NASA welcomed home two astronauts from the International Space Station (ISS) and continued a much-delayed plan to send others to it as another year of its space program draws to a close.
Two U.S. astronauts and one Russian cosmonaut reached Earth this week after spending five months on the ISS, which celebrated its 10-year anniversary Nov. 2.
Meanwhile, NASA has determined that the delayed last mission of the Space Shuttle Discovery -- which is meant to travel to the ISS -- won't happen before Dec. 17.
The space shuttle and its crew of six was originally meant to fly Nov. 1 on mission STS-133, but fuel leaks caused by cracks in components of the shuttle's external tank have forced multiple launch delays.
As the space shuttle waits to fly, the Soyuz spacecraft made it successfully back from the ISS Thursday. Aboard were Expedition 25 commander Doug Wheelock and flight engineers Shannon Walker and Fyodor Yurchikhin, who had spent five months on the ISS.
Of the three, cosmonaut Yurchikhin has spent the longest amount of time in space, with 371 days in total. Wheelock has spent 178 days, while Walker has spent 163.
The three landed on the Kazakhstan steppe Thursday, northeast of the town of Arklyk, according to NASA. Following their landing and re-acclimation to gravity, Yurchikhin will return to the Gagarin Cosmonaut Training Center in Star City, outside of Moscow, while Wheelock and Walker will return home to Houston.
The trio launched into space together on the Soyuz TMA-19 spacecraft on June 15, departing from the Baikonur Cosmodrome in Kazakhstan.
During their mission, they worked a variety of experiments, including those involving microgravity and its effects on humans. They also engaged in experiments in biology and biotechnology; physical and materials sciences; technology development; and Earth and space sciences.
Wheelock also took three unplanned spacewalks with fellow astronaut Tracy Caldwell Dyson to replace a faulty pump module that caused a shutdown in the space station's critical cooling system.
When Discovery finally makes it off the ground on the delayed STS-133 mission, it will bring a series of components to improve the ISS.
They include the Permanent Multipurpose Module, which was converted from the multipurpose logistics module Leonardo to provide additional storage for station crew, as well as a place for astronauts to experiment.
The space shuttle also will deliver some unique cargo to the ISS -- a humanoid robot called Robonaut 2 co-developed by NASA and General Motors.
Once it arrives at the station, the robot will become a permanent resident, performing mundane tasks and setting up work sites for astronauts to eliminate some of their busywork.