STS-42 Payload Specialist Ulf D. Merbold (upside down) tumbles with fellow German Space Agency (DFVLR) scientist in the fuselage of KC-135 NASA 930 during a zero gravity flight the week of 05-16-88. Merbold is representing the European Space Agency (ESA) on the International Microgravity Laboratory 1 (IML-1) mission aboard Discovery, Orbiter Vehicle (OV) 103.