The Deformation, Ecosystem Structure, and Dynamics of Ice

The National Research Council's Decadal Survey for Earth Science identified the Deformation, Ecosystem Structure, and Dynamics of Ice (DESDynI) mission among the highest priorities for new NASA Earth missions. The primary mission objectives for DESDynI are to: (1) Determine the likelihood of earthquakes, volcanic eruptions, and landslides; (2) Predict the response of ice sheets to climate change and impact on sea level; and (3) Characterize the effects of changing climate and land use on species habitats and carbon budget. In addition to these science-focused areas, it is becoming increasingly clear that DESDynI's wide area mapping capability can play a key role in the nation's strategy for hazard monitoring and mitigation. DESDynI consists of an L-band Synthetic Aperture Radar configured for repeat-pass interferometric observations (InSAR), and a nadir pointing lidar suitable for vegetation canopy structure characterization. The mission is now in pre-formulation, with studies underway to evaluate efficient combinations of science objectives and mission/instrument scenarios. A key trade has been the antenna concept: The InSAR component can be satisfied by a traditional phased array deployable aperture as flown in space on SeaSAT, JERS-1, and ALOS. Alternatively, the SAR can be designed as an offset-fed reflector, capitalizing on large commercial mesh reflector antenna and transmit/receive modules developed for the NASA UAVSAR airborne radar. This InSAR system addresses several shortcomings of existing InSAR capable satellites. To reduce temporal decorrelation, L-band (24 cm wavelength) is used. A 340 km wide-swath SAR mode with near-weekly exact repeat intervals enhances study of ice dynamics, pre/post earthquake deformation, volcano monitoring, and other dynamic phenomena. Fully polarimetric capability allows wide-area extension of key parameters of the vegetation canopy, such as biomass and land cover change, firmly anchored through the fine detail provided by the lidar in globally distributed profiles. Similarly polarimetric InSAR measurements allow further refinement of canopy structure in appropriate canopies. Key challenges involve scheduling and observational strategy to optimize overlapping observational requirements of various science communities served. This paper describes the mission science, current design, and observational trades that affect the science return.