Indigenous Aryans were inter-related, and the notion of biological race came to the forefront The "Aryan race," the presumed identity of Indo-European language speakers was prominent among such races, which was seen to be further subdivided into "European Aryans" and "Asian Aryans," each with their own homelands. Max Mueller, who translated the Rigveda during 1849–1874, postulated an original homeland for all Aryans in central Asia, from where a northern branch was believed to have migrated to Europe and a southern branch came to India and Iran. The Aryans were fair-complexioned Indo-European speakers who conquered the dark-skinned "dasas" of India. The upper castes,
In-space propulsion technologies mission- enabling breakthroughs that will revolutionize space exploration. There is no single propulsion technology that will benefit all missions or mission types. The requirements for in-space propulsion vary widely due according to their intended application. The described technologies should support everything from small satellites and robotic deep space exploration to space stations and human missions to Mars applications. The technology areas are divided into four basic groups: (1) Chemical propulsion, (2) Nonchemical propulsion, (3) Advanced propulsion technologies, and (4) Supporting technologies; based on the physics of the propulsion system and how it derives thrust as well as its technical maturity.