History of SpaceX
en.wikipedia.org

... After being ousted as the CEO of PayPal in late 2000, Elon Musk started to gain an interest in space exploration ventures. This spark of interest, according to Musk, came when he is being asked by his friend entrepreneur Adeo Ressi about his plan for the future after PayPal. Musk looked up at NASA's website and was surprised that NASA did not have any concrete plan for a human mission to Mars.[1]:9"10 He then began to attend space conferences and provided funding for private space projects, which include The Planetary Society's solar sail and the Ansari X Prize crewed spaceflight competition.[1]:10 Musk also pledged US$100,000 to the Mars Society and was invited to be in its board of directors.[2][3] As early as August 2001, in contemporary sources, Musk has publicly expressed his support for making humans an interplanetary species at the Mars Society's annual convention.[4] The same month, Musk resigned from his position at Mars Society.[2]

According to Robert Zubrin, Mars Society's founder, he provided Musk contact to aerospace engineer Jim Cantrell as a technical adviser for the society's Mars Gravity Biosatellite project.[5]:30"31 From there, Musk, Cantrell, along with a few other engineers worked on Mars Oasis, a project that aimed to grow a plant in Martian soil as a publicity stunt for garnering interest to Mars missions.[2][1]:10 Mars Oasis project is independent from the Mars Society.[4] Musk and his team travelled twice to Russia, once in October 2001 and another in February 2002 with Michael D. Griffin, to obtain a refurbished intercontinental ballistic missile to launch Mars Oasis. Both attempts failed " the missiles were outrageously priced by the ISC Kosmotras at $8 million per missile when queried,[3] and the team was concerned that the price would go up even higher after the deal had been finalized.[1]:10 Reportedly, this is because Musk and his team were not regarded highly by the Russians.[3][1]:10

After the second failed attempt to procure a missile, the Mars Oasis plan was abandoned and Musk pondered the feasibility of building a rocket himself. As he learned more about the United States space industry, in retrospect, Musk realized that the Mars Oasis mission would more likely lead to an unsustainable Mars program, similar to how the Apollo program operated. According to Musk, the crucial component for a sustainable Mars program is a low launch cost.[1]:11"12

In early 2002, with that realization, Musk met with aerospace engineers at a hotel in Los Angeles International Airport to discuss founding a space launch company, with reportedly some having scoffed at the idea. In April, from that group he invited five that could join the company as early employees: Michael Griffin, Jim Cantrell, John Garvey, Tom Mueller, and Chris Thompson. Griffin, Cantrell and Garvey declined the invitation, while Mueller and Thompson became the company's first and second employee respectively. Musk provided half of his $180 million from PayPal stocks to the newly founded company securing both employees with two-years' worth of salary. The company was named "Space Exploration Technologies Corporation", originally with "S.E.T." as a shortened name, but it was quickly changed to be "SpaceX".[1]:12"14 According to filings, SpaceX was incorporated on 14 March 2002,[6] but according to various sources SpaceX's de facto founding date might instead be 6 May[1] or around June.[3][7] ...