The last great challenge on earth: but will the best man win?

Antarctic adventurer left at the starting gate as sponsors melt away

It is one of the last great challenges left to man - a challenge that fires the imagination of buccaneering explorers and has also fuelled a battle for big company sponsorship.

The goal is to become the first man to achieve a solo crossing of the frozen wastes of Antarctica and if only Roger Mear's vacuum cleaner had broken down earlier this year, he might be the one going to the Antarctic in a week's time.

Instead, the veteran explorer Sir Ranulph Fiennes - whose purchase of a new vacuum cleaner last January indirectly led to pounds 150,000 of sponsorship - will be heading south to Punta Arenas, the world's most southerly airfield, later this month to attempt to be the first person to cross the frozen continent solo.

Sir Ranulph says he "doesn't approve" of solo expeditions - but that is what the record demands. Mr Mear, though, is entirely prepared for a solo trek, as he has tried it before.

Last December, Mr Mear, 46, was forced to abandon an attempt to walk the 1,800 miles across Antarctica after only 43 days, when problems developed on the sledge he had towed for 500 miles with his provisions, clothing and tent.

After a year's work, the sledge should now fulfil its task perfectly. But it, and Mr Mear, will have to stay at home in Derbyshire, unless he can find pounds 100,000 of sponsorship in the next seven days. "It will be a little bit of a disappointment if I can't go," he said, with typical understatement, last week.

Sir Ranulph, 53, is quick to admit that his place on the flight south is due as much to luck as determination. "I have a folder of refusals as thick as your arm from companies," he said. But he does have one crucial supporter.

His sponsor for the expedition is Dyson Vacuum, based in Malmesbury, Wiltshire. "Our old vacuum cleaner broke down in January, so my wife sent me out to buy a new one. The man in the shop told me to spend the extra money on a Dyson. And I noticed a booklet which talked about James Dyson, the owner of the company, who is also an inventor."

He called Mr Dyson, arranged a meeting, and eight hours after the two men met in January, had a sponsor for his expedition. However, Sir Ranulph did not announce his plan until the beginning of this month.

Mr Mear, though, has found sponsors surprisingly slow to back him. Last year, he had the support of Sainsbury's, Continental Tyres, the Internet company Planet Online, two water boards, and Kwik Fit.

This year, only Sainsbury's has returned - which at least means he has all the food he needs for a crossing. "I'm sitting here surrounded by 110 days worth of vacuum-packed rations hoping that I will be going down there," he said.

The problems have intensified since last week. "Ranulph hasn't been poaching my sponsors or anything, but since he announced his plans some of the people I had been talking to have decided they don't want to sponsor me. That leaves me without enough money to get down there." He is still talking, though, to a couple of companies who might be forthcoming.

He plans to use a specially-designed kite to help drag the sledge, which he succeeded in using last year.

Sir Ranulph, by contrast, finds kites "like trying to learn windsurfing, only harder." Practice sessions had led to him almost being dragged on to a motorway and entangling the kites in a barbed-wire fence. "I think I'll use something called an upski, which is a type of sail that I used when I crossed the Antarctic with Mike Stroud," he said. "The only problem is that you get extremely cold hands."

Whoever does win the race to be first across the continent, Mr Mear believes that the Antarctic could in time be the new Mount Everest - a challenge accessible to anyone prepared to pay for it.

"We're at the dawn of a new age because of kite technology," he said. "Just as better support and oxygen made Everest feasible, I think the Antarctic will become open to the majority of people who can afford it. I think polar travel will be there for those who want it."