PARIS — The Australian government’s multibillion-dollar broadband development program will need to provide Ka-band satellite connectivity not only in the nation’s vast rural regions, but also along the east coast in the suburbs of urban centers, according to the government enterprise assigned to deploy the network.

“Even within 40 or 50 kilometers of Sydney and Melbourne, there are places you can really only get to by satellite,” said Michael Quigley, chief executive of NBN Co., the Australian government-owned company that is building the fiber, wireless and satellite network. “Fiber is too difficult, and the terrain is such that you cannot get [sufficient] propagation with wireless.”

Financed in part by a bond issue, the Australian National Broadband Network has been budgeted at 43 billion Australian dollars ($38.4 billion) over eight years. Its goal is to provide 90 percent of all Australian homes, schools and businesses with fiber-optic connectivity at 100 megabits per second.

The remaining 10 percent of users will be covered by wireless terrestrial links, or by two Ka-band satellites. For these users, the goal is connectivity at 12 megabits per second in downlink and 1 to 2 megabits per second on the uplink.

The satellite network would serve more than 200,000 users and feature 10 gateway Earth stations throughout Australia, with two antennas at each station. The company has apparently settled on the DVB-RCS transmission standard for its network.

Unlike the U.S. broadband stimulus package, Australia’s includes satellite links as instrumental to the plan’s stated deployment goals. NBN Co., which expects to take on private investors, plans two Ka-band satellites covering Australia.

In a July 9 presentation to the Committee for the Economic Development of Australia’s 2010 ICT Review organized by Australian information and communications technologies services provider CSG, Quigley implied that NBN Co. is still some distance from selecting a prime contractor for the satellites, which he said could take four years to develop.

He said the company has already discarded the idea of launching only one satellite, even though a single spacecraft would have more than enough capacity to serve the intended market.

“You could potentially do it with one,” Quigley said. “But the trouble is that — I know it’s unlikely — if one gets hit by a piece of space junk, I don’t want to wake up in the morning and find there’s 200,000 people without a service and it would take four years to restore it. So our intention is to have two satellites with some redundancy.”

Quigley, whose background is in terrestrial telecommunications, said he understood that the latest Ka-band satellites could provide “30, 40, 50 or even approaching 100” gigabits per second of throughput. He said he is assuming it will cost about 500 million Australian dollars to build, launch and insure each one.

All-Ka-band broadband satellites under construction in the United States and Europe are designed to produce between 70 gigabits and 120 gigabits per second of throughput.

NBN Co.’s current design features satellites in two different orbital slots over Australia. But Quigley said the company is investigating how closely spaced the satellites need to be to enable users to switch their rooftop antennas from one to the other seamlessly if needed.

“We’re just looking into the engineering aspects now,” Quigley said. “Is it possible to have something clever in the smaller dishes at the [user] premises so that they can effectively point at both satellites?” Another issue to be addressed, he said, is the latency of voice links to satellites in geostationary orbit 36,000 kilometers above the equator, where the two Australian spacecraft will operate.

“We’re still trying to figure out how to avoid the double-hop problem,” Quigley said. “We’d like people to be able to use this for voice as well as for broadband.”

Australia and the Middle East have long been considered ideal markets for Ka-band because signal attenuation from rain is less of an issue in both regions, and both feature large expanses of flat, lightly populated territory with relatively high per-capita income.

Aided by Australian government subsidies for broadband rollout in recent years, satellite fleet operator Thaicom of Thailand has made Australia one of the biggest markets for its Ipstar broadband satellite, which operates in Ku-band.

Peter B. de Selding was the Paris bureau chief for SpaceNews.