Although the U.S. has been using digital photography in satellites since the late 1970s, this technique has only entered wide military use in the last decade. A lot of this has to do with price. As digital cameras became a consumer item, the price came way down. More importantly, the flash memory cards used to store the digital pictures got a lot cheaper. Flash cards (which come in many shapes) are microchip based devices that do not need electric power to retain their data. It didn't take long for these devices to start replacing video tape in aircraft gun and reconnaissance cameras. In 1998, military aircraft began to carry these solid state video recorders. With 8-100 gigabytes of data storage in a 32 pound unit, or 8-16 gigabytes in a smaller model, these systems have since begin to show up all over the place. Again, price and reliability is the driving factor. Last year, consumer flash memory prices fell below a thousand dollars per gigabyte. The military stuff is made to stiffer specifications, but it's still basically flash memory. It's low cost and reliable (no moving parts) equipment like this that had made UAVs so much cheaper and effective. In fact, the main bottleneck is now satellite capacity. While commanders can often wait for aircraft and UAVs to land and download their flash memory images, there's increased demand for real time video, and the easiest way to transmit this is via a satellite link. There's never enough satellite capacity. For this reason, recon pilots have video editing capability in the cockpit, so they can send back just what is needed. For UAVs, still images of interesting discoveries can be sent, before the decision is made to send the much larger amount of data taken up in a video image. Depending on the amount of detail shown, digital video data can be from one to ten megabytes per minute.