An unknown number of guns are being built with the mechanisms, causing problems for the police and ATF officials. Photo: An ATF agent holds a generic unfinished receiver, back, and one that has been manufactured, front, at an ATF field office in Washington, on May 06, 2014. The ATF is trying to crack down on the trade in the makeshift guns by targeting shops and individuals who offer to turn the unfinished receivers into functional pieces for firearms. (Photo by Bill O'Leary/The Washington Post)

“The Space Launch System, or SLS, is a Shuttle-Derived heavy launch vehicle being designed by NASA, following the cancellation of the Constellation Program, to replace the Space Shuttle after its retirement. The NASA Authorization Act of 2010 envisions the transformation of the Ares I and Ares V vehicle designs into a single launch vehicle usable for both crew and cargo. It is to be upgraded over time with more powerful versions. The proposed SLS is visually similar to the legacy Saturn V booster and in particular the proposed, two-stage, Saturn INT-20”. – Wikipedia

Photo: In this illustration provided by NASA, the design for a new space rocket system, the Space Launch System, is seen. NASA's new rocket design will reportedly cost about $35 billion and be ready to for test launch in 2017. According to NASA, the rocket will be used to carry Orion Multi-Purpose Crew Vehicle as well as cargo and science experiments to earth's orbit, as a backup for the space station and possibly destinations beyond that. (Illustration by NASA via Getty Images)

A girl carries a rifle as she attends a rally by followers of the Shi'ite Houthi movement commemorating the death of Imam Zaid bin Ali in Sanaa, Yemen October 26, 2016. (Photo by Khaled Abdullah/Reuters)

Kurdish gunmen hold their rifles in front of the burning house of a Shi'ite militiaman during clashes in Tuz Khurmato, Iraq, April 24, 2016. (Photo by Goran Tomasevic/Reuters)

People inspect hookahs shaped like rifles on display for sale in a souk at the port city of Sidon, southern Lebanon, December 23, 2015. (Photo by Ali Hashisho/Reuters)

A military instructor teaches a schoolboy shooting with Kalashnikov rifles, during a training session at a military unit of the National Guard of Ukraine in western Ukrainian city of Lviv on February 15, 2022. (Photo by Yuriy Dyachyshyn/AFP Photo)

A woman athlete aims an air rifle while competing in a local shooting championship in Yemen's Huthi rebel-held capital Sanaa on January 3, 2023. (Photo by Mohammed Huwais/AFP Photo)

Factory landlord Lawrence Taylor (L), portraying a Colour Sergeant from the King's Royal Rifle Corps, part of the Rifles Living History Society, performs a drill with Connor Young (R) of the Queen's Own Royal West Kent Regiment Living History Group as they recreate the life of a First World War soldier at the Eden Valley Museum in Edenbridge in southeast England May 10, 2014. Lawrence has always had an interest in military history and specifically “The Rifles” – his veteran father's WWII regiment. When he became a re-enactor he chose not to re-enact WWII as many of the veterans are still alive, and he felt uncomfortable as he remembers his father would have flashbacks and nightmares about the war. United by a fascination with military history and a fondness for dressing up, groups such as the Rifles Living History Society and the Queen's Own Royal West Kent Regiment Living History Group get together to recreate aspects of life during the First World War. Reuters photographer Luke MacGregor photographed members of the groups, both as they took part in living history events and at their day jobs. (Photo by Luke MacGregor/Reuters)