Rubicon is a 29 km long river in northern Italy. The river flows from the Apennine Mountains to the Adriatic Sea through the southern Emilia-Romagna region between the towns of Rimini and Cesena.
"Crossing the Rubicon" is a popular idiom meaning to pass a point of no return.
The Rubicon point of the Antares mission is located between Earth and Venus. After passing this point the Antares and her crew can no longer abort the mission and make a quick return to Earth. After reaching this point, they would have to swing around Venus to make their return safely.
- See Also: wikipedia:Rubicon