Roll up for the Red Planet Another entrepreneur, the American Dennis Tito, announced earlier this year that his Inspiration Mars Foundation will send two people, probably a married couple, on a fly-past of the Red Planet. He intends to launch in January 2018, taking advantage of an unusually favourable alignment of the planets - and beating Nasa by at least two decades. The 501-day mission can be accomplished, says Tito, using existing technology, specifically a SpaceX capsule and Falcon rocket, coupled with off-the-shelf Nasa-derived life- support technologies. The craft would be sent on its way by a powerful rocket, with the flight to Mars and back governed entirely by celestial mechanics (so there would be no possibility of turning around to go home). The crew of the capsule, which would have as much space as a small car, would not have much to do except enjoy the view and try to stay alive, by drinking water from recycled urine and eating rehydrated food. Such a trip could be made a little more comfortable with the addition of an inflatable capsule provided by another privateer, Robert Bigelow, a hotel magnate who runs what amounts to a mini-space programme from his Las Vegas base. Bigelow Aerospace has tested an experimental inflatable habitat; this is thought to be the cheapest and quickest way of providing large pressurised areas in which astronauts can live comfortably in orbit, en route to the planets or on the lunar or Martian surface. Then there is the great Dutch plan for a one-way trip to Mars. Started by Bas Lansdorp, an entrepreneur, Mars One aims to establish a permanent colony by 2023, with groups of four astronauts arriving every four years. The project, which again uses SpaceX rockets and as many off-the-shelf components as possible, is to be financed using reality television and online media tie-ins. The astronauts, effectively participants in the ultimate Big Brother (another Dutch creation), will spend the rest of their lives at least 35 million miles from home, on a planet with no breathable air, significant radiation exposure and no hope of rescue should something go horribly wrong. Thousands of people have already applied online. Even 10 years ago, you could have dismissed all of these plans as crazy. And although many private space- flight initiatives still amount to no more than a pretty website, a new atmosphere of credibility has settled around the privateers. Tito, for instance, is an engineer of repute, who 12 years ago became the world's first space tourist when he bought himself a stay on the ISS. The billionaire's new plan is actually relatively conservative: the couple will not even go into orbit around Mars, but will graze the planet at an altitude of 100 miles before whizzing home at 30,000mph - faster than any humans have travelled before. The mission will be cheap, too, coming in at under $2 billion (£1.3 billion), or less than 1 per cent of the realistic cost of a Nasa Mars shot. Why is it that we might see an entrepreneur get to Mars before Nasa even gets back to the Moon? In a word: risk. Going into space is horribly dangerous. And Nasa, as a government agency, is legally not permitted to put its astronauts at the sort of risk that a private outfit could happily countenance. The trip to Mars in Tito's rocket will be horribly cramped and uncomfortable. A study earlier this month showed that such astronauts face potentially dangerous levels of radiation exposure; one way to minimise this, suggest engineers, may be to line the inside of the capsule with bags of radiation-absorbing human waste. Humanity's pioneers would thus voyage in a flying toilet. Even so, there is a good chance they would not get back alive. The sort of re-entry speeds being discussed would involve potentially lethal G-forces (after their bodies have already been weakened by 17 months of weightlessness). The counter-argument is that all space flight carries risk: the radiation hazards of a Mars trip have probably been overstated, since the real danger is - and always has been - catastrophic technical failure. As Dr David Harland, a British space historian, says, exploration, even on Earth, can kill. Look at the explorers of yesteryear who lost their lives. Who knows, these folks might actually survive. And if they do, they will grab the attention of millions on Earth, for whom the excitement of space has been forgotten for far too long.