Two U.S. astronauts have completed a six and a half-hour spacewalk to repair the Hubble Space Telescope.
The complex repair mission was the third spacewalk in as many days for the crew of the shuttle Atlantis.
During their work outside the shuttle Saturday, astronauts John Grunsfeld and Drew Feustel replaced an electronics board on the telescope with a sophisticated instrument (the Cosmic Origins Spectrograph) used to capture images that will help explain how planets, stars and galaxies are formed.
The astronauts plan to carry out two more spacewalks in their mission to upgrade the 19 year-old telescope and extend its life for at least five more years.
The mission is more dangerous than others because the telescope is sharing an orbit filled with debris left behind by satellite collisions and rocket launches.
The astronauts are further challenged because they can only work with the supplies they are able to carry with them. In other missions to the International Space Station, astronauts have enough support on the station to last up to three months.
On Friday, two shuttle crew members spent nearly eight hours working on the giant telescope. The U.S. space agency NASA said it was the eighth longest spacewalk in history.
The astronauts replaced two large battery modules and worked on installing new gyroscopes that help the telescope point in the right direction.
A day earlier, a new camera was installed that will allow the telescope to take detailed photos with a wide range of colors.
Some information for this report provided by AFP.