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The TSIS (Total and Spectral Solar Irradiance Sensor) is an instrument on the International Space Station (ISS) to measure the total and spectral solar irradiance.

TSIS is a project of NASA/GSFC (Goddard Space Flight Center) and the University of Colorado CU/LASP (Laboratory for Atmospheric and Space Physics).

The objective of TSIS is to acquire measurements of total and spectral solar irradiance (TSI and SSI, respectively). TSI (Total Solar Irradiance) is required for establishing Earth's total energy input while SSI (Solar Spectral Irradiance) is needed to understand how the atmosphere responds to changes in the sun's output. Solar irradiance is one of the longest and most fundamental of all climate data records derived from space-based observations.

The TSIS instrument was originally built for the cancelled NPOESS satellites. It was then moved to the SIDAR (JPSS Free Flyer 1) freeflying satellite, which was also cancelled. Finally it was reconfigured as an ISS attached payload. It provides continuation of the TIM (Total Irradiance Monitor) and the SIM (Spectral Irradiance Monitor) on NASA’s SORCE satellite launched in 2003 and on the failed Glory satellite. In 2012, a plan to maintain continuity of the TSI calibration scale between SORCE and TSIS was rapidly implemented through the USAF Space Test Program STPSat-3 that launched in late 2013 an carries the TCTE (TSI Calibration Transfer Experiment).

TSIS will be transported in the unpressurized trunk of a Dragon cargo craft to the ISS, where it will be mounted on the ELC 3 carrier.

Nation: USA
Type / Application: Earth Science
Operator: NASA GSFC, University of Colorado CU/LASP (Laboratory for Atmospheric and Space Physics),
Contractors: NASA GSFC, University of Colorado CU/LASP (Laboratory for Atmospheric and Space Physics),
Equipment: TIM, SIM
Configuration: Attached ISS payload
Propulsion: None
Power: Via ISS
Lifetime: 3 years
Orbit: 400 km × 400 km, 51.6° (typical)
Satellite COSPAR Date LS Launch Vehicle Remarks
TSIS 1 - 2017 CC Falcon-9 v1.2 with Dragon CRS-xx