Even with x-rays theoretically providing a future 1 Gbps link to Mars, the underlying issue is that the growth of data vastly outpaces the advancements in speed technologies.

In other words, by the time x-ray communication is a reality to the Mars colony, we'd want to copy 50-petabytes (~15 years transfer[1]) or 50-exabytes (~15000 years transfer). The 6-month rocket journey is still faster than those scenarios.

[1]http://www.wolframalpha.com/input/?i=(50*10%5E15)+%2F+((1*10...