Aerial dancers from Voloa, perform a dress rehearsal ahead of their performance at the opening night of Salisbury International Arts Festival on May 20, 2011 in Salisbury, England. The 39th Salisbury International Arts Festival runs from tonight until Saturday 4 June 2011 and features a programme of theatre, dance, circus, film, music, comedy and spoken word in locations around the historic city, from Salisbury Cathedral to Stonehenge. (Photo by Matt Cardy/Getty Images)

Playboy founder Hugh Hefner (not pictured) arrives at Stansted Airport on June 2, 2011 in Stansted, England. The photograph is a recreation of a picture originally taken in the 1960's, with ten of the new London Bunnies. Mr Hefner is back in the UK to mark the launch of the new Playboy Club in Mayfair, which opens on June 4. The clubs opening will welcome back the iconic Playboy Bunny to Londonafter a 30 year absence. Famous Bunnies have included Debbie Harry and Lauren Hutton. (Photo by Dan Kitwood/Getty Images)

Microsoft co-founder Paul Allen has spent the last six years working on a giant aircraft capable of launching rockets to space. Today, his company Stratolaunch Systems literally rolled that plane out of its hangar in the Mojave Desert for the first time ever.

Chinese security stands near a Long March 2F rocket carrying Tiangong-1, China's first unmanned space module, stands at the Jiuquan Satellite Launch Center on September 28, 2011 in Jiuquan, Gansu Province of China. Tiangong-1,a small unmanned space lab, will be launched at 21:19 (Beijing time) on September 29, 2011, and will attempt a docking procedure with a Shenzhou 8 spacecraft later in the mission. (Photo by Lintao Zhang/Getty Images)

Free runners “3run” take advantage of O2's empty Slough HQ on the company's flexible working day on February 8, 2012 in Slough, England. (Photo by Ian Gavan/Getty Images for O2)

Model Jennifer Hawkins showcases designs by Yeojin Bae on the catwalk at the Myer A/W 2012 Collection Launch on March 1, 2012 in Melbourne, Australia. (Photo by Scott Barbour/Getty Images)

Artist Richard Neave admires the sculpture “Sprinting” that he created with Denise Smith on March 12, 2012 in London, England. The model shows the body of elite athlete, Richard Whitehead, and forms the centre piece at the Anatomy Of An Athlete Exhibition opening at the Hunterian Museum. (Photo by Bethany Clarke/Getty Images)

A Russian Soyuz 2.1a rocket carrying Lomonosov, Aist-2D and SamSat-218 satellites lifts off from the launch pad at the new Vostochny Cosmodrome outside the city of Uglegorsk, about 200 kilometers (125 miles) from the city of Blagoveshchensk in the far eastern Amur region Thursday, April 28, 2016. The launch of the first rocket from Russia's new space facility has been delayed after a last-minute problem. (Photo by Kirill Kudryavtsev/Pool Photo via AP Photo)