The four "cubesats," each about the size of a loaf of bread, were deployed from the space station this morning and began zipping freely around Earth. Twenty-four more will join them over the coming days, filling out the "Flock 1" satellite fleet operated by San Francisco-based startup Planet Labs.

Planet Labs' Flock 1 will provide frequent, low-cost, high-resolution imagery of Earth that could serve a variety of purposes, company officials say, from tracking deforestation and natural disasters to monitoring leaks in oil pipelines. [Planet Labs Photos of Earth from Space (Gallery)]