Elon Musk is an entrepreneur best known in space circles for Space Exploration Technologies (SpaceX), which became the first private company to ship cargo to the International Space Station in 2012.
A long-time advocate of Mars exploration, Musk has publicly talked about ventures such as building a greenhouse on the Red Planet and more ambitiously, establishing a Mars colony. He also is rethinking transportation concepts through ideas such as the Hyperloop, a proposed high-speed system that would run between major cities.
The South African-born businessman describes himself as "an engineer and entrepreneur who builds and operates companies to solve environmental, social and economic challenges."
Besides his work at SpaceX, Musk is the founder of electric car company Tesla Motors, and is the chair of a solar energy designer/installer called SolarCity.
Musk grew up in South Africa and earned degrees in physics and business from the University of Pennsylvania. His first venture after school was Zip2 Corp., an Internet company that provided software and services for businesses.
"Things were pretty tough in the early going. I didn't have any money — in fact I had negative money [because] I had huge student debts," Musk recalled in a 2003 Stanford lecture.
He showered at a local YMCA and lived in his office, managing to keep expenses very low despite his low revenue stream. "So when we went to VCs [venture capitalists], we could say we had positive cash flow," he said.
After Compaq bought Zip2 for more than $300 million in 1999, Musk turned his attention to online bill payments. That company, later known as PayPal, sold to eBay for $1.5 billion in 2002.
Musk now had a small fortune in hand, and at the tender age of 30 was looking to put his energies into something new. He began SpaceX in 2002 with ambitious plans to launch a viable, privately funded space company. In the face of naysayers, he doubled down and worked on a business plan.
'Ridiculously recalcitrant problem'
Musk has repeatedly said that humans must be an interplanetary species to combat the threat of asteroids, and potential human catastrophes such as nuclear war or engineered viruses.
What is blocking us from doing that, Musk wrote in a 2008 Esquire piece, is "the ridiculously recalcitrant problem of big, reusable reliable rockets."
"Somehow we have to ... reduce the cost of human spaceflight by a factor of 100," he added. "That's why I started SpaceX. By no means did I think victory was certain. On the contrary, I thought the chances of success were tiny, but that the goal was important enough to try anyway."
This problem has been one of the themes of Musk's work since starting SpaceX. The first successful rocket the company flew, the Falcon 1, took four tries to get off the ground before a successful test flight in September 2008.
Musk funded SpaceX through his own money at first, and then gained enough experience to attract millions of dollars for NASA to develop his rockets and spacecraft, and to bring cargo to the ISS. He has also received launch contracts from entities such as the U.S. Air Force. [Infographic: How SpaceX's Dragon Space Capsule Works]
The company's track record was a factor in NASA awarding it money to develop the Dragon spacecraft for cargo runs to the International Space Station. Dragon won multiple rounds of funding under NASA's Commercial Crew program and made a world-first docking with the International Space Station in 2012. It is now sending regular shipments of cargo to the station.
SpaceX is now developing a human-rated version of Dragon that is expected to bring astronauts to the orbiting complex around 2018. Like its cargo counterpart, the human-rated Dragon spacecraft received money from NASA for development and is now one of two spacecraft types (along with Boeing's CST-100) in the final stages of funding for human certification.
Dragon is hefted using a heavier rocket called the Falcon 9. Since 2014, SpaceX has attempted to re-use the first stage of the rocket by landing it in various situations. To date, SpaceX has successfully achieved ocean and land-based soft landings of the Falcon 9's first stage. It is also trying to do a pinpoint landing on an automated ocean barge. All attempts so far have been unsuccessful, but the company says it's close; a landing in January 2016 failed because a landing leg strut didn't deploy.
Dreams of Mars
Musk has often said that around 2002, he looked up the schedule for when NASA was supposed to send astronauts there, and was shocked to see there was no timeline. (Today, NASA says it hopes to land astronauts there in the 2030s). That's when, he told Wired, he came up with an idea to do a simple Mars mission "to spur the national will."
"The idea was to send a small greenhouse to the surface of Mars, packed with dehydrated nutrient gel that could be hydrated on landing. You’d wind up with this great photograph of green plants and red background — the first life on Mars, as far as we know, and the farthest that life’s ever traveled," he said.
"It would be a great money shot, plus you’d get a lot of engineering data about what it takes to maintain a little greenhouse and keep plants alive on Mars."
He eventually turned aside from the idea due to financial concerns, but in 2012 he sketched out plans to establish a Mars colony, along with other entities, with 80,000 people living on the Red Planet. (Musk later tweeted he meant to say 80,000 making the journey per year.)
The settlers would live off the land as much as possible, using equipment to generate methane, fertilizer and oxygen from Mars' atmosphere and subsurface water ice. They would arrive using a fully reusable rocket that will be a next generation to the Falcon 9 booster.
Still, the cost for such an ambitious plan would be around $36 billion, Musk told Space.com in 2012.
"Some money has to be spent on establishing a base on Mars. It’s about getting the basic fundamentals in place," Musk said.
"That was true of the English colonies [in the Americas]; it took a significant expense to get things started. But once there are regular Mars flights, you can get the cost down to half a million dollars for someone to move to Mars. Then I think there are enough people who would buy that to have it be a reasonable business case.