Unmanned SpaceX rocket Falcon-9 has exploded minutes after lifting off from Cape Canaveral in Florida.
Rocket debris tumbled out of the sky into the Atlantic Ocean.
Falcon-9, which had 18 straight successes prior to Sunday’s flight, was in the process of sending a cargo ship to the International Space Station (ISS).
NASA says important supplies have been lost but the orbiting lab’s crew is secure.
Even now, the three astronauts have sufficient stores of food, water and equipment to operate until late October, and there should be visits from Russian and Japanese freighters before then.
The problem occurred 139 seconds into the flight, just before the first-stage of the rocket was about to separate from the upper-stage, or top segment of the Falcon-9.
“The vehicle has broken up,” said NASA commentator George Diller, as TV images showed the white rocket falling to pieces.
“We appear to have had a launch vehicle failure,” he added.
“There was an overpressure event in the upper-stage liquid oxygen tank,” tweeted SpaceX CEO Elon Musk.
“Data suggests counterintuitive cause. That’s all we can say with confidence right now. Will have more to say following a thorough fault tree analysis.”
SpaceX will now lead an investigation, overseen by the Federal Aviation Administration (FAA) and NASA, which contracts the California company commercially to resupply the station.
This means there will be no further Falcon-9 launches in the immediate future.
SpaceX president Gwynne Shotwell said: “Once we identify the issues we will submit that documentation to the FAA and it will be considered prior to the next flight.”
“I don’t have a timeline for that right now. It certainly isn’t going to be a year – (more likely) a month or so.”
NASA had loaded SpaceX’s Dragon freighter on the top of the Falcon with just over two tonnes of supplies.
These included a new docking mechanism that will be needed when future astronaut vehicles – one of them based on the robotic Dragon itself – come into service later this decade.
The agency has a second mechanism that it will be sending up shortly, but it will now also have to build a third to replace the one lost in the Atlantic.
NASA’s associate administrator for human spaceflight, Bill Gerstenmaier, said:“I think this points out the challenges and difficulties we face in spaceflight.
“We are operating systems at the edge of their ability. This is a very demanding environment that requires tremendous precision and tremendous amounts of engineering skill – for hardware to perform exactly as it should.”
SpaceX has postponed an experiment to bring part of its Falcon 9 rocket down to a soft landing on a floating sea platform.
The space company has now rescheduled the Cape Canaveral demonstration for January 9.
Once the first stage of the rocket launches, and has finished its work, it will head back to Earth to try to touch down on a sea barge in the Atlantic.
If this kind of capability can be proven, it promises dramatically lower launch costs in the future.
All segments of a rocket are usually discarded after use and are destroyed as they fall back down.
SpaceX, however, has been practicing the controlled return of the first stage of its Falcon 9 vehicle.
The problem responsible for today’s scrub decision related to a technical issue detected in the steering mechanism of the rocket’s upper stage.
The next chance to send up the vehicle will be on January 9 at 05:09AM local Florida time.
SpaceX itself has been playing down expectations, rating the chances of success at no more than 50-50.
“I’m pretty sure this will be very exciting, but, as I said, it’s an experiment,” cautioned Hans Koenigsmann, vice president for mission assurance at SpaceX.
“There’s a certain likelihood that this will not work out all right, that something will go wrong. It’s the first time we have tried this – nobody has ever tried it as far as we know.”
The primary purpose of the flight is to send the Dragon cargo ship on a path to rendezvous with the International Space Station (ISS).
It will be the first American re-supply mission to the orbiting platform since October’s spectacular explosion of a freighter system operated by competitor Orbital Sciences Corporation.
However, it is the outcome of the SpaceX experiment that is likely to make the headlines.
SpaceX believes it can return, refurbish and re-use key elements of its rockets.
To this end, it has been testing first-stage boosters that relight their engines to try to slow their fall through the atmosphere, attaching fins to help guide them downwards, and legs to make a stable touchdown.
So far, there have only been mock landings, in which the stage is brought to a hovering position at the surface of the ocean, where, without a solid platform to set down, every booster has subsequently been lost in the water.
The experiment at the end of this week will be different in that SpaceX has sent a floating barge to the targeted return site some 200 miles northeast of Cape Canaveral, Florida.
The first commercially contracted re-supply mission to the International Space Station (ISS) has begun.
A Falcon rocket carrying a Dragon cargo capsule lifted clear of Cape Canaveral in Florida at 20:35 (00:35 GMT).
The robotic Dragon ship will deliver 400 kg of food, clothing, experiments and spares to the orbiting platform’s six astronauts.
It is the maiden flight in a sequence of 12 missions that California’s SpaceX company is performing for NASA.
NASA is looking to the private sector to assume routine transport duties to and from low-Earth orbit.
It has given SpaceX a $1.6 billion contract to keep the ISS stocked up with essentials, restoring a re-supply capability that the US lost when it retired the shuttles last year.
The terms of the contract kicked in following a successful test of Dragon’s systems in May.
That demonstration saw the capsule berth with the ISS – the first commercially designed and built vehicle to do so – and then return safely to Earth.
NASA has a second company it hopes also can soon begin operational cargo deliveries to the station.
The Orbital Sciences Corporation (OSC) will shortly test its new Antares rocket before undertaking its own ISS demonstration with a robotic vessel called Cygnus.
If that mission – tipped to take place next year – goes well then it will trigger a $1.9 billion contract for Orbital.
NASA wants eventually to put astronaut transport in the hands of the private sector, too.
SpaceX is eyeing this business as well, and is developing the critical life-support and safety systems that would turn Dragon into a human-rated vehicle. The company says it is just a few years away from being able to provide an astronaut “taxi” service.
NASA’s policy of outsourcing its cargo and crew transport needs is intended to find savings that can be ploughed back into building a rocket and capsule system capable of taking humans beyond low-Earth to more challenging destinations.
“We’re handing off to the private sector our transportation to the International Space Station so that NASA can focus on what we do best – exploring even deeper into our Solar System, with missions to an asteroid and Mars on the horizon,” explained agency administrator Charles Bolden.
Sunday’s nine-minute, 14-second ascent to orbit appeared flawless.
The Falcon dropped the Dragon off in an elliptical path running from 197 km above the Earth out to 328 km.
“Dragon was inserted into a picture-perfect orbit,” said SpaceX president Gwynne Shotwell.
“Its solar arrays deployed and it’s driving its way to station. So, that’s just awesome.”
Dragon must raise itself to the ISS’s altitude, which is presently at more than 400 km.
It is scheduled to arrive at the station on Wednesday. It will follow the routine established in May of parking itself just below the platform so that it can be grabbed by a robotic arm and pulled into a berthing port.
The attachment should take place at about 05:40 GMT.
Dragon is expected to return to Earth at the end of the month.
Its cargo then will include broken machinery and science materials that need to be handed back to researchers.