NASA advances world's first spaceborne sodium lidar

It's used as a coolant in nuclear power plants and as a desiccant to remove humidity that otherwise would ruin moisture-sensitive products. Found in every cell in the human body, it transmits nerve impulses and regulates blood pressure. And as it turns out, sodium--the sixth most abundant element in Earth's crust--also is useful as a tracer for characterizing Earth's mesosphere, a poorly understood region of Earth's atmosphere that's sensitive to both the influences from the sun above and the at...