By Kim Tong-hyungAfter a half-century of conflict, South Koreans find they have fewer and fewer things in common with their North Korean neighbors. But one unique feature shared by both nations is the talent to build rockets that blow up prematurely.South Korean rocket scientists had anticipated North Korea’s rocket launch with equal concern and curiosity. After North Korea’s state media confirmed the country’s latest setback in its vaunted attempts to launch a satellite into orbit, which many believe is a cover for its efforts to strengthen its long-range missile capabilities, experts here offered differing opinions about the level of skills displayed by engineers in Pyongyang.Whether the intention is to boost its long-range weaponry or jump into the Asian space race, North Korea has clearly hit a wall in the advancement of its rocket technology, according to most scientists here.The Unha-3 (Milky Way 3), which exploded shortly after take-off from northwest North Korea Friday, seems essentially a variation of the Taepodong-2 missile launched in 2006.Kim Seung-jo, a leading rocket scientist and president of the Korea Aerospace Research Institute (KARI), South Korea’s space agency, believes that North Korea is relying on technology used by the Russians and Americans in the late-1950s or early-1960s.``Reports say the rocket broke up after just a minute or so. This means that there was a malfunction in the liquid-fuel first-stage of the rocket,’’ Kim said in a telephone conversation.``It’s clear that North Korea’s liquid-fueled rocket is not as stable as those used by nations with more advanced space technologies. So while North Korean engineers are reading the trends in rocket technology, they still don’t seem to have the sophistication to tighten the loose ends and execute the process properly.’’South Korea’s track record in rockets isn’t something to brag about either. It’s been nearly two years since the Korea Space Launch Vehicle-1 (KSLV-1) exploded moments after take-off and spun the South’s aspirations to join the space-launch industry further out of orbit.And that represented the country’s second major space setback in the span of less than a year, triggering a verbal dispute between KARI and its Russian technology providers over who’s to blame and who must pay for a potential third launch.``As a scientist, I was curious about this launch, as South Korea has yet to develop its own liquid-fuel rocket engine. Since Unha-3 was a failure, I would say I am a little less interested,’’ laughed Kim.The last time the North conducted a rocket launch was in 2009. On that occasion, U.S. and South Korean analysts said the rocket failed to reach orbit, while Pyongyang announced it a success.Tak Min-jae, an aerospace scientist at the Korea Advanced Institute of Science and Technology (KAIST), suspects that the North is developing its current rockets based on the Chinese three-stage models used in the 1970s.These rockets were built around a massive first stage with four liquid-fuel engines, an additional liquid-fuel engine in the second stage, and a payload-controlling third-stage that was powered by either liquid or solid fuel.``I wouldn’t say North Korea’s rocket technology is good, but it isn’t something to laugh about either. Failures happen but it was apparent that the second and third stages of the rocket separated properly in the launch in 2009,’’ said Tak.August 1998: Test-fires Taepodong-1 over Japan as part of failed satellite launch April 5, 2009: North Korea launches long-range rocket which flies over Japan and lands in the Pacific, in what it says is an attempt to put a satellite into orbit.Feb 18, 2011: Satellite images show the North has completed a launch tower at its new west coast missile base at Tongchang-ri, experts say.May 15, 2011: North Korea and Iran are suspected of sharing ballistic missile technology.March 16, 2012: North Korea announces it will launch a long-range rocket between April 12-16 to put a satellite into orbit.April 13, 2012: Rocket is launched from the Tongchang-ri base and appears to have disintegrated soon after blastoff and fallen into the ocean, South Korean authorities said.