Robot always a 'long shot' - academic

The Defence Force robot. Photo / NZDF

Sending a robot into the Pike River coal mine where 29 men are trapped was always a "long shot", an expert says.

Rescue robot expert Professor Robin Murphy of Texas A&M University said a military robot sent into the Pike River mine was not designed for the conditions.

"It is always a long shot using a robot for a situation or environment that it's not designed for - we don't know much about using robots underground."

Dr Murphy said when "you bring [a robot] over from the bomb squad" you were always bound to run into complications.

"The environment [in the mine] is tough - dark, wet, cold so even on a level floor that would be easy for a person to walk on a 'regular' robot can quickly short out, get its sensors covered in muck, mechanically seize up, or the operator make a mistake," she told the Science Media Centre (SMC).

Police said the Defence Force robot broke down about 550m into the Pike River mine.

Relatives of the trapped miners said they were told the robot malfunctioned after water fell on it.

West Coast police superintendent Gary Knowles has confirmed the Defence Force robot will no longer be used.

More sophisticated robots are now being flown in from Western Australia and the United States.

However, Dr Murphy said there was only one robot in the world that was "mine permissible" and specifically designed to withstand mine conditions.

She said this was built and used in the collapse of Utah's Crandall Canyon in 2007.

Although the Defence Force robot was unsuited to the mine, Dr Murphy said the attempt was the right move.

"With 29 lives at stake, it was a reasonable try," she said.

University of Arizona mine technology expert Dr. Sean D. Dessureault also told the SMC that robots had never been used effectively in mine rescues.

Mobility was a major issue, with the robots being hindered by rubble and the fact they could not be manoeuvred by wireless controllers in mine conditions, he said.

Dr Murphy said authorities would have hoped the robot could have informed on the conditions in the mine.

"Normally robots are used to asses the air quality and whether it's safe for people to move in. It would have also looked for survivors," she said.

Its failure to obtain useful information has frustrated family members of the trapped miners and the Grey District Mayor Tony Kokshoorn.

"I thought this robot is going to go in and tell us the condition of the miners. But when they said the water had got in it was just demoralising," he said.