Atmosphere and climate explorer plus (ACE+)

The baseline constellation of four small satellites, tracking L-band GPS/GALILEO signals and X/K-band LEO-LEO cross-link signals, will be launched in two counter-rotating orbits with two satellites in each at 650 and 850 km, respectively. The system design is aimed to optimise the science return by proper distribution of the observations in space and time. The LEO-LEO cross-link instrument is driven by accuracy requirements that drive antenna design, transmitter power, and transmitter and receiver stability. Spacecraft design is driven by relatively high power consumption of the instruments, and their pointing requirements. Satellite characteristics include a mass of 160 kg, and available power of 125 W. In order to meet the cost envelope of the Earth Explorer Opportunity Missions the spacecraft will be a simple and robust design and will make use of the latest, but proven, technology. Low-cost launch is envisaged to be with Rockot or START-1, and can take place in 2006-2007. Finally, the ground segment processes data from all satellites, also using data obtained on ground, and distributes it to the meteorological community.