The Total and Spectral Solar Irradiance Sensor (TSIS-1), first selected in 1998 for the National Polar-orbiting Operational Environmental Satellite System (NPOESS), re-manifested in 2010 on the NOAA-NASA Joint Polar Satellite System (JPSS), then the NOAA Polar Free Flyer, launched successfully to the International Space Station on December 15, 2017.
TSIS-1 makes measurements of total and spectral solar irradiance (TSI and SSI, respectively). TSI is required for establishing Earth’s total energy input while SSI 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.
TSIS-1 provides continuation of the Total Irradiance Monitor (TIM) and the Spectral Irradiance Monitor (SIM), both also currently flying on the NASA Solar Radiation and Climate Experiment (SORCE). Launched in 2003, SORCE is now more than six years beyond its prime-mission lifetime. The launch failure of the NASA Glory mission in 2011, coupled with diminished battery capacity on SORCE and delays in the launch of TSIS-1 put the continuous 39-year TSI record at risk. In 2012, a plan to maintain continuity of the TSI calibration scale between SORCE and TSIS-1 was rapidly implemented through the USAF Space Test Program STPSat-3 that launched in late 2013.
Highly accurate, stable, and continuous observations of solar irradiance are critical to understanding the present climate epoch and for predicting future climate.
- The Total Irradiance Monitor (TIM) instrument
- The Spectral Irradiance Monitor (SIM) instrument
- Precision solar pointing of the TIM and SIM instruments
- TSIS Principal Investigator, Peter Pilewskie
- Mission operations for TSIS-1
TSIS-1 is a dual-instrument package that is acquiring solar irradiance measurements from the International Space Station over a nominal period of five years. TSIS-1 has been identified as providing critical data in determining the natural forcings of the climate system and ensures the continuity of the solar irradiance Climate Data Record (CDR).
TSIS-1 is comprised of the Total Irradiance Monitor, or TIM, which measures the total solar irradiance (TSI) that is incident at the outer boundaries of the atmosphere; and the Spectral Irradiance Monitor, or SIM, which measures solar spectral irradiance (SSI) from 200 nm to 2400 nm (96 percent of the TSI). The TSIS-1 TIM and SIM are heritage instruments to those currently flying on the SORCE satellite. Both were selected as part of TSIS-1 because of their unprecedented measurement accuracy and stability, and because both measurements are essential to constraining the energy input to the climate system and interpreting the response of climate to external forcing. TSIS-1 is required in order to continue the 39-year record of TSI, extend the newer 15-year record of SSI, and ensure the stewardship of the solar irradiance Climate Data Record into the future.
Launch date: Delivery to ISS on December 15, 2017; Instruments powered on in March 2018
Launch location: Cape Canaveral Air Force Station
Launch vehicle: SpaceX Falcon 9 and Dragon capsule
Mission target: Low Earth orbit
Mission duration: 5 years
Other key dates:
Other organizations involved:
- NASA’s Goddard Space Flight Center (GSFC)