April 23, 12:00 pm - 1:00 pm

April 23, 12:00 pm - 1:00 pm

Exospheric environments of Mercury and the Moon: findings by MESSENGER and outlook for LADEE

Menelaos Sarantos (University of Maryland/GSFC)

The surface-bounded, collisionless exospheres of Mercury and Earth’s Moon are among the investigational objectives of two spacecraft missions that have GSFC participation. The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft probed the Hermean exosphere during three flybys prior to its expected insertion into orbit next year, whereas the Lunar Atmosphere and Dust Experiment Explorer (LADEE) will monitor the lunar exosphere during a brief, three-month period in 2012. We detail some of MESSENGER’s findings regarding the source and loss processes for exospheric neutrals, and assess the role that resulting planetary ions might play in Mercury’s magnetospheric processes. Furthermore, exospheric models are applied to support the neutral mass and visible/ultraviolet spectrometry investigations planned by LADEE. The models provide useful insight on how to accomplish the mission’s science requirements for a wide inventory of species that are either known or expected to be present in the exosphere of our Moon.