During long duration missions space-ground communications will involve delays up to 20 minutes one way, a reality that poses a formidable challenge to team communication and task performance. In the present research we examined how transmission delays impacted the interactions between mission controllers and space crews during routine and off-nominal tasks. Method: Four teams of NASA flight controllers and astronauts participated in a space simulation study involving two 2-hour scenarios with transmission delays of 50 sec and 300 sec. Audio-recordings of space - ground communications were transcribed and their structure (turn taking and sequence) and content examined; specifically, whether speakers identified addressees or themselves, and whether listeners confirmed their understanding. Results and Discussion: Transmission delays disrupted the structure of space-ground communications as contributions by flight controllers and astronauts overlapped or were out of sequence. Space crewmembers and flight controllers did not consistently mark the end of their turn; however, our findings suggest that they were more likely to do so under the longer transmission delay. Omissions of identifiers and inadequate listener feedback were observed under both delay conditions. Strategies supportive of grounding processes were also identified.
