A SpaceX Falcon 9 rocket exploded shortly after its launch from Cape Canaveral Air Force Station on Sunday, June 28, 2015.
Update, 2:30 p.m.:
SpaceX launch failure today will not delay plans to send three more astronauts to the International Space Station next month, NASA officials said at a press conference today.
The officials said the mishap -- the third in less than a year by three different resupply vehicles -- also showed the wisdom of the agency's selection of two providers, SpaceX and Boeing, to launch astronauts commercially in a few years.
"This is a tough day," said Bill Gerstenmaier, head of NASA's human spaceflight programs. "Spaceflight is not easy."
"It's a pretty important loss to us," he added. "But from a macro-level standpoint, the (station) crew's in no danger, we're moving forward."
The lost cargo, which NASA could not immediately place a value on, included a docking ring that was supposed to help prepare for the arrival of astronauts in commercial space capsules in a few years.
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Raw video: SpaceX rocket explodes after liftoff. NASA TV June 28, 2015
It also included a spacesuit, important water filters and many experiments. Some of the hardware and student experiments were repeats of payloads lost when an Orbital Sciences rocket exploded after liftoff last October.
SpaceX believes a problem with pressure in the Falcon 9 rocket's upper stage liquid oxygen tank caused the rocket to break apart more than two minutes after its 10:21 a.m. launch from Cape Canaveral.
The company has several boats searching for rocket debris that were already staged in the Atlantic Ocean for what the company hoped would be an attempt to land the Falcon 9 booster on a ship.
NASA set up a hotline for the public to report any sitings of debris: (321) 867-2121.
SpaceX will lead a mishap investigation with oversight by the Federal Aviation Administration, which licensed the launch.
"We'll be continuing to monitor all the data that we collect to identify the issue that we experienced, fix it, and get back to flight," said SpaceX President Gwynne Shotwell.
Shotwell would not speculate on how long the investigation might take, but said it would be a matter of months, not a year.
SpaceX had at least four more launches planned this year that will likely be delayed.
Meanwhile, NASA said the ISS has enough food and other supplies to last until at least October, and needs more crew members on board to perform science research.
A Russian resupply ship is expected to launch next Friday, followed by a Japanese vehicle in August, then another launch by a U.S. commercial partner, ATK Orbital, possibly as soon as October.
An unmanned SpaceX Falcon 9 rocket carrying supplies for the International Space Station broke apart less than three minutes after a 10:21 a.m. blastoff from Cape Canaveral Air Force Station.
SpaceX confirmed the 208-foot rocket experienced a problem before its nine first-stage engines shut down, as it climbed through clear skies. Engineers have begun analyzing flight data to pinpoint what went wrong.
"Falcon 9 experienced a problem shortly before first stage shutdown," SpaceX CEO Elon Musk said on Twitter. "Will provide more info as soon as we review the data."
A press conference is planned at 12:50 p.m.
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Some early speculation suggested that the failure occurred in the rocket's upper stage, which was carrying a Dragon cargo capsule.
The Air Force's 45th Space Wing confirmed the mishap came about two minutes and 28 seconds into flight.
The failure was SpaceX's first by a Falcon 9 rocket after 18 successful missions.
In a statement, NASA chief Charlie Bolden said the launch failure was disappointing but that the agency would work with SpaceX to return the Falcon 9 to flight.
"The commercial cargo program was designed to accommodate loss of cargo vehicles," he said. "We will continue operation of the station in a safe and effective way as we continue to use it as our test bed for preparing for longer duration missions farther into the solar system."
"SpaceX has demonstrated extraordinary capabilities in its first six cargo resupply missions to the station, and we know they can replicate that success," he continued. "We will work with and support SpaceX to assess what happened, understand the specifics of the failure and correct it to move forward. This is a reminder that spaceflight is an incredible challenge, but we learn from each success and each setback. Today's launch attempt will not deter us from our ambitious human spaceflight program."
Said NASA astronaut Scott Kelly, who watched the launch from the space station: "Space is hard."
Lost were more than 4,300 pounds of food, supplies and spare parts bound for the ISS, and a docking adapter intended to be use by future commercial U.S. crew vehicles in a few years.
SpaceX's Falcon 9 is expected to launch some of those crew missions, and the rocket failure is sure to raise questions about NASA's Commercial Crew Program, which is led from Kennedy Space Center.
In addition to SpaceX, Boeing is also developing the CST-100 capsule to fly atop United Launch Alliance's Atlas V rocket, which has more than 50 successful flights.
The failure also raises questions about how to keep the International Space Station fully staffed and able to continue a normal research schedule.
Currently three astronauts and cosmonauts are living on board, including two who are expected to live there for a full year.
Another three-person crew is scheduled to launch late next month from Kazakhstan in a Russian Soyuz spacecraft.
NASA said before the launch that the station had enough food to last into October without any additional resupply. If SpaceX's Dragon had arrived successfully, it would have extended supplies through the end of the year.
The Falcon 9 failure follows an April failure by a Russian rocket carrying a Progress resupply ship just as it was reaching orbit. Last November, an Orbital Sciences Corp. Antares rocket carrying a Cygnus cargo ship blew up shortly after liftoff from Virginia's Eastern Shore.
The next Progress is scheduled to launch next Friday, and a Japanese resupply ship is expected to fly in August. Orbital is now targeting a November launch of a Cygnus cargo craft on an Atlas V rocket from Cape Canaveral.
Today's countdown had appeared to proceed very smoothly, and the weather was nearly perfect for launch.
The Falcon 9 rocket booster is powered by nine Merlin 1D engines. During one previous launch of a NASA resupply mission the rocket did lose one of its engines, but the Dragon was able to reach orbit and complete its mission.
The Air Force recently certified the Falcon 9 to compete with United Launch Alliance for contracts to launch national security satellites.
NASA said anyone who finds debris from the failed Falcon 9 launch should call 321-867-2121.
Check back here for updates.