An artist's illustration of a future airliner concept designed through NASA's Advanced Aircraft Concepts for Environmental Sustainability (AACES) 2050 initiative. (Image credit: Electra) NASA is looking to develop a new generation of low-emission commercial aircraft that will offer a more efficient and sustainable mode of travel.The space agency has commissioned five new design studies as part of its Advanced Aircraft Concepts for Environmental Sustainability (AACES) 2050 initiative. The organiz...