Space safety risk analysis

• Analysis of the risk of collision and re-entry of space objects is the final product of SSA. This is based on risk monitoring, optical and radar observation data, and public sources abroad.
• Distribution and long-term prediction analysis of the artificial space objects that are in Earth orbit shows the status of the collision risk between space objects and the re-entry risk analysis of artificial space objects.
• Collision risk analysis for an artificial space object is performed to identify any space debris that could cause damage to active satellites in order to protect domestic space assets. If the risk of collision is large, we can then determine the potential collision avoidance probability using precise orbit analysis.
• Crash safety risks of space objects can be categorized into controllable and uncontrollable reentry. The prediction of the motion of an uncontrolled reentry object is relatively difficult, and requires technology and monitoring systems developed by risk analysis.
• Risk analysis of space objects is used to identify space objects, and then to calculate the orbital period, predict the reentry point, perform analysis on the Earth impact point, and predict the break up point of the space object.
• If reentry of a space object is uncontrolled, the object can cause enormous damage to personnel and ground and space based assets. Therefore, it is necessary to predict the reentry time and the impact foot print long before the event occurs.

Space catalog

• Appropriate observations of space objects can be processed and used to estimate the orbit of the space object. The ephemeris will predict the precise position of the object for a considerable period of time depending on the precision.
• The space catalog is a well organized list of collected data including the characteristics, orbital information, and other general information about space objects. This catalog is used by the SSA for position prediction, risk monitoring, tracking, identification and risk analysis of space objects.
• Currently we have two internationally well known standard Space Catalogs of artificial space objects.
  - Satellite catalog (NORAD Catalog)
  - NSSDC master catalog
• In addition, individual space catalogs necessary for each institute or country are maintained.
• The space catalog contains publicly released orbital information of regular space objects. However, the orbital information of a space object launched in secrecy is usually not known.
• The simple orbital element form of the space catalog can be used to predict the trajectory at space object with a general perturbation theory such as TLE orbital information. This is a very effective way to maintain accurate orbital information over the long-term.
• To maintain an independent domestic space surveillance system requires acquiring data from the publicly released space catalog, followed by selective follow-up observations of the target object. Maintenance of this unique space catalog independently requires precise orbit information generated by proper observations and analysis of the observed data.

30 minutes after the collision between Cosmos 2251 and Iridium 33 (AGI, Inc.)

Number of space debris increases near Erath (SDA, AGI)

Titanium fuel tank burn during re-entry (NASA)