This article is a few days old on the IEEE Spectrum webpage, but it's about NASA testing the Delay Tolerant Network protocol that has been developed for space communications and is currently being tested (link: Interplanetary Internet Tested).
Pretty fascinating about the challenges the engineers are working with when it comes to inter-networking in outer space. According to the article, eight minutes is the minimum propagation delay from Earth to Mars! That's definitely one reason to not use TCP as the transport layer protocol, hah!
Other useful links about DTN:
RFC 4838 - Delay-Tolerant Networking Architecture
Delay-Tolerant Networking Research Group (DTNRG)
NASA - Delay Tolerant Networking