The US space shuttle Discovery began its earthward journey Wednesday after completing a 14-day mission to carry out further construction and maintenance work on the International Space Station (ISS).
The shuttle is scheduled for landing on Saturday at the Kennedy Space Centre at Cape Caneveral, Florida.
Discovery undocked from the ISS for the return journey after a mission in which astronauts carried out three spacewalks chiefly devoted to installing and preparing the Japanese scientific laboratory module Kibo, reported dpa.
About 100 scientific experiments are already planned for the 12-metre by 5-metre Kibo, including efforts to examine the effects of weightlessness and help develop allergy medications.
Kibo is to be completed in a third mission later this year.