Downlink delay

Earth-observing satellites travel in low-Earth orbit (LEO) gathering data and making a full circuit of Earth about every 100 minutes. They must wait to be over their respective ground stations to downlink the information they have acquired, however. Generally, this leaves only 10 minutes out of every 100 to transfer their information to the users on the ground. Any data gathered between these windows must be stored until the next downlink opportunity.