RESULTS
The first experiment, which occurred on July 10, 2009, involved downlinking images of a
previous CGBA-5 experiment over a planned Tracking and Data Relay Satellite System (TDRSS)
handover, during which the space-to-ground and ground-to-space links were interrupted for
several minutes. The CBGA-5, which had no feedback regarding the state of the space-to-
ground link, responded to the disruption as designed, by custodial retransmission of the data
after a configurable timeout. This
initial deployment of the DTN-on-ISS
network demonstrated the success of
the bundle protocol in handling
disruptions. The next test involved
using DTN for unattended
operations. The CGBA-5 downlinked
its status telemetry files via the non-
DTN transmit-in-the-blind
configuration as well as via a DTN
configuration. During a 3-day period
in which 14 files were generated per
hour, the non-DTN scheme resulted
in an average of 3 504 redundant
receptions per file. The DTN scheme
performed much better at an average of 0.06 redundant receptions per file. During the next
phase of investigation, the DTN-on-ISS network will be extended to include a second payload,
CGBA-4, which will expand the network to 2 space nodes and 2 ground nodes and enable
experimentation with cross-node routing and 1-way custody transfer (Jenkins 2010).
PUBLICATION(S)
Jenkins A, Kuzminsky S, Gifford K, Pitts RL, Nichols K. Delay/Disruption-tolerant networking:
Flight test results from the International Space Station. 2010 IEEE Aerospace Conference, Big
Sky, MT; March 6-13, 2010.
This investigation is ongoing and additional results are pending publication.
Expedition 29 Flight Engineer Satoshi Furukawa works on the
CGBA-5/CSI-5 experiment in the Columbus Laboratory.