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Staff Reporter
Engineers and officials are still not sure what caused the nation's Korea Space Launch Vehicle (KSLV-1) rocket to fail to deliver its payload satellite into orbit on its maiden flight last August.
The KSLV-1 achieved the desired speed and altitude during its Aug. 25 launch from the Naro Space Center in South Jeolla Province, but failed to properly unload the Science and Technology Satellite No. 1 (STSAT-1).
The spacecraft is believed to have burned up in the atmosphere as it crashed back to Earth.
An independent panel, led by Korea Advanced Institute of Science and Technology (KAIST) aerospace expert Lee In, narrowed the possibilities to either electrical problems or a mechanical flaw in announcing the final results of their investigation into the rocket failure, Monday.
The Russian-made KSLV-1 was the country's first launch from the brand new Naro spaceport. Russia's Khrunichev State Research and Production Space Center, which is providing the technology for the KSLV-1 project, is contracted for at least one more launch, which is likely to be scheduled around late May or June.
Shortly after the first launch, the Korea Aerospace Research Institute (KARI), the country's space agency, said that the KSLV-1's failure to deliver the satellite into orbit was because one of the fairings, the part of the rocket that protects the satellite during the ascent, didn't separate properly.
The pair of fairings was designed to be broken off by a set of explosives connected to the bolts that attached them to the launcher.
However, one of the fairings somehow remained attached 216 seconds after liftoff, when the explosives were timed to go off.
The remaining fairing was attached to the launcher until 540 seconds after liftoff, and was likely knocked off by the satellite as it ejected.
In a news conference at the Ministry of Education, Science and Technology, Lee said it was plausible that an electrical discharge prevented a section of the explosive bolts from going off properly.
He downplayed the possibility that there was anything wrong with the explosives themselves.
``The data achieved from our simulation tests on the ground prove that a difference in the size of electrical discharge could prevent one of the fairings from separating by cutting off the electrical current that was supposed to ignite the explosives. The other part, where the level of discharge wasn't as powerful, may have gotten just enough of a jolt to have the ignited the explosives,'' Lee said.
``The flaw in the wiring of the fairing separation drive unit (FSDU) may have caused the discharge. Another possibility is that a flaw in the mechanical structure may have jammed the `near' fairing and prevented it from separating from the launcher, despite the explosives going off on time.''
Lee, who said the Khrunichev Center didn't have any objections to the findings, admitted that a lack of data made it hard to pinpoint the cause of the failure.
``Right now, we have no data to tell us for sure whether the explosives went off normally after 216 seconds or if a part of them did or did not go off after 540 seconds. Our only clues are the flight vibration data at the 240-second and 540-second marks,'' Lee said.
``There was a distinct difference in vibration between 540 seconds and 540.8 seconds, and this backs up the theory that the remaining fairing collided with the ejecting satellite.''
Cho Gwang-rae, a senior researcher of rocket development at KARI, said the agency is working to improve the design of KSLV-1's KARI-built second-stage, the part of the rocket that holds the satellite, re-examining the wiring and mechanical structures to prevent the problem from reoccurring.
The Khrunichev Center is expected to deliver the first-stage of the KSLV-1, which includes the rocket engine and liquid-fuel propulsion system, to Korea between March and April.
Korea spent 502.5 billion won (about $428.5 million) to develop the 140 ton rocket that stands 33 meters tall with a diameter of 2.9 meters.
thkim@koreatimes.co.kr
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