A Tachyon is a type of particle capable of travelling faster than light and allows for real-time communications over enormous distances and hyperspace navigation.
Though the existence of tachyons had long been theorised by humans it wasn't until 2091 that Earth scientists were able to confirm their existence. Shortly afterwards, the DeepProbe Network was activated in a renewed effort to detect extraterrestrial life and did indeed locate tachyon emissions that pointed towards the existence of alien intelligence.
Tachyon communications requires a great deal of power and is usually facilitated by the use of dedicated tachyon relay stations to boost the signal through hyperspace. This can be a problem for a small ship that has suffered a power drain.