title: Return to Mercury: a global perspective on MESSENGER's first Mercury flyby.
abstract: In January 2008, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft became the first probe to fly past the planet Mercury in 33 years. The encounter revealed that Mercury is a dynamic system; its liquid iron-rich outer core is coupled through a dominantly dipolar magnetic field to the surface, exosphere, and magnetosphere, all of which interact with the solar wind. MESSENGER images confirm that lobate scarps are the dominant tectonic landform and record global contraction associated with cooling of the planet. The history of contraction can be related to the history of volcanism and cratering, and the total contractional strain is at least one-third greater than inferred from Mariner 10 images. On the basis of measurements of thermal neutrons made during the flyby, the average abundance of iron in Mercury's surface material is less than 6% by weight.
authors.affiliation: Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA. scs@dtm.ciw.edu
authors.forename: Sean C
authors.initials: SC
authors.lastname: Solomon
authors.forename: Ralph L
authors.initials: RL
authors.lastname: McNutt
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Watters
authors.forename: David J
authors.initials: DJ
authors.lastname: Lawrence
authors.forename: William C
authors.initials: WC
authors.lastname: Feldman
authors.forename: James W
authors.initials: JW
authors.lastname: Head
authors.forename: Stamatios M
authors.initials: SM
authors.lastname: Krimigis
authors.forename: Scott L
authors.initials: SL
authors.lastname: Murchie
authors.forename: Roger J
authors.initials: RJ
authors.lastname: Phillips
authors.forename: James A
authors.initials: JA
authors.lastname: Slavin
authors.forename: Maria T
authors.initials: MT
authors.lastname: Zuber