Phillip Christensen holds a non-working replica of Europa Clipper’s thermal imager (called the Europa Thermal Emission Imaging System, or E-THEMIS) that has the exact same mass and dimensions as the real flight instrument. To avoid unnecessary handling of the actual E-THEMIS camera, engineers use this mass model for tests that don't require a functioning instrument. These include doing initial vibration testing and checking that electrical cables fit properly in the space provided.