Elon Musk, who set up the online payment company PayPal, is one of a group of entrepreneurs who made their fortune in IT and then turned their attention to space travel. He is now boss of California-based SpaceX: “I think it would be cool to be born on Earth and die on Mars. Hopefully not at the point of impact.”

He has reason to celebrate. His space capsule Dragon returned safely to Earth on 31 May 2012 after a successful rendezvous with the International Space Station (ISS). “After Sputnik and the cold war space race, followed by the Shuttle era, the first successful launch of a privately developed rocket and capsule on a fee-paying mission is without doubt a major event,” wrote the magazine Flight International (1). SpaceX is contracted to carry out 12 resupply missions to the ISS, delivering 450kg of food and supplies and bringing back waste, at a cost of $1.6bn.

The competitor firm Orbital Sciences, based in Virginia, has a similar contract with Nasa. Obama’s administration told the space sector to seek external funding after the Shuttle’s costs became unsustainable and it had to be retired. While the eventual aim of the commercial companies is independent, manned, space flight, they could also help Nasa end the “embarrassing inability of the world’s largest space agency to launch its own astronauts into space” (2) — Nasa currently has to use Russian Soyuz rockets launched from Baikonur in Kazakhstan.

A Shuttle resupply mission to ISS costs between $300m and $1bn, while launching a Falcon 9 rocket (SpaceX’s craft) only costs $60m. SpaceX, set up in 2002, employs 1,800 people and already has customers for its next 40 launches. “We’ll be doing every kind of space transport, except for suborbital [over 100km],” said Musk. “We’ll launch satellites of all shapes and sizes, servicing the space station with cargo and crew, and then the long term objective is to develop a space transport system that will enable humanity to become a multi-planet species” (3).

The entrepreneur Peter Diamandis (4) and Google launched the Lunar X competition — a $30m prize to the first privately funded team that can land a robot on the Moon, have it move 500m and send back pictures and data. Twenty-six companies have entered, and Nasa is already imploring them not to interfere with anything from the Apollo landing site.

“It’s like the advent of the internet in the mid-1990s, when commercial companies entered what was originally a government endeavour,” said Musk. “That move dramatically accelerated the pace of advancement and made the internet accessible to the mass market. I think we’re at a similar inflection point for space. I hope and I believe that this mission [to the ISS] will be historic in marking that turning point towards a rapid advancement in space transportation technology.”

Tourism to pay

But how will it work economically? The cost of space travel is not a function of the distance but of the force required to escape Earth’s gravity. Services are organised into strata — orbits or particular stations between the Earth and the Moon — that the market could colonise successively.

The lowest stratum is suborbital flight. Richard Branson (eager for publicity for his Virgin airline), the more discreet but more advanced XCOR, and the mysterious Blue Origin, have their eye on this for manned space flight. Other companies such as Masten Space Systems and Armadillo Aerospace plan unmanned flights. Many tourists are prepared to pay $200,000 to look at the Earth from the stratosphere. The lack of friction means crafts can reach extreme speeds, and two-hour flights from New York to Tokyo are being considered in the not-too-distant future. Since gravity is lessened for a few minutes on these flights, physical, chemical and biological experiments could be carried out for companies in industries ranging from construction to pharmaceutical research.

The first ring of satellites is within the low Earth orbit, just above the atmosphere and up to an altitude of 2,000km. Within that, the ISS maintains an orbital altitude of 300-410km; it can be reached by commercial space stations such as those built by Bigelow Aerospace. Fuel tanks and zero-gravity factories could be stationed there, to carry out long-term experiments. Flights reaching these altitudes could supply the ISS, deliver fuel to satellites, repair them, or even bring them back to Earth.

Far beyond them at 20,000km, and requiring much more energy to reach, is the constellation of GPS (Global Positioning System) satellites, while “fixed” television and telecommunications satellites orbit within the geostationary Earth orbit at 35,800km. There are ideas for solar power systems that convert the sun’s energy into microwaves, and send it back to Earth or to other spacecraft. There is also a growth market in recovering the large number of broken or uncontrollable “zombie” satellites. Experts warn of overpopulated orbits, with a growing risk of collisions, and their knock-on effects, as each accident produces new debris (see Space junk graph). The “armament” of space, with orbital weapons and satellite killers is a threat to space exploration. “Tests of Chinese and US anti-satellite weapons in 2007 and 2008 have shown that space is already a theatre of conflict between powers,” wrote Brigadier General Yves Arnaud, head of the French Joint Space Command (5).

Reaching the Moon

The next stop in the sequence is Lagrange point number 1 of the Earth-Moon system (Earth-Moon L1), close to the Moon, which requires relatively little energy to reach from the geostationary orbit: an ideal location for stationing spacecraft. The Lagrange points, also called libration points, are where the gravitational pull of two massive bodies (the Earth and Moon) is balanced, allowing a smaller body to orbit without using much energy. There are no other natural bodies or any of the artificial debris that pollutes terrestrial orbits. Ken Murphy, president of the Moon Society in the US, explained in an article: “Activity is going to expand outward, and once activity has reached the neighbourhood of the Earth-Moon L1 point, [reaching] the Moon (and so much more) becomes a no-brainer” (6).

From L1, it does not take much energy to land on the Moon, or Mars, or travel in the direction of near-Earth objects, whose trajectory crosses the Earth’s orbit. It might be possible to use L1 as a launching point for free flyers, which would go into terrestrial orbits to collect satellites to repair or clean up debris and boomerang back. A service station could be set up there by installing tanks of hydrogen (from Earth) and oxygen (of terrestrial origin, or extracted from material on the Moon’s surface).

Mars remains expensive in terms of time. A manned mission would take several years. Nasa aims to do it in 2030, but private operators dream, and promise their investors, to reach it perhaps by 2025 (7). The space industry would like an infrastructure of cislunar services (between the Earth and Moon) as a platform for as yet unimagined enterprises, for example the surveillance and destruction of asteroids that threaten humanity — a private company is already thinking about this (8). The Moon’s reserves of metals, rare minerals and oxygen have already led to science fiction scenarios. The Moon is home to “20 times more titanium and platinum than anywhere on Earth, not to mention helium 3, a rare isotope that many feel could be the future of energy on Earth and in space,” says the billionaire Naveen Jain, formerly of Microsoft. “We want to solve the problem of energy on Earth by using the Moon as the eighth continent” (9). Sergey Brin, co-founder of Google, fantasises about lassoing asteroids and bringing them into the Earth’s orbit to extract their minerals.