Instrument designer and lead scientist Philip Christensen stands next to the box-like "tent" that surrounds both Europa Clipper’s thermal imager (called the Europa Thermal Emission Imaging System, or E-THEMIS), left, and its optical test equipment. With the tent doors closed and sealed, the team can flood the tent with dry nitrogen gas to remove all water vapor inside. This lets engineers accurately test E-THEMIS' thermal sensitivity, which water vapor greatly interferes with.