Deployment Mechanism fo r Thermal Pointing System Kraig Koski* Abstract The Deployment Mechanism for the Total and Spectral Solar Irradiance Sensor (TSIS) is responsible for  bringing the Thermal Pointing System (TPS) from its stowed, launch locked position to the on-orbitdeployed, operational position. The Deployment Mechanism also provides structural support for the TSIS  optical bench and two-axis gimbal. An engineering model of the Deployment Mechanism has been environmentally qualified and life tested. This paper will give an overview of the TSIS mission and then describe the development, design, and testing of the Deployment Mechanism. Introduction The goal of the TSIS instrument suite is to accurately measure Total Solar Irradiance (TSI) and Solar  Spectral Irradiance (SSI) and make the data available to the research community and public. TSI is  defined as the Sun’s radiant power per unit area (watts/m 2) incident on a plane surface at the top of the  atmosphere that is normal to the direction from the Sun and normalized to 1 astronomical unit. SSI is the power per unit area per unit wavelength interval. These two measurements are important for measuring the magnitude and variability of natural radiative forcing on the Earth’s climate system. Radiative forcings are variations in the radiant energy received by the Earth or the energy radiated back to space. Long term measurements of solar and spectral irradiance provided by TSIS are required to continue the Climate Data Record and to fully understand the causes of climate change.  The University of Colorado/Laboratory for Atmospheric and Space Physics (LASP) is responsible for the  delivery of the TSIS instrument. The TSIS dual instrument package was originally selected to fly on National Polar-orbiting Operational Environment Satellite System (NPOESS). It was de-manifested in  2006 during the restructuring of NPOESS, and then restored in 2007 following a decision by the NPOESS Executive Committee because of its critical role in determining the natural forcings of the climate system  and the high priority given by the Earth Science Decadal Survey. Further restructuring of NPOESS  transitioned all climate sensors, including TSIS, to the Joint Polar Satellite System (JPSS). The JPSS is  the next generation of low Earth, polar orbiting, environmental satellites that are procured by the National  Oceanic and Atmospheric Administration (NOAA) through NASA [1].   TSIS Mission Design TSIS is comprised of two instruments:  the Total Irradiance Monitor (TIM) and the Spectral Irradiance  Monitor (SIM). The TIM instrument measures TSI, integrating all wavelengths of solar energy (W/m2) at  the outer boundaries of the atmosphere. The SIM instrument measures SSI from 200 nm to 2400 nm (96% of TSI)[2]. Both instruments along with associated electronics boxes are mounted to an optical  bench which is mounted on a two-axis gimbal that provides the required solar pointing accuracy. The twoaxis gimbal is mounted inside a mast that can be deployed and stowed (see Figure 1).  The TSIS is slated to launch in 2017 on JPSS Free Flyer 1 (JPSS-FF1), which is a smaller spacecraft relative to NPOESS with solar pointing capability. Since the JPSS-FF1 spacecraft will provide solar  pointing, the need for the TPS and Deployment Mechanism is eliminated. Much of the fabrication and assembly of the TPS and Deployment Mechanism was already completed at the time of this decision, so approval was provided to continue the design and testing. This decision was based on the possibility that  *Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO  /g51/g85/g82/g70/g72/g72/g71/g76/g81/g74/g86/g3/g82/g73/g3/g87/g75/g72/g3/g23/g21/g81/g71/g3/g36/g72/g85/g82/g86/g83/g68/g70/g72/g3/g48/g72/g70/g75/g68/g81/g76/g86/g80/g86/g3/g54/g92/g80/g83/g82/g86/g76/g88/g80/g15/g3/g49/g36/g54/g36/g3/g42/g82/g71/g71/g68/g85 /g71/g3/g54/g83/g68/g70/g72/g3/g41/g79/g76/g74/g75/g87/g3/g38/g72/g81/g87/g72/g85/g15/g3/g48/g68/g92/g3/g20/g23/g16/g20/g25/g15/g3/g21/g19/g20/g23 435