ASI FORUM-Balloon

In view of future Cal/Val campaigns of far infrared spectral measurements, which will be carried out for the first time from space by the ESA EE9 FORUM mission, planned to be launched in 2027, a prototype, named FORUM-Balloon is under development within the Implementation Agreement (n. 2021-33-HH.0) between ASI and CNR-INO. FORUM-Balloon will be designed for stratospheric balloon far infrared spectral measurements that simulate more accurately the observations that will be carried out by the satellite.

The instrument

FORUM-Balloon drawing

The activity involves the design and construction of a Fourier transform spectrometer with all the subsystems developed for applications in typical environmental conditions that are present during a stratospheric balloon flight. Laboratory qualification measurements of the spectrometer, with particular regard to spectral and radiometric calibration accuracy, and functionality checks in the conditions present during a stratospheric flight, that present many similarities with the typical conditions of a space mission, will also be carried out.

High-accuracy black-body calibration sources

Each onboard black-body calibration source includes a mini-cell at the fixed point of gallium for high-accuracy temperature qualification. The mini-cells are developed and metrologically characterization at INRiM. The solid/liquid phase transition temperature of this metal is a fixed point of the International Temperature Scale of 1990 (ITS-90) whose value (29.7646 °C) conveniently falls within the temperature range of possible operation of black-body sources. Consequently, these cells are well suited to be used as a reference for the verification of the temperature sensors present onboard the FORUM-balloon calibration unit.