Timekeeping in Space
In the 2004 brief Timekeeping in the Interplanetary Internet, David L. Mills describes the Interplanetary Internet (IPIN) research program funded by DARPA and NASA. He covers IPIN issues, architecture, timekeeping models, astronomical timescales, and interplanetary NTP.
In his 2008 brief Time Transfer in Space, he discusses time transfer between earth and satellites, the space shuttle, the moon, the Mars orbiter and rovers, as well as the deep space network.