SpaceX CEO Elon Musk has congratulated India on successfully conducting the third long-duration "hot test" of Vikas engine, a key part of the ambitious Gaganyaan mission to take Indians to space in an Indian vehicle. Replying to a tweet by the Indian Space Research Organisation (ISRO) on the engine test, Mr Musk just wrote one word -- "Congratulations!" with India's flag emoticon. The ISRO said on Wednesday that it tested the human rated GSLV MkIII vehicle for engine qualification requirements for the manned mission and it was successful.