Good stamp.   Vostok 3 and Vostok 4 were launched a day apart on trajectories that brought the spacecraft within approximately 6.5 km (4.0 mi) of one another. The cosmonauts aboard the two capsules also communicated with each other via radio, the first ship-to-ship communications in space. These missions marked the first time that more than one manned spacecraft was in orbit at the same time, giving Soviet mission controllers the opportunity to learn to manage this scenario.