Complex sentence: Tereshkova, Solovyova and Ponomaryova were the leading candidates, and a joint mission profile was developed that would see two women launched into space, on solo Vostok flights on consecutive days in March or April 1963.
Split into simpler sentences: Tereshkova, Solovyova, and Ponomaryova were the leading candidates, and a joint mission profile was developed that would send two women into outer space. These would have been on two Vostok flights on consecutive days in March or April 1963.