Russian cosmonaut Yury Lonchakov and NASA astronaut Mike Fincke have successfully completed a five-hour space walk outside the International Space Station.

They were wrapping up maintenance work that began a few months ago and comes ahead of a visit by NASA's shuttle Discovery. The launch is scheduled for Wednesday night and, if everything goes smoothly, Discovery will arrive at the ISS on Friday.

During the space walk, the American commander and his Russian colleague also installed test equipment to study how plant seeds, bacteria and fungus behave in space.

Also, the astronauts took photos of the Russian section of the station as well as of each other in front of the ISS and the Earth.

According to Lonchakov, our planet looks splendid and magnificent at night from outer space. He took Fincke’s photo with the Indian Ocean in the background.

The third crewmember of the 18th expedition to the ISS – NASA astronaut Sandra Magnus – was staying aboard the Zvezda service module.

Tuesday's space walk was the 120th walk in support of the ISS assembly and maintenance.

Meanwhile, on Earth the preparation for the Discovery launch is underway. The shuttle will deliver solar panels for the ISS. Its arrival will be a relief for the crew since it’s bringing new toilet facilities for the ISS, including a urine processor for the station's water-recycling system.