Measurements of the Earth's radiation budget are necessary for understanding our climate and its changes. Clouds and Earth Radian Energy System (CERES) scanning radiometers have operated on the Terra spacecraft since 2000 and on the Aqua spacecraft since 2002. A CERES instrument, Flight Model 5, is now scheduled to fly on the MPOESS Preparatory Platform in 2010, at which time the Terra will have been in space for a decade and the Aqua for eight years. FM-5 has been vacuum-tested, calibrated and shipped for integration to the NPP spacecraft. Another CERES instrument, Flight Model 6, will be assembled mainly from parts from the CERES project and will fly on the NPOESS C1 platform in 2013. The next step in the continuation of Earth radiation budget measurements is the development of a successor to the CERES instruments. The first model of that instrument is planned for flight on the NPOESS C3 platform in 2018. It is planned that each of these missions will overlap so that the climate data record of radiation budget will be seamless. By the flight of the NPP, the CERES and Earth Radiation Budget Experiment records will span a quarter of a century, enabling studies of climate variations with periods of decades.