“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)

The public get the first view at the opening of the new miniature model Knuffingen Aiport at Miniatur Wunderland on the airport's opening day on May 4, 2011 in Hamburg, Germany. Miniatur Wunderland is the world's largest model railroad landscape, and the model airport, also the world’s largest, goes into operation following 6 years of development and construction and an investment of EUR 3.5 million. The airport is a reproduction of Hamburg’s international airport and includes 40 aircraft that take off and land and 90 vehicles that autonomously move around the runways on May 4, 2011 in Hamburg, Germany. (Photo by Stuart Franklin/Getty Images)

Britain's Prince Harry meets Chewbacca during a visit to the Star Wars film set at Pinewood Studios near Iver Heath, west of London, Britain, April 19, 2016. Prince William and Prince Harry are touring Pinewood to visit the production workshops and meet the creative teams working behind the scenes on the Star Wars films. (Photo by Adrian Dennis/Reuters)

Members of the Prizma Ensemble wearing full solid-coloured bodysuits walk pest ultra orthodox jewish men as they take part in the 6th Jane's walk Jerusalem in Jerusalem, Israel May 6, 2016. Jane's Walk is a global walking tour movement, inspired by US-Canadian author and activist Jane Jacobs. (Photo by Baz Ratner/Reuters)

Giffords Circus’s show is touring the UK. Established in 2000, Giffords Circus is a small circus company that delivers circus / theatre fusion to the villages and market towns of the south west. It combines dance, comedy, horses and live music in a two-hour show, located on village greens in a small white tent surrounded by handmade burgundy and gold showman’s wagons. Photographer Tom Pilston goes behind the scenes to meet the performers. Here: The incredible, gravity-defying Konjowoch Troupe. (Photo by Tom Pilston/The Guardian)

A grey whale greets tourists in boat in, Baja California, Mexico, March 2017. A pair of newly born grey whale calves intrigued by visiting tourists eagerly swim over to the group to get a closer look. Urged on by their mother, the small calves confidently went up to the tour group who were visiting San Ignacio Lagoon in Baja California, Mexico. This adorable moment was captured by zoologist and wildlife photographer, Mark Carwardine on his visit to the area in March 2017. (Photo by Mark Carwardine/Barcroft Images)

A North Korean soldier looks through a window at Australian Prime Minister Julia Gillard (L) and her partner Tim Mathieson (C) while they visit the United Nations Command Military Armistice Commission (UNCMAC) meeting room at the border village of Panmunjom, between South and North Korea, on April 24, 2011 South Korea. Gillard will visit Japan, the Republic of Korea and China during a bilateral tour of North Asia from April 20-27. (Photo by Jeon Heon-Kyun-pool/Getty Images)

United States Marines perform a fighting demonstration in Times Square as part of Fleet Week festivities May 27, 2011 in New York City. Fleet Week, which has been held in New York since 1984, brings thousands of military members to the city where they engage the public with numerous activities, demonstrations, tours and contests. Fleet Week concludes on Memorial Day with a military flyover to honor those killed while serving in the military. (Photo by Spencer Platt/Getty Images)