Mars to Earth communications through orbiters: Delay-Tolerant/Disruption-Tolerant Networking performance analysis

Delay-Tolerant/Disruption-Tolerant Networking (DTN) architecture will be used in future deep space missions, to enable autonomous networking operations and disruption-tolerant data communications. Therefore, it is worth analyzing the performance of the DTN Bundle Protocol (BP) in a realistic deep space environment, reproducing the characteristics of Mars missions. After a comprehensive introduction on data communications between Mars and Earth, the paper presents the essential features of both the BP DTN architecture and the Licklider Transmission Protocol (LTP), adopted here as BP convergence layer on deep space links, thanks to its ability to cope with the very long delays typical of this environment. The focus of our experiments is on analysis of the bundle flow from a Mars lander to an Earth control center through an intermediate relay node, for which two configurations are considered, inspired to Odyssey and Mars Reconnaissance Orbiter missions, respectively. Results are obtained by means of a test bed consisting of some GNU/Linux personal computers running either Interplanetary Overlay Network (ION) or DTN2 BP implementations. The analysis of results aims to highlight the role played by BP and LTP in tackling the challenges of Mars to Earth communications. Copyright © 2013 John Wiley & Sons, Ltd. The paper focuses on the experimental validation of the Delay Tolerant Network (DTN)/Bundle Protocol architecture, for which, a dedicated testbed has been developed. The presented study revisits the cases of ongoing Odyssey and Mars Reconnaissance Orbiter scientific missions consisting in data transfer from Mars to Earth. The conducted performance assessment confirms the added value of Bundle Protocol and Licklider Transmission Protocol in enabling automatic data transfer over long distance even in the presence of very large latency and link intermittencies.