Nose fairing malfunction caused S. Korea`s first rocket launch mishap: experts

(ATTN: UPDATES with more details, comments throughout)
By Lee Joon-seung
SEOUL, Nov. 5 (Yonhap) -- The partial failure of South Korea's first rocket
launch earlier this year was caused by problems in the nose fairing assembly, an
independent panel of experts said Thursday.
The seven-person civilian panel said it had reviewed all data collected during
the launch of the 140-ton Korea Space Launch Vehicle-1 (KSLV-1) on Aug. 25 and
confirmed that other systems on the rocket, like the separation of the first and
second stage rockets and ignition of the kick-motor booster, functioned normally.
The KSLV-1, also called Naro-1, is a two-stage rocket jointly developed with
Russia and designed to place a 100kg scientific satellite into low Earth orbit.
The rocket lifted off successfully from the Naro Space Center 485km south of
Seoul, but the satellite did not gain proper orbital velocity which caused it to
fall back to the Earth shortly after takeoff.
"Failure to place the scientific satellite into orbit was caused by 'abnormal'
separation of one fairing cover," said Lee In, an aerospace engineering professor
at Korea Advanced Institute of Science and Technology (KAIST) who headed the
probe.
The expert said that detailed analysis of possible causes and land-based tests
raised two possibilities for the failure.
"In the first scenario, the explosives used to separate the two nose fairings
from the rocket exploded on time at 216 seconds after blastoff, yet unexplained
mechanical problems caused one fairing to stay attached for another 324 seconds,"
he said.
"Another possibility involves only one of the explosive charges going off on
time, while the second detonated 540 seconds into the flight almost at the same
time that the satellite separated from the rocket," the KAIST expert said.
He hinted that judging by various telemetry information checked by engineers so
far, the second case may have actually occurred, although it is impossible to
tell for certain.
"There was a slight rise in temperature and release of unidentified debris that
is consistent with an explosion just as the satellite separated from the second
stage rocket," the aerospace professor said.
He said that because the second stage booster had no "thrust vector control" at
this time and was tumbling out of control, there is a chance that part of the
rocket may have hit the satellite as it was being released.
Lee, however, said that even if there was a collision, the satellite was already
doomed because its overall speed had slowed to around 6.4km per second by this
time, instead of the 8km that must be maintained to keep it in orbit. The
satellite had also reached an altitude of 370km from Earth which is higher than
the 302km that was planned.
The KAIST professor said that the panel will conduct more simulations to mimic
conditions of the actual launch to determine the exact reason for the fairing
malfunction. The simulation is planned for late November and will be attended by
Russian engineers from the Khrunichev State Research and Production Space Center
"Every effort will be made to find the exact cause by year's end, so
recommendations can be made for remedial actions," he said.
The report by the panel supports the initial assessment of a fairing malfunction
made by the state-run Korea Aerospace Research Institute (KARI) the day after the
launch.
KARI is responsible for the Naro-1 project and worked with Khrunichev to make the
two-stage rocket.
The first stage rocket was made in Russia with the second stage, including the
fairing assembly and the satellite, being manufactured in South Korea.
The government, meanwhile, said that it is examining the findings made by the
independent panel and any recommendations made so as to prevent a recurrence of
the mishap.
"All information provided by the expert panel and the separate South
Korean-Russian review board will be checked and reflected prior to the second
Naro-1 launch," said Moon Hai-joo, the chief coordinator of the launch at the
Ministry of Education, Science and Technology.
He said that while the second launch was originally scheduled for May, there is a
chance of a slight delay of about a month.
"We expect the blastoff to occur in the first half of 2010," he said.
yonngong@yna.co.kr
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