[Solving Science Story] Everything about Nuri Lake 2nd launch

On the 15th, the Korean-style launch vehicle Nuri will be in the second space challenge at the Goheung Naroju Center in Jeonnam. The goal is to verify the process of entering space and putting satellites into orbit.

It is noteworthy that it will be able to successfully secure projectile technology after failing the pain that failed at the final stage of the target of the target after arriving in the first launch in October 2021.

The main contents of Nuri's second launch were composed of question and answer.

■ Nuri, no failure twice

Q. Wait, what was Nuri?

A. The Korean-style launch-ya who started development in 2010. In other words, it's a rocket. The goal is to develop a projectile that carries a 1.5-ton-class satellite and flies into space and puts it in a low-level 600-800 km district. Korea also has its own space projectile technology.

Q. I think I saw it in the news that I was 'Danuri' these days?

A. Danuri is a moon probe, Nuri is a projectile. Danuri is a spaceship that observes the moon with various exploration equipment around the moon orbit. On August 3, in the United States, he will be carried on space on SpaceX's Falcon 9 rocket and go into the moon orbit.

Nuri is a Palcon 9, and the satellite in Nuri is Danuri. Nuri is part of an effort to make things like Palcon 9. Yes, I want to stop using the name 'Nuri'.

Q. Nuri, I fired it a while ago, but it wasn't good?

A. I launched the first launch on October 21, 2021. At that time, I fired only satellite simulation. After the launched rocket flies and separates the 1st and 2nd stage, the three-stage engine reaches 700 km, which is the target altitude, where the satellite mimics should be separated to confirm the satellite mimics into the track.

The goal has climbed, but the three-stage engine combustion ended earlier than scheduled, so I couldn't put the satellite simulation on the track. It failed in the last stage.

Q. Why is it so?

A. I think there was a structural problem in the oxidant tank. Nuri uses liquid fuel. I need an oxidative agent that lit liquid fuel. The total weight of Nuri is 200 tons, of which 126 tons are oxidants.

There is a helium tank inside the oxidant tank. When the oxidizer is supplied to the engine, the pressure in the oxidant tank is reduced. Helium supplements the pressure so that the oxidant is well supplied to the engine.

But the support that holds this helium tank has been released. The helium tank moved around in the oxidant tank, causing problems with the pipe, and cracked in the oxidant tank.

The oxidant leaks, so there's a problem with fuel supply. The three-tier rocket was planned to burn for 521 seconds and put the satellite simulation on track, but it only burned 475 seconds. So, as the speed drops, it is dragged by the gravity of the earth.

Q. Why did the helium tank support loose?

A. When the rocket speeds up, the buoyancy increases as the acceleration increases during the flight. But I couldn't reflect that in the design. So the helium tank support could not afford the buoyancy that was large.

■ Preparation is over, scheduled for launch 4 pm on the 15th

Q. Will it be good this time?

A. The Korea Aerospace Research Institute reinforces the design. The lower part of the helium tank and reinforced the government, and the cover of the oxidant tank thickened. So the weight was increased by 9kg, and the firing performance did not affect Jang Young-soon.

Q. What is the difference between this second launch?

A. This time, it fires with the actual performance verification satellite as well as the satellite simulation. It is equipped with satellites made by our hands on a projectile made by our hands.

Put the performance verification satellite to the track, and there are four small cube satellites from this satellite. Performance verification satellite was created by a company called AP satellite, and cube satellites were made by Chosun University, KAIST, Seoul National University, and Yonsei University.

Q. There are several satellites.

A. The cube satellite created by universities is a small satellite of about 10cm wide and about 1 kg. For six months to one year, I observe the earth's atmosphere or monitor fine dust.

Performance verification satellite is a six-shape, which is a little less than 1m in height, and weighs 162.5 kg. It is equipped with a heating battery that can be used as a power source in space, an S band antenna and a cube satellite launcher that exchanges commands with the control center. The biggest task is to verify that the projectile can properly put the satellite into the track.

Q. Are you firing while counting down on the 15th?

A. Yes. The assembly and inspection are all over. On the 14th, the day before launch, we will move the projectile to the second launch in the Naroju Center in Goheung, Goheung, Jeollanam-do. And connect 'Um Village', which supplies fuel, oxidizer, and electricity to the projectile on the ground.

On the 15th, on the 15th, the electronic equipment that controls the projectile and the system 'Evonix', and charges liquid fuel, oxidizer, and helium. The standing device is not withdrawn.

Ten minutes before the launch, automatic launch of launch, which automatically continues to be ready for launch by the system, starts, and when the first-stage engine thrust reaches 300 tons, the projectile is shipped and the projectile is shipped. If there is no other variable, it will proceed in this order.

Q. Is it okay to rain?

A. The projectile itself is not a problem because it is thoroughly waterproof. However, there is a problem in transferring the projectile and connecting or working on various equipment. If it rains a lot, I'll review the launch.

In addition, weather conditions such as the customs and the space environment also affect the launch on the day of launch. If the average wind speed exceeds 15m/s, it becomes difficult to transfer or install. You have to be careful with lightning. You shouldn't collide with other objects in space, so the projectile entered the track and adjusted it to at least 200 km away from other manned spacecraft during the first cycle.

It is unlikely that there is a problem with the launch because of the launch schedule in consideration of these problems as much as possible. The preliminary schedule is scheduled for about a week from the 15th.

Q. What will happen after launching Nuri?

A. After 127 seconds of launch, the first rocket is separated at 59km altitude, and the pairing is separated at 191km high after 233 seconds, and the two-stage rocket is separated at 258 km after 274 seconds.

After 897 seconds, the performance verification satellite is separated at 700 km altitude, and after 967 seconds the satellite simulation is separated. It's about 15 minutes after the launch, and all of this should be finished, and it will take about 30 minutes to accurately check the satellite separation.

After 11 hours of launch, you can see if you have completely settled in the track by communicating with satellites in the main ground in Daejeon the next day.

Q. If it fails?

A. If it fails, the third launch will be decided by consultation with related agencies. It is likely that the first launch of the Korean-style projectile advancement project will be the third launch of Nuri.

■ Self space transport-We will secure space exploration capabilities

Q. Do you think there is a follow-up development project?

A. After the launch of the Nuri Lake twice, the Korean projectile development project is finished. And by 2027, the Korean projectile advancement project continued. The goal is to increase the technology reliability by firing more than four satellites by repeating more than four times. Since 2026, I have been carrying five satellites to one projectile.

Q. Don't you have to recycle rocket like SpaceX?

A. The next-generation projectile development project is now undergoing a preliminary feasibility study. We can develop thrust so that moon landers and large satellites can be carried out, and we are also trying to develop solid booster technology in preparation for reusable projectile conversion.

I can turn it off and turn on the engine several times, and I plan to control my thrust. This is the foundation technology for recycling rocket recycling once.

The projectile structure is now changed from three to two stages, and the first-stage engine has changed from 4 to 100 ton of liquid engine. It can also be equipped with 10 tons of large cargo and multipurpose satellites.

If this project is successful, Korea will have its own space transport and space exploration ability. We plan to invest KRW 1.93 trillion, similar to the Nuri business.