Abstract
Libera is a next generation scanning radiometer that will fly on the Joint Polar Satellite System-4 (JPSS-4), which is set to launch in late 2027. Libera will provide continuity of the Clouds and Earth’s Radiant Energy System (CERES) Earth radiation budget observations, advance the development of a self-contained observing system, and provide enhanced observing capability to further support earth radiation budget science goals. Data collected by Libera will be used by the Earth radiation budget community to continue the long-term measurements of radiation being reflected and emitted by Earth. The Libera science channels include shortwave (0.3-5 μm) to measure solar radiation reflected by the Earth, longwave (5-50 μm) to measure IR radiation emitted from Earth, and total (0.3-100+ μm) to measure the total radiation being reflected and emitted by Earth. In addition to these three channels shared with CERES, there will be a new science channel, the split shortwave channel (0.7-5 μm) to further quantify the shortwave energy deposition in the Earth system, and a wide field of view camera for scene identification and split-SW angular distribution model development.
LASP is also developing a next-generation instrument under the Earth Science Technology Office Instrument Incubator Program – the Black Array of Broadband Absolute Radiometers Earth Radiation Imager (BABAR-ERI). BABAR-ERI is a twochannel push broom imager with a 32 km swath width and a ground sample distance of 1 km. The two instrument channels will measure the total (0.3-100+ μm) and shortwave (0.3-5 μm) outgoing radiation from Earth. BABAR-ERI would operate in a similar manner to Libera, but with higher spatial resolution and reduced geographic coverage.
The integrated instruments will undergo extensive component-level and end-to-end calibration before flight. The instrument response in the infrared (5 μm to 100 μm) will be characterized at LASP using two blackbodies which are currently under development. During on-orbit operation Libera and BABAR-ERI will successively observe Earth and deep space, using the deep space observation to set the measurement baseline. The blackbodies are designed to simulate the IR part of the observed radiation from 5 μm to 100 μm. The Earth-View-Simulator (EVS) is designed to operate under vacuum and realizes a temperature range from 20 °C to 90 °C while the Space-View-Simulator (SVS) is designed to operate at 77 K. Additionally, the EVS features an aperture plate whose temperature can be controlled independently from the blackbody cavity to measure the total out-of-field response of Libera and BABAR-ERI. This paper presents the guiding principles and the current design of the blackbody sources.
Development of Variable Temperature Blackbodies for the In-lab Broadband End-to-end Calibration of Libera and BABAR-ERI at LASP
Libera is a next generation scanning radiometer that will fly on the Joint Polar Satellite System-4 (JPSS-4), which is set to launch in late 2027. Libera will provide continuity of the Clouds and Earth’s Radiant Energy System (CERES) Earth radiation budget observations, advance the development of a self-contained observing system, and provide enhanced observing capability to further support earth radiation budget science goals. Data collected by Libera will be used by the Earth radiation budget community to continue the long-term measurements of radiation being reflected and emitted by Earth. The Libera science channels include shortwave (0.3-5 μm) to measure solar radiation reflected by the Earth, longwave (5-50 μm) to measure IR radiation emitted from Earth, and total (0.3-100+ μm) to measure the total radiation being reflected and emitted by Earth. In addition to these three channels shared with CERES, there will be a new science channel, the split shortwave channel (0.7-5 μm) to further quantify the shortwave energy deposition in the Earth system, and a wide field of view camera for scene identification and split-SW angular distribution model development.
LASP is also developing a next-generation instrument under the Earth Science Technology Office Instrument Incubator Program – the Black Array of Broadband Absolute Radiometers Earth Radiation Imager (BABAR-ERI). BABAR-ERI is a twochannel push broom imager with a 32 km swath width and a ground sample distance of 1 km. The two instrument channels will measure the total (0.3-100+ μm) and shortwave (0.3-5 μm) outgoing radiation from Earth. BABAR-ERI would operate in a similar manner to Libera, but with higher spatial resolution and reduced geographic coverage.
The integrated instruments will undergo extensive component-level and end-to-end calibration before flight. The instrument response in the infrared (5 μm to 100 μm) will be characterized at LASP using two blackbodies which are currently under development. During on-orbit operation Libera and BABAR-ERI will successively observe Earth and deep space, using the deep space observation to set the measurement baseline. The blackbodies are designed to simulate the IR part of the observed radiation from 5 μm to 100 μm. The Earth-View-Simulator (EVS) is designed to operate under vacuum and realizes a temperature range from 20 °C to 90 °C while the Space-View-Simulator (SVS) is designed to operate at 77 K. Additionally, the EVS features an aperture plate whose temperature can be controlled independently from the blackbody cavity to measure the total out-of-field response of Libera and BABAR-ERI. This paper presents the guiding principles and the current design of the blackbody sources.