Russian space programme chiefs are to move the International Space Station into a different orbit to avoid possible collision with a fragment of debris.
The Russian Zvevda module will fire booster rockets to carry out the operation early on Thursday, mission control centre spokeswoman Nadyezhda Zavyalova said.
The space station performs evasive manoeuvres when the likelihood of a collision exceeds one in 10,000.
Nasa estimates that more than 21,000 fragments of orbital debris larger than 4in are stuck in Earth's orbit, and experts worry that orbiting junk is becoming a growing problem for the space industry.
There are six astronauts - three Russians, two Americans and one from Japan - on the orbiting laboratory.