Global coverage requirements for NISAR science are specified in the Level 1 requirements. The mission aims to achieve global coverage of land where biomass exists (which is nearly everywhere on land), full coverage of land and sea ice at both poles and in mountains, frequent coverage of land areas that are deforming rapidly, and regular infrequent global coverage elsewhere to be prepared to respond to events that are unusual, for example mid-plate earthquakes.
Because of the broad science goals of the mission, and the wide variety of modes that could be employed over any given area, there is a great potential for complexity in the observation plan. The original plan proposed at the Mission Concept Review developed an observation plan by discipline, where each discipline created a set of science targets and observation attributes to optimize the science. These target maps and optimized modes are shown to the right (or bottom on small browser screens). Each colored region represents a radar mode (polarization state and bandwidth) and sampling strategy in the optimized plan.
When these strategies are taken together they lead to a number of conflicts. To address these conflicts, the Science Definition Team worked out a simplified target strategy that assigns a single mode to a given target area on Earth. Where target areas overlap, the modes are compatible such that no science discipline loses information. The modes assigned to these targets are shown in the mode table below. This strategy is highlighted in the following two figures.
Reduced Set of Target Types for more Uniform Global Coverage
This figure shows the reduced set of target types for global observations, and the second shows the radar modes associated with these targets. Note that the observation plan calls for nearly continuous global coverage over most land and ice.
For each of the observation targets, there is a single mode (polarization, bandwidth, radar band combination) that is used over that area. For overlapping targets, such as background land and US Agriculture, the more capable mode is a superset of capability of the other mode. In the table, SP = Single Polarization, DP = Dual Pol, QP = Quad Pol, CP = Compact Pol, H = Horizontal, V = Vertical, "s = 1 p" is short for sampling is every pass, "cull by lat" means that at higher latitudes, redundant overlapping data are not acquired. The arrows to the right indicate whether data will be acquired on ascending orbits, descending orbits, or both.
Baseline Deformation Targets