## 6 Conclusions and Outlook  
The IR sensors of BIRD, TET-1 and BIROS provided image data in the mid-IR (MIR, at 3.8 \(\upmu\)m) and thermal IR (TIR, at 9.2 \(\upmu\)m) bands with ground sampling distances (GSD) of \(\sim\)180 m in both and noise equivalent difference temperatures (NEDT) of 0.4 K (at 300 K) in the MIR band and 0.2 K (at 300 K) in the TIR band, and they comprise a very high radiometric dynamic in both bands, necessary to avoid signal saturation from strong high-temperature events (HTEs), such as large wildfires or major volcanic eruptions. The IR sensors of BIRD and FireBIRD delivered more detailed, locally based information on fire occurrence than the operational IR sensors currently used for fire applications, and they allowed fire dynamic measurements that were previously not possible. The BIRD and FireBIRD missions offered an opportunity to monitor the true fire situation from space and to estimate attributes or characteristics of small and large fires, such as the Fire Radiative Power from 0.3 MW upward, the effective fire temperature, the effective fire area, the fire front length and the radiative fire front intensity, i.e., the ratio of the FRP to the front length of a fire cluster. The provision of active fire information products requires data records of appropriate bi- or multi-spectral IR imagery, for example, through the following classes of instruments and satellites:  
* A set of geostationary meteorological satellites, providing frequent but lower-spatial resolution MIR/TIR fire application-relevant data with a ground resolution of 2 km or better at their sub-satellite points (SSPs);
* Polar orbiting satellites with instruments of the MODIS, SLSTR and/or VIIRS class, operated in a \"24/7\" mode;
* FireBIRD-type IR instruments operated in a small satellite constellation, providing:
* Higher-spatial resolution data acquisition without signal saturation from large fires;
* An augmentation and validation possibility of the more frequent but lower-spatial resolution active fire datasets, provided by the systems mentioned above, for detecting smaller and weaker fires, including the derivation of their FRP values;
* Higher-spatial resolution MIR and TIR band data of fires (a) at different local times and (b) at afternoon local time when fires are at a maximum (see Figure 5). Except for the ECosystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) (see [[https://ecostress.jpl.nasa.gov](https://ecostress.jpl.nasa.gov)]([https://ecostress.jpl.nasa.gov](https://ecostress.jpl.nasa.gov)) (accessed on 1 December 2021) with six spectral bands in the TIR band (with pixel saturation temperatures at \(\sim\)380 K) and the proposed Dynamic Infrared Earth Observation on ISS Orbit (DIEGO) in Germany (see [16]), proposed with an MIR band and several TIR bands, there are no existing or planned multi-spectral mid and thermal IR missions delivering higher-spatial resolution (\(<\)100 m) data at varying times of the day, including repeated acquisitions at afternoon local times. It should be stressed that this type and the varying and afternoon local times of measurements are very essential for many climate change-related applications, such as urban heat islands (UHI), epidemiology, evapotranspiration and water stress of plants and water management. For these climate change-related applications and for higher-spatial resolution fire monitoring, there are very similar requirements with regard to the radiometric and spatial resolution of IR imaging data records conducted at different local times and at the afternoon local time (including short revisit times).