A solid-fuel rocket over Jeju and Korea’s space future

Audio report: written by reporters, read by AI

Kim Seung-jo

The author is a professor emeritus at Seoul National University. 

Later this month, a solid-fuel space launch vehicle is expected to rise above the waters south of Jeju Island.

From a floating launch platform in the seas south of Jeju, a plume of fire will shoot skyward as the Agency for Defense Development conducts its fourth test launch of a solid-fuel space rocket. This mission is more than a technical demonstration. It is a significant milestone for Korea’s space program.

The launch will test a full-configuration vehicle integrating solid-propellant stages from the first through third stages. Its mission is to place a 100-kilogram (220-pound) synthetic aperture radar reconnaissance satellite developed by Hanwha Systems into a 500-kilometer (311-mile) sun-synchronous orbit. If successful, Korea will secure a key transportation capability that would allow it to deploy and replenish an independent low-earth-orbit surveillance satellite network around the Korean Peninsula whenever necessary.

The greatest advantage of a solid-fuel rocket is rapid responsiveness. Unlike liquid-fuel rockets, which require complex piping systems and cryogenic fuel loading before launch, solid rockets remain fueled and ready. They can place satellites into orbit within hours or days without revealing extensive launch preparations in advance.

At a time when neighboring powers are increasingly integrating space assets into military strategy, such rapid-launch capability is more than a technological achievement. It serves as a strategic national security tool and a symbol of space sovereignty. The ability to launch satellites on short notice gives a country flexibility in responding to crises and replacing damaged or disabled space assets.

This security logic helps explain why advanced space nations continue to maintain solid-fuel launch vehicles despite recurring criticism over cost and efficiency.

One of the clearest examples is the Epsilon rocket developed by the Japan Aerospace Exploration Agency (JAXA). Although Japan possesses the H3, one of the world’s most advanced large liquid-fuel rockets, it has not abandoned solid-fuel launch systems. Epsilon is closely associated with technologies relevant to long-range missile capabilities and relies heavily on automation. Launch operations can be conducted by relatively small teams using streamlined procedures.

JAXA has long promoted Epsilon as a low-cost launcher, but its strategic significance extends far beyond economics. The rocket’s real value lies in deterrence. It functions as an invisible shield, strengthening Japan’s ability to respond rapidly to security challenges and discouraging potential provocations from neighboring states.

Europe’s Vega program provides another example. Although the newer Vega-C has experienced repeated failures associated with solid-motor control systems, Europe has not abandoned the project. The determination reflects a desire to preserve independent access to space rather than depend entirely on the United States for the launch of security-related assets. Around the world, solid-fuel rockets continue to be maintained not because they are commercially attractive but because they are regarded as strategic national assets.

Korea must nevertheless confront a difficult reality. Military value does not automatically translate into competitiveness in the global commercial space market.

The New Space era is increasingly defined by constellations of hundreds or even thousands of small satellites operating in low-Earth orbit. In this market, solid-fuel rockets face inherent limitations. Japan’s Epsilon costs more than $30 million per launch, resulting in a cost per kilogram that is difficult to justify commercially. Compared to the dramatic cost reductions achieved by reusable launch systems, relying on solid-fuel rockets to build large commercial satellite constellations is economically inefficient.

Environmental concerns are even more serious. China and India have launched substantial numbers of solid-fuel vehicles and large solid upper stages into low-Earth and sun-synchronous orbits. Critics argue that such activities have contributed to growing orbital debris problems. Aluminum powder used to improve combustion efficiency can become aluminum oxide particles and molten aluminum residue after launch. Traveling at orbital velocities of seven to eight kilometers per second, these tiny particles can remain in space and pose hazards to operational satellites.

Commercial spacecraft passing through contaminated orbital regions face continuous exposure to microscopic impacts. Solar panels can deteriorate, optical instruments can erode and thermal control coatings can be damaged. Over time, some orbital paths risk becoming environments in which satellite operations become increasingly difficult and costly.

As Korea enters a more advanced stage of space development, it should avoid repeating the environmental mistakes made by earlier space powers.

The country’s space strategy should therefore adopt a clear two-track approach separating security objectives from industrial and environmental goals. First, the solid-fuel rocket technology being completed through the Jeju sea launch should be further developed as a specialized defense asset capable of protecting national security and rapidly replenishing critical space infrastructure during emergencies.

Second, Korea should concentrate national resources on environmentally sustainable commercial launch systems. If the country hopes to build large satellite networks and become a major space economy, it must invest in large liquid-propellant launch vehicles and reusable systems that can increase launch frequency while minimizing orbital debris.

The solid-fuel rocket expected to illuminate the waters off Jeju this month offers both reassurance and a warning. It strengthens confidence in Korea’s security capabilities while reminding policymakers of their responsibility to pursue space sustainability. Korea must maintain a strong security shield while developing commercial space capabilities based on sound economics and environmental stewardship. Beyond celebrating a successful launch, the country must solve the broader challenge of balancing national defense, commercial growth and protection of the space environment. That balance will define the maturity and direction of Korea’s future space policy.

This article was originally written in Korean and translated by a bilingual reporter with the help of generative AI tools. It was then edited by a native English-speaking editor. All AI-assisted translations are reviewed and refined by our newsroom.