A satellite designed to deliver high-speed internet services to 400,000 Australian homes has been launched from French Guiana.

A rocket carrying the half-a-billion-dollar satellite, nicknamed Sky Muster and considered the great hope of the National Broadband Network (NBN), was launched about 6:30am (AEST).

Key points: Rocket with Sky Muster launched from French Guiana

Rocket with Sky Muster launched from French Guiana NBN users to be connected from mid-2016

NBN users to be connected from mid-2016 NBN acknowledges risk of failure

NBN acknowledges risk of failure Communications Minister says speed will be sufficient despite congestion fears

NBN said Sky Muster was designed to deliver broadband internet services to more than 400,000 rural and remote homes, including on Norfolk, Christmas, Macquarie and Cocos islands.

The company said of the 400,000 premises in the total footprint for the satellite, it expected around 200,000 to take up a service.

NBN spokeswoman Frances Kearey said governments around the world would be watching how Sky Muster delivered on its promises.

"It's one of the world's largest communication satellites and is purpose-built to deliver broadband to Australia — an incredibly vast country," she said.

"The NBN satellite service will provide speeds that people in the cities take for granted — opening up new opportunities in education, health, social connectivity and business."

Sky Muster will be connected to NBN users from the second half of next year once a number of tests are conducted.

Before the launch NBN acknowledged the risk of the satellite failing, either on the launch pad or in orbit, but has stressed there was a number of mitigation strategies in place to manage the risk.

Sky Muster lifts off from French Guiana on a 780-tonne rocket ( ABC News )

"These including the selection of reliable vendors with proven industry track records and launch & in-orbit insurance," Ms Kearey said.

Communications Minister Mitch Fifield yesterday said people in rural and regional areas of Australia would get better broadband services from the first half of next year.

He rebutted claims the satellite would not provide sufficient internet speeds for regional areas, which already suffers from poor mobile phone coverage.

"There will be 110 beams coming from each satellite to locations throughout Australia, and even to offshore Australian territories," Mr Fifield said.

"We'll have 25 megabits per second (Mbps) download from Sky Muster, and that is high-speed broadband.

"This will meet the bulk of needs which people in regional Australia have."

The Sky Muster satellite designed to deliver broadband internet services to more than 200,000 rural and remote Australians. ( Supplied: NBN )

Malcolm Turnbull 'backflipped' over satellite: Opposition

He shrugged off comments that when in opposition, then communications spokesman Malcolm Turnbull described Labor's then communications minister Stephen Conroy's planned satellites as an unnecessary and expensive "Rolls Royce" option for delivering internet services.

"There were many things that were in train when we came into office," Senator Fifield said.

"I think Malcolm, as communications minister, did a terrific job in recasting the roll out of the NBN.

"Australians are going to get the NBN six to eight years faster [than what Labor had planned]".

Labor's communications spokesman Jason Clare seized upon the Government's change of heart.

Sorry, this video has expired 2012: Malcolm Turnbull criticises NBN satellites from opposition

"Fortunately for rural and regional Australians, Labor signed the contracts for delivery of these satellites before the last election," he said.

"In a backflip worthy of Nadia Comneci, Malcolm Turnbull now calls these satellites a 'game changer'.

"Labor welcomes the belated support from Malcolm Turnbull and the Liberal Party for the NBN satellite program.

"As they say — better late than never."

Mr Turnbull was due to attend the launch before being elevated to the nation's top job.

The name Sky Muster was devised by six-year-old Bailey Brooks, who lives on a station 400 kilometres from Alice Springs in the Northern Territory.

She painted a picture of the satellite, which is painted on the side of the high-tech equipment.

'High likelihood' of slow speeds in peak times: RMIT expert

But some remain sceptical about whether Sky Muster can muster its promised download speeds when all 200,000 properties connect to it.

"During peak times, there's going to be a very high likelihood that traffic is going to become congested, and there's going to be less throughput of traffic, and therefore people can expect the network to slow down considerably," Doctor Mark Gregory, from RMIT University's School of Computer Engineering, said.

Sky Muster at a glance Launch date: 1 October 2015

Launch date: 1 October 2015 Operational from: mid-2016

Operational from: mid-2016 Weight: Approximately 6,400 kgs

Weight: Approximately 6,400 kgs Build time: three years

Build time: three years Promised download speeds: 25Mbps download and 5Mbps upload

Promised download speeds: 25Mbps download and 5Mbps upload Orbit speed:11,000km/h

Orbit speed:11,000km/h Name: Devised by six-year-old Bailey Brooks, who lives on a station 400km from Alice Springs in NT. Attends school over the internet.

"So if they're trying to look at high-definition videos, then they're likely to find that they'll have problems during those peak times.

"If they're connecting to something like an internet radio, which uses a relatively low bandwidth connection, then they shouldn't have any problems.

"We need to understand that this is going to lead to some congestion, and also going to lead to NBN Co putting in place rules to prevent some users from dominating the service by downloading too much material over a monthly period, or even during a short period of time."

Dr Gregory said there would be an early improvement in broadband services for rural and regional areas.

"The estimate of customers being able to achieve 25 megabits per second (Mbps) download speed, depends upon how many customers are connected to the satellites," he said.

"The early people onto the satellites are going to find that their connections operate very well, they're going to achieve the 25Mbps, and they're going to be very happy with their service."

Ms Kearey said bandwidth from the satellite would be closely monitored.

"The NBN satellite service will be a finite resource; it will be carefully managed to ensure all users in rural and remote Australia get a fair go," she said.

"Once the satellite service is commercially launched, homes and businesses will be able to choose a plan that suits their needs from their preferred service provider."