Liquid-propellant rockets offer more efficient and controllable alternatives, but solid rockets are used in military armament or as light launch vehicles because of their simplicity and reliability. Rockets using solid fuel are more economical to place small satellites weighing less than 500 kilograms in low orbit. South Korea's mid-term goal is to put a lot of small low-orbit satellites into orbit.
The Agency for Defense Development (ADD), a state-run defense technology research body, successfully conducted the combustion test of a solid propulsion engine on July 29, the Defense Ministry and the Ministry of Science and ICT said in a joint statement on September 16, adding the test would strengthen South Korea's defense space power by securing key technologies for solid space launch vehicles.
Technology related to a solid propulsion engine and the scheduled launch of a space rocket installed with home-grown liquid fuel engines in October will be transferred to the private sector, the two ministries said, referring to the Korea Space Launch Vehicle-2 (KSLV-2), known as "Nuri" capable of deploying 1.5-ton satellites into 600 to 800 kilometers (497 miles) of orbit. Nuri's first stage uses a cluster of four 75-ton liquid engines.
In early September, the Defense Acquisition Program Administration (DAPA) controlled by the defense ministry, disclosed a project to establish a fleet of ultra-small spy satellites that would be used to quickly detect asymmetric threats from North Korea's nuclear weapons and missiles. The combination of a military reconnaissance satellite and ultra-small spy satellites would help South Korea enhance its early warning capabilities and quickly monitor signs of provocations.