Two robotic legged squad support system (LS3) machines by the Defense Advanced Research Project Agency follow a technician during a demonstration at Joint Base Myer-Henderson Hall, Virginia, on September 10, 2012. (U.S. Marine Corps photo by Sgt. Mallory S. VanderSchans via The Atlantic)

“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)

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)

A demonstrator wears a mask during a protest inside the Bay Area Rapid Transit (BART) Civic Center station on August 15, 2011 in San Francisco, California. The hacker group “Anonymous” staged a demonstration at a BART station this evening after BART officials turned off cell phne service in its stations last week during a disruptive protest following a fatal shooting of a man by BART police. (Photo by Justin Sullivan/Getty Images)

Anti-nuclear activists demonstrate during a “Say to Goodbye to Nuclear Energy” protest on September 11, 2011 in Kobe, Japan. Japan is marking sixth months since a magnitude 9.0 earthquake struck Japan offshore on March 11 at 2:46pm local time, triggering a tsunami wave of up to ten metres which engulfed large parts of north-eastern Japan and also damaged the Fukushima nuclear plant, causing the worst nuclear crisis in decades. The current number of dead and missing is reportedly estimated to be 22,900. (Photo by Buddhika Weerasinghe/Getty Images)

A protester holds a sign in front of riot policemen during an anti-G20 demonstration through the streets of Nice on November 1, 2011 in Nice, France. Anti-G20 demonstrators are gathered in Nice ahead of the arrival of the world's top economic leaders for the G20 summit in Cannes on November 3rd and 4th. The leaders are expected to debate current issues surrounding the global financial system in the hope of fending off a global recession and finding an answer to the Eurozone crisis. (Photo by Christopher Furlong/Getty Images)

Police detain a protester during a demonstration against the recent gang-rape of a woman in a moving car, according to local media, in Kolkata, India May 31, 2016. A woman was kidnapped and gang-raped by at least four men on May 29 in the Salt Lake area of the city and is currently being treated in hopsital, local media reported. (Photo by Rupak De Chowdhuri/Reuters)

A soldier from the South Korean army special forces breaks stone plates with her head during a martial arts demonstration for Memorial Day at Korea War Memorial Museum in Seoul, South Korea, Monday, June 6, 2016.(Photo by Ahn Young-joon/AP Photo)