NKorean Rocket Capable of Hitting Half the U.S: Scientists
July 1, 2009
SEOUL, July 1 (Bernama) -- The long-range North Korean rocket, which was launched in April, could be converted into a ballistic missile, that can theoretically hit half the United States with a payload of 1 tonne or more, two U.S. physicists have concluded from their joint study.
Quoting MIT professor Theodore Postol and a physicist at the Union of Concerned Scientists (UCS) David Wright, South Korea's Yonhap news agency reported Wednesday that the rocket could fly even further as of over 10,000 kilometres, if the rocket is turned into a missile.
"The Unha launcher represents a significant advance over North Korea's previous launchers and would have the capability to reach the continental United States with a payload of 1 tonne or more if North Korea modified it for use as a ballistic missile," they said.
"We estimate that it could have a range of 10,000-10,500 kilometers, allowing it to reach Alaska, Hawaii, and roughly half of the lower 48 states," they said in an article posted this week on the Bulletin of the Atomic Scientists, reports Yonhap.
On April 5, North Korea launched what it claims was a rocket designed to carry a satellite into orbit. The U.S. and its allies say nothing entered orbit, calling the "Unha-2" rocket a disguised form of a ballistic missile capable of flying over 6,700 kilometers.
Noting that a "first-generation plutonium warhead could have a mass of 1,000 kilograms or more," Postol and Wright said the rocket could carry a 1-tonne payload as far as 7,000-7,500 kilometers even if it had only two of its three stages.
"This would allow it to reach Alaska and parts of Hawaii, but not the lower 48 states," they said, writing on the assumption that the rocket was designed to carry a lightweight satellite.
"The mass of the satellite plus the deployment mechanism and the structure that attached the satellite to the third stage may have been about 300 kilograms," they said.
Both the scientists based their analysis partly on the video footage of the rocket launch North Korea released in April, adding computer modeling and past analysis also contributed to their study.
"By measuring the distance the launcher moves as a function of time in these videos, we determined the thrust-to-weight ratio of the Unha vehicle at launch.
"Using estimates of the mass of the Unha launcher, we then estimated the thrust at liftoff generated by the engines," they said.
Drawing similarities between the North Korean rocket and the components previously developed by China, Russia and Iran, the physicists concluded that "it's extremely unlikely that these technologies were indigenously produced by North Korea."
"The third stage appears to be very similar, if not identical, to the upper stage of the Iranian Safir-2 launch vehicle, which placed a small satellite in orbit in February," they said.
Therefore, the Unha-2 appears to use a third stage with liquid rather than solid fuel, unlike the Taeopdong-1 launcher, they wrote.
Postol, whose expertise lies in ballistic missile technologies, teaches science, technology and national security policy at MIT. Wright co-directs the Global Security Program at the UCS.