THE history of manned space flight since the end of America's moon missions in 1973 can be summed up by a single fact: nearly half a century after its maiden flight in 1967, the Saturn V, the immense, building-sized rocket that powered the Apollo programme, remains the most powerful space vehicle ever flown. After 1973 the space-faring nations were content to confine themselves to low earth orbit. With no appetite to return to the moon, let alone venture any farther afield (at least among the politicians who control the purse strings), comparably powerful rockets have simply not been needed.

Over the past few years, though, manned space exploration has come back onto the agenda. China has announced a lunar programme of its own. In 2005 George Bush announced a plan to send Americas back to the moon as well, with a view to building a permanent base there as a precusor to trips further afield. Last year, Barack Obama cancelled that plan, instead instructing America's space agency to send a manned mission to an asteroid as a prelude to a flight to Mars, pencilled in for some time in the 2030s.

Sending astronauts into the solar system would require a beefier rocket than any currently operating. On September 14th NASA unveiled its design for just such a rocket. Dubbed the "Space Launch System" (one might think that NASA's legion of PR people might have come up with a less quotidian name), the $18 billion rocket is a mish-mash of previous designs that will eventually be able to loft 130 tons into low-earth orbit, compared with 119 for the Saturn V. The basic shape—a cone-shaped capsule mounted atop a three-stage rocket body—is reminiscent of that of the Saturn, while the solid-fuel booster rockets strapped to the side are similar to the ones used in space shuttle launches. Indeed, the rocket will reuse quite a bit of space shuttle technology; the lower stage will be propelled by five of the liquid-fuelled RS-25 engines that powered the space shuttle.

That evolutionary approach is deliberate, says NASA. Much of the technology has a proven flight history (although it was a flaw in the booster rockets that led to the loss of the space shuttle Challenger in 1986), and that should cut development time and help to keep costs down. Assuming, of course, that the SLS ever actually flies. NASA promises that the new rocket will make its maiden flight in 2018. But six years is a long time in the space business, and big cuts in government spending are planned in the meantime. The reign of the Saturn V is not over yet.