North Korean scientists are scrambling to find out what caused their much-hyped long-range rocket to crash into the sea shortly after it was launched on Friday, causing a public embarrassment for the new leadership of Kim Jong Un.

North Korea's state television acknowledged that the three-stage Unha-3 rocket disintegrated barely a minute into its flight, falling harmlessly into the Yellow Sea off the South Korean coast.

While Pyongyang has provided no explanation about what went wrong, the U.S. Northern Command, which was closely monitoring the launch, said the final two stages of the rocket appeared to have failed, sending the missile plummeting to the water.

Morris Jones, an independent space analyst who follows Asian rocket programs, tells VOA the failure seems to have happened when the first stage of the rocket was attempting to separate from the final two stages.

“It seems to me that the most likely explanation is that something went wrong when they were trying to separate the first stage from the second stage of the rocket. The first stage seems to have worked pretty well, otherwise the rocket wouldn't have been able to travel as far as it did.”

Japanese officials, who were on high alert because of the potential of falling debris, said the rocket was in the air for about a minute, reaching up to 120 kilometers in the sky, before splitting into four pieces.

Jones says if those figures are true, then the rocket technically did reach “outer space.” But he says the first stage of the rocket apparently did not provide it with enough momentum to successfully enter orbit.

“This was a suborbital trajectory, and it appears that when it did reach its highest point, it was not under powered flight, it was simply travelling with the momentum it had before the first stage disengaged.”

South Korean defense officials say they are currently searching for the debris of the rocket, which landed approximately 165 kilometers off the coast of Seoul. Jones says it is likely that the U.S. will also send submarines to retrieve parts of the rocket.

North Korea's previous attempts to launch satellites in 1998 and 2009 are widely regarded to have failed. Its last attempt lasted only 40 seconds after liftoff.

But North Korea insists that it has successfully launched at least one satellite into orbit, and that it is broadcasting patriotic songs.

Jones says he was a “bit surprised” that North Korea admitted the failure of the latest attempt, considering the unflinching patriotism of North Korea's propaganda machine.

But still, he says, the unsuccessful launch is a considerable setback for North Korea's missile program and a huge embarrassment for Kim Jong Un.

“It's definitely a major step back, and it's yet another attempt they've made to launch a satellite in a very high profile way. It's the third satellite that has failed for them…at least this time they have admitted that the launch was a failure.”

Jones says North Korea may have felt pressure to acknowledge the failure of the mission partly because of the large and unprecedented presence of foreign press that were invited to witness the event firsthand.