Space firm founded by billionaire Paul Allen closing operations

Allen's Stratolaunch had been compared to billionaire Richard Branson's Virgin Galactic

Stratolaunch Systems Corporation, the space company founded by late billionaire and Microsoft Corp co-founder Paul Allen, is closing operations, cutting short ambitious plans to challenge traditional aerospace companies in a new “space race,” four people familiar with the matter said on Friday.

The company, a unit of Allen’s privately held investment vehicle Vulcan Inc, had been developing a portfolio of launch vehicles including the world’s largest airplane by wingspan to launch satellites and eventually humans into space.

Allen, who founded Seattle-based Stratolaunch in 2011, died at age 65 in October.

Vulcan has been exploring a possible sale of Stratolaunch’s assets and intellectual property,