Naro Satellite Destroyed

http://www.koreatimes.co.kr/www/news/tech/2009/08/133_50747.html

GOHEUNG, South Jeolla Province ― Engineers and officials say that the cone of the Korean rocket that contained the satellite opened later than it was supposed to, causing the satellite to miss the designated orbit.

However, they say the exact cause can't be determined until further investigations are carried out.

The initial conclusion acquitted the Russians, the provider of the first-stage rocket and related technologies, of any responsibility in the failed deployment.

Officials are trying to confirm whether an object which fell near Darwin, Australia, was debris from the upper stage of the Korea Space Launch Vehicle 1 rocket, which carried the satellite and was intended to push it into proper position.

In a video session disclosed only to a limited number of reporters Wednesday, the Korea Aerospace Research Institute (KARI), the country's space agency, revealed footage taken from two built-in cameras planted on the KSLV-1 second stage.

The images show that the pair of "nose fairings," a cone which covers and protects the satellite, did not separate properly, with one of the fairings remaining attached 216 seconds after the 5 p.m. launch.

The second fairing fell off only 540 seconds after the launch, which was when the satellite was programmed to separate itself from the second-stage of the rocket.

The fairings weighed 300 kilograms each, compared to the 100-kilogram satellite. The extra 300 kilograms was enough to prevent the second-stage of the rocket from achieving the desired speed, causing the satellite to miss its planned position, KARI officials said.

Data indicates that the second-stage and satellite crashed back to Earth, with most of the debris likely to have burned up in the atmosphere.

However, heat-resistant materials made from carbon-carbon composites, which were used to protect the nozzle of the second-stage rocket engine, would have survived the crash, KARI officials said. This may explain the space junk that landed near Darwin.

A team of engineers from KARI and Russia's Khrunichev State Space Science and Production Center, which provided technology for the Korean rocket project, has yet to confirm what caused the rocket malfunction.

KARI refused to release the images publically, citing confidentially issues.

"The second-stage tumbled back to Earth, and the satellite soon followed, as the remaining fairing was heavy enough to prevent the rocket from achieving desired speed and pushing the satellite to a speed faster than 8 kilometers per second that was required for the spacecraft to remain in orbit," Park Jeong-joo, who heads KARI's KSLV systems unit, said.

"The second fairing stayed until the satellite separated from the second stage. The satellite likely knocked off the fairing in the process," he said.

KARI officials are reluctant to get deep into a guessing game over what prevented the fairings from separating properly, but Tahk Min-jae, a KAIST rocket scientist who worked as an advisor for the KSLV-1 project, says the problem is likely related to the set of explosives used to break the fairings from the rocket.

The KSLV-1 second-stage uses an "explosive bolt" technique whereby a dozen or more bolts stitching the fairings with the rocket are ignited and popped, he said.

There were eight bolts circled around the bottom of the fairings, the part that is attached to the rocket, Tahk said. Four other bolts, probably more, are positioned to cut the fairings in half.

He pointed out that a misfire on just one or two of the explosive bolts would be enough to keep the fairing attached to the rocket, disrupting the whole plan.

The explosive bolts were produced by Hanwha, a Korean conglomerate involved in explosives among many other business areas, based on KARI design.

"The separation of fairings account for nearly 10 percent of failed space missions. There could be a lot of problems, including turbulence or electricity malfunction, but I think that this is likely to be a case of the explosives misfiring," Tahk said.

The 13.6-billion-won (about $10.8 million) satellite, jointly developed by the Korea Advanced Institute of Science and Technology (KAIST) and the Gwangju Institute of Science and Technology (GIST), was expected to have a space life of two years and be used to observe the Earth's radiant energy and satellite orbits.

The satellite was programmed to send back signals to a Korea Advanced Institute of Science and Technology (KAIST) research center in Daejeon starting early Wednesday. It did not send any signal.

Lee Sang-mok, who heads the science and technology policy department at the Ministry of Education, Science and Technology, said the government will cooperate with local authorities to identify the debris found in Darwin, after being first informed by the Korean embassy in Australia late Tuesday.