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The Use of the Satellite Breakup Risk Assessment Model (SBRAM) to Characterize Collision Risk to Manned SpacecraftNASA uses environment models such as ORDEM96 to characterize the long-term orbital debris collision hazard for spacecraft in LEO. Occasionally, however, there are breakups of satellites or rocket bodies that create enhanced collision hazard for a period of time. This enhanced collision hazard can pose increased risks to space operations - especially those involving manned missions where the tolerance for risk is very low. NASA has developed SBRAM to simulate the enhanced debris environment in the days and weeks that follow such a breakup. This simulation provides the kind of risk probabilities that can be used by mission planners to consider if changes are warranted for the mission. Announcements of breakups come to NASA from US Space Command as soon as they are identified. The pre-breakup orbit and time of breakup are used to determine the initial conditions of the explosion. SBRAM uses the latest explosion models developed at NASA to simulate a debris cloud for the breakup. The model uses a Monte Carlo technique to create a random debris cloud from the probability distributions in the breakup model. Each piece of debris randomly created in the cloud is propagated in a deterministic manner to include the effects of drag and other orbital perturbations. The detailed geometry of each simulated close approach to the target spacecraft is noted and logged and the collision probability is computed using an estimated probability density in down-range and cross-range positions of both the target spacecraft and debris object. The collision probability is computed from the overlap of these probability densities for each close-approach geometry and summed over all computed conjunctions. Cloud propagation runs over the desired time interval are then repeated until the scale of the collision risk can be estimated to a desired precision. This paper presents an overview of the SBRAM model and a number of examples, both real and hypothetical, to demonstrate its use. In addition, a number of different examples are shown how the data can be used by decision makers on issues such as spacecraft orientation and timing of EVAs.
Document ID
20000105134
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Matney, Mark J.
(Lockheed Martin Space Mission Systems and Services Houston, TX United States)
Theall, Jeffrey R.
(NASA Johnson Space Center Houston, TX United States)
McKay, Gordon A.
Date Acquired
August 19, 2013
Publication Date
January 1, 1999
Subject Category
Spacecraft Design, Testing And Performance
Report/Patent Number
IAA-99-IAA.6.5.09
Meeting Information
Meeting: International Astronautical Congress
Location: Amsterdam
Country: Netherlands
Start Date: October 4, 1999
End Date: October 8, 1999
Sponsors: International Astronautical Federation
Funding Number(s)
CONTRACT_GRANT: NAS9-17900
PROJECT: RTOP 478-80-00
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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