The Thermal Infrared Sensor 2 (TIRS-2) will fly aboard the Landsat 9 spacecraft and leverages the Thermal Infrared Sensor (TIRS) design currently flying on Landsat 8. TIRS-2 will provide similar science data as TIRS, but is not a buildto-print rebuild due to changes in requirements and improvements in absolute accuracy. The heritage TIRS design has been modified to reduce the influence of stray light and to add redundancy for higher reliability over a longer mission life. The TIRS-2 development context differs from the TIRS scenario, adding to the changes. The TIRS-2 team has also learned some lessons along the way.

The Thermal InfraRed Sensor (TIRS) instrument was launched into space on board Landsat 8 in February 2013. This instrument was added to Landsat 8 to measure water evaporation and transpiration as well as provide two thermal infrared bands to complement the optical suite.TIRS has a refractive telescope which focuses a light onto a focal plane cooled to 43K with a two-stage cryocooler. This paper will detail the mechanical aspects of TIRS including a description of its composite honeycomb box design, flexures, large deployable earth shield, and accommodations for the telescope, detector, and cryocooler. The design, build, test, and delivery of TIRS was accomplished in three years on an accelerated schedule at NASA Goddard Space Flight Center.The assembly and test flow are discussed including qualification of the structure in vibration and acoustic tests.