Synthetic aperture radar (SAR)

Also known as “persistent imaging,” synthetic aperture radar is an active sensor that can create an image through cloud cover or at night. The image is rendered in black and white based on the concentration of radar returns (also known as “backscatter”). Radar sends out a signal and waits to see how much signal is “returned”—the time it takes to return and if it returns determines the shade. Black represents low returns while white represents higher returns.

There are several new companies offering this type of satellite imagery and an increasing number of companies are launching satellites with this type of sensor.