hankyoreh

By Lee Geun-young, science correspondent

The scheduled Oct. 26 launch of South Korea’s Naro rocket was delayed after a problem was found with the first stage rocket. Attention is now focusing on finding the root of the problems and coming up with a revised timeline for the postponed launch.

The delay has been attributed to a leak in the connection between the first stage rocket and the launch pad, or CD-2, inlet of helium gas. The cause of the leak and why it wasn’t found during preparations held the previous day are still unknown, which is a source of great curiosity for those who closely monitored the launch.

Analysis of component damage can be a drawn out process

The Ministry of Education, Science and Technology (MEST) and the Korea Aerospace Research Institute were scheduled to announce the final launch time after convening the third launch committee for the rocket in the morning. The first meeting was held at 10 a.m., and the Korean and Russian technical staff had been preparing for the launch since 7:30 that morning by injecting helium into the craft as the Korean and Russian flight test committee judged that the launch would be possible based on various data and analysis collected during tests. Helium was injected to turn on the various valves and equipment inside the rocket that operate under gas pressure

At approximately 10am, technical staff at the Mission Control Center found that the helium pressure figures on the dashboard had not risen sufficiently, so they carried out a naked-eye inspection of the launcher and found gas leakage caused by a part of the seal protruding from a connecting region. The seal, a ring-shaped component, made from rubber, serves to stop gas leaks from the connecting pipe. The management committee for the Naro space rocket suspended the launch procedure right away. It is reportedly quite rare for rocket launches to be delayed due to damage to gas inlet seals.　

Yoon Woong-sup, a professor of mechanical engineering at Yonsei University, said, “Unlike in automobiles where the seal is closed after the injection of gasoline, rockets are designed to function so that fuel is injected until the very moment of launch and the inlet then separates as the launcher lifts off. First we have to lay the rocket on its side to remove all the helium and nitrogen to get at the cause, and if problems are found inside the inlet, we have to dissemble the rocket, so restoration is still a long way off.”

Cho Kwang-rae, the head of the Korea Aerospace Research Institute’s satellite launch project said, “No problems with the components were discovered throughout many repeated tests. The problem can be simply resolved by the replacement of the seal but if the cause of the breakage cannot be ascertained, considerable time will be needed.”

Some wondered if problems might have arose in the process of converting the engine (RD-191, with 200 tons of thrust), which was originally designed for Russia’s next-generation rocket the “Angara,” into a mini-size configuration used for the Naro rocket (RD-151, with 170 tons of thrust). However, Prof. Yoon said, “The problem was not related to rocket engine itself, so it is more than likely that the problem was related to materials of parts or structure, and not to its design.”

A launch by Oct. 31 is uncertain. Even if the cause of damaged seal is uncovered quickly, it looks as though it will not be easy to reattempt the launch by Oct. 31, the last day of the launch window that the Korea Aerospace Research Institute requested with international bodies.

Late afternoon on Oct. 26, the Korean and Russian technology team moved the rocket to the vehicle assembly building and dissembled the connection areas for examination. Roh Kyung-won, Director General of Space & Nuclear Technology of the Ministry of Education, Science and Technology said, “If the cause is uncovered early, the flight test committee can meet on Saturday, but the management committee for the Naro rocket will be held on Oct. 28 at the earliest.” After that, another two days will be needed for transportation and standing of the launcher and rehearsal.

If the launch is impossible this time, at least one week will be needed for another trial as South Korea has to convey the new launch date to the International Civil Aviation Organization and the International Maritime Organization.

Please direct questions or comments to [englishhani@hani.co.kr]