For astronauts, chasing down and docking with the International Space Station has been a tedious two-day process on Russia’s Soyuz spacecraft. A new technique cuts this to only six hours. Following three unmanned, cargo-only test flights, the Expedition 35/36 crew is the first to try the technique.
For the Soyuz crew of three, the fast track rendezvous is much the same as before, except that tasks are compressed. In any docking maneuver, the ferry spacecraft must fire its rocket engines several times to raise its orbit to match that of its prey, in this case the International Space Station. [What It’s Like to Ride a Soyuz (Video)] The Soyuz spacecraft can fly autonomously in orbit for only about four days total, so the faster rendezvous frees up more fuel, oxygen and other supplies for possible use in an emergency.
Source SPACE.com: All about our solar system, outer space and exploration