Two Russian cosmonauts are preparing for a spacewalk to install experiments on the outside of the International Space Station (ISS).
Sergei Volkov and Yuri Malenchenko are expected to exit the Pirs docking compartment at 13:10 GMT, for the second spacewalk of 2016.
The cosmonauts are set to work outside for an estimated five-and-a-half hours.
A spacewalk on 15 January by Briton Tim Peake and American Tim Kopra was halted when water was found in Kopra’s helmet.
Lt Col Volkov and Col Malenchenko will don their Orlan spacesuits and head out to install and retrieve several experimental packages on the Russian Zvezda and Poisk modules.
They will also deploy devices called gap spanners on the hull of the station to facilitate the movement of crew members on future spacewalks.
Among the experiments to be installed is Vinoslivost, which will test how various structural materials are affected by the harsh environment of space.
The Russian Space Agency (Roscosmos) crew members will also test the Restavratsiya experiment, which could be used to glue special coatings to external surfaces of the station’s Russian segment.
The veteran cosmonauts will also retrieve the European Space Agency’s (Esa) Expose-R experiment, which investigates how cosmic radiation, microgravity and temperature extremes affect a variety of microbes and organic molecules divulged to the vacuum of space.
This will be the sixth spacewalk for Malenchenko and the fourth for Volkov – whose father Aleksandr was also a cosmonaut.
Col Malenchenko is one of the most experienced spacefarers in the world; during his stay on the ISS, he should become only the third person to have spent more than 800 cumulative days in space. The current record holder is fellow cosmonaut Gennady Padalka, who has spent 879 days in orbit.
Investigators have been studying data from the spacewalk on 15 January, which had to be stopped early due to the water in Tim Kopra’s helmet. The event was another reminder that spacewalking remains the riskiest activity undertaken by astronauts and cosmonauts.
A similar, but much more serious, water leak nearly drowned Italian astronaut Luca Parmitano on a spacewalk on 9 July 2013. Col Kopra was wearing the same spacesuit used by Parmitano on that occasion; it was apparently given a thorough overhaul after the 2013 incident.
On 15 December, Yuri Malenchenko had to pilot the Soyuz spacecraft to a manual docking with the space station after the failure of the vehicle’s Kurs radar (which determines the relative distance of the capsule and its target).
The Soyuz eventually docked safely, allowing the Russian, along with Col Kopra and Major Peake to join the crew of the ISS.
On Tuesday, British astronaut Tim Peake spoke to hundreds of children from across England and Wales in a live video chat – the first of its kind since he arrived on the orbiting outpost.