The SMOS and Aquarius/SAC-D are explorer missions that aim to measure ocean salinity for the first time from space, and usher in the new era of ocean remote sensing. Here we provide a brief description of the evolution and development of the missions since the last Oceans from Space a decade ago. Salinity remote sensing is done in the microwave frequency band centered at 1.413 GHz (L-band). The two missions apply very different technical approaches. SMOS sensor is phased array synthetic aperture radiometer, whereas the Aquarius sensor is a real aperture 3-beam push broom design with both radiometer and radar measurements to better correct for the surface roughness effects. Both will require data averaging to map surface salinity at 150–200 km resolution and monthly time scales needed to understand the links between ocean circulation, changes in the water cycle, and climate. These pathfinder missions will likely provide a decade of salinity data to evaluate at the 2020 Oceans from Space meeting, and will guide the future technology development to improve resolution and accuracy.