MIRAS (Microwave Imaging Radiometer using Aperture Synthesis) is an L-band radiometer with 69 receivers mounted on three deployed arms to measure the radiation coming from Earth. In order to measure accurately, the receivers must be within a +/-3 degrees C temperature range of each other, with the optimal operating temperature at 22 degrees C. Heaters are installed on the satellite to achieve the temperature needed. Switching on the instrument begins with activating the central payload computer, which controls many of the instrument's subsystems and gives instructions to the distributed command and monitoring modes on each arm. To assess the electrical performance of the instrument after switch-on while limiting the consumption of heater power, the physical temperature for start up was set to 10 degrees C.
The central payload computer also controls the 'mass memory', which collects all the science data from the receivers and sends them to receiving stations on the ground. The high-speed downlink, which transmits the data to the ground station, was switched on, and data have been transmitted to ESA's European Space Astronomy Centre (ESAC), in Villafranca, Spain. The data acquisition and processing systems located at ESAC are also working well, and the first test of the product generation system has been successful.