TDRS: An era of continuous space communications
(PHYSorg.com Space & Earth)

More than 50 years ago, at the dawn of human spaceflight, the first brave astronauts were only able to communicate with mission control operators on Earth for about 15 percent of each orbit. If this were true today, the International Space Station would only be in contact with the ground for less than 15 minutes out of its 90-minute orbit. Today, nearly continuous communications with the space station and other Earth-orbiting missions is possible through a space-based communications network allowing nearly continuous global communications coverage for astronauts and robotic missions alike.