By David Shukman
Science and environment correspondent, BBC News
Use of the yellow Sprite radar has now been abandoned
Half-way through their expedition to survey the Arctic sea-ice, British explorers have been jinxed by yet more technical problems and are resorting to old-fashioned techniques to carry out research.
On Day 44 of the trek, both a radar device meant to measure the ice thickness and a satellite communications unit to relay the data are still not working - despite being brought back to the UK for repairs and then delivered to the team last week.
As a result, the explorers are now drilling more sampling holes than planned, which means they are progressing more slowly than hoped.
It now looks much less likely that the team will reach its destination of the North Pole.
The radar system, known as Sprite and meant to be dragged over the ice making millions measurements, is now being carried on a sledge instead.
Pen Hadow, leading the Catlin Arctic Survey, describes losing the use of the equipment as frustrating but concedes that the hostile conditions have overwhelmed the technology.
"It's never wise to imagine that either man or technology has the upper hand in the natural world," he said. "It's truly brutal at times out here on the Arctic Ocean and a constant reminder that Mother Nature always has the final say."
The expedition was blighted in the first few weeks by temperatures well below minus 40 Celsius, the equivalent of minus 70 allowing for the wind chill.
The failures are blamed on problems with power supplies, either with batteries not working or with cables snapping in the cold.
The loss of the hi-tech equipment has focused attention on the data gathered by the tried-and-tested method of drilling through the ice by hand.
One-hundred-and-two holes have been dug so far and 1,100 measurements have been made of ice thickness, snow density and other features - data deemed vital by scientists evaluating the future of the Arctic sea-ice.
The latest findings show that virtually all the ice surveyed is what is called first-year ice, ice that only grew this past winter, as opposed to tougher multi-year ice which survives the warmth of summer.
Figures indicate an average ice thickness of 1.15-3.75m, much of which might be expected to melt between June and September.
Organisers in London insist the expedition's data-gathering is still important for research - despite the setbacks - and describe reaching the Pole as "largely irrelevant".
According to Simon Harris-Ward, operations director, "what matters most is gathering the maximum amount of data possible over a scientifically interesting route."