Space System Research Lab of Korea Aerospace University
Space System Research Lab of Korea Aerospace University
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  • 승인 2007.10.11 15:36
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This year marks the 50th anniversary of Sputnik 1, the world's first artificial satellite, which was launched on October 4, 1957. Sputnik 1 weighed 85kg. Equipped with a wireless antenna, the satellite was barely capable of sending a simple signal to Earth.

Since then, humanity has launched a countless number of satellites that cover the vicinity of the Earth. Until the early 1960s, most satellites were quite small in size due to the limitations of rockets. As rocket performance drastically increased, larger satellites such as geo-stationary orbit communication satellites started to fill up the sky. In the 1990s advancements in miniaturization and weight reduction technologies such as nanoelectro technology and nano-manufacturing technology, has been great. In recent years micro-size machines that can perform amazing tasks such as a micro-robot the size of a fingernail that can take pictures inside a human body and perform surgery, cell phones the size of a credit card, and a mini TV screen that can be attached to a pair of glasses have been developed. This kind of miniaturization and weight reduction trend can also be seen in satellite development.

Currently, many countries world wide are paying much attention to the development of small satellites that can drastically reduce cost and shorten development time. Korea is seen as being self sufficient in developing small satellites, with the international recognition of certain precision machine and electronic component technologies. Although Korea has entered space development at a later stage, it is expected that this country can still have a competitive edge due to the fact that the field of small satellites has projects of a lower cost and shorter timeline compared to medium or large satellites.

In particular, the Space System Research Lab of Korea Aerospace University has developed a 1kg class satellite named Hannuri-1 which was launched in July of last year. Unfortunately, the satellite did not enter orbit due to launch vehicle failure, but it clearly demonstrated the advanced level of small satellite technology.

The Korea IT Times visited Professor Chang for an interview at the Space System Research Lab where a 20kg-class follow-up nano-satellite Hannuri-2 is under development, following the unfortunate launch failure of Hannuri-1.

Space System Research Laboratory (SSRL) of Korea Aerospace University, led by Professor Chang Young-keun, is researching and developing an integrated system engineering technology through nano-satellite system development, such as the Hannuri-2 nanosatellite, under the funding from National Research Lab program since 2003. Professor Chang Young-keun, the project manager, graduated from Korea Aerospace University in 1981, received a Mechanical Engineering Master's Degree from Seoul National University in 1983, and was conferred a PhD in Aerospace Engineering at University of Tennessee-Knoxville in 1991. As a national satellite expert, he concurrently holds office as a professor in the Department of Aerospace Engineering at Korea Aerospace University and Director of the Space R&D Program of the Korea Science and Engineering Foundation.

Definition of ultra-small satellite

Satellites weighing less than 500kg are generally called small satellites. This group is further divided into mini-satellites (100- 500kg), micro-satellites (around 100kg), nano-satellites(around 10kg), and pico-satellites (around 1kg). Sometimes micro, nano, and pico-satellites are categorized as ultrasmall satellites. Therefore, one key element of ultra-small satellites is their small size, and the utility value and technological effectiveness compared to the size is the core strength of these small satellites.

The paradigm for satellite development is shifting from developing and operating one large satellite to operating multiple small satellites that are much more advantageous from the system reliability perspective due to the minimized cost and risk associated with launch failures. Professor Chang explains that SSRL is focusing on the research and development of light-weight, high-performance core component and ultra-small satellite technologies.

"Reduction in satellite size does not mean reduced functionalities. Ultra-small satellites are already being applied over a wide area including earth surveillance, low orbit satellite mobile communication, space science experiments, planetary exploration, etc. by space technology leaders such as the US, Europe, Japan, and others. They are also widely utilized as a test bed for new technologies and equipment due to the shorter amount of time required from mission selection to launch and operation. Of course, current technology level does not allow for ultrasmall satellites to accomplish 100% of larger satellite functionalities. The goal of ultrasmall satellites currently under development is to be able to accomplish 80% of larger satellite functionalities at 20% of the cost. It is called the 80/20 rule. Small satellites also have an advantage from an educational perspective.

