Measurements of the radiation environment at commercial aircraft altitudes above 8 km (26,000 ft) have historically been done by instruments that record the data on board where the data are then processed later on the ground. However, a system of real-time radiation measurements on-board aircraft has been developed through the NASA Automated Radiation Measurements for Aerospace Safety (ARMAS) program.[27] ARMAS has flown hundreds of flights since 2013, mostly on research aircraft, and sent the data to the ground through Iridium satellite links. The eventual goal of these types of measurements is to data assimilate them into physics-based global radiation models, e.g., NASA's Nowcast of Atmospheric Ionizing Radiation System (NAIRAS), so as to provide the weather of the radiation environment rather than the climatology.