Two Russian astronauts will embark on a spacewalk outside the International Space Station on Tuesday to inspect a mysterious hole that has appeared.
Oleg Kononenko and Sergey Prokopyev, of the Russian space agency Roscosmos, are expected to spend more than six hours outside the station from about 4pm GMT.
The hole was spotted on August 30 in the Russian Soyuz spacecraft attached to the ISS.
The crew quickly located and sealed it and officials said the station has remained safe to operate.
The astronauts will remove the thermal insulation covering the patched hole and take samples to be studied by experts.
Mr Kononenko, who arrived at the station earlier this month with NASA astronaut Anne McClain and David Saint-Jacques of the Canadian Space Agency, said that the spacewalk would be a strenuous effort.
"It's going to be challenging both physically and technically," he said.
