Overcoming bad weather and component defects, the Nuri-ho re-challenge for the second launch

The launch was delayed twice due to strong winds and problems with the first stage oxidizer level sensor
Weather variables still… Rainy rain from Jeju this evening

After two delays last week alone due to weather and technical flaws, the Korean launch vehicle Nuri (KSLV-II) will challenge the second launch from the Naro Space Center in Goheung-gun, Jeollanam-do on the 21st.

The Ministry of Science and ICT (Ministry of Science and Technology) and the Korea Aerospace Research Institute (KAI) held a launch management committee on the 17th and have been preparing for the second launch of Nuri on the 21st.

Accordingly, on the morning of the 20th, the day before the scheduled launch date, the ‘standing operation’ of taking the Nuri out of the assembly building, moving it to the launch pad, and raising it toward the sky is carried out.

On the afternoon of the 20th, the ‘umbilical connection’ to supply power to the Nuri and to charge propellants such as fuel (kerosene) and oxidizer (liquid oxygen), and to identify whether there is a possibility of clogging or leakage during the charging process of the propellant Preparation for launch, such as ‘confidentiality check’, continues.

So far, the second launch schedule of the Nuri has been delayed little by little as it goes through the process, such as supplementing technical problems and taking into account the weather conditions.

When the government started the Nuri-ho development project in March 2010, the government set the goal of securing its own launch vehicle technology to put a 1.5-ton practical satellite into low-Earth orbit (600-800 km).

The project plan included a schedule to launch the launch vehicle twice by 2023, and the Ministry of Science and ICT will hold the National Space Committee in 2020 to conduct the first launch of the Nuri in October 2021 and the second in May 2022. caught

In the first launch on October 21, last year, Nuri succeeded in separating the payload and reaching an altitude of 700 km, but the combustion of the three-stage engine ended sooner than expected, and the target speed was not reached. failed.
As a result of an anti-accident investigation with the Ministry of Science and ICT, it was estimated that the fixed support of the helium tank in the three-stage oxidizer tank was loosened due to a design error that overlooked the fact that the buoyancy increased due to the acceleration of the Nuri during flight.

Reflecting this analysis, the anti-accidental agency reinforced the lower fixing part of the helium tank of the projectile, and accordingly, the scheduled second launch date was pushed back by one month from May 19th to June 15th, which was originally planned.

The pre-launch period was set from June 16 to 23.

However, on the 14th, one day before the scheduled launch date, strong winds blew around the Naro Space Center, and the schedule of moving the Nuri to the launch pad from the assembly building and the launch schedule were delayed by one day.

On the 15th, when the rain and wind subsided and the weather improved, the Nuri was transferred from the assembly building to the launch pad smoothly, but after standing up, an abnormality was detected by the first stage oxidizer tank level sensor.

Immediately after the problem was discovered, there were concerns that the first and second stages of the Nuri may have to be removed altogether and that the launch schedule may have to be postponed again until the fall of this year. way to solve the problem.

The parts used for replacement were originally prepared for use in Nuri 3, which will be launched next year.

Kwon Hyun-joon, director of the Ministry of Science and ICT’s gigantic public research policy, explained at an online briefing on the 17th that “there were no more technical problems found in the first, second, and third stages.”

It is said that Nuriho was fully prepared with repeated supplements, but since it is not known what other variables there will be in the future, the Nuriho officials are not giving up their tension.

The biggest variable that will affect the launch is the weather.

According to the Korea Meteorological Administration, it is expected to rain on the evening of the 20th, starting with the Jeju area, and on the 21st, when the Nuri will be launched, along the southern coast of Jeollanam-do and the southern coast of Gyeongnam, including the Naro Space Center.

Expected precipitation is less than 5 mm.

In an online briefing on the 17th, Koh Jung-hwan, head of the Korean launch vehicle development division, Hang Woo-yeon, said, “I set the launch date by looking at the weather, but I think we should continue to closely monitor the weather.” could be,” he said.

For the Nuri to be launched, lightning must not strike within a 20km radius of the launch pad, and the instantaneous maximum wind speed must be less than 21m/s.

The temperature is suitable between -10 and +35 degrees, and it is advantageous for preparation work such as moving to the launch pad when it does not rain.

/yunhap news