Although they are smaller in size, their composition is almost identical to larger satellites. This means that they can be used as a tool for the cultivation of professionals, and also enable the accumulation of space development capabilities over the entire process including mission analysis, design, manufacture, test, launch and operation."

As Professor Chang pointed out, ultrasmall satellites of the space development leaders have already exceeded the level of new technology verification, and are now looking to overtake functionality previously reserved for medium/large satellites. One satellite to note is Space Technology 5 (ST5), supported by New Millennium Program of the US. Three 25kg-class satellites are planned to be launched by March of 2006 to execute a formation flying core technology verification mission. Also, Britain is currently carrying out a variety programs such as Disaster Monitoring Constellation (DMC) satellite, small reconnaissance satellites with drastically-improved performance cameras, and geo-stationary small communication satellites, through the MOSAIC Small Satellite Project. CubeSat Program that combines a world-wide effort in developing ultrasmall satellites is also a program to note.

Development of ultra-small satellites

SSRL was selected as a National Reseach Lab in 2003, and is developing a 20kg-class nano-satellite, Hannuri-2. At 600 to 800km low earth orbit, Hannuri-2 will perform science missions such as animal tracking, measurement of space plasma environments, and measurement of space radiation, as well as space technology verification missions by testing the performance of the nationally developed star tracker and integration of GPS receiver in space environment.

Currently, the flight model (FM) of Hannuri- 2 is under development, and is progressing to meet the year 2008 launch goal.

"The ultimate goal of Hannuri satellite development is to steer away from the traditional engineering education and show that the ultra-small satellite projects can be an excellent educational tool at universities by providing the involved students with interdisciplinary integration design opportunities, systems engineering design education, teambased research and development activities through a system of systems development projects."

Professor Chang anticipates that SSRL will lead the future space development according to the world space development trend of Responsive Space that aims to achieve a faster and more efficient approach to space through accumulated ultra-small satellite engineering technology and new technologies tested on small satellite developments.

Niche market of the next generation satellite field

Recently, countries like the US, Russia, China, and Israel are focusing their research efforts on utilizing ultra-small satellites as tactical weapons. As can be seen from the Gulf War and the war with Iraq in 1990s and 2000s, expansion of war into space in the 21st century is becoming more of an established fact. "The U.S. launched two 20kg-class ultrasmall satellites, XSS-10 and 11, in 2003 and 2005. In particular, XSS-10 was equipped with an autonomous navigation control system, miniaturized communication system, lithium polymer batteries, and a camera.

After being separated from the second stage of a Delta launch vehicle, it separated to a distance of 200m before closing in to 35m distance and taking a picture of the second stage motor. The official goal of the satellite was verification of science technology.

However, if it was equipped with a weapon, instead of a camera, XSS would have been capable of destroying an enemy satellite, like a space weapon." Satellites have so far been used as strategic war fighting support in real wars, but an increase in ultra-small satellites for tactical goals in the future can be expected. As the number of countries capable of procuring and developing satellites increases, satellites will become a target during wars or conflicts, and accordingly, a capability to counter a direct attack to space assets is needed. In other words, it is vital to be able to support military operations within seven days by developing, launching, and operating satellites within a week.

Professor Chang says that ultra-small satellites such as Hannuri-1 and Hannuri-2, under development by SSRL, can be manufactured with a comparatively low budget and in a short time period. This in turn will contribute to the procurement of satellite system technology for national satellite development programs in variety of ways. In particular, by promoting research of satellite systems and technology centered around universities, formation of educational foundations will be accelerated, and serve as an educational institutions in establishing national satellite system development structure.

"Satellite system integrated technology can be established and the future professionals can be cultivated through real development experiences provided by ultra-small satellite development programs. It is expected to contribute to the advancement of national satellite core technology by establishing an infrastructure in the field of international satellite technology."

Professor Chang also hopes to promote the generation of additional values through early dissemination of developed technology and acceleration of industrialization by focusing on the satellite-related core technology development through cooperation across the industry, academia, and research institutes.

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