H. E. Ross was one of the leading figures in the British Interplanetary Society from the time of its inception in 1933. Ross wrote a 1939 article in the BIS's Journal that outlined a method of accomplishing a lunar mission. The effort leading to the article had begun in London in February 1937 when the BIS formed a technical committee to conduct feasibility studies. In January 1949, Ross published a paper in which he suggested the most efficient strategy for a manned lunar expedition would be to the leave the propellants for the return trip to Earth in lunar orbit – exactly the method eventually used by Apollo. He concluded that this method, now known as lunar-orbit rendezvous (LOR) would, compared with a direct flight to the Moon's surface from Earth, reduce the Earth-launch weight by a factor of 2.6. In his paper he credited Hermann Oberth, Guido von Pirquet, Hermann Noordung, Walter Hohmann, Konstantin Tsiolkovsky, and Fridrikh Tsander for having earlier discussed ideas pertinent to the LOR concept.