Billionaire and Microsoft co-founder Paul Allen is picking up where NASA left off -- announcing this week his plans to launch a new commercial space travel company.

Allen has teamed up with aerospace pioneer Burt Rutan to launch tourists into orbit in what will be the largest aircraft ever flown.

The plane will be large enough to carry a manned rocket ship under its wing.

When the plane gets to about 30,000 feet the rocket will separate and blast into orbit.

Allen said the first test launch will take place in 2016.

Allen and Rutan won a prize in 2004 with a separate private spaceship that went into space, but not orb