NASA’s TSIS-2 spacecraft has passed environmental tests that reproduced the vacuum, temperature changes, and vibration associated with spaceflight. The agency reported the milestone on November 2, 2026, with launch targeted for early 2027 aboard Rocket Lab’s Electron from New Zealand.
The Total and Spectral Solar Irradiance Sensor-2 mission will measure sunlight arriving at the top of Earth’s atmosphere. Its observations will extend records used to quantify changes in the Sun’s energy output and its contribution to Earth’s climate.
General Atomics Electromagnetic Systems performed the testing. Thermal-vacuum trials operated the spacecraft and instruments through hot and cold conditions at very low pressure. Vibration testing subjected the spacecraft to mechanical loads representing launch. Engineers also measured its mass, center of gravity, and mass distribution.
Measuring Total Energy and Its Wavelengths
TSIS-2 carries two instruments with complementary jobs. The Total Irradiance Monitor measures the overall solar energy arriving at Earth. The Spectral Irradiance Monitor measures how that energy is distributed across ultraviolet, visible, and near-infrared wavelengths.
NASA states that the spectral instrument covers wavelengths accounting for approximately 96% of the energy in the solar spectrum. Separating the measurements by wavelength allows researchers to examine changes that a single total-energy value would combine.
Measurements above the atmosphere establish the incoming solar signal before atmospheric absorption and scattering alter it. NASA’s mission overview notes that total solar brightness changes by approximately 0.1% over the roughly 11-year solar cycle.
Continuing Two Measurement Records
TSIS-2 will continue total solar irradiance observations that began in 1978 and spectral observations dating to 2003. Its instruments resemble those on TSIS-1, which operates aboard the International Space Station. TSIS-2 will fly as an independent spacecraft.
The University of Colorado’s Laboratory for Atmospheric and Space Physics developed the instruments and will support science-data processing and orbital operations. General Atomics designed and manufactured the spacecraft and will operate it through its Satellite Mission Observatory Center.
With environmental testing complete, the next preparation steps include transport in a custom shipping container and integration with the launch vehicle.
