The International Space Station has become home to the first node in the "interplanetary internet". The Delay Tolerant Networking (DTN) system uses "store-and-forward techniques within the network in order to compensate for intermittent link connectivity".
As NASA explained during ground-based simulation tests last year, DTN "differs significantly from the normal Internet's Transmission-Control Protocol/Internet Protocol, TCP/IP". It is designed to "cope with the huge latencies of space communication and the long interruptions which occur during solar storms or when a spacecraft moves behind a planet".
The old school internet assumes an uninterrupted connection, and two computers communicating via TCP/IP will, in the event of connection problems, try to "keep communicating until everything has been sent" - something New Scientist describes as "impractical" in space.
DTN, on the other hand, tackles such interruptions by "commanding each node in the network to store information until it can find another node that can receive it". All data should, therefore, only need to be sent once, progressively and automatically working its way across the network.
Leigh Torgerson, manager of the DTN Experiment Operations Center at NASA's Jet Propulsion Laboratory in California, said last November: "In space today, an operations team must manually schedule each link and generate all the commands to specify which data to send, when to send it, and where to send it. With standardized DTN, this can all be done automatically."
The ISS's first DTN node is a BioServe Space Technologies combined computer/Commercial Generic Bioprocessing Apparatus package, which has just dispatched its first data, comprising "images of crystals formed by metal salts in free-fall", to ground controllers.
BioServe's Kevin Gifford says the system has "already speeded up the transfer of data back to Earth by about four times".
Later this year, a second Bioserve payload will be loaded with the DTN software, creating the interplanetary internet's second node. NASA hopes that, following testing and debugging, the system will be ready for deployment on new spacecraft from 2011.
NASA has further details on DTN here. ®