USA-221

USA-221, also known as FalconSat-5, is an American military minisatellite, which was launched in 2010. The fifth FalconSat spacecraft to be launched, it carries four technology development and ionospheric research experiments. The satellite was constructed and is operated by the United States Air Force Academy.

Spacecraft

USA-221 is a 180-kilogram (400 lb) spacecraft, measuring 70 centimetres (28 in) by 64 centimetres (25 in) by 54 centimetres (21 in). It operates in a low Earth orbit with an apogee of 652 kilometres (405 mi), a perigee of 641 kilometres (398 mi), and 72 degrees of orbital inclination.

The Space Plasma Characterization Source (SPCS) studies how a cold gas ammonia thruster and a Hall effect thruster behave in space, and how they affect the spacecraft's surroundings. Meanwhile, the Wafer-Integrated Spectrometer, WISPERS, will observe the plume generated by the Hall thruster, allowing a comparison to be made to theoretical data. The other two experiments will study the Earth's ionosphere. SmartMESA, the Smart Miniaturized Electrostatic Analyzer, was designed to record the ion density of the ionosphere, as well as the temperature, to allow a study of how temperature affects ion density. It is a reflight of the original SmartMESA mission, which was lost when FalconSat-2 failed to achieve orbit. The Receiver UHF/VHF Signal Strength or RUSS, experiment, is intended to receive radio signals in the UHF and VHF bands, to determine the levels and effects of ionospheric interference.