NISAR's flight antenna system sitting in the thermal vacuum testing chamber.
Source: NASA/JPL-Caltech
Published: January 4, 2022

This view shows NISAR’s flight antenna system before the chamber door was closed, as it underwent thermal vacuum testing at NASA’s Jet Propulsion Laboratory in Southern California.

The antenna system is tested in its stowed configuration and exposed to the full range of temperatures it will see in orbit prior to deployment. Testing includes functional checks of deployment motors and release of some launch restraints.