A marathon spacewalk met with disappointment after a failed effort by two Russian cosmonauts to install a pair of Canadian-made, high-fidelity cameras outside the International Space Station. 

The medium- and high-resolution cameras did not respond as expected and, some five hours into Friday's spacewalk, cosmonauts Oleg Kotov and Sergey Ryazanskiy were told by mission control in Russia to unhook both units and return them to the space station's airlock. 

The cosmonauts, who were orbiting more than 400 kilometres over the Great Lakes at the time, first took photos of the connections in the hope of diagnosing the problem with help from mission control.

"The crew ran into roadblocks mating the connectors," NASA's announcer noted during the space agency's broadcast of the spacewalk, while Kotov and Ryazanskiy discussed the problem, in Russian, in the background. "Some connectors were very stubborn, very difficult." 

'I never thought I'd have to take one of these off again.'- Unidentified cosmonaut

The cosmonauts left the ISS at 8 a.m. ET with plans to install a pair of new cameras on the station's Zvezda module — part of a commercial effort by Vancouver-based Urthecast, working in co-operation with the Russian space agency, to stream detailed views of the Earth from orbit. 

"I never thought I'd have to take one of these off again," one remarked, through a translator, at one point. It was unclear which cosmonaut had spoken. 

A medium-resolution still camera is meant to take a continuous, 50-kilometre wide shot of the Earth as the ISS orbits 16 times each day.

The second, higher-resolution video camera will allow people to see things as small as cars, boats and small groups of people, though not individuals. Many of the images will be available free in "near real time" — just a few hours after they were captured.

The pair also installed new earthquake-monitoring equipment outside the ISS, which worked properly. 

Rigorous testing

Speaking to CBC News shortly before the problems arose, Urthecast CEO Scott Larson described the cameras' rigorous pre-flight testing. 

Both were "put into a space environment here on Earth," he said. "Hot and cold — they warm them up and cool them down, because it gets very hot and cold in space, and they vibrate them and blast them with radiation to make sure the cameras, when they get into space, will work. It's a long process." 

Larson said the cameras are intended for environmental and educational efforts, among other things. Groups including the UN want to use them to monitor animal migration, earthquakes and the weather, for example, though the company has other, loftier goals. 

Astronauts, he said, often come home with a different worldview and a new sense of "stewardship" for the Earth. 

"One of the goals we have at Urthecast is to take the astronaut's view and give it to everyone here on Earth," he said. 

Record-breaker

The installation effort marked the third recent spacewalk outside the ISS, after U.S. astronauts Rick Mastracchio and Michael Hopkins went out twice to repair a conked-out component of its cooling system. 

It also broke the record for the longest spacewalk by Russians. The pair spent eight hours and seven minutes in space, well past the previous record of seven hours and 29 minutes. 

If all had gone according to plan the spacewalk was expected to last some seven hours. 

It was not possible, given the limits of their spacesuits, for Kotov and Ryazanskiy to break the all-time spacewalk record of just under nine hours. 

"We feel good. We're ready to keep going," said one of the cosmonauts as they worked to return the cameras to the ISS. 

helmet-cam-urthecast

A piece of equipment, bearing the Urthecast logo, is visible as cosmonauts install cameras from the Vancouver-based company outside the International Space Station. (NASA)