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Mark Greenberg

SpaceShipTwo undergoes an unpowered glide flight test over Mojave in late 2010.

Virgin Galactic officials have long been closed-mouthed about exactly when they schedule test flights of their new rocketplane, SpaceShipTwo.

News reporters usually don't learn about the flights at Mojave Air & Space Port until after the fact.

This week was a major exception.

In an interview published Tuesday by the Las Vegas Sun, Virgin's founder, Sir Richard Branson, said the six-passenger, two-pilot suborbital spaceship is scheduled to go faster than the speed of sound on Monday.

"We're hoping to break the sound barrier," Branson told the Sun. "That's planned Monday. It will be a historic day. This is going to be Virgin Galactic's year.

"We'll break the sound barrier Monday, and from there, we build up through the rest of the year, finally going into space near the end of the year," he continued.

That can only mean SpaceShipTwo is slated for its first rocket-powered test flight, a significant benchmark in the space tourism program's development. Up until now, all test flights of SS2 have been "glide tests," meaning the space plane is carried by its mothership, WhiteKnightTwo, thousands of feet up, then released.

Like the space shuttle, SS2 returns to Earth unpowered. And several test flights have shown it can glide home to Mojave with no problems.

But Monday's test is expected to mark the first time the suborbital space vehicle will fire its rocket motor in flight -- a huge step forward as Virgin moves toward its goal of launching private space adventurers on short hops to the edge of space -- for a hefty price of $200,000.

Enrico Palermo, vice president of operations of The Spaceship Co., Virgin's development arm, is in charge of building the world's first fleet of commercial spaceships at the company's huge hangar in Mojave.

Palermo acknowledged earlier this month that there have been some delays in the development of SpaceShipTwo and its carrier aircraft. But safety, he said, comes first.

"We do encounter challenges along the way," he said.

But doing it safely is more important than doing it quickly, he added.

Of course, like any test flight, weather issues or technical concerns on Monday could cause flight managers to scrub the launch until another day.

When the first commercial tourism flight blasts off as early as 2014, Branson has promised to be on it.

"I'll be on the first official flight, which we look to have in the first quarter of next year," he told the Sun. "We're doing a number of test flights into space first."