Last shuttle boldly goes into retirement

Defying forecasts of poor weather conditions - and a last-minute hitch that halted the countdown with just 31 seconds left on the clock and left millions holding their breath while it was resolved - Nasa's iconic spacecraft lifted off the launchpad and into history books.

Carrying four crew on a 12-day mission to the International Space Station, its flight represents the final chapter in a story that began in 1981 with the maiden mission of Columbia. In the past 30 years, the shuttle fleet has flown 537 billion miles, circling the Earth nearly 21,000 times.

"The shuttle's always going to be a reflection of what a great nation can do when it commits to be bold and follow through," said astronaut Chris Ferguson, commander of Atlantis, minutes before the launch.

"We're completing a chapter of a journey that will never end. Let's light this fire one more time, and witness this great nation at its best."

As Atlantis lifted off, shaking the ground around Kennedy Space Centre where 45,000 invited guests watched on, with one million more people packing the beaches and roads around Florida's Space Coast, debate over the legacy of the world's first reusable spacecraft remained divided.

Originally designed as a space "taxi" to launch several times a month, Nasa's fleet of shuttle orbiters never lived up to that expectation, averaging fewer than five flights a year. Additionally, each mission cost about $1.5 billion, far in excess of original estimates.

The cost angered Washington and gave fuel to critics who suggested that the shuttle programme was an expensive, unambitious white elephant that constrained astronauts to lower Earth orbit for three decades after the literal highs of the Apollo moon missions.

But even that, according to astronaut Steve Robinson, who flew four space shuttle missions between 1997 and 2010, was progress.

"What the shuttle programme has given us is an understanding of what routine access to space costs and requires," he said. "It's taught us how to operate and service an orbiting outpost, something that we didn't have 30 years ago."

Supporters point to the construction of the $100bn International Space Station and the stunning images returned to Earth from the Hubble space telescope, which was launched from Discovery in 1990 and has allowed astronomers to peer back 13.2bn years in time, as the benchmark achievements.

Alongside the highs came the two darkest moments in the history of human spaceflight.Until the orbiter Challenger exploded 73 seconds after lift-off in January 1986, Nasa had never lost an astronaut in flight.

Seven died in that disaster, blamed on a faulty fuel tank seal, and seven more were killed when Columbia tore apart as it returned from space in February 2003. Insulating foam from the shuttle's external fuel tank came away during the launch - a flaw that regularly dogged the orbiters - knocking a briefcase-sized hole in the spacecraft's wing and allowing deadly hot gases to seep in during re-entry.

Mike Leinbach, Nasa's launch director, is among critics of Nasa's lack of direction, but nonetheless sees much to celebrate, one being the construction of mankind's biggest ever habitat off planet Earth.

"We've gone into international partnerships in lower Earth orbit, something that hadn't been done before," he said.

"It's not too much of a stretch to think of Star Trek and the international flavour of the bridge of the Enterprise, so we're really beginning the next step of evolution off of the planet Earth. Exploration is in the human soul, it's part of what makes humans human."