a SnapShot of current and future mISSIonS There have been many recent small satellite missions that have successfully launched or are currently in formulation that will demonstrate new technologies for Earth observation (see [5] for examples). The Cyclone Global Navigation Satellite System (CYGNSS), with launch expected in 2016, will make frequent and accurate measurements of ocean surface winds throughout the life cycle of tropical storms Launch History of Nano and Pico Satellites 20 18 Number of Satellites providing 89 CubeSat launches in the last 4 years at no cost to selected proposers. Second, small satellites allow for rapid development and lower costs through use of common parts/frameworks. Economies of scale do exist for small satellites, where parts and subsystems are relevant for a wider variety of missions, instead of a single application in traditional flagship missions. Third, small satellites allow for a more relaxed risk posture due to the significantly lower cost. In terms of distributed risk, a single $100 million mission is inherently riskier than one hundred $1 million missions. Radically new mission architectures consisting of very large constellations or clusters of CubeSats promise to combine the temporal resolution of GEO missions with the spatial resolution of LEO missions, thus breaking a traditional trade-off in Earth observation mission design [9]. Figure 1 shows the growing number of launches of nano and pico satellites since the 1990s [2]. 16 14 12 10 8 6 4 2 0 1960 1970 1980 1990 Launch Year 2000 2010 fIgure 1. Launch history of nano and pico satellites since 1955. and hurricanes. The CYGNSS mission comprises eight Low Earth Orbiting 18-kg spacecraft (see Figure 2) that receive both direct and reflected signals from GPS satellites to determine position and ocean surface roughness. The Canadian CanX-4 and CanX-5 mission will demonstrate two nanosatellites flying autonomously in precise formations with relative position determination accurate to a few centimeters using carrier-phase differential GPS techniques. Its success may someday enable a constellation of nanosatellite 59.0 cm (Stowed) 176.3 cm (Deployed) Stowed (Launch Configuration) Thermal Radiator Torque Rod (2 of 3) Momentum Wheel Batteries (×2) DMR Avionics S/A (Ram) Diplexer & Hybrid Nadir Sci Antennas (2) 28° 18.6 cm Horizon Sensors S/A During Deployment Zenith S-Band Antenna Zenith DDMI Antenna 42.5 cm S/A Wing (×2) S/A Deployed (Flt Config) Nadir S-Band Antenna Nadir Baseplate & Radiator Z (Zenith) Y X (Ram) fIgure 2. The CYGNSS Observatory. The exploded view shows individual subsystems, including the science payload's Delay Doppler Mapping Imager (DDMI) antennas and receiver electronics (DMR). June 2013 ieee Geoscience and remote sensing magazine 69