Design Concepts for a New Arecibo Radar and Radio Telescope

We present a plan for a new Arecibo instrument capable of observing all the layers of the atmosphere and geospace with multi-scale high-resolution vector measurements, extending measurements to the plasmapause and beyond, observing high-resolution interplanetary scintillation, and opening a new radar window on coronal mass ejections, the solar corona, and perhaps elsewhere in the heliosphere.