I am a bit nervous about the first night - on the first night I will find out if everything works

Steve Fossett

Six weeks after his previous abortive attempt, the Solo Spirit slowly rose from the ground at the launch site in Northam, about 100km (60 miles) east of Perth, the Western Australia state capital.

The launch won cheers and applause at Mr Fossett's mission control at Washington University in St Louis, Missouri.

Click here for a map of the route

The 1998 attempt ended in the sea

Winds blowing in the wrong direction delayed the lift-off by about five hours, but inflation of the balloon finally started late Saturday night and continued into Sunday morning.

Mr Fossett said shortly before lift-off: "I am a bit nervous about the first night. On the first night I will find out if everything works, if there are any leaks in the balloon, if there are any failures in communications and if the all-important heating works."

Approaching thunderstorms

The beginning of the journey sees Mr Fossett speeding over Australia's central desert at a height of 6km to 8km (four to five miles).

Solo Spirit facts

Height: 43m Width: 18m Helium: 15,000 cubic metres Hot air: 3,000 cubic metres Cruising altitude: 7.5km Maximum altitude: 9km

The Solo Spirit should reach speeds of up 210km/h (130mph) in jet stream winds.

Mr Fossett will face his first serious challenge on day two, when there is a chance of thunderstorms east of Brisbane, Australia, the mission's chief meteorologist, Bob Rice, said from the United States.

"We have something coming up right away and quick to focus our attention and Steve's attention," Mr Rice said.

And, he added, "There is no point when a balloon is in the air that you feel comfortable."

Wind damage

Try, try again

First attempt: Downed in Canada Second attempt: Ran low on fuel after Libyan refusal to use airspace Third attempt: Forced down over southern Russia Fourth attempt: Brought down in Pacific by storm four days short of goal Fifth attempt: Winds destroy balloon during inflation in Australia

In Fossett's last attempt six weeks ago, a gust of wind at Kalgoorlie in Australia toppled the helium canisters, ripping the balloon's membrane.

The balloon was repaired and readied for another attempt at the record from Northam, which was chosen for its more favourable local weather conditions.

Fossett's balloon, which stands 43m (140 feet) high and 18m (60 feet) wide, is very vulnerable to winds at ground level.

The team hopes the flight eastward around the globe will take about 15 days.

Fossett nearly succeeded in his long-held ambition of flying around the world solo on his fourth attempt, in 1998, but he was dumped into the sea east of Australia by a violent thunderstorm.