Monday, September 15, 2008

Transfer Sensor Data Using Bundle Protocol

The first use of the 'bundle' protocol in space has been demonstrated with the UK-DMC satellite built by Surrey Satellite Technology (SSTL).

Sensor data was successfully delivered from the satellite using this disruption- and delay-tolerant networking protocol designed for the Interplanetary Internet.Wireless ad-hoc communication networks and networks operating in extreme environments suffer frequent outages and disruption, and require careful engineering to meet their needs. Spacecraft and probes operating beyond Earth orbit have intermittent communication contact limited by orbital dynamics.

These space communication links create worst-case scenarios for disruption and long communication outages. Delay-Tolerant Networking techniques address these issues for systems that lack continuous network connectivity. The 'bundle' protocol has been developed in a co-operative research effort to support continuous communications across disrupted links.The UK-DMC satellite has delivered delay-tolerant networking 'bundles' carrying remote-sensing image data to NASA Glenn Research Center in Cleveland, Ohio, via SSTL's Guildford, England, Mission Control Centre. The first complete image, of South Africa's Cape of Good Hope, was downloaded in fragments across two separate satellite passes to a 'bundle agent' in SSTL's ground station.The fragments were then sent across the Internet to NASA Glenn's agent, and reassembled into the image file. That file was then delivered back to SSTL for post-processing and orthorectification.

Proactive bundle fragmentation protects against the disruption and link outage that occurs between the two separate satellite passes over the ground station. SSTL's high-performance Saratoga protocol enabled the bundles to be transferred quickly and effectively to the ground.

The DMC effectively extends the Internet to orbit, and its farsighted adoption of IP has made it possible to take the backbone of the Internet even further into space. Networking technologies new to the space environment, such as the bundle protocol and the Cisco Systems Internet router onboard the UK-DMC satellite, can be experimented with and evaluated for further use.



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