A Russian mission to explore the ocean floor below the North Pole is back on track after engineers fixed an engine problem aboard one of the vessels.
The ship was following an icebreaker through the Arctic
The Akademik Fyodorov research ship had suffered engine failure a day after setting off from Murmansk port.
A nuclear-powered icebreaker turned back to help, but reports say the engine was fixed before it arrived.
Russia plans to send a mini-submarine 4,200m (14,000 ft) down to help back a claim to the energy-rich Arctic seabed.
An assistance team was also sent to the research vessel from Murmansk, Russian state media reported.
The mini-submarine was expected to be launched on Sunday - but the delay may mean the dive will take place later.
Melting ice in the Arctic has raised hopes of accessing energy reserves.
Russia's claim to a vast swathe of territory in the Arctic, thought to contain oil, gas and mineral reserves, has been challenged by other powers, including the US.
Moscow argued before a UN commission in 2001 that waters off its northern coast were in fact an extension of its maritime territory.
The claim was based on the argument that an underwater feature, known as the Lomonosov Ridge, was an extension of its continental territory. The UN has yet to rule upon the claim.
The team aboard the mini-submarine Mir is expected to carry out scientific experiments and measurements on the seabed.
The Law of the Sea Convention allows states an economic zone of 200 nautical miles, which can sometimes be expanded.
To extend the zone, a state has to prove that the structure of the continental shelf is similar to the geological structure within its territory.
At the moment, nobody's shelf extends up to the North Pole, so there is an international area around the Pole administered by the International Seabed Authority.