Using Measurements on Multiple Satellites Arranged in Global, Regional, and Local Configurations to Obtain Fundamental Knowledge of the Earth's Upper Atmosphere/Ionosphere System - The Great Prospects of NASA's Geospace Dynamics Constellation

Observations, theory, and modeling have underscored that the Earth's upper atmosphere/ionosphere must be understood as a system. This is due to its highly variable nature, its wide range of scales that extend across regions, and the strong coupling of the co-located ionized and neutral gases that respond to energy sources from the sun and magnetosphere above and the lower atmosphere below.

Whereas single satellites reveal key aspects of the near-space environment and are important for case studies and statistical averages, a single platform cannot capture the highly dynamic nature of the global ionosphere/thermosphere (I-T) system, unravel its spatial and temporal variations, or reveal how the coupled gases both configure and re-configure across a wide range of scales.

To make significant progress, the next step is to deploy multiple satellites as an ensemble to address transformational science objectives and significant space weather effects. NASA's Geospace Dynamics Constellation (GDC) presents precisely this unprecedented opportunity with multiple satellites arranged (1) in different orbit planes to address global and regional distributions with synchronous measurements, and (2) as successive satellites traveling on similar orbits to unravel spatial and temporal variations.

We describe how a suite of satellites could be configured to address: Global Objectives, such as understanding how imposed magnetospheric plasma convection sets the entire high latitude upper atmosphere in motion, as well as how magnetic storms alter the global I-T system; Regional Objectives, such as understanding the creation and evolution of ionized and neutral structures that pervade the high latitudes; and Local Objectives such as those determining how ionized and neutral gases reconfigure when driven by external energy sources.

Nominally, GDC will gather comprehensive measurements on identical platforms in circular, high inclination orbits in the critical altitude region of 300 to 400 km where the ionized and neutral gases are efficiently coupled and where space weather effects are profound.

This talk provides an overview of how an unprecedented suite of observational platforms such as those expected to comprise the GDC mission will transform our understanding of Earth's critically important near-space environment.