“The Lockheed Martin X-33 is an unmanned, sub-scale technology demonstrator suborbital spaceplane developed in the 1990s under the U.S. government-funded Space Launch Initiative program”. – Wikipedia

Photo: An Artist's Rendering Shows How Nasa's X-33 Technology Demonstrator, A Cost-Cutting Fully Reusable Single-Stage-To-Orbit Space Vehicle, Will Look Upon Completion. The 67 Foot-Long, 278,600 Pound, Twin Engine Space Vehicle, Capable Of Reaching Speeds In Excess Of Mach 15, Will Lead To The Construction Of A 127 Foot-Long, 2,186,000 Pound Version With Seven Engines And A 50,000 Pound Payload Capacity Called The “Venturestar”. (Photo By Nasa/Getty Images)

Kashmiri children play with snow on a wooden foot bridge in the interiors of Dal Lake in Srinagar on January 16, 2017. A cold wave has further tightened its grip in Jammu and Kashmir, with most places in the state recording sub-zero temperatures. (Photo by Tauseef Mustafa/AFP Photo)

A miniature model of Chichen Itza in Mexico, part of Gulliver's Gate, a miniature world being recreated in a 49,000-square-foot exhibit space in Times Square, is seen during a preview April 10, 2017 in New York City. (Photo by Timothy A. Clary/AFP Photo)

A robot is seen on Mount Etna, Italy on July 4, 2017. Mount Etna, in Sicily, is a test bed for the approximately three-foot high, four-wheeled machine ahead of a future mission to the moon. It is being conducted by the German Aerospace Centre, the agency which runs Germany's space programme. (Photo by Antonio Parrinello/Reuters)

A 40-foot sculpture of the swimmer Rebecca Adlington was unveiled at the Serpentine in London’s Hyde Park on July 25, 2016 to launch a campaign by Kelloggs to encourage the public to support Team GB at the Rio Olympics. (Photo by David Parry/PA Wire/Barcroft Images)

Jeison Rodriguez (L), 19, the living person with the largest feet in the world, poses for a picture with his older brother Wilmer, 24, outside their house in Maracay, Venezuela, October 14, 2015. Rodriguez, holds the Guinness World Record for the largest feet, with 40.1 cm (1 ft 3.79 in) on the right foot and 39.6 cm (1 ft 3.59 in) on the left foot. (Photo by Carlos Garcia Rawlins/Reuters)

These pictures show a five-year-old boy who is already extremely comfortable around alligators. Blaise's dad T-Mike runs the Kliebert Gator Farm, the biggest and oldest in the world and which was started by his grandfather Harvey in 1957. Photo: T-Mike Kliebert and his son Blaise tackle Chinaman a 12 foot alligator in Hammond, Louisiana. (Photo by Barcroft Media)

Friends of Li Guojun drive a homemade tank-shaped vehicle in Kangping county, China. Li, a farmer who is a fan of tanks, spent six months with help from his friends to construct the almost 20-foot vehicle which weighs 2.5 tons. (Photo by Sheng Li/Reuters)