Re-entry event analysis process and data sources

UKSA re-entry analysis process

A re-entry event occurs when an object found in space re-enters Earth’s atmosphere, either burning up in the atmosphere or reaching the Earth’s surface. Monitor Space Hazards provides data on re-entry events identified by the 18th Space Defence Squadron and distributed via Space-Track (space-track.org), with additional event analysis from the UK Space Agency. 

The UK Space Agency’s Orbital Analysts receive Tracking and Impact Prediction (TIP) messages and perform additional Monte Carlo analysis on those which show a potential risk to the UK or objects for which the UK is liable. This provides more information on the UK overflight time, the regions at risk of impact, and the probability of impact in various regions.  

The reported parameters of analysis are:

  • Risk to the UK (Low/Medium/High)
  • Probability of re-entry over the UK (%)
  • UK overflight time(s) (UTC)
  • Expected survivability to ground
  • Estimated mass
  • UK nations/regions potentially affected
  • British Overseas Territories potentially affected
  • Overflight map
  • Event history

Data sources for UKSA’s re-entry analysis are listed below.

Space-Track data sources

Space-Track (space-track.org) is the source of all object data shown on Monitor Space Hazards event pages. 

Monitor Space Hazards’ re-entry service ingests all Tracking and Impact Prediction messages (TIPs) from Space-Track. Notifications are sent out for re-entry events which pose a potential risk to the UK or for objects where the UK is liable. Users are able to edit their notification thresholds to ensure that they only receive notifications about events with probabilities and impact regions that they are interested in. 

UKSA`s orbital analysis data sources

The UK Space Agency’s Orbital Analyst team will use a wider range of sources than just Space-Track for their orbital analysis. These include:

  • US SATCAT (United States satellite catalogue), ESA DISCOS (the European Space Agency's Database and Information System Characterising Objects in Space), UCS (Union of Concerned Scientists database) and other available data sources for object information.
  • Observation data on objects from either UK Space Surveillance Network (SSN) observations, procured UK sensor data, or other data sources
  • CDMs, UK sensor data and orbital analysts for event parameters.

Sensor data used by UKSA

Sensor data is taken from both national HMG sensors and commercial sensor providers.

At LEO (Low-Earth orbit), optical and radar sensor data and Satellite Laser Ranging (SLR) data is available from the SSN, the Science and Technology Facilities Council (STFC), NORSS (Northern Space and Security), RAF Fylingdales and Natural Environment Research Council (NERC).

At MEO (Medium Earth orbit), HEO (Higher Earth orbit), GTO (geostationary transfer orbit) and GEO (geosynchronous equatorial orbit), optical sensor data is available from STFC, NERC, SpaceFlux and Satellite Laser Ranging (SLR)

Data storage

Event information including all parameters, analysis and event history will be stored indefinitely. 

User information will be stored indefinitely, or until users request that it is deleted.

These pages will be reviewed every 3 months and updated to align with current processes.