NASA Jet Propulsion Laboratory (JPL) engineers have successfully tested the first deep space communications network based on the Internet, using the Disruption-Tolerant Networking (DTN) protocol to transmit dozens of images to and from a spacecraft more than 20 million miles from Earth. NASA and Google's Vint Cerf jointly developed the DTN protocol, which replaces the Internet's TCP/IP protocol for managing data transmissions. "This is the first step in creating a totally new space communications capability, an interplanetary Internet," says NASA's Adrian Hooke. An interplanetary Internet needs to be strong enough to withstand delays, disruptions, and lost connections that space can cause. For example, errors can happen when a spacecraft slips behind a planet, or when solar storms or long communication delays occur. Even traveling at the speed of light, communications sent between Mars and Earth take between three-and-a-half minutes to 20 minutes. Unlike TCP/IP, DTN does not assume there will be a constant end-to-end connection. DTN is designed so that if a destination path cannot be found, the data packets are not discarded but are kept in a network node until it can safely communicate with another node. In October, engineers started a month-long series of demonstrations, with data being transmitted using NASA's Deep Space Network twice a week. Researchers say the interplanetary Internet could allow for new types of complex space missions that involve multiple landed, mobile, and orbiting spacecraft, as well as ensure reliable communications for astronauts on the surface of the moon.
From Jet Propulsion Laboratory
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