IMF direction than those of other planets. Nearly global compositional mapping of surface units shows that volcanic smooth plains occupy 40% of the surface area, while low-reflectance material, largely in deposits excavated by impact, occupy 15%, consistent with having formed within the crust or upper mantle. The second flyby also revealed the 700-km-diameter Rembrandt basin, less volcanically infilled than Caloris, but also a focus for concentrated magmatic and deformational activity. The third and final Mercury flyby, on 29 September, targeted observations of the surface, exosphere, and tail optimized from the experiences of the first two flybys.
Anderson Benjamin J.
Chapman Clark R.
Evans Larry G.
Gold Robert E.
Head James W.
No associations
LandOfFree
Mercury after Three MESSENGER Flybys does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Mercury after Three MESSENGER Flybys, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Mercury after Three MESSENGER Flybys will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1331986