Complex sentence: The Russian language is also one of two official languages aboard the International Space Station-NASA astronauts who serve alongside Russian cosmonauts usually take Russian language courses-this goes back to the Apollo-Soyuz mission which first flew in 1975.
Split into simpler sentences: The Russian language is also one of two official languages aboard the International Space Station-NASA astronauts who serve alongside Russian cosmonauts usually take Russian language courses. This practice goes back to the Apollo-Soyuz mission, which first flew in 1975.