November 28, 2013 12:23
In his book "Physics for Future Presidents," Richard Muller, professor of physics at the University of California, Berkeley, described rockets as one of the "most ignorant" ways to travel to space. Muller says rockets waste 96 percent of the energy they gain from burning fuel. In the case of South Korea's first-ever space rocket, the combined weight of fuel and oxidizing agents account for 120 tons out of the vehicle's entire 140 ton weight.
Most of the energy produced by the fuel and oxidizing agents is expended to carry their weight. This is simply inefficient.
It takes a lot of fuel for a rocket to gain enough thrust to fly into space. But due to the weight of the fuel, it needs to carry even more fuel. This led to the design of multiple-stage rockets, which reduce weight in stages by shedding their carriages once their fuel has been expended. Most of the energy is still wasted, but there is enough thrust to propel the rocket into orbit.
South Korea's first space launch vehicle Naro was a two-stage rocket. North Korea's, which was launched late last year, was a three-stage rocket. The Lamda 4S that Japan launched in 1970 was a four-stage rocket. The stronger the booster, the shorter a rocket can be.
The Naro's booster has a 170-ton thrust, while the North Korean rocket's had a 120-ton thrust. But unlike North Korea, South Korea had to rely on Russia to provide the booster rocket, which is the most important part. This is why the South is considered to be 10 years behind the North in terms of rocket technology.
The government now says it wants to launch a space rocket with a homegrown booster in 2020, a year earlier than originally planned. It also vowed to send a landing craft to the moon as well as put a satellite into orbit.
The rocket will have a booster with a 300-ton thrust, which is stronger than the Naro, but that will have to be made into three stages to reach the moon. If all goes as planned, South Korea would significantly narrow the technology gap with North Korea.
But this will not be easy. China, Japan, Russia and the U.S., which boast advanced space exploration technology, spent decades of trial and error reaching that level. Rockets exploded and people were killed, but they were able to press ahead with their space ambitions because of unwavering public support, strong determination of their leaders and government-wide backing.
Space development requires more than just good scientists. It requires unified public support borne of a clear vision of the need for space development from technological, economic and national security standpoints.
By Chosun Ilbo columnist Kim Ki-cheon
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