Moro - A European moon orbiting observatory

Provisional results are presented from the current ESA-funded Phase A Study of a Moon O Rbiting Observatory (MORO) which is one of five candidates for selection as the third medium-class mission (M3) in ESA's Horizon 2000 Science Programme.If selected for development, MORO spacecraft will be launched in 2003 and targeted towards the Moon, where it will enter a nominal circular polar operating orbit at 100 km altitude. During a mission life of at least 1 year in this orbit, global characterisation of the Moon's topography, geochemistry and gravity will be achieved. In the baseline mission concept (Option 1) a payload mass of about 80 kg will be carried on a spacecraft weighing about 1300 kg in total. A reduced "smallsat" version (Option 2) is also being investigated in which the payload and spacecraft masses would be reduced significantly. In both options the scientific payload includes a high-resolution stereo camera, a mapping spectrometer, a microwave instrument, and a geodesy subsatellite equipped with the means for accurate range-rate determination with respect to MORO main spacecraft. The selection of nadir-pointing 3-axis stabilisation as the preferred mode of spacecraft control is just one of many important trade-off studies which has been carried out. Summary descriptions of Options 1 and 2 will be given with due emphasis on approaches that are being proposed to minimise the total programme cost.