The agency needs around 12 of these small satellites orbiting the Earth to get the coverage it wants, but it's not going to be easy making that happen. Aside from launches being really costly, the scientists can't put a conventional rocket motor on the SMDC-ONEs, because they might explode and take the rest of a rocket's payload with them. Those rocket motors are necessary for the devices to be able to propel themselves to the right orbit -- that's why Taylor and his team designed a new one using a plastic printer (see image below) and filling it with liquid nitric oxide and a sparker. The plastic and propellant combust together once the sparkler's lit, but this design's apparently safe enough to be loaded onto a rocket.

In addition, the Army's also designing an imaging nanosatellite that's a bit larger than the one for communications. It will be able to generate images with a ground resolution of two to three meters, enough to tell if there's a tank on the way. It hasn't been tested yet, though it's scheduled to be launched from the ISS in February next year. As we mentioned, though, the SMDC-ONE has already been tested; in fact, one is orbiting the planet right now. If all goes well, the Army will launch a few more units this year and the next until there are 12 or more out there circling the Earth.

[Image credit: US Army]