The Navy has launched an experimental spacecraft to test new SATCOM techniques. The TacSat-4 uses small, relatively low cost satellite and launch vehicle technology. It will be used to provide UHF communications to troops on the ground using their existing radios and a wide-band "MUOS-like" channel for early testing. The small satellites will operate in a highly elliptical orbit, with an apogee of 12,050 kilometers and a 4-hour orbital period, providing close to continuous global communications on the move to the battlefield and access to mountainous regions that previously had problems with communications. While it seems likely that enthusiasts with the right equipment will be able to receive transmissions from the satellite, I would expect them to be encrypted or use spread spectrum technology to make the communications impossible to decipher.
The satellite was launched from the Alaskan Aerospace Corporation's Kodiak Launch Complex aboard a Minotaur IV+ launch vehicle. It was built by the Naval Research Laboratory and John Hopkins University Applied Physics Laboratory.
The satellite weights 450 kg and includes a 1,000 watt solar array and a 12 foot diameter high gain payload antenna. It has 10 UHF channels. More information is available in the Tactical Microsatellite (TacSat) fact sheet.
How small could satellites be and still do useful work? Last month IEEE Spectrum covered Exploring Space with Chip-sized Satellites.
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