People look at a man, who residents said was killed by al Qaeda militants, hanging on a bridge in Yemen's southeastern city of Mukalla June 17, 2015. Al Qaeda militants in Yemen killed two alleged Saudi spies, residents said, accusing them of planting tracking devices which enabled the assassination of the group's leader in a suspected U.S. drone strike. (Photo by Reuters/Stringer)

The Swiss Air Force Patrouille Suisse aerobatic team performs during the men's downhill race at the Alpine Skiing FIS Ski World Cup in Wengen, Switzerland, Saturday, January 19, 2019. (Photo by Anthony Anex/Keystone via AP Photo)

The Rakotzbrücke bridge in the autumnal azalea and rhododendron park in Kromlau in the district of Görlitz, Saxony near the state border with Brandenburg on November 7, 2023. More than four million euros have been invested in the restoration and reconstruction of this Lusatian landmark in recent years. The complex includes the listed group of Rakotzbrücke bridges and the so-called organ made of basalt. Friedrich Hermann Rötschke had these built between 1842 and 1875. (Photo by Patrick Pleul/dpa)

The tempestuous stellar nursery called the Carina Nebula, located 7,500 light-years away from Earth in the southern constellation Carina. (Photo by Reuters/NASA)

Icicles are seen on a handrail along the coast at Donggang business district in Dalian, Liaoning province, China on December 27, 2018. (Photo by Reuters/China Stringer Network)

An army cadet contestant with his kart trailing smoke hits the ramp hard and crashes during the 70 year anniversary soap box derby on April 02, 2023 in Hunstanton, England. Over 40 home built karts raced through the streets of the Norfolk town, around bends and over jumps. The race was first held in1953. (Photo by Martin Pope/Getty Images)

Cars slowly move along a bridge in traffic jam in central Moscow, Russia on December 11, 2018. (Photo by Yuri Kadobnov/AFP Photo)

“A small British company with a dream of building a re-usable space plane has won an important endorsement from the European Space Agency (ESA) after completing key tests on its novel engine technology. Reaction Engines Ltd believes its Sabre engine, which would operate like a jet engine in the atmosphere and a rocket in space, could displace rockets for space access and transform air travel by bringing any destination on Earth to no more than four hours away”. – Chris Wickham via Reuters. Photo: Artist's impression of Skylon. (Photo by Reaction Engines Ltd)