1. Armada • Science Objectives: • Develop an understanding of the global ionospheric, thermospheric, and plasmaspheric dynamics. • Understand how high-latitude heating during storms and solar flares affects the global atmospheric structure and dynamics. • Understand how forcing from the lower atmosphere affects the thermospheric structure. • Understand how waves and the neutral winds redistribute energy throughout the global thermosphere. • Understand the global plasmaspheric structure and dynamics during quite and active time periods. • Associated RFAs: • F2.2, F2.4, F3.1, F3.3, F3.5, H2.1, H2.3, H3.2, J1.1, J4.3 Mission Implementation Description: *Number of spacecraft: 25-100 *Location: The orbit needs to be started around 500 km altitude and is expected to degrade over ~1-2 years. Orbits can be relatively random, from high to low inclination. *Attitude control: Need to make sure that GPS antenna is pointing roughly up and comm antenna is pointing roughly down. *Instrumentation: Dual frequency GPS using civilian bands. *Payload resources: There is significant flexibility in the launching of Armada. This can be done in a staged cluster deployment over a long time period (1-2 years), utilizing free space on various launchers or small launch vehicles. Measurement Strategy: We will utilize high-resolution GPS measurements to determine the acceleration and drag on each satellite to infer the thermospheric mass density at each satellite location. The dual-frequency measurements will provide slant-path TEC above the satellites. The use of data assimilation within global ionosphere-thermosphere models will allow specification of the global mass density. The time-history of this (within the model) will allow determination of the neutral winds and other quantities. • Enabling and Enhancing Technology Development: • No “Enabling” technology required. • Multiple, identical spacecraft will benefit from streamlined fabrication, test, and management approach. • Communicating with 100 satellites will involve a distributed array of (low cost) ground-based systems. This can be done with amateur radio groups within universities around the world. • Determining launches for 100 satellite will involve some planning and clustering of satellites.