Holger Krag

The MASTER-99 space debris and meteoroid environment model

Abstract MASTER-99 is a space debris and meteoroid environment model produced by TU Braunschweig (D), eta_max space (D), and DERA (UK) under an ESA contract. The model allows to compute particulate impact fluxes on any terrestrial target orbit up to geostationary altitudes. Flux contributions can be discriminated with respect to debris source types (catalog objects, explosion and collision fragments, NaK droplets, solid rocket motor dust and slag, impact ejecta, and surface degradation products), meteoroid source types (Divine-Staubach populations, and annual stream events), and with respect to origin and impact direction of each flux contributing particulate. Impact fluxes of meteoroids and debris down to 1 μm sizes can be determined for spherical targets, for tumbling plates, or for oriented, planar surfaces which are controlled according to standard attitude steering laws. MASTER-99 is distributed by ESA/ESOC on a CD ROM which includes user documentation, and the necessary data files, executables, and GUI driven installation scripts for the most common operating systems and computer platforms. MASTER-99 is delivered together with PROOF-99, a program for radar and optical observation forecasting. Based on the MASTER-99 population larger than 1 mm, it predicts debris detections from ground-based or space-based sensors (radars or telescopes) of user-defined system performances.

Debris model validation and interpretation of debris measurements using ESA's proof tool

Abstract During the last years a number of observation campaigns to monitor the Earths space debris environment using radar and optical sensors have been performed. In addition, space debris models like the ESA MASTER Model have been developed based on the simulation of debris generating events. To validate the models using the results of a measurement campaign, a filter has to be applied to transform the object data into detection rates considering the observation scenario and the instrument parameters. PROOF (Program for Radar and Optical Observation Forecasting, developed under ESA-ESOC contract) is such a filter and thus a link between models and measurements. This paper addresses validation aspects of the MASTER-99 debris population using the PROOF tool. Besides, emphasis is given to the method of PROOF and on the demonstration of the consistency of its results. It is shown in this context that the sensitivity of the modelled instruments matches measured thresholds for both instrument types (telescope and radar). For the validation of the MASTER-99 model, PROOF has been applied for the simulation of the latest TIRA and Haystack beam-park experiments. The comparison shows that the modelling of the space debris environment shows some deficiencies in the 80° inclination band and at altitudes of 900–1000km. For the GEO region, data from the ESA Space Debris Telescope have been used. The PROOF results reveal a lack of decimetre sized GEO objects in the MASTER model.

Global Trends in Achieving Successful End-Of-Life Disposal in LEO and GEO

Guidelines for space debris mitigation have been formulated by the IADC (Inter Agency Debris Coordination Committee) in 2002. The principal mitigation actions are the passivation of space systems after the end of operations, the limitation of the remaining post-mission dwell time in the LEO and GEO protected region and the limitation of the release of debris. In the past ten years, these recommendations and associated threshold values have been included in several national and international standards and should now be applicable to numerous new missions. Verification of the implementation of mitigation measures in the design of a mission is the responsibility of each nations’ or agencies’ project control during design reviews. The proper implementation of the measures will be followed up by the review of procedures, mission logs and reports.

Operational collision avoidance of small satellite missions

Collision avoidance is a topic of increasing importance. The number of satellites in Earth orbit is steadily growing and with the high amount of space debris, either crossing through or resident in orbit, collision probabilities between two such objects can become critical. Small satellite missions usually operate with limited capabilities when it comes to locating potential collision occurrences and deriving the associated collision probability. Accordingly, they have to rely on external organizations, such as the Joint Space Operation Center (JSpOC) and their information system to plan for contingency operations. This paper reviews the benefits of using such an external service for a small satellite constellation. It analyses the relevant data for use in daily operations and shows collision avoidance approaches based on the available data. Conjunction summaries for the RapidEye satellite constellation are evaluated and their influence on the planning of collision avoidance maneuvers is shown.

Conjunction Evolutions: The Process of Adapting and Evolving Operational Collision Warning Software from Server to Service Oriented Architecture

In 2002, the European Space Agency developed the first generation of conjunction warning tools in order to provide alerts and warnings for operational ESA satellites. Through numerous developments since the initial delivery, this tool became a fundamental part of the operational process for all ESA spacecraft. With the advent of the European Space Surveillance precursor programme, it was seen that the original software would have to be reengineered in order to improve dynamic services to customers outside of ESA. As a result, the first phase of the space surveillance and tracking segment to provide pre-operational services adapted the original software by providing a modern web-based front-end to the core software, hence retaining the original core algorithms but improving the interaction with the end user. This process also identified various requirements to modify the core software in order to comply with the SSA mission requirements. This was performed in phase two of the pre-operational services by dramatically improving the scope and capabilities of the core software as well as providing the ability to form part of a service oriented architecture. This paper will describe and investigate the steps taken in this development journey and the lessons learnt on the way.

Identification of Solid Rocket Motor Retro-Burns in the LDEF IDE Impact Data

The Interplanetary Dust Experiment (IDE) carried by the Long Duration Exposure Facility (LDEF) satellite detected a large amount of impact events recurring for a number of LDEF orbits. Such events show signatures of particle clouds that intersect the orbit of LDEF. In an effort to identify the impact of particles released during specific solid rocket motor burns, a new look at the IDE impact records was taken. The generation of dust particles due to solid rocket burns and the orbit conjunction of the released objects with LDEF was simulated. For the first time, an agreement of specific IDE impact features with the re-entry firings of Russian photo-reconnaissance satellites could be derived.