● Shouldn't the satellite be mounted on the'test projectile' already developed? "Developing a small projectile"

On May 30th of this year, Space X in the United States was the first private projectile (rocket) company to succeed in carrying people to space. It was a historic moment that opened the door to civilian space travel. Compared to this, Korea has yet to send a satellite or an object to the universe with its own technology. We are looking forward to realizing that dream with the'Nuriho', a Korean three-stage projectile that is still under development.

However, on November 28, 2018, our country succeeded in sending out my'test projectile' by removing only the second stage of Nuri, a three-stage launch vehicle. It has been confirmed that the Nuri's core technology, the 75-ton engine, works normally. If so, wouldn't it be possible to send a satellite into a small rocket (projectile) made of this 75-ton engine? In fact, Hwang started developing a small projectile with a 75-ton engine as its main engine.

● Small satellite demand surges… You also need a

small projectile Why build a small projectile? The most fundamental reason is the growing demand for small satellites. Small satellites are relatively light satellites weighing less than 500kg. The Korean satellite'Cheonrian 2B' launched this year is a large satellite weighing 3.5 tons.

From 1998 to 2018, 1,860 satellites were launched worldwide. Of these, 48% were small satellites under 500kg. However, in 2018, the proportion of small satellites is increasing, with 69.2% being small satellites. Among the small satellites, there are very small satellites weighing less than 10kg, and there are statistics that 58% of small satellites are less than 10kg.

In recent years, the performance of cameras (mounted vehicles) mounted on satellites has been greatly improved, and even these small satellites have been able to obtain high-resolution images, such as identifying buildings and vehicles. In fact, Planet Labs in the United States is providing a service that provides pictures from all over the Earth through a small satellite. Utilization increased, so demand increased.

The demand for small satellites is increasing, but the problem is that there are fewer launch opportunities. Currently, small satellites are'floated' when a large projectile sends a'large satellite' into space. As a result, it is necessary to meet the launch schedule of a large satellite and it is difficult to launch on a desired date. In particular, small satellites often have a short life expectancy of about 3 years, and they often need to be launched and replaced due to frequent breakdowns. Of course, only small satellites are fired, but in some cases, it is difficult to tune a certain number among satellite companies when more than 100 aircraft are carried on a single projectile.

Therefore, in order to increase the chance of launching, there is an active movement to make small projectiles at all. Rocket Lab, an American projectile company founded in 2006, has already secured technology for small projectiles, and has recently been developing a projectile that aims to launch a rocket once a week.

● Blocked by Japanese soil… 3 t Engine should also develop

as I said earlier our country has already succeeded to launch a projectile utilizing 75 tons engine. Since the main engine of the small projectile was secured, the 75 ton engine was secured, and the 7 ton engine to be installed in the first stage carrying the satellite was also developed.

But there was another big challenge. When you shoot a rocket, the satellite stays in space, but the rest of the rocket's body and propellant fall into the sea. Since our country has China and Russia in the north and Japan in the east, the rocket will only shoot about 10° to the south. However, when a 7-ton engine was tied to a 75-ton engine to make a projectile, the projectile's debris was calculated to fall on Okinawa, Japan.

For this reason, we need to put more fuel into the first-stage projectile so that the projectile debris falls into the ocean farther than Okinawa. Therefore, we decided to make the first stage of the rocket longer for more fuel, and reduce the top two stage as the first stage became heavy.

So we have to develop a small engine that we haven't created yet. This is the reason why Hyeon-yeon recently wants to develop a new 3-ton small engine. Unfortunately, because of its geopolitical location, it is impossible to use a 7-ton engine that has already been created and to develop another engine.

● 1,900 billion won for development of Nuri Lake… There

are some mountains to overcome, not only technical problems, but also to develop small projectiles by actively utilizing the technology . Basically, a small projectile has lower transportation efficiency than a large projectile. The transportation cost of a large rocket carrying 1kg in space has dropped to the level of 3.6 million won (based on Falcon 9). Because the small projectile itself is small and inexpensive, you can shoot it often, but the actual cost-effectiveness is falling. Even at such cost inefficiencies, it seems to be necessary to analyze whether a small projectile can be commercially successful.

However, as the space industry expands to the extent that even civilian space travel is possible, small projectiles have unlimited possibilities. You can also consider the business of urgently supplying materials to space as well as satellites. For example, it may be possible to supply supplies such as parts of a spacecraft or food from a space station, and even supplying fuel for a spacecraft like air refueling. In a word, let's jump into the'space gas station' and'space delivery' business. Of course, it's all a dream story, but it's not impossible.

Our country spent 1.91 trillion won in developing Nuri Lake. It's a waste of money to end with a one-time event only. As the development cost is considerable, the technology secured must be actively reused. As it is possible to develop a small projectile using the 75-ton engine technology created during the development of the Nuri, it is time to discuss in depth the commerciality and utilization of the small projectile